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New submissions for Friday, 21 June 2024 (showing 125 of 125 entries )

[1] arXiv:2406.12869 [pdf, other]

Title: Graph Neural Network-Based Pipeline for Track Finding in the Velo at LHCb

Anthony Correia, Fotis Giasemis, Nabil Garroum, Vladimir Vava Gligorov, Bertrand Granado

Comments: CTD2023 Workshop

Subjects: Instrumentation and Detectors (physics.ins-det); High Energy Physics - Experiment (hep-ex); Data Analysis, Statistics and Probability (physics.data-an)

Over the next decade, increases in instantaneous luminosity and detector granularity will amplify the amount of data that has to be analysed by high-energy physics experiments, whether in real time or offline, by an order of magnitude. The reconstruction of charged particle tracks, which has always been a crucial element of offline data processing pipelines, must increasingly be deployed from the very first stages of the real time processing to enable experiments to achieve their physics goals. Graph Neural Networks (GNNs) have received a great deal of attention in the community because their computational complexity scales nearly linearly with the number of hits in the detector, unlike conventional algorithms which often scale quadratically or worse. This paper presents ETX4VELO, a GNN-based track-finding pipeline tailored for the Run 3 LHCb experiment's Vertex Locator, in the context of LHCb's fully GPU-based first-level trigger system, Allen. Currently implemented in Python, ETX4VELO offers the ability to reconstruct tracks with shared hits using a novel triplet-based method. When benchmarked against the traditional track-finding algorithm in Allen, this GNN-based approach not only matches but occasionally surpasses its physics performance. In particular, the fraction of fake tracks is reduced from over 2\% to below 1\% and the efficiency to reconstruct electrons is improved. While achieving comparable physics performance is a milestone, the immediate priority remains implementing ETX4VELO in Allen in order to determine and optimise its throughput, to meet the demands of this high-rate environment.

[2] arXiv:2406.12870 [pdf, html, other]

Title: Water Cherenkov muon veto for the COSINUS experiment: design and simulation optimization

G. Angloher, M. R. Bharadwaj, M. Cababie, I. Dafinei, N. Di Marco, L. Einfalt, F. Ferroni, S. Fichtinger, A. Filipponi, T. Frank, M. Friedl, Z. Ge, M. Heikinheimo, M. N. Hughes, K. Huitu, M. Kellermann, R. Maji, M. Mancuso, L. Pagnanini, F. Petricca, S. Pirro, F. Pröbst, G. Profeta, A. Puiu, F. Reindl, K. Schäffner, J. Schieck, D. Schmiedmayer, P. Schreiner, C. Schwertner, K. Shera, M. Stahlberg, A. Stendhal, M. Stukel, C. Tresca, F. Wagner, S. Yue, V. Zema, Y. Zhu

Subjects: Instrumentation and Detectors (physics.ins-det)

COSINUS is a dark matter (DM) direct search experiment that uses sodium iodide (NaI) crystals as cryogenic calorimeters. Thanks to the low nuclear recoil energy threshold and event-by-event discrimination capability, COSINUS will address the long-standing DM claim made by the DAMA/LIBRA collaboration. The experiment is currently under construction at the Laboratori Nazionali del Gran Sasso, Italy, and employs a large cylindrical water tank as a passive shield to meet the required background rate. However, muon-induced neutrons can mimic a DM signal therefore requiring an active veto system, which is achieved by instrumenting the water tank with an array of photomultiplier tubes (PMTs). This study optimizes the number, arrangement, and trigger conditions of the PMTs as well as the size of an optically invisible region. The objective was to maximize the muon veto efficiency while minimizing the accidental trigger rate due to the ambient and instrumental background. The final configuration predicts a veto efficiency of 99.63 $\pm$ 0.16 $\%$ and 44.4 $\pm$ $5.6\%$ in the tagging of muon events and showers of secondary particles, respectively. The active veto will reduce the cosmogenic neutron background rate to 0.11 $\pm$ 0.02 cts$\cdot$kg$^{-1}$$\cdot$year$^{-1}$, corresponding to less than one background event in the region of interest for the whole COSINUS-1$\pi$ exposure of 1000 kg$\cdot$days.

[3] arXiv:2406.12873 [pdf, other]

Title: Evidence for polyimide redeposition and possible correlation with sparks in Gas Electron Multipliers working in CF$_4$ mixtures

Thiago B. Saramela, Tiago F. Silva, Marco Bregant, Marcelo G. Munhoz, Tien T. Quach, Richard Hague, Ian S. Gilmore, Clive J. Roberts, Gustavo F. Trindade

Comments: 19 pages and 10 figures

Subjects: Instrumentation and Detectors (physics.ins-det); High Energy Physics - Experiment (hep-ex); Nuclear Experiment (nucl-ex)

Research on aging processes of Gas Electron Multipliers (GEMs) is important to obtain insights on how to increase detector's longevity, stability and performance, as highlighted in the latest developments roadmap by the European Council of Future Accelerators (ECFA). In this work, through the analysis of the molecular content on the surface of a used GEM, we provide evidences for polyimide redeposition as a source of organic material contributing to the formation of insulating layers on the electrodes, which eventually lead to sparks and detector failure. Furthermore, we show that chromium, used to promote adhesion between copper and polyimide, in the device undergoes a diffusion process, effectively blurring the layered structure. We demonstrate the significance of surface-sensitive chemical analysis to investigate the aging process of gaseous detectors and our results reveal the necessity of standardization and more stringent study protocols.

[4] arXiv:2406.12874 [pdf, html, other]

Title: The Design, Implementation, and Performance of the LZ Calibration Systems

J. Aalbers, D.S. Akerib, A.K. Al Musalhi, F. Alder, C.S. Amarasinghe, A. Ames, T.J. Anderson, N. Angelides, H.M. Araújo, J.E. Armstrong, M. Arthurs, A. Baker, S. Balashov, J. Bang, E.E. Barillier, J.W. Bargemann, K. Beattie, T. Benson, A. Bhatti, A. Biekert, T.P. Biesiadzinski, H.J. Birch, E. Bishop, G.M. Blockinger, B. Boxer, C.A.J. Brew, P. Brás, S. Burdin, M. Buuck, M.C. Carmona-Benitez, M. Carter, A. Chawla, H. Chen, J.J. Cherwinka, Y.T. Chin, N.I. Chott, M.V. Converse, A. Cottle, G. Cox, D. Curran, C.E. Dahl, A. David, J. Delgaudio, S. Dey, L. de Viveiros, L. Di Felice, C. Ding, J.E.Y. Dobson, E. Druszkiewicz, S.R. Eriksen, A. Fan, N.M. Fearon, S. Fiorucci, H. Flaecher, E.D. Fraser, T.M.A. Fruth, R.J. Gaitskell, A. Geffre, J. Genovesi, C. Ghag, R. Gibbons, S. Gokhale, J. Green, M.G.D.van der Grinten, J.J. Haiston, C.R. Hall, S. Han, E. Hartigan-O'Connor, S.J. Haselschwardt, M.A. Hernandez, S.A. Hertel, G. Heuermann, G.J. Homenides, M. Horn, D.Q. Huang, D. Hunt, E. Jacquet, R.S. James, J. Johnson, A.C. Kaboth, A.C. Kamaha, M. Kannichankandy, D. Khaitan, A. Khazov, I. Khurana, J. Kim, Y.D. Kim, J. Kingston, R. Kirk, D. Kodroff, L. Korley, E.V. Korolkova, H. Kraus, S. Kravitz, L. Kreczko, V.A. Kudryavtsev, D.S. Leonard, K.T. Lesko, C. Levy, J. Lin

Subjects: Instrumentation and Detectors (physics.ins-det); High Energy Physics - Experiment (hep-ex)

LUX-ZEPLIN (LZ) is a tonne-scale experiment searching for direct dark matter interactions and other rare events. It is located at the Sanford Underground Research Facility (SURF) in Lead, South Dakota, USA. The core of the LZ detector is a dual-phase xenon time projection chamber (TPC), designed with the primary goal of detecting Weakly Interacting Massive Particles (WIMPs) via their induced low energy nuclear recoils. Surrounding the TPC, two veto detectors immersed in an ultra-pure water tank enable reducing background events to enhance the discovery potential. Intricate calibration systems are purposely designed to precisely understand the responses of these three detector volumes to various types of particle interactions and to demonstrate LZ's ability to discriminate between signals and backgrounds. In this paper, we present a comprehensive discussion of the key features, requirements, and performance of the LZ calibration systems, which play a crucial role in enabling LZ's WIMP-search and its broad science program. The thorough description of these calibration systems, with an emphasis on their novel aspects, is valuable for future calibration efforts in direct dark matter and other rare-event search experiments.

[5] arXiv:2406.12875 [pdf, html, other]

Title: Machine learning evaluation in the Global Event Processor FPGA for the ATLAS trigger upgrade

Zhixing Jiang, Scott Hauck, Dennis Yin, Bowen Zuo, Ben Carlson, Shih-Chieh Hsu, Allison Deiana, Rohin Narayan, Santosh Parajuli, Jeff Eastlack

Comments: 14 pages, 4 figures, 6 tables. Accepted by JINST on April 3, 2024

Subjects: Instrumentation and Detectors (physics.ins-det); High Energy Physics - Experiment (hep-ex)

The Global Event Processor (GEP) FPGA is an area-constrained, performance-critical element of the Large Hadron Collider's (LHC) ATLAS experiment. It needs to very quickly determine which small fraction of detected events should be retained for further processing, and which other events will be discarded. This system involves a large number of individual processing tasks, brought together within the overall Algorithm Processing Platform (APP), to make filtering decisions at an overall latency of no more than 8ms. Currently, such filtering tasks are hand-coded implementations of standard deterministic signal processing tasks.
In this paper we present methods to automatically create machine learning based algorithms for use within the APP framework, and demonstrate several successful such deployments. We leverage existing machine learning to FPGA flows such as hls4ml and fwX to significantly reduce the complexity of algorithm design. These have resulted in implementations of various machine learning algorithms with latencies of 1.2us and less than 5% resource utilization on an Xilinx XCVU9P FPGA. Finally, we implement these algorithms into the GEP system and present their actual performance.
Our work shows the potential of using machine learning in the GEP for high-energy physics applications. This can significantly improve the performance of the trigger system and enable the ATLAS experiment to collect more data and make more discoveries. The architecture and approach presented in this paper can also be applied to other applications that require real-time processing of large volumes of data.

[6] arXiv:2406.12877 [pdf, html, other]

Title: Design of a SiPM-on-Tile ZDC for the future EIC and its Performance with Graph Neural Networks

Ryan Milton, Sebouh J. Paul, Barak Schmookler, Miguel Arratia, Piyush Karande, Aaron Angerami, Fernando Torales Acosta, Benjamin Nachman

Comments: 9 pages, 9 figures. Code and datasets included

Subjects: Instrumentation and Detectors (physics.ins-det); High Energy Physics - Experiment (hep-ex); Nuclear Experiment (nucl-ex)

We present a design for a high-granularity zero-degree calorimeter (ZDC) for the upcoming Electron-Ion Collider (EIC). The design uses SiPM-on-tile technology and features a novel staggered-layer arrangement that improves spatial resolution. To fully leverage the design's high granularity and non-trivial geometry, we employ graph neural networks (GNNs) for energy and angle regression as well as signal classification. The GNN-boosted performance metrics meet, and in some cases, significantly surpass the requirements set in the EIC Yellow Report, laying the groundwork for enhanced measurements that will facilitate a wide physics program. Our studies show that GNNs can significantly enhance the performance of high-granularity CALICE-style calorimeters by automating and optimizing the software compensation algorithms required for these systems. This improvement holds true even in the case of complicated geometries that pose challenges for image-based AI/ML methods.

[7] arXiv:2406.12878 [pdf, html, other]

Title: Beam test results of the prototype of the multi wire drift chamber for the CSR external-target experiment

Zhi Qin, Zhoubo He, Zhe Cao, Tao Chen, Zhi Deng, Limin Duan, Dong Guo, Rongjiang Hu, Jie Kong, Canwen Liu, Peng Ma, Xianglun Wei, Shihai Wen, Xiangjie Wen, Junwei Yan, Herun Yang, Zuoqiao Yang, Yuhong Yu, Zhigang Xiao

Subjects: Instrumentation and Detectors (physics.ins-det); High Energy Physics - Experiment (hep-ex); Nuclear Experiment (nucl-ex)

The half-size prototype of the multi wire drift chamber (MWDC) for the cooling storage ring (CSR) external-target experiment (CEE) was assembled and tested in 350 MeV/u Kr+Fe reactions on the heavy ion research facility in Lanzhou (HIRFL). The prototype consists of 6 sense layers, where the sense wires are stretched in three directions X, U and V, meeting $0^\circ$, $30^\circ$ and $-30^\circ$ with respect to the vertical axis, respectively. The sensitive area of the prototype is $76 {\rm cm} \times 76 {\rm cm}$. The amplified and shaped signals from the anode wires are digitized in a serial capacity array. Being operated with 1500 V high voltage on the anode wires, the efficiency for each layer is beyond 95\%. The tracking residual is about $301 \pm 2 \rm \mu m$. The performance meets the requirements of CEE.

[8] arXiv:2406.12879 [pdf, html, other]

Title: Bayesian Approach to Particles Identification in the MPD Experimen

V.A. Babkin, V.M. Baryshnikov, M.G. Buryakov, A.S. Burdyko, S.G. Buzin, A.V. Dmitriev, V.I. Dronik, P.O. Dulov, A.A. Fedyunin, V.M. Golovatyuk, E.Yu. Kidanova, S.P. Lobastov, A.D. Pyatigor, M.M. Rumyantsev, K.A. Vokhmyanina

Subjects: Instrumentation and Detectors (physics.ins-det); High Energy Physics - Experiment (hep-ex); Data Analysis, Statistics and Probability (physics.data-an)

Identification of particles generated by ion collisions in the NICA collider is one of the basic functions of the Multipurpose Detector (MPD). The main means of identification in MPD are the time-of-flight system (TOF) and the time-projection chamber (TPC). The article considers the optimization of the algorithms of particles identification by these systems. Under certain conditions, the use of the statistical Bayesian approach has made it possible to achieve an optimal ratio of the efficiency of particle identification and contamination by incorrectly defined particles.

[9] arXiv:2406.12880 [pdf, other]

Title: Technical design report for the CODEX-$\beta$ demonstrator

CODEX-b collaboration: Giulio Aielli, Juliette Alimena, James Beacham, Eli Ben Haim, Andras Burucs, Roberto Cardarelli, Matthew Charles, Xabier Cid Vidal, Albert De Roeck, Biplab Dey, Silviu Dobrescu, Ozgur Durmus, Mohamed Elashri, Vladimir Gligorov, Rebeca Gonzalez Suarez, Thomas Gorordo, Zarria Gray, Conor Henderson, Louis Henry, Philip Ilten, Daniel Johnson, Jacob Kautz, Simon Knapen, Bingxuan Liu, Yang Liu, Saul Lopez Solino, Titus Mombacher, Benjamin Nachman, David Northacker, Gabriel Nowak, Michele Papucci, Gabriella Pasztor, Eloi Pazos Rial, Jake Pfaller, Luca Pizzimento, Maximo Plo Casasus, Gian Andrea Rassati, Dean Robinson, Emilio Xose Rodriguez Fernandez, Debashis Sahoo, Sinem Simsek, Michael Sokoloff, Aditya Suresh, Paul Swallow, James Swanson, Riccardo Vari, Carlos Vazquez Sierra, Gabor Veres, Nigel Watson, Michael Wilkinson, Michael Williams

Subjects: Instrumentation and Detectors (physics.ins-det); High Energy Physics - Experiment (hep-ex)

The CODEX-$\beta$ apparatus is a demonstrator for the proposed future CODEX-b experiment, a long-lived-particle detector foreseen for operation at IP8 during HL-LHC data-taking. The demonstrator project, intended to collect data in 2025, is described, with a particular focus on the design, construction, and installation of the new apparatus.

[10] arXiv:2406.12881 [pdf, html, other]

Title: Towards Unlocking Insights from Logbooks Using AI

Antonin Sulc, Alex Bien, Annika Eichler, Daniel Ratner, Florian Rehm, Frank Mayet, Gregor Hartmann, Hayden Hoschouer, Henrik Tuennermann, Jan Kaiser, Jason St. John, Jennefer Maldonado, Kyle Hazelwood, Raimund Kammering, Thorsten Hellert, Tim Wilksen, Verena Kain, Wan-Lin Hu

Comments: 5 pages, 1 figure, 15th International Particle Accelerator Conference

Subjects: Accelerator Physics (physics.acc-ph); Computation and Language (cs.CL)

Electronic logbooks contain valuable information about activities and events concerning their associated particle accelerator facilities. However, the highly technical nature of logbook entries can hinder their usability and automation. As natural language processing (NLP) continues advancing, it offers opportunities to address various challenges that logbooks present. This work explores jointly testing a tailored Retrieval Augmented Generation (RAG) model for enhancing the usability of particle accelerator logbooks at institutes like DESY, BESSY, Fermilab, BNL, SLAC, LBNL, and CERN. The RAG model uses a corpus built on logbook contributions and aims to unlock insights from these logbooks by leveraging retrieval over facility datasets, including discussion about potential multimodal sources. Our goals are to increase the FAIR-ness (findability, accessibility, interoperability, and reusability) of logbooks by exploiting their information content to streamline everyday use, enable macro-analysis for root cause analysis, and facilitate problem-solving automation.

[11] arXiv:2406.12882 [pdf, html, other]

Title: Examining LEGEND-1000 cosmogenic neutron backgrounds in Geant4 and MCNP

C.J. Barton, W. Xu, S.R. Elliott, R. Massarczyk

Comments: Pre-print for article submission to JINST

Journal-ref: JINST 19 P05056 (2024)

Subjects: Instrumentation and Detectors (physics.ins-det); Nuclear Experiment (nucl-ex)

For next-generation neutrinoless double beta decay experiments, extremely low backgrounds are necessary. An understanding of in-situ cosmogenic backgrounds is critical to the design effort. In-situ cosmogenic backgrounds impose a depth requirement and especially impact the choice of host laboratory. Often, simulations are used to understand background effects, and these simulations can have large uncertainties. One way to characterize the systematic uncertainties is to compare unalike simulation programs. In this paper, a suite of neutron simulations with identical geometries and starting parameters have been performed with Geant4 and MCNP, using geometries relevant to the LEGEND-1000 experiment. This study is an important step in gauging the uncertainties of simulations-based estimates. To reduce project risks associated with simulation uncertainties, a novel alternative shield of methane-doped liquid argon is considered in this paper for LEGEND-1000, which could achieve large background reduction without requiring significant modification to the baseline design.

[12] arXiv:2406.12883 [pdf, other]

Title: Optimization of a Welding Procedure for Making Critical Aluminum Welds on the LBNF Absorber Core Block

K. E. Anderson, A. Deshpande, V. I. Sidorov, J. Zahurones (Fermi National Accelerator Laboratory, Batavia, IL, USA)

Comments: IPAC'24 - 15th International Particle Accelerator Conference

Journal-ref: JACoW IPAC2024 (2024) TUPS43

Subjects: Accelerator Physics (physics.acc-ph)

The LBNF Absorber consists of thirteen 6061-T6 aluminum core blocks. The core blocks are water cooled with de-ionized (DI) water which becomes radioactive during beam operations. The cooling water flows through gun-drilled channels in the core blocks. A weld quality optimization was performed to produce National Aeronautical Standard 1514 Class I quality welds on the aluminum core blocks. This was not successful in all cases. An existing Gas Tungsten Arc Welding Procedure Specification was fine tuned to minimize, in most cases, and eliminate detect-able tungsten inclusions in the welds. All the weld coupons, however passed welding inspection as per the piping code: ASME B31.3 Normal Fluid Service. Tungsten electrode diameter, type, and manufacturer were varied. Some of the samples were pre-heated and others were not. It was observed that larger diameter electrodes, 5/32 in., with pre-heated joints resulted in welds with the least number of tungsten inclusions. It is hypothesized that thinner electrodes breakdown easily and get lodged into the weld pool during the welding process. This breakdown is further enhanced by the large temperature differential between the un-preheated sample and the hot electrode.

[13] arXiv:2406.12885 [pdf, html, other]

Title: neuSIM4: A comprehensive GEANT4 based neutron simulation code

J. Park, F. C. E. Teh, M. B. Tsang, K. W. Brown, Z. Chajecki, B. Hong, T. Lokotko, W. G. Lynch, J. Wieske, K. Zhu

Subjects: Instrumentation and Detectors (physics.ins-det); Nuclear Experiment (nucl-ex)

A new neutron SIMulation program based on the versatile GEANT4 toolkit, neuSIM4, has been developed to describe interactions of neutrons in the NE213 liquid scintillator from 0.1 to 3000 MeV. neuSIM4 is designed to accommodate complicated modern detector geometry setups with multiple scintillator detectors, each of which can be outfitted with more than one photo-multiplier. To address a broad spectrum of neutron energies, two new neutron interaction physics models, KSCIN and NxQMD, have been implemented in GEANT4. For neutrons with energy below 110 MeV, we incorporate a total of eleven neutron induced reaction channels on hydrogen and carbon nuclei, including nine carbon inelastic reaction channels, into KSCIN. Beyond 110 MeV, we implement a neutron induced reaction model, NxQMD, in GEANT4. We use its results as reference to evaluate other neutron-interaction physics models in GEANT4. We find that results from an existing cascade physics model (INCL) in GEANT4 agree very well with the results from NxQMD, and results from both codes agree with new and existing light response data. To connect KSCIN to NxQMD or INCL, we introduce a transition region where the contribution of neuSIM4 linearly decreases with corresponding increased contributions from NxQMD or INCL. To demonstrate the application of the new code, we simulate the light response and performance of a 2 x 2 m2 neutron detector wall array consisting of 25 2m-long scintillation bars. We are able to compare the predicted light response functions to the shape of the experimental response functions and calculate the efficiency of the neutron detector array for neutron energies up to 200 MeV. These simulation results will be pivotal for understanding the performance of modern neutron arrays with intricate geometries, especially in the measurements of neutron energy spectra in heavy-ion reactions.

[14] arXiv:2406.12887 [pdf, html, other]

Title: Scintillating low-temperature calorimeters for direct dark matter search

Margarita Kaznacheeva, Karoline Schäffner

Comments: 20 pages, 11 figures

Subjects: Instrumentation and Detectors (physics.ins-det); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

The lack of an unambiguous signal for thermally produced dark matter particles in direct detection, indirect detection, and collider searches calls for broadening the search strategies by probing a wider range of dark matter masses with different detection techniques. One of the most common approaches is to search for nuclear recoils induced by dark matter particles scattering off the target material's nuclei. Low-temperature detectors have proven to provide the required performance to probe dark matter masses from 100 MeV/c$^2$ to 100 GeV/c$^2$ via this channel. Using scintillation light as an ancillary channel is a powerful tool for particle identification and background suppression at the keV-recoil energy scale. The CRESST-III experiment, employing scintillating cryogenic detectors with highly sensitive transition edge sensors and multi-target absorber crystals, achieved unprecedented sensitivities to explore sub-GeV dark matter masses. COSINUS, instead, is a new experiment exploiting the phonon-light technique using sodium iodide crystals with the scope to clarify the long-lasting dark matter claim of the DAMA/LIBRA collaboration. This article reviews the principle of scintillating low-temperature calorimeters with emphasis on the benefits and challenges of this technique for direct dark matter searches in light of the current status and future developments.

[15] arXiv:2406.12892 [pdf, other]

Title: Synthesis and Characterization of NiCoMn MOFs for Wastewater Treatment

Muhammad Farhan, Osama Aziz

Comments: 9 pages, 6 figures

Subjects: Chemical Physics (physics.chem-ph); Physics and Society (physics.soc-ph)

Water pollution has become a global problem. Sources of wastewater majorly include industrial and commercial sectors. To cater to the exponential increase in clean water, efficient technologies are needed to treat wastewater. Several techniques such as redox reactions, membrane filtrations, mechanical processes, chemical treatment and adsorption techniques have been employed. However, their cost and effectiveness is still a major problem. In this study, we employed an effective wastewater treatment technique by synthesizing NiCoMn MOFs using a simple hydrothermal technique and characterized the properties using XRD and SEM for their possible characteristics. XRD analysis confirmed the successful synthesis of NiCoMn MOFs. Sufficient information regarding the surface morphology and topology was given by the SEM analysis which proved a nanoporous structure with high surface area effective for adsorption and oxidative catalysis of contaminants in wastewater. Moreover, a high electrostatic attraction between the MOFs was observed which could attract oppositely charged contaminants. The results showed a high potential for the synthesized NiCoMn MOFs for wastewater treatment applications.

[16] arXiv:2406.12898 [pdf, html, other]

Title: A Comprehensive Evaluation of Generative Models in Calorimeter Shower Simulation

Farzana Yasmin Ahmad, Vanamala Venkataswamy, Geoffrey Fox

Subjects: Instrumentation and Detectors (physics.ins-det); Artificial Intelligence (cs.AI); High Energy Physics - Experiment (hep-ex); Data Analysis, Statistics and Probability (physics.data-an)

The pursuit of understanding fundamental particle interactions has reached unparalleled precision levels. Particle physics detectors play a crucial role in generating low-level object signatures that encode collision physics. However, simulating these particle collisions is a demanding task in terms of memory and computation which will be exasperated with larger data volumes, more complex detectors, and a higher pileup environment in the High-Luminosity LHC. The introduction of "Fast Simulation" has been pivotal in overcoming computational bottlenecks. The use of deep-generative models has sparked a surge of interest in surrogate modeling for detector simulations, generating particle showers that closely resemble the observed data. Nonetheless, there is a pressing need for a comprehensive evaluation of their performance using a standardized set of metrics. In this study, we conducted a rigorous evaluation of three generative models using standard datasets and a diverse set of metrics derived from physics, computer vision, and statistics. Furthermore, we explored the impact of using full versus mixed precision modes during inference. Our evaluation revealed that the CaloDiffusion and CaloScore generative models demonstrate the most accurate simulation of particle showers, yet there remains substantial room for improvement. Our findings identified areas where the evaluated models fell short in accurately replicating Geant4 data.

[17] arXiv:2406.12899 [pdf, other]

Title: Structural design of the acrylic vessel for the Jinping Neutrino Experiment

Zongyi Wang, Yuhao Liua, Shaomin Chen, Yuanqing Wang, Zhe Wang, Ming Huang

Comments: 27 pages, 11 figures,7 tables

Subjects: Instrumentation and Detectors (physics.ins-det); High Energy Physics - Experiment (hep-ex)

The Jinping neutrino experiment is designed to have multiple purposes in the China Jinping Underground Laboratory. Following the acrylic vessel design requirements proposal, a structural scheme has been developed and optimized. Subsequently, the stability of the acrylic shell structure was calculated using finite element analysis, as well as the load-bearing capacities under various working conditions. Further, the effects of temperature changes, rope failures, and Young's modulus of the ropes on the static behavior of the structure were analyzed. The results indicated that the stress level and structural displacement of the structure scheme satisfies the design requirements, as well as the stability of the vessel under compression. Moreover, the stress and displacement of the acrylic shell satisfies the given working conditions and temperatures. The structural scheme ensures basic safety if the rope fails.

[18] arXiv:2406.12901 [pdf, html, other]

Title: Interpretable machine learning approach for electron antineutrino selection in a large liquid scintillator detector

A. Gavrikov, V. Cerrone, A. Serafini, R. Brugnera, A. Garfagnini, M. Grassi, B. Jelmini, L. Lastrucci, S. Aiello, G. Andronico, V. Antonelli, A. Barresi, D. Basilico, M. Beretta, A. Bergnoli, M. Borghesi, A. Brigatti, R. Bruno, A. Budano, B. Caccianiga, A. Cammi, R. Caruso, D. Chiesa, C. Clementi, S. Dusini, A. Fabbri, G. Felici, F. Ferraro, M. G. Giammarchi, N. Giugice, R. M. Guizzetti, N. Guardone, C. Landini, I. Lippi, S. Loffredo, L. Loi, P. Lombardi, C. Lombardo, F. Mantovani, S. M. Mari, A. Martini, L. Miramonti, M. Montuschi, M. Nastasi, D. Orestano, F. Ortica, A. Paoloni, E. Percalli, F. Petrucci, E. Previtali, G. Ranucci, A. C. Re, M. Redchuck, B. Ricci, A. Romani, P. Saggese, G. Sava, C. Sirignano, M. Sisti, L. Stanco, E. Stanescu Farilla, V. Strati, M. D. C. Torri, A. Triossi, C. Tuvé, C. Venettacci, G. Verde, L. Votano

Subjects: Instrumentation and Detectors (physics.ins-det); Machine Learning (cs.LG); High Energy Physics - Experiment (hep-ex); Data Analysis, Statistics and Probability (physics.data-an)

Several neutrino detectors, KamLAND, Daya Bay, Double Chooz, RENO, and the forthcoming large-scale JUNO, rely on liquid scintillator to detect reactor antineutrino interactions. In this context, inverse beta decay represents the golden channel for antineutrino detection, providing a pair of correlated events, thus a strong experimental signature to distinguish the signal from a variety of backgrounds. However, given the low cross-section of antineutrino interactions, the development of a powerful event selection algorithm becomes imperative to achieve effective discrimination between signal and backgrounds. In this study, we introduce a machine learning (ML) model to achieve this goal: a fully connected neural network as a powerful signal-background discriminator for a large liquid scintillator detector. We demonstrate, using the JUNO detector as an example, that, despite the already high efficiency of a cut-based approach, the presented ML model can further improve the overall event selection efficiency. Moreover, it allows for the retention of signal events at the detector edges that would otherwise be rejected because of the overwhelming amount of background events in that region. We also present the first interpretable analysis of the ML approach for event selection in reactor neutrino experiments. This method provides insights into the decision-making process of the model and offers valuable information for improving and updating traditional event selection approaches.

[19] arXiv:2406.12903 [pdf, other]

Title: Open-Source Optimization of Hybrid Monte-Carlo Methods for Fast Response Modeling of NaI(Tl) and HPGe Gamma Detectors

Matthew Niichel, Stylianos Chatzidakis

Subjects: Instrumentation and Detectors (physics.ins-det); Nuclear Theory (nucl-th)

Modeling the response of gamma detectors has long been a challenge within the nuclear community. Significant research has been conducted to digitally replicate instruments that can cost over $100,000 and are difficult to operate outside a laboratory setting. Subsequently, there have been multiple attempts to create codes that replicate the response of sodium-iodide and high purity germanium detectors for the purpose of deriving data related to gamma ray interaction with matter. While robust programs do exist, they are often subject to export controls and/or they are not intuitive to use. Through the use of the Hybrid Monte-Carlo methods, MATLAB can be used to produce a fast first-order response of various gamma ray detectors. The combination of a graphics user interface with a numerical based script allows for an open-source and intuitive code. When benchmarked with experimental data from Co-60, Cs-137, and Na-22 the code can numerically calculate a response comparable to experimental and industry standard response codes. Through this code, it is shown that a savings in computational requirements and the inclusion of an intuitive user experience does not heavily compromise data when compared to other standard codes or experimental results. When the application is installed on a computer with 16 cores, the average time to simulate the benchmarked isotopes is 0.26 seconds and 1.63 seconds on a four-core machine. The results indicate that simple gamma detectors can be modeled in an open-source format. The anticipation for the MATLAB application is to be a tool that can be easily accessible and provide datasets for use in an academic setting requiring the gamma ray detectors. Ultimately, providing evidence that Hybrid Monte-Carlo codes in an open-source format can benefit the nuclear community.

[20] arXiv:2406.12912 [pdf, html, other]

Title: Burn-in Test and Thermal Performance Evaluation of Silicon Photomultipliers for the JUNO-TAO Experiment

X. Chen, G.F. Cao, M.H. Qu, H.W. Wang, N. Anfimov, A. Rybnikov, J.Y. Xu, A.Q. Su, Z.L. Chen, J. Cao, Y.C. Li, M. Qi

Comments: 15 pages, 15 figures, submitted to JINST

Subjects: Instrumentation and Detectors (physics.ins-det); High Energy Physics - Experiment (hep-ex)

This study evaluates more than 4,000 tiles made of Hamamatsu visual-sensitive silicon photomultipier (SiPM), each with dimensions of 5 $\times$ 5 cm$^2$, intended for the central detector of the Taishan Anti-neutrino Observatory (TAO), a satellite experiment of the Jiangmen Underground Neutrino Observatory (JUNO) aimed at measuring the reactor anti-neutrino energy spectrum with unprecedented energy resolution. All SiPM tiles underwent a room temperature burn-in test in the dark for two weeks, while cryogenic testing analyzed the thermal dependence of parameters for some sampled SiPMs. Results from these comprehensive tests provide crucial insights into the long-term performance and stability of the 10 square meters of SiPMs operating at -50°C to detect scintillation photons in the TAO detector. Despite some anomalies awaiting further inspection, all SiPMs successfully passed the burn-in test over two weeks at room temperature, which is equivalent to 6.7 years at -50°C. Results are also used to guide optimal SiPM selection, configuration, and operation, ensuring reliability and sustainability in reactor neutrino measurements. This work also provides insights for a rapid and robust quality assessment in future experiments that employ large-scale SiPMs as detection systems.

[21] arXiv:2406.12926 [pdf, html, other]

Title: Diffusion on assortative networks: from mean-field to agent-based, via Newman rewiring

L. Di Lucchio, G. Modanese

Comments: 26 pages, 8 figures

Subjects: Physics and Society (physics.soc-ph)

In mathematical models of epidemic diffusion on networks based upon systems of differential equations, it is convenient to use the Heterogeneous Mean Field approximation (HMF) because it allows to write one single equation for all nodes of a certain degree $k$, each one virtually present with a probability given by the degree distribution $P(k)$. The two-point correlations between nodes are defined by the matrix $P(h|k)$, which can typically be uncorrelated, assortative or disassortative. After a brief review of this approach and of the results obtained within this approximation for the Bass diffusion model, in this work we look at the transition from the HMF approximation to the description of diffusion through the dynamics of single nodes, first still with differential equations, and then with agent-based models. For this purpose, one needs a method for the explicit construction of ensembles of random networks or scale-free networks having a pre-defined degree distribution (Configuration Model) and a method for rewiring these networks towards some desired or "target" degree correlations (Newman Rewiring). We describe Python-NetworkX codes implemented for the two methods in our recent work and compare some of the results obtained in the HMF approximation with the new results obtained with statistical ensembles of real networks, including the case of signed networks.

[22] arXiv:2406.12932 [pdf, html, other]

Title: Brownian Motion of the Quantum States on a String and the Polyakov Action of String Theory: Is String Theory a Quantum Mechanical Model of the Brain?

Amir Abbass Varshovi

Comments: The paper has 33 pages and one figure

Subjects: General Physics (physics.gen-ph)

The Brownian motion of a number of quantum states in a compact one-dimensional space is studied via the Wiener fractal measure, and it is shown that the derived path-integral measure coincides precisely with the Polyakov path-integral formula for bosonic string theory. Thus, it is concluded that the Polyakov action of bosonic string theory does not have a unique, distinguishable foundation specifically dedicated to describing the fundamental forces of nature, but rather, it is merely a standard formulation of the Wiener stochastic process for Brownian motion of the quantum states on one-dimensional objects. It is also demonstrated that the time-dimension field is, in practice, the localization of the non-local effects of the coordinate fields. This indicates that the interpretation intended for spacetime fields in the formulation of string theory allegedly faces fundamental flaws in its underlying theoretical aspects. In this regard, we will defend string theory against its experimental flaws in particle physics due to unreliable interpretation of the theory and relate its elaborated mathematical framework to another significant topic: Quantum Brain. ....

[23] arXiv:2406.12942 [pdf, other]

Title: Double PN Benchmark Solution for the 1D Monoenergetic Neutron Transport Equation in Plane Geometry

Barry Ganapol

Comments: 19 pgs 2 tablws 1 figure

Subjects: Computational Physics (physics.comp-ph)

As more and more numerical and analytical solutions to the linear neutron transport equation become available, verification of numerical results is increasingly important. This presentation concerns the development of another benchmark for the linear neutron transport equation. There are numerous ways of solving the transport equation, such as the Wiener-Hopf method based on analyticity, method of singular eigenfunctions, Laplace and Fourier transforms and ana-lytical discrete ordinates, which is arguably one of the most straightforward, to name a few. Another potential method is the PN method, where the solution is expanded in terms of full range orthogonal Legendre polynomials and with orthogonality and truncation, the moments form a set of second order ODEs. Because of the half-range boundary conditions for incoming particles however, full range Legendre expansions are inaccurate near material discontinuities. For this reason, a double PN (DPN) expansion is more appropriate, where the incoming and exiting flux distributions are expanded separately to preserve the discontinuity at material interfaces. Here, a new method of solution for the DPN equations is proposed and demonstrated for an isotropically scattering medium.

[24] arXiv:2406.12951 [pdf, other]

Title: Reviewing climate change attribution in UK natural hazards and their impacts

Regan Mudhar, Dann M. Mitchell, Peter A. Stott, Richard A. Betts

Subjects: Physics and Society (physics.soc-ph); Atmospheric and Oceanic Physics (physics.ao-ph)

The field of Detection and Attribution is rapidly moving beyond weather and climate, and towards incorporating hazards and their impacts on natural and human systems. Here, we review the comprehensive literature base relevant for the UK ahead of the next Climate Change Risk Assessment. The current literature highlights a detectable and non-trivial influence of climate change in many UK impact sectors already - notably health, agriculture, and infrastructure. We found that heatwaves were the most studied hazard overall, with a unanimous consensus on a strong attributable signal of human-induced climate change in their increased frequency and intensity over the last century. The most notable gap identified overall was in attributing climate-related impacts to human influence, with a few impact studies for only a handful of the hazards assessed. Furthermore, just under half of the 29 hazards were not found to have any UK-relevant attribution studies, with most of the remainder having three or fewer. This review highlights requirements for and opportunities to develop attribution scicnce to meet the needs of the UK. Diversifying hazards and impacts studied, in conjunction with the techniques and approaches used, will undoubtedly benefit the community.

[25] arXiv:2406.13003 [pdf, html, other]

Title: Simulating nonlinear optical processes on a superconducting quantum device

Yuan Shi, Bram Evert, Amy F. Brown, Vinay Tripathi, Eyob A. Sete, Vasily Geyko, Yujin Cho, Jonathan L DuBois, Daniel Lidar, Ilon Joseph, Matt Reagor

Comments: 26 pages, 5 figures

Subjects: Plasma Physics (physics.plasm-ph); Quantum Physics (quant-ph)

Simulating plasma physics on quantum computers is difficult, because most problems of interest are nonlinear, but quantum computers are not naturally suitable for nonlinear operations. In weakly nonlinear regimes, plasma problems can be modeled as wave-wave interactions. In this paper, we develop a quantization approach to convert nonlinear wave-wave interaction problems to Hamiltonian simulation problems. We demonstrate our approach using two qubits on a superconducting device. Unlike a photonic device, a superconducting device does not naturally have the desired interactions in its native Hamiltonian. Nevertheless, Hamiltonian simulations can still be performed by decomposing required unitary operations into native gates. To improve experimental results, we employ a range of error mitigation techniques. Apart from readout error mitigation, we use randomized compilation to transform undiagnosed coherent errors into well-behaved stochastic Pauli channels. Moreover, to compensate for stochastic noise, we rescale exponentially decaying probability amplitudes using rates measured from cycle benchmarking. We carefully consider how different choices of product-formula algorithms affect the overall error and show how a trade-off can be made to best utilize limited quantum resources. This study provides a point example of how plasma problems may be solved on near-term quantum computing platforms.

[26] arXiv:2406.13016 [pdf, other]

Title: Verhulst Equation and the Universal Pattern for the Global Population Growth

Agata Angelika Sojecka, Aleksandra Drozd-Rzoska

Comments: 29 pages, 3 figures

Subjects: Physics and Society (physics.soc-ph)

The global population growth from 10,000 BC to 2023 is discussed within the Verhulst scaling equation and its extensions framework. The analysis focuses on per the capita global population rate coefficient Gp(P)=[dP(t)/P(t)]/dt=dlnP(t)/d, which reveals two linear domains: from 700CE till 1966 and from 1966 till 2023. Such a pattern can be considered a universal reference for reliable scaling relations describing P(t) changes. It is also the distortions-sensitive test indicating domains of their applicability and yielding optimal values of parameters. For models recalling the Verhulst equation, a single pair of growth rate and system capacity coefficients (r,s) should describe global population rise in the mentioned periods. However, the Verhulst equation with such effective parameters does not describe P(t) changes. Notable is the new way of data preparation, based on collecting data from various sources and their numerical filtering to obtain a smooth set of optimal values enabling the derivative-based analysis. The analysis reveals links between P(t) changes and some historical and pre-historical references influencing the global scale.

[27] arXiv:2406.13019 [pdf, other]

Title: Data-driven fingerprint nanomechanical mass spectrometry

John E. Sader, Alfredo Gomez, Adam P. Neumann, Alexander R. Nunn, Michael L. Roukes

Comments: 41 pages, 14 figures

Subjects: Instrumentation and Detectors (physics.ins-det)

Fingerprint analysis is a ubiquitous tool for pattern recognition with applications spanning from geolocation and DNA analysis to facial recognition and forensic identification. Central to its utility is the ability to provide accurate identification without an a priori mathematical model for the pattern. We report a data-driven fingerprint approach for nanoelectromechanical systems mass spectrometry (NEMS-MS) that enables mass measurements of particles and molecules using complex, uncharacterized nanoelectromechanical devices of arbitrary specification. NEMS-MS is based on the frequency shifts of the NEMS vibrational modes induced by analyte adsorption. The sequence of frequency shifts constitutes a fingerprint of this adsorption, which is directly amenable to pattern matching. Two current requirements of NEMS-based mass spectrometry are: (1) a priori knowledge or measurement of the device mode-shapes, and (2) a mode-shape-based model that connects the induced modal frequency shifts to mass adsorption. This may not be possible for advanced NEMS with three-dimensional mode-shapes and nanometer-sized features. The advance reported here eliminates this impediment, thereby allowing device designs of arbitrary specification and size to be employed. This enables the use of advanced NEMS devices with complex vibrational modes, which offer unprecedented prospects for attaining the ultimate detection limits of nanoelectromechanical mass spectrometry.

[28] arXiv:2406.13030 [pdf, other]

Title: Point containment algorithms for constructive solid geometry with unbounded primitives

Paul K. Romano, Patrick A. Myers, Seth R. Johnson, Aljaž Kolšek, Patrick C. Shriwise

Subjects: Computational Physics (physics.comp-ph); Computational Geometry (cs.CG)

We present several algorithms for evaluating point containment in constructive solid geometry (CSG) trees with unbounded primitives. Three algorithms are presented based on postfix, prefix, and infix notations of the CSG binary expression tree. We show that prefix and infix notations enable short-circuiting logic, which reduces the number of primitives that must be checked during point containment. To evaluate the performance of the algorithms, each algorithm was implemented in the OpenMC Monte Carlo particle transport code, which relies on CSG to represent solid bodies through which subatomic particles travel. Two sets of tests were carried out. First, the execution time to generate a high-resolution rasterized image of a 2D slice of a detailed CSG model of the ITER tokamak was measured. Use of both prefix and infix notations offered significant speedup over the postfix notation that has traditionally been used in particle transport codes, with infix resulting in a 6$\times$ reduction in execution time relative to postfix. We then measured the execution time of neutron transport simulations of the same ITER model using each of the algorithms. The results and performance improvements reveal the same trends as for the rasterization test, with a 4.59$\times$ overall speedup using the infix notation relative to the original postfix notation in OpenMC.

[29] arXiv:2406.13054 [pdf, html, other]

Title: Characterization of a radiation detector based on opaque water-based liquid scintillator

LiquidO Collaboration

Comments: 20 pages, 14 figures

Subjects: Instrumentation and Detectors (physics.ins-det)

We present the characterization of a novel radiation detector based on an opaque water-based liquid scintillator. Opaque scintillators, also known as LiquidO, are made to be highly scattering, such that the scintillation light is effectively confined, and read out through wavelength-shifting fibers. The 1-liter, 32-channel prototype demonstrates the capability for both spectroscopy and topological reconstruction of point-like events. The design, construction, and evaluation of the detector are described, including modeling of the scintillation liquid optical properties and the detector's response to gamma rays of several energies. A mean position reconstruction error of 4.4 mm for 1.6 MeV-equivalent events and 7.4 mm for 0.8 MeV-equivalent events is demonstrated using a simple reconstruction approach analogous to center-of-mass.

[30] arXiv:2406.13058 [pdf, html, other]

Title: Quantum Systems Other Than the Universe

David Wallace

Subjects: History and Philosophy of Physics (physics.hist-ph); Quantum Physics (quant-ph)

How should we interpret physical theories, and especially quantum theory, if we drop the assumption that we should treat it as an exact description of the whole Universe? I expound and develop the claim that physics is about the study of autonomous, but not necessarily isolated, dynamical systems, and that when applied to quantum mechanics this entails that in general we should take quantum systems as having mixed states and non-unitary dynamics. I argue that nonetheless unitary dynamics continues to have a special place in physics, via the empirically-well-supported reductionist principles that non-unitarity is to be explained by restriction to a subsystem of a larger unitary system and that microscopic physics is governed by unitary and largely known dynamics. I contrast this position with the `Open Systems View' advocated recently by Michael Cuffaro and Stephan Hartmann.

[31] arXiv:2406.13061 [pdf, html, other]

Title: Effect of free surface, oxide and coating layers on rafting in $\gamma-\gamma'$ superalloys

Wajih Jbara, Vincent Maurel, Kais Ammar, Samuel Forest

Subjects: Applied Physics (physics.app-ph)

Complex microstructure evolution has been observed \rev{both bare and coated } Ni-based single crystal superalloys. Rafting and $\gamma'$ depletion are investigated in this study through a brief experimental analysis and a detailed phase field model to account for mechanical-diffusion coupling. The proposed model has been implemented in a finite element code. As a main result, it is shown that rafting, $\gamma'$ depletion close to free surface/oxide layer or $\gamma'$ coalescence close to coating layer, and mechanical behavior are strongly coupled. The local additional flux of Al explains this coupling to a large extent. Finally, a discussion of strain localization and local flux of Al paves the way for clarification of these cases that degrade the performance of superalloys.

[32] arXiv:2406.13065 [pdf, other]

Title: Self-Hybridized Exciton-Polariton Photovoltaics

Adam D. Alfieri, Tobia Ruth, Cheryl Lim, Jason Lynch, Deep Jariwala

Subjects: Optics (physics.optics); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Materials Science (cond-mat.mtrl-sci)

Excitonic semiconductors are attractive for next-generation photovoltaics (PVs) with lower cost, lighter weight, and lower material consumption than conventional technologies. Among them, transition metal dichalcogenide materials like WS2 are especially interesting due to exceptionally strong light-matter interaction. Photocurrent generation in excitonic PVs relies on exciton diffusion to heterointerfaces. However, efficiencies of excitonic PVs are often limited by short exciton diffusion lengths. Here we report that the strong coupling of excitons to cavity photons in a WS2 absorber layer can enhance the external quantum efficiency by a factor of >10, internal quantum efficiency by a factor of ~3, and power conversion efficiency of excitonic PVs by an order of magnitude. The resulting hybrid states, exciton-polaritons, enhance the resonant absorption and exciton transport while the use of the WS2 layer as its own optical cavity enables broadband absorption. Thickness dependent device characterization reveals anomalous internal quantum efficiency and fill factor behavior that are attributed to novel exciton-polariton transport. Exciton-polariton enhanced transport occurs for both resonant and off-resonant excitation, emphasizing the value and practicality of the self-hybridized device structure. Our work presents a route towards excitonic PVs with broadband absorption and improved exciton transport without strict requirements of donor/acceptor structure of other excitonic PVs.

[33] arXiv:2406.13078 [pdf, other]

Title: A universal bioluminescence tomography system for pre-clinical image-guided radiotherapy research

Zhishen Tong, Zijian Deng, Xiangkun Xu, Ciara Newman, Xun Jia, Yuncheng Zhong, Merle Reinhart, Paul Tsouchlos, Tim Devling, Hamid Dehghani, Iulian Iordachita, Debabrata Saha, John W. Wong, Ken Kang-Hsin Wang

Subjects: Medical Physics (physics.med-ph)

CBCT-guided small animal irradiators encounter challenges in localizing soft-tissue targets due to low imaging contrast. Bioluminescence tomography (BLT) offers a promising solution, but they have largely remained in laboratorial development, limiting accessibility for researchers. In this work, we develop a universal, commercial-graded BLT-guided system (MuriGlo) designed to seamlessly integrate with commercial irradiators and empower researchers for translational studies. We demonstrate its capabilities in supporting in vitro and in vivo studies. The MuriGlo comprises detachable mouse bed, thermostatic control, mirrors, filters, and CCD, enabling multi-projection and multi-spectral imaging. We evaluate that the thermostatic control effectively sustains animal temperature at 37°C throughout imaging, and quantify that the system can detect as few as 61 GL261-AkaLuc cells in vitro. To illustrate how the MuriGlo can be utilized for in vivo image-guided research, we present 3 strategies, BLT-guided 5-arc, 2-field box, and BLI-guided single-beam, ranging from complicated high-conformal to simplest high-throughput plans. The high conformal BLT-guided 5-arc plan fully covers the gross tumor volume (GTV) at prescribed dose with minimal normal tissue exposure (3.9%), while the simplified, high-throughput BLT-guided 2-field box achieves 100% GTV coverage but results in higher normal tissue exposure (13.1%). Moreover, we demonstrate that the localization accuracy of MuriGlo for both widely-used SARRP and SmART irradiators is within1 mm, and the tumor coverage reaches over 97% with 0.75mm margin. The universal BLT-guided system offers seamless integration with commercial irradiators, achieving comparable localization accuracy, expected to supporting high-precision radiation research.

[34] arXiv:2406.13083 [pdf, html, other]

Title: Design and Performance of a Magnetic Bottle Electron Spectrometer for High-Energy Photoelectron Spectroscopy

Kurtis Borne, Jordan T ONeal, Jun Wang, Erk Isele, Razib Obaid, Nora Berrah, Xinxin Cheng, Philip H Bucksbaum, Justin James, Andri Kamalov, Kirk A Larsen, Xiang Li, Ming-Fu Lin, Yusong Liu, Agostino Marinelli, Adam Summers, Emily Thierstein, Thomas Wolf, Daniel Rolles, Peter Walter, James P Cryan, Taran Driver

Subjects: Instrumentation and Detectors (physics.ins-det)

We describe the design and performance of a magnetic bottle electron spectrometer~(MBES) for high-energy electron spectroscopy.
Our design features a ${\sim2}$~m long electron drift tube and electrostatic retardation lens, achieving sub-electronvolt (eV) electron kinetic energy resolution for high energy (several hundred eV) electrons with close to 4$\pi$ collection efficiency.
A segmented anode electron detector enables the simultaneous collection of photoelectron spectra in high resolution and high collection efficiency modes.
This versatile instrument is installed at the TMO endstation at the LCLS x-ray free-electron laser (XFEL).
In this paper, we demonstrate its high resolution, collection efficiency and spatial selectivity in measurements where it is coupled to an XFEL source.
These combined characteristics are designed to enable high-resolution time-resolved measurements using x-ray photoelectron, absorption, and Auger-Meitner spectroscopy.
We also describe the pervasive artifact in MBES time-of-flight spectra that arises from a periodic modulation in electron detection efficiency, and present a robust analysis procedure for its removal.

[35] arXiv:2406.13085 [pdf, other]

Title: Ultralow thermal conductance across the [FePt/h-BN/FePt] interface

chengchao Xu, Enbo Zhang, Bo-Yuan Yang, B.S.D.Ch.S. Varaprasad, David E. Laughlin, Jian-Gang (Jimmy)Zhu

Comments: 22 page, 5 figures

Subjects: Applied Physics (physics.app-ph); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Materials Science (cond-mat.mtrl-sci)

Heat transfer in nanocomposite materials has attracted great interest for various applications. Multilayer structures provide an important platform to study interfacial thermal transport and to engineer materials with ultralow thermal conductivity. Here we report on the fabrication and thermal characterization of [h-BN/$L1_0$-FePt]xN multilayers, where hexagonal boron nitride (h-BN) nanosheets (2.5 nm thick) and $L1_0$-FePt layers (6.5 nm thick) alternate periodically. Differential three-omega($3\omega$) measurements reveal an ultralow effective thermal conductivity of $ 0.60 \pm 0.05 W \cdot m^{-1}K^{-1}$ across the multilayer films, and a low thermal boundary conductance (TBC) of $ 67.9 \pm 6.6 MW \cdot m^{-2}K^{-1}$ for the [FePt/h-BN(2.5nm)/FePt] interface at room temperature. We attribute the ultralow thermal conductivity to the weak van der Waals bonding at h-BN/FePt interfaces, which dominates the thermal resistance of the multilayer structure. These findings provide insights into the thermal transport in 2D-material/metal multilayer nanostructures and suggest the [h-BN/FePt] superlattice as a promising material for nanoscale thermal barrier coating. Furthermore, the obtained TBC lays the foundation for analyzing heat transfer in FePt-(h-BN) nanogranular films, a promising magnetic recording media which can potentially provide high thermal gradient for heat-assisted magnetic recording (HAMR). This work advances the understanding of thermal transport in 2D-material/metal nanocomposites and demonstrates interface engineering as an effective approach to achieve materials with ultralow thermal conductivity.

[36] arXiv:2406.13112 [pdf, other]

Title: Nutmeg and SPICE: Models and Data for Biomolecular Machine Learning

Peter Eastman, Benjamin P. Pritchard, John D. Chodera, Thomas E. Markland

Comments: 24 pages, 8 figures, 7 tables

Subjects: Chemical Physics (physics.chem-ph); Machine Learning (cs.LG)

We describe version 2 of the SPICE dataset, a collection of quantum chemistry calculations for training machine learning potentials. It expands on the original dataset by adding much more sampling of chemical space and more data on non-covalent interactions. We train a set of potential energy functions called Nutmeg on it. They use a novel mechanism to improve performance on charged and polar molecules, injecting precomputed partial charges into the model to provide a reference for the large scale charge distribution. Evaluation of the new models shows they do an excellent job of reproducing energy differences between conformations, even on highly charged molecules or ones that are significantly larger than the molecules in the training set. They also produce stable molecular dynamics trajectories, and are fast enough to be useful for routine simulation of small molecules.

[37] arXiv:2406.13134 [pdf, other]

Title: Mode Coupling and Breathing Oscillation in Partially Magnetized Cross-Field Plasmas

Jong Yoon Park, June Young Kim

Subjects: Plasma Physics (physics.plasm-ph)

We report on investigations of mode coupling between rotating spokes during the onset of the breathing oscillation. Demonstrating the existence of nonlinear coupling between the sporadic spokes and the breathing oscillation, we suggest the oscillating azimuthal electric field as the energy source for additional ionization within the plasma. Our results indicate that intermittent three-wave coupling is a possible mechanism for triggering low-frequency breathing oscillations in partially magnetized cross-field plasma.

[38] arXiv:2406.13143 [pdf, html, other]

Title: Picturing global substorm dynamics in the magnetotail using low-altitude ELFIN measurements and data mining-based magnetic field reconstructions

Xiaofei Shi, Grant K. Stephens, Anton V. Artemyev, Mikhail I. Sitnov, Vassilis Angelopoulos

Subjects: Space Physics (physics.space-ph); Plasma Physics (physics.plasm-ph)

A global reconfiguration of the magnetotail characterizes substorms. Current sheet thinning, intensification, and magnetic field stretching are defining features of the substorm growth phase and their spatial distributions control the timing and location of substorm onset. Presently, sparse in-situ observations cannot resolve these distributions. A promising approach is to use new substorm magnetic field reconstruction methods based on data mining, termed SST19. Here we compare the SST19 reconstructions to low-altitude ELFIN measurements of energetic particle precipitations to probe the radial profile of the equatorial magnetic field curvature during a 19~August 2022 substorm. ELFIN and SST19 yield a consistent dynamical picture of the magnetotail during the growth phase and capture expected features such as the formation of a thin current sheet and its earthward motion. Furthermore, they resolve a V-like pattern of isotropic electron precipitation boundaries in the time-energy plane, consistent with earlier observations but now over a broad energy range.

[39] arXiv:2406.13157 [pdf, html, other]

Title: Genetics-based deperturbation analysis for the spin-orbit coupled ${\rm A}^1\Sigma^+$ and ${\rm b}^3\Pi_{0^+}$ states of LiRb

Yide Yin, Xuhui Bai, Xuechun Li, Xin-Yu Luo, Jie Yu, Gaoren Wang, Yongchang Han

Comments: 12 pages, 9 figures

Subjects: Atomic Physics (physics.atom-ph); Computational Physics (physics.comp-ph)

We present a deperturbation analysis of the spin-orbit coupled $\rm A^1\Sigma^+$ and $\rm b^3\Pi_{0^+}$ states of LiRb based on the rovibrational energy levels observed previously by photoassociation spectroscopy in bosonic $^7$Li$^{85}$Rb molecule. Using the genetic algorithm, we fit the potential energy curves of the $\rm A^1\Sigma^+$ state and the $\rm b^3\Pi$ state into point-wise form. We then fit these point-wise potentials along with the spin-orbit coupling into expanded Morse oscillator functional form and optimise analytical parameters based on the experimental data. From the fitted results, we calculate the transition dipole moment matrix elements for transitions from the rovibrational levels of the coupled $\rm A^1\Sigma^+$-$\rm b^3\Pi_{0^+}$ state to the Feshbach state and the absolute rovibrational ground state for fermionic $^6$Li$^{87}$Rb molecule. Based on the calculated transition dipole moment matrix elements, several levels of the coupled $\rm A^1\Sigma^+$-$\rm b^3\Pi_{0^+}$ state are predicted to be suitable as the intermediate state for stimulated Raman adiabatic passage transfer from the Feshbach state to the absolute rovibrational ground state. In addition, we also provide a similar estimation for ${\rm B}^1\Pi$-${\rm c}^3\Sigma_1^+$-${\rm b}^3\Pi_1$ state based on available $ab\ initio$ interaction potentials.

[40] arXiv:2406.13159 [pdf, html, other]

Title: Ultrastable vacuum-gap Fabry-P\'erot cavities operated in air

Yifan Liu, Naijun Jin, Dahyeon Lee, Charles McLemore, Takuma Nakamura, Megan Kelleher, Haotian Cheng, Susan Schima, Nazanin Hoghooghi, Scott Diddams, Peter Rakich, Franklyn Quinlan

Comments: 10 pages, 6 figures

Subjects: Optics (physics.optics); Instrumentation and Detectors (physics.ins-det)

We demonstrate a vacuum-gap ultrastable optical reference cavity that does not require a vacuum enclosure. Our simple method of optical contact bonding in a vacuum environment allows for cavity operation in air while maintaining vacuum between the cavity mirrors. Vacuum is maintained long term, with no observed degradation in cavity stability for over 1 year after bonding. For a 1550 nm laser stabilized to a 9.7 mL in-vacuum bonded cavity, the measured Allan deviation is $2.4\times 10^{-14}$ at 1 s and its phase noise is thermal-noise-limited from 0.1 Hz to 10 kHz, reaching about -105 dBc/Hz at 10 kHz offset frequency. This represents the highest stability of any oscillator operated without a vacuum enclosure. Furthermore, we demonstrate a 0.5 mL in-vacuum bonded cavity created using microfabricated mirrors and cavity dicing, with phase noise reaching -95 dBc/Hz at 10 kHz offset frequency. By relieving the need for high-vacuum enclosures, we greatly enhance the portability and utility of low noise, compact cavity-stabilized lasers, with applications ranging from environmental sensing to mobile optical clocks to ultralow noise microwave generation.

[41] arXiv:2406.13171 [pdf, other]

Title: Super-resolution 3D tomography of vector near-fields in dielectric resonators

Bingbing Zhu, Qingnan Cai, Yaxin Liu, Sheng Zhang, Weifeng Liu, Qiong He, Lei Zhou, Zhensheng Tao

Comments: 26 pages, 4 figures

Subjects: Optics (physics.optics)

All-dielectric optical resonators, exhibiting exotic near-field distributions upon excitations, have emerged as low-loss, versatile and highly adaptable components in nanophotonic structures for manipulating electromagnetic waves and enhancing light-matter interactions. However, achieving experimental full three-dimensional characterization of near-fields within dielectric materials poses significant challenges. Here, we develop a novel technique using high-order sideband generation to image near-field wave patterns inside dielectric optical resonators. By exploiting the phase-sensitivity of various harmonic orders that enables the detection of near-field distributions at distinct depths, we realize three-dimensional tomographic and super-resolution near-field imaging inside a micrometer-thick silicon anapole resonator. Furthermore, our method offers high-contrast polarization sensitivity and phase-resolving capability, providing comprehensive vectorial near-field information. Our approach can potentially be applied to diverse dielectric metamaterials, and becomes a valuable tool for comprehensive characterization of near-field wave phenomena within dielectric materials.

[42] arXiv:2406.13190 [pdf, html, other]

Title: A programmable wafer-scale chiroptical heterostructure of twisted aligned carbon nanotubes and phase change materials

Jichao Fan, Ruiyang Chen, Minhan Lou, Haoyu Xie, Nina Hong, Yingheng Tang, Weilu Gao

Subjects: Optics (physics.optics); Materials Science (cond-mat.mtrl-sci)

The ability to design and dynamically control chiroptical responses in solid-state matter at wafer scale enables new opportunities in various areas. Here we present a full stack of computer-aided designs and experimental implementations of a dynamically programmable, unified, scalable chiroptical heterostructure containing twisted aligned one-dimensional (1D) carbon nanotubes (CNTs) and non-volatile phase change materials (PCMs). We develop a software infrastructure based on high-performance machine learning frameworks, including differentiable programming and derivative-free optimization, to efficiently optimize the tunability of both excitonic reciprocal and linear-anisotropy-induced nonreciprocal circular dichroism (CD) responses. We experimentally implement designed heterostructures with wafer-scale self-assembled aligned CNTs and deposited PCMs. We dynamically program reciprocal and nonreciprocal CD responses by inducing phase transitions of PCMs, and nonreciprocal responses display polarity reversal of CD upon sample flipping in broadband spectral ranges. All experimental results agree with simulations. Further, we demonstrate that the vertical dimension of heterostructure is scalable with the number of stacking layers and aligned CNTs play dual roles - the layer to produce CD responses and the Joule heating electrode to electrically program PCMs. This heterostructure platform is versatile and expandable to a library of 1D nanomaterials and electro-optic materials for exploring novel chiral phenomena and photonic and optoelectronic devices.

[43] arXiv:2406.13220 [pdf, other]

Title: Acoustically Transparent Alumina-based Cranial Implants Enhance Ultrasound Transmission Through a Combined Mechano-Acoustic Resonant Effect

Mario Ibrahin Gutierrez, Pathikumar Sellappan, Elias H. Penilla, Irais Poblete-Naredo, Arturo Vera, Lorenzo Leija, Javier E. Garay

Comments: Journal of Physics: Materials

Subjects: Medical Physics (physics.med-ph); Materials Science (cond-mat.mtrl-sci)

Therapeutic ultrasound for brain stimulation has increased in the last years. This energy has shown promising results for treating Alzheimers disease, Parkinsons disease, and traumatic brain injury, among other conditions. However, the application of ultrasound in the brain should trespass a natural but highly attenuating and distorting barrier, the cranium. Implantable ceramic materials can be used to replace part of the cranium as an alternate method to enhance ultrasound transmission. In this work, it is presented the acoustic characterization of alumina ceramic disks that can be employed as cranial implants for acoustic windows-to-the-brain. Alumina samples were prepared using current-activated pressure-assisted densification and were acoustically characterized. Acoustic impedance and attenuation of the samples were determined for different porosities. Additionally, measured and modeled acoustic fields are presented and analyzed in terms of the total ultrasound transmitted through the ceramics. Results indicate a resonant behavior in the alumina disks when the thickness corresponds to a half-wavelength of ultrasound; this resonance permits a total of 95.4% of ultrasound transmission; for thicknesses out of the resonant zone, transmission is 53.0%. Alumina proves to be an excellent medium for ultrasound transmission that, in conjunction with its mechanical and optical properties, can be useful for cranium replacement in mixed opto-acoustic applications.

[44] arXiv:2406.13238 [pdf, other]

Title: Fast Small-Angle X-ray Scattering Tensor Tomography: An Outlook into Future Applications in Life Sciences

Christian Appel, Margaux Schmeltz, Irene Rodriguez-Fernandez, Lukas Anschuet, Leonard C. Nielsen, Ezequiel Panepucci, Tomislav Marijolovic, Klaus Wakonig, Aleksandra Ivanovic, Anne Bonnin, Filip Leonarski, Justyna Wojdyla, Takashi Tomizaki, Manuel Guizar-Sicairos, Kate Smith, John H. Beale, Wayne Glettig, Katherine McAuley, Oliver Bunk, Meitian Wang, Marianne Liebi

Subjects: Medical Physics (physics.med-ph); Materials Science (cond-mat.mtrl-sci)

Small Angle-X-ray Scattering Tensor Tomography (SAS-TT) is a relatively new, but powerful technique for studying the multiscale architecture of hierarchical structures, which is of particular interest for life science applications. Currently, the technique is very demanding on synchrotron beamtime, which limits its applications, especially for cases requiring a statistically relevant amount of sample. This study reports the first SAS-TT measurement at a macromolecular X-ray crystallography beamline, PX-I at the SLS, with an improvement in data acquisition time from 96 h/Mvoxel in the pilot experiments to 6 h/Mvoxel, defining a new standard for fast SAS-TT and allowing the measurement of a full tomogram in 1.2 hours. Measurements were performed on the long and lenticular process of the incus bone, one of the three human auditory ossicles. The main orientation and degree of alignment of the mineralised collagen fibrils are characterised, as well as the size and shape of the mineral particles which show relevant variations in different tissue locations. The study reveals three distinct regions of high fibril alignment, most likely important pathways of sound throughout the ossicular chain, and highlights the potential of the technique to aid in future developments in middle ear reconstructive surgery.

[45] arXiv:2406.13252 [pdf, html, other]

Title: Self-Supervised Diffusion Model for 3-D Seismic Data Reconstruction

Xinyang Wang, Qianyu Ge, Xintong Dong, Shiqi Dong, Tie Zhong

Comments: 43 pages, 13 figures

Subjects: Geophysics (physics.geo-ph)

Seismic data reconstruction is an effective tool for compensating nonuniform and incomplete seismic geometry. Compared with methods for 2D seismic data, 3D reconstruction methods could consider more spatial structure correlation in seismic data. In the early studies, 3D reconstruction methods are mainly theory-driven and have some limitations due to their prior assumptions on the seismic data. To release these limitations, deep learning-based reconstruction methods rise and show potential in dealing with reconstruction problems. However, there are mainly two shortcomings in existing deep learning-methods. On the one hand, most of existing deep learning-based methods adopt the convolutional neural network, having some difficulties in dealing with data with complex or time-varying distributions. Recently, the diffusion model has been reported to possess the capability to solve data with complex distributions by gradually complicating the distribution of data to optimize the network. On the other hand, existing methods need enough paired-data to train the network, which are very hard to obtain especially for the starved 3D seismic data. Deep prior-based unsupervised and sampling-based self-supervised networks offer an available solution to this problem. In this paper, we develop a self-supervised diffusion model (S2DM) for 3D seismic data reconstruction. The proposed model mainly contains a diffusion restoration model and a variational time-spatial module. Extensive synthetic and field experiments demonstrate the superiority of the proposed S2DM algorithm.

[46] arXiv:2406.13284 [pdf, other]

Title: The association of domain-specific physical activity and sedentary activity with stroke: A prospective cohort study

Xinyi He, Shidi Wang, Yi Li, Jiucun Wang, Guangrui Yang, Jun Chen, Zixin Hu

Subjects: Medical Physics (physics.med-ph); Quantitative Methods (q-bio.QM)

Background The incidence of stroke places a heavy burden on both society and individuals. Activity is closely related to cardiovascular health. This study aimed to investigate the relationship between the varying domains of PA, like occupation-related Physical Activity (OPA), transportation-related Physical Activity (TPA), leisure-time Physical Activity (LTPA), and Sedentary Activity (SA) with stroke. Methods Our analysis included 30,400 participants aged 20+ years from 2007 to 2018 National Health and Nutrition Examination Survey (NHANES). Stroke was identified based on the participant's self-reported diagnoses from previous medical consultations, and PA and SA were self-reported. Multivariable logistic and restricted cubic spline models were used to assess the associations. Results Participants achieving PA guidelines (performing PA more than 150 min/week) were 35.7% less likely to have a stroke based on both the total PA (odds ratio [OR] 0.643, 95% confidence interval [CI] 0.523-0.790) and LTPA (OR 0.643, 95% CI 0.514-0.805), while OPA or TPA did not demonstrate lower stroke risk. Furthermore, participants with less than 7.5 h/day SA levels were 21.6% (OR 0.784, 95% CI 0.665-0.925) less likely to have a stroke. The intensities of total PA and LTPA exhibited nonlinear U-shaped associations with stroke risk. In contrast, those of OPA and TPA showed negative linear associations, while SA intensities were positively linearly correlated with stroke risk. Conclusions LTPA, but not OPA or TPA, was associated with a lower risk of stroke at any amount, suggesting that significant cardiovascular health would benefit from increased PA. Additionally, the positive association between SA and stroke indicated that prolonged sitting was detrimental to cardiovascular health. Overall, increased PA within a reasonable range reduces the risk of stroke, while increased SA elevates it.

[47] arXiv:2406.13296 [pdf, html, other]

Title: Critical temperature of the classical XY model via autoencoder latent space sampling

Brandon Willnecker, Mervlyn Moodley

Comments: 6 pages, 11 figures. To be published in Physical Review E

Subjects: Computational Physics (physics.comp-ph); Statistical Mechanics (cond-mat.stat-mech)

The classical XY model has been consistently studied since it was introduced more than six decades ago. Of particular interest has been the two-dimensional spin model's exhibition of the Berezinskii-Kosterlitz-Thouless (BKT) transition. This topological phenomenon describes the transition from bound vortex-antivortex pairs at low temperatures to unpaired or isolated vortices and anti-vortices above some critical temperature. In this work we propose a novel machine learning based method to determine the emergence of this phase transition. An autoencoder was used to map states of the XY model into a lower dimensional latent space. Samples were taken from this latent space to determine the thermal average of the vortex density which was then used to determine the critical temperature of the phase transition.

[48] arXiv:2406.13323 [pdf, html, other]

Title: An alkali-referenced vector spectrum analyzer for visible-light integrated photonics

Baoqi Shi, Ming-Yang Zheng, Yunkai Zhao, Yi-Han Luo, Jinbao Long, Wei Sun, Wenbo Ma, Xiu-Ping Xie, Lan Gao, Chen Shen, Anting Wang, Wei Liang, Qiang Zhang, Junqiu Liu

Subjects: Optics (physics.optics)

Integrated photonics has reformed our information society by offering on-chip optical signal synthesis, processing and detection with reduced size, weight and power consumption. As such, it has been successfully established in the near-infrared (NIR) telecommunication bands. With the soaring demand in miniaturized systems for biosensing, quantum information and transportable atomic clocks, extensive endeavors have been stacked on translating integrated photonics into the visible spectrum, i.e. visible-light integrated photonics. Various innovative visible-light integrated devices have been demonstrated, such as lasers, frequency combs, and atom traps, highlighting the capacity and prospect to create chip-based optical atomic clocks that can make timing and frequency metrology ubiquitous. A pillar to the development of visible-light integrated photonics is characterization techniques featuring high frequency resolution and wide spectral coverage, which however remain elusive. Here, we demonstrate a vector spectrum analyzer (VSA) for visible-light integrated photonics, offering spectral bandwidth from 766 to 795 nm and frequency resolution of 415 kHz. The VSA is rooted on a widely chirping, high-power, narrow-linewidth, mode-hop-free laser around 780 nm, which is frequency-doubled from the near-infrared via an efficient, broadband CPLN waveguide. The VSA is further referenced to hyperfine structures of rubidium and potassium atoms, enabling 8.1 MHz frequency accuracy. We apply our VSA to showcase the characterization of loss, dispersion and phase response of passive integrated devices, as well as densely spaced spectra of mode-locked lasers. Combining operation in the NIR and visible spectra, our VSA allows characterization bandwidth exceeding an octave and can be an invaluable diagnostic tool for spectroscopy, nonlinear optical processing, imaging and quantum interfaces to atomic devices.

[49] arXiv:2406.13325 [pdf, other]

Title: Advances in perovskite nanocrystals and nanocomposites for scintillation applications

Abhinav Anand, Matteo L. Zaffalon, Andrea Erroi, Francesca Cova, Francesco Carulli, Sergio Brovelli

Journal-ref: ACS Energy Letters 2024

Subjects: Applied Physics (physics.app-ph); Materials Science (cond-mat.mtrl-sci)

In recent years, the field of radiation detection has witnessed a paradigm shift with the emergence of plastic scintillators incorporating perovskite nanocrystals (PNCs). This innovative class of scintillators not only capitalizes on the superior luminescent properties of PNCs but also harnesses the flexibility and processability of polymers. This review explores the intricate landscape of synthesizing and fabricating scintillating PNCs and nanocomposites, delving into the methods employed in their production. From solution-based methods to innovative solid-state approaches, the synthesis of PNCs for scintillators application is explored comprehensively. Furthermore, embedding strategies within polymeric matrices are scrutinized, shedding light on the various techniques utilized to achieve optimal dispersion and compatibility. The evaluation of the final nanocomposites is finally discussed, with a particular emphasis on their scintillating performance and radiation hardness. Through a meticulous exploration of synthesis methodologies, embedding techniques, and performance assessments, this review aims to provide a multilayered understanding of the state-of-the-art in PNCs-based nanoscintillators.

[50] arXiv:2406.13330 [pdf, other]

Title: The Paradox of the Recoil Force Acting on a Leaking Water Tank

Avi Marchewka, Yiftah Navot

Comments: 19 pages, 6 figurer, 5 graph

Subjects: Classical Physics (physics.class-ph)

In the first part of the article, we will outline the paradoxical picture that arises when attempting to calculate the recoil force of water that leaks at the bottom of a water tank. We will present three different options for recoil force acting on the water tank as a result of this leakage (in Chapters 1, 2 and 3). In the second part of the article, we will present an experiment that resolves this question (in Chapter 4). Finally (in Chapter 5), we will present a coherent picture of the description of the leakage and the result recoil force.

[51] arXiv:2406.13350 [pdf, html, other]

Title: Microwave amplification chain calibration in an axion haloscope via cavity-emitted radiation

Hsin Chang, Han-Wen Liu, Hien Thi Doan, Yung-Fu Chen

Comments: 6 journal pages, 5 figures, and 1 table in the main text

Subjects: Instrumentation and Detectors (physics.ins-det); Applied Physics (physics.app-ph)

In an axion haloscope, the weak photon signal, theoretically converted from axions, is captured by a detection cavity. The amplification chain assists the signal receiver to read the signal from the cavity and requires accurate calibration. Typically, the readout line is calibrated using the Y-factor method, involving a switch that directs the signal from either the detection line or the calibration line. However, this switch introduces several disadvantages. In response, we propose a calibration method that eliminates the need for a switch. In this approach, the cavity temperature is decoupled to its incoming noise source and can be controlled, resulting in excess or deficiency of the noise spectrum near its resonance frequency. The experimental result shows that the amplification chain can be calibrated directly using the temperature-varied cavity-emitted radiation.

[52] arXiv:2406.13354 [pdf, other]

Title: Scintillation Properties of CsPbBr3 Nanocrystals Prepared by Ligand-Assisted Reprecipitation and Dual Effect of Polyacrylate Encapsulation toward Scalable Ultrafast Radiation Detectors

Francesca Cova, Andrea Erroi, Matteo L. Zaffalon, Alessia Cemmi, Ilaria Di Sarcina, Jacopo Perego, Angelo Monguzzi, Angiolina Comotti, Francesca Rossi, Francesco Carulli, Sergio Brovelli

Journal-ref: Nano Letters 2024

Subjects: Applied Physics (physics.app-ph); Instrumentation and Detectors (physics.ins-det)

Lead halide perovskite nanocrystals (LHP-NCs) embedded in polymeric hosts are gaining attention as scalable and low-cost scintillation detectors for technologically relevant applications. Despite rapid progress, little is currently known about the scintillation properties and stability of LHP-NCs prepared by the ligand assisted reprecipitation (LARP) method, which allows mass scalability at room temperature unmatched by any other type of nanostructure, and the implications of incorporating LHP-NCs into polyacrylate hosts are still largely debated. Here, we show that LARP-synthesized CsPbBr3 NCs are comparable to particles from hot-injection routes and unravel the dual effect of polyacrylate incorporation, where the partial degradation of LHP-NCs luminescence is counterbalanced by the passivation of electron-poor defects by the host acrylic groups. Experiments on NCs with tailored surface defects show that the balance between such antithetical effects of polymer embedding is determined by the surface defect density of the NCs and provide guidelines for further material optimization.

[53] arXiv:2406.13400 [pdf, other]

Title: Climate control in termite mounds: A review and new insights from X-ray tomography and flow field simulations

Nengi F Karibi-Botoye, Guy Theraulaz, Bagus Muljadi, Vasily Demyanov, Kamaljit Singh

Subjects: Geophysics (physics.geo-ph)

Investigating the thermoregulation and ventilation processes in termite mound holds great interest, in particular for its potential implications in advancing eco-friendly building designs. In this article we discuss major results on these processes in termite mounds of varying sizes and ventilation types. Additionally, we propose the integration of X-ray tomography to gain insights into the contribution of architectural features of termite mounds to thermoregulation and ventilation. Finally, we assess the contributions of numerical flow field simulations to this research domain. Our objective is to consolidate existing knowledge, identify research gaps, and propose an interdisciplinary approach to foster our understanding of temperature regulation and gas exchange in termite mounds.

[54] arXiv:2406.13410 [pdf, html, other]

Title: Exploring atom-ion Feshbach resonances below the s-wave limit

Fabian Thielemann, Joachim Siemund, Daniel von Schoenfeld, Wei Wu, Pascal Weckesser, Krzysztof Jachymski, Thomas Walker, Tobias Schaetz

Subjects: Atomic Physics (physics.atom-ph)

Revealing the quantum properties of matter requires a high degree of experimental control accompanied by a profound theoretical understanding. At ultracold temperatures, quantities that appear continuous in everyday life, such as the motional angular momentum of two colliding particles, become quantized, leaving a measurable imprint on experimental results. Embedding a single particle within a larger quantum bath at lowest temperatures can result in resonant partial-wave dependent interaction, whose strength near zero energy is dictated by universal threshold scaling laws. Hybrid atom-ion systems have emerged as a novel platform in which a single charged atom in an ultracold bath serves as a well-controlled impurity of variable energy. However, entering the low-energy s-wave regime and exploring the role of higher-partial-wave scattering within has remained an open challenge. Here, we immerse a Barium ion in a cloud of ultracold spin-polarized Lithium atoms, realize tunable collision energies below the s-wave limit and explore resonant higher-partial-wave scattering by studying the energy dependence of Feshbach resonances. Utilizing precise electric field control, we tune the collision energy over four orders of magnitude, reaching from the many-parital-wave to the s-wave regime. At the lowest energies, we probe the energy dependence of an isolated s-wave Feshbach resonance and introduce a theoretical model that allows to distinguish it from higher-partial-wave resonances. Additionally, at energies around the p-wave barrier, we find and identify an open-channel f-wave resonance, consistent with threshold laws. Our findings highlight and benchmark the importance of higher-partial-wave scattering well within the s-wave regime and offer control over chemical reactions and complex many-body dynamics in atom-ion ensembles - on the level of individual angular momentum quanta.

[55] arXiv:2406.13446 [pdf, html, other]

Title: Linear stability of turbulent channel flow with one-point closure

P. V. Kashyap, Y. Duguet, O. Dauchot

Comments: 13 pages, 8 figures

Journal-ref: Physical Review FLUIDS 9, 063906 (2024)

Subjects: Fluid Dynamics (physics.flu-dyn); Soft Condensed Matter (cond-mat.soft)

For low enough flow rates, turbulent channel flow displays spatial modulations of large wavelengths. This phenomenon has recently been interpreted as a linear instability of the turbulent flow. We question here the ability of linear stability analysis around the turbulent mean flow to predict the onset and wavelengths of such modulations. Both the mean flow and the Reynolds stresses are extracted from direct numerical simulation (DNS) in periodic computational domains of different size. The Orr-Sommerfeld-Squire formalism is used here, with the turbulent viscosity either ignored, evaluated from DNS, or modeled using a simple one-point closure model. Independently of the closure model and the domain size, the mean turbulent flow is found to be linearly stable, in marked contrast with the observed behavior. This suggests that the one-point approach is not sufficient to predict instability, at odds with other turbulent flow cases. For generic wall-bounded shear flows we discuss how the correct models for predicting instability could include fluctuations in a more explicit way.

[56] arXiv:2406.13448 [pdf, html, other]

Title: Demonstration of High-Efficiency Microwave Heating Producing Record Highly Charged Xenon Ion Beams with Superconducting ECR Ion Sources

X. Wang, J. B. Li, V. Mironov, J. W. Guo, X. Z. Zhang, O. Tarvainen, Y. C. Feng, L. X. Li, J. D. Ma, Z. H. Zhang, W. Lu, S. Bogomolov, L. Sun, H. W. Zhao

Subjects: Accelerator Physics (physics.acc-ph); Plasma Physics (physics.plasm-ph)

Intense highly charged ion beam production is essential for high-power heavy ion accelerators. A novel movable Vlasov launcher for superconducting high charge state Electron Cyclotron Resonance (ECR) ion source has been devised that can affect the microwave power effectiveness by a factor of about 4 in terms of highly charged ion beam production. This approach based on a dedicated microwave launching system instead of the traditional coupling scheme has led to new insight on microwave-plasma interaction. With this new understanding, the world record highly charged xenon ion beam currents have been enhanced by up to a factor of 2, which could directly and significantly enhance the performance of heavy ion accelerators and provide many new research opportunities in nuclear physics, atomic physics and other disciplines.

[57] arXiv:2406.13467 [pdf, html, other]

Title: Simulation of sympathetic cooling efficiency in a linear Paul trap driven by alternative waveforms

Oskar Sund, Andreas W. Schell

Comments: 13 pages, 10 figures

Subjects: Atomic Physics (physics.atom-ph); Applied Physics (physics.app-ph); Atomic and Molecular Clusters (physics.atm-clus); Classical Physics (physics.class-ph); Computational Physics (physics.comp-ph)

Cooling of ions or other charged particles in electromagnetic traps is an essential tool to achieve control over their degrees of freedom on the quantum level. For many objects, there is no viable route for direct cooling, such as an accessible laser cooling transition. In such a case, the sympathetic cooling can be used, where a particle with such a direct route is used to cool down the other particle via Coulomb interaction. On the downside, this cooling process often is inefficient. Here, we numerically evaluate the sympathetic cooling performance in a quadrupole ion trap for different driving waveforms. We find that using different driving waveforms and optimized trap parameters the sympathetic cooling performance can be enhanced. These results will open up the way to achieve larger sympathetic cooling rates from which many techniques, such as aluminum ion clocks, might profit.

[58] arXiv:2406.13472 [pdf, html, other]

Title: Extraordinary Quality Factors in Dual-Band Polarization-Insensitive QuasiBound States in the Continuum

Maryam Ghahremani, Carlos J. Zapata-Rodríguez

Subjects: Optics (physics.optics)

In this study, we investigate a novel "dimerized" dielectric metasurface featuring dual-mode resonances governed by symmetry-protected bound states in the continuum (BICs). The metasurface design offers advantages such as insensitivity to incident light polarization and exceptionally high quality factors exceeding 10$^5$ for low and moderate structural deviations from the monoatomic array. By introducing mastered perturbations in the metasurface via the Brillouin zone folding method, without reducing symmetry, we explore the behavior of symmetry-protected BIC states and their polarization-independent responses. Through numerical simulations and analysis, we demonstrate the superiority of Q factors for specific BIC-based resonances, leading to precise control over interaction behaviors and light engineering in both near and far fields. Our findings contribute to the understanding of BIC resonance interactions and offer insights into the design of high-performance sensing applications and meta-devices with enhanced functionalities.

[59] arXiv:2406.13497 [pdf, other]

Title: Sheath effects with thermal electrons on the resonance frequency of a DC-biased hairpin probe

Pawandeep Singh, Avnish Pandey, Swati Dahiya, Yashashri Patil, Nishant Sirse, Shantanu Karkari

Comments: 9 pages, 13 figures

Subjects: Plasma Physics (physics.plasm-ph)

The dielectric constant of a sheath, whether ionic or electronic, formed around the cylindrical limbs of a hairpin probe, is often considered the same as that of a vacuum. However, this assumption does not hold true for electron sheaths and electron-permeating ionic sheaths, resulting in a deviation of the sheath dielectric constant from that of a vacuum. This deviation significantly influences the effective dielectric between the cylindrical limbs. As a result, it impacts the theoretically estimated resonance frequency characteristic curve of a DC-biased hairpin probe. In this study, we investigate the influence of electron temperature on the sheath dielectric and, consequently, on the resonance frequency characteristic curve. The findings shows that electron temperature primarily determines the resonance frequency characteristic curve. With increasing electron temperature, the peak in the resonance frequency characteristic curve shifts towards higher positive probe bias values and exhibits a broadening near the maxima instead of a sharp peak. This broadening near the maxima has also been validated with an experimentally measured resonance frequency characteristic curve in a capacitively coupled argon discharge.

[60] arXiv:2406.13501 [pdf, html, other]

Title: Assessing the 3D resolution of refocused correlation plenoptic images using a general-purpose image quality estimator

Gianlorenzo Massaro

Subjects: Optics (physics.optics); Image and Video Processing (eess.IV)

Correlation plenoptic imaging (CPI) is emerging as a promising approach to light-field imaging (LFI), a technique enabling simultaneous measurement of light intensity distribution and propagation direction from a scene. LFI allows single-shot 3D sampling, offering fast 3D reconstruction for a wide range of applications. However, the array of micro-lenses typically used in LFI to obtain 3D information limits image resolution, which rapidly declines with enhanced volumetric reconstruction capabilities. CPI addresses this limitation by decoupling light-field information measurement using two photodetectors with spatial resolution, eliminating the need for micro-lenses. 3D information is encoded in a four-dimensional correlation function, which is decoded in post-processing to reconstruct images without the resolution loss seen in conventional LFI. This paper evaluates the tomographic performance of CPI, demonstrating that the refocusing reconstruction method provides axial sectioning capabilities comparable to conventional imaging systems. A general-purpose analytical approach based on image fidelity is proposed to quantitatively study axial and lateral resolution. This analysis fully characterizes the volumetric resolution of any CPI architecture, offering a comprehensive evaluation of its imaging performance.

[61] arXiv:2406.13506 [pdf, other]

Title: Development of Volume Produced Negative Ion Source using a CCRF Discharge

Pawandeep Singh, Swati Dahiya, Avnish Pandey, Yashashri Patil, Shantanu Karkari

Comments: 5 pages, 7 figures

Subjects: Plasma Physics (physics.plasm-ph)

This work shows the development of a volume-produced negative ion source that consists of annular parallel plates driven by a 13.56 MHz capacitively coupled radio frequency in a push-pull configuration. This source shows advantages in controlling plasma conditions by varying the pressure, power, and applied axial magnetic field. It is found that the push-pull configuration allows the plasma potential to remain in the range of 20 to 40 Volts. Conversely, the application of a magnetic field helps serves to augment the production of negative ions in the central hollow part of the annular plate. Further, a plausible explanation to the obtained experimental results is presented.

[62] arXiv:2406.13523 [pdf, html, other]

Title: Measurement of the Crystallization and Phase Transition of Niobium Dioxide Thin-Films for Neuromorphic Computing Applications Using a Tube Furnace Optical Transmission System

Zachary R. Robinson, Karsten Beckmann, James Michels, Vincent Daviero, Elizabeth A. Street, Fiona Lorenzen, Matthew C. Sullivan, Nathaniel Cady, Alexander Kozen, Marc Currie

Subjects: Applied Physics (physics.app-ph); Materials Science (cond-mat.mtrl-sci); Emerging Technologies (cs.ET)

Significant research has focused on low-power stochastic devices built from memristive materials. These devices foster neuromorphic approaches to computational efficiency enhancement in merged biomimetic and CMOS architectures due to their ability to phase transition from a dielectric to a metal at an increased temperature. Niobium dioxide has a volatile memristive phase change that occurs $\sim$800$^\circ$C~that makes it an ideal candidate for future neuromorphic electronics. A straightforward optical system has been developed on a horizontal tube furnace for \emph{in situ} spectral measurements as an as-grown \NbtOf\ film is annealed and ultimately crystallizes as \NbOt. The system measures the changing spectral transmissivity of \NbtOf\ as it undergoes both reduction and crystallization processes. We were also able to measure the transition from metallic-to-non-metallic \NbOt\ during the cooldown phase, which is shown to occur about 100$^\circ$C~ lower on a sapphire substrate than fused silica. After annealing, the material properties of the \NbtOf\ and \NbOt\ were assessed via X-ray photoelectron spectroscopy, X-ray diffraction, and 4-point resistivity, confirming that we have made crystalline \NbOt.

[63] arXiv:2406.13538 [pdf, html, other]

Title: Farey tree locking of terahertz semiconductor laser frequency combs

Guibin Liu, Xuhong Ma, Kang Zhou, Binbin Liu, Lulu Zheng, Xianglong Bi, Shumin Wu, Yanming Lu, Ziping Li, Wenjian Wan, Zhenzhen Zhang, Junsong Peng, Ya Zhang, Heping Zeng, Hua Li

Comments: 22 page, 7 figures

Subjects: Optics (physics.optics); Instrumentation and Detectors (physics.ins-det)

Frequency combs show various applications in molecular fingerprinting, imaging, communications, and so on. In the terahertz frequency range, semiconductor-based quantum cascade lasers (QCLs) are ideal platforms for realizing the frequency comb operation. Although self-started frequency comb operation can be obtained in free-running terahertz QCLs due to the four-wave mixing locking effects, resonant/off-resonant microwave injection, phase locking, and femtosecond laser based locking techniques have been widely used to broaden and stabilize terahertz QCL combs. These active locking methods indeed show significant effects on the frequency stabilization of terahertz QCL combs, but they simultaneously have drawbacks, such as introducing large phase noise and requiring complex optical coupling and/or electrical circuits. Here, we demonstrate Farey tree locking of terahertz QCL frequency combs under microwave injection. The frequency competition between the Farey fraction frequency and the cavity round-trip frequency results in the frequency locking of terahertz QCL combs, and the Farey fraction frequencies can be accurately anticipated based on the downward trend of the Farey tree hierarchy. Furthermore, dual-comb experimental results show that the phase noise of the dual-comb spectral lines is significantly reduced by employing the Farey tree locking method. These results pave the way to deploying compact and low phase noise terahertz frequency comb sources.

[64] arXiv:2406.13545 [pdf, html, other]

Title: Optimal Diffractive Focusing of Quantum Waves

Maxim A. Efremov, Felix Hufnagel, Hugo Larocque, Wolfgang P. Schleich, Ebrahim Karimi

Subjects: Optics (physics.optics); Quantum Physics (quant-ph)

Following the familiar analogy between the optical paraxial wave equation and the Schrödinger equation, we derive the optimal, real-valued wave function for focusing in one and two space dimensions without the use of any phase component. We compare and contrast the focusing parameters of the optimal waves with those of other diffractive focusing approaches, such as Fresnel zones. Moreover, we experimentally demonstrate these focusing properties on optical beams using both reflective and transmissive liquid crystal devices. Our results provide an alternative direction for focusing waves where phase elements are challenging to implement, such as for X-rays, THz radiation, and electron beams.

[65] arXiv:2406.13549 [pdf, other]

Title: Hardware Realization of Neuromorphic Computing with a 4-Port Photonic Reservoir for Modulation Format Identification

Enes Şeker, Rijil Thomas, Guillermo von Hünefeld, Stephan Suckow, Mahdi Kaveh, Gregor Ronniger, Pooyan Safari, Isaac Sackey, David Stahl, Colja Schubert, Johannes Karl Fischer, Ronald Freund, Max C. Lemme

Comments: 32 pages, including supporting information

Subjects: Applied Physics (physics.app-ph)

The fields of machine learning and artificial intelligence drive researchers to explore energy-efficient, brain-inspired new hardware. Reservoir computing encompasses recurrent neural networks for sequential data processing and matches the performance of other recurrent networks with less training and lower costs. However, traditional software-based neural networks suffer from high energy consumption due to computational demands and massive data transfer needs. Photonic reservoir computing overcomes this challenge with energy-efficient neuromorphic photonic integrated circuits or NeuroPICs. Here, we introduce a reservoir NeuroPIC used for modulation format identification in C-band telecommunication network monitoring. It is built on a silicon-on-insulator platform with a 4-port reservoir architecture consisting of a set of physical nodes connected via delay lines. We comprehensively describe the NeuroPIC design and fabrication, experimentally demonstrate its performance, and compare it with simulations. The NeuroPIC incorporates non-linearity through a simple digital readout and achieves close to 100% accuracy in identifying several configurations of quadrature amplitude modulation formats transmitted over 20 km of optical fiber at 32 GBaud symbol rate. The NeuroPIC performance is robust against fabrication imperfections like waveguide propagation loss, phase randomization, etc. and delay line length variations. Furthermore, the experimental results exceeded numerical simulations, which we attribute to enhanced signal interference in the experimental NeuroPIC output. Our energy-efficient photonic approach has the potential for high-speed temporal data processing in a variety of applications.

[66] arXiv:2406.13591 [pdf, other]

Title: Highly Sensitive Label-free Biomolecular Detection Using Au-WS2 Nanohybrid Based SERS Substrates

Om Prakash, Abhijith T, Priya Nagpal, Vivekanandan Perumal, Supravat Karak, Udai B. Singh, Santanu Ghosh

Subjects: Applied Physics (physics.app-ph); Materials Science (cond-mat.mtrl-sci)

Recent advancements in nanotechnology have led to the development of surface-enhanced Raman spectroscopy (SERS) based rapid and low-cost technologies for ultra-sensitive label-free detection and identification of molecular analytes. Herein, we utilized the synergistic plasmonic and chemical enhancement effects of Au-WS2 nanohybrids to attain the high-intensity Raman signals of targeted analytes. To develop these nanohybrids, a series of monodispersed Au nanoparticles (NPs) of varying diameters from 20 to 80 nm was chemically synthesized and successively blended with liquid-phase exfoliated WS2 nano-flakes of average lateral size 90 nm. They provided a maximum enhancement factor (EF) of ~1.80 109 corresponding to the characteristic peaks at 1364 cm-1 and 1512 cm-1 for R6G analyte molecules. Theoretical studies based on the finite-difference time-domain simulations on Au-WS2 nanohybrid systems revealed a huge field-intensity enhancement with an EF of more than 1000 at the plasmonic hotspots, which was induced by the strong coupling of individual plasmon oscillations of the adjacent Au NPs upon light interactions. These electromagnetic effects along with the chemical enhancement effects of WS2 nanoflakes were found to be mainly responsible for such huge enhancement in Raman signals. Furthermore, these hybrids were successfully employed for achieving highly sensitive detection of the E. coli ATCC 35218 bacterial strain with a concentration of 104 CFU/mL in phosphate-buffered saline media, indicating their real capabilities for practical scenarios. The findings of the present study will indeed provide vital information in the development of innovative nanomaterial-based biosensors, that will offer new possibilities for addressing critical public health concerns.

[67] arXiv:2406.13596 [pdf, other]

Title: SDR Common View on Generic Signals for Time Transfer Applications

Fabrizio Pollastri

Comments: 7 pages, 8 figures, article

Subjects: Instrumentation and Detectors (physics.ins-det)

This paper presents a new time transfer system that works with any radio signal with sufficient bandwidth, regardless of its content and modulation, by adopting the common view approach. This system, based on a network client-server architecture with SDR receivers offers a number of advantages. It can compare remote atomic clocks or disseminate reference time scales to end users with precision at the level of tens of nanoseconds. Its improved features in terms of flexibility, robustness, reliability, and security will potentially make positive contributions in the field of time transfer, as an alternative or complement to existing methods.

[68] arXiv:2406.13598 [pdf, html, other]

Title: Cryogenic cesium iodide as a potential PET material

S. R. Soleti, A. Castillo, M. del Barrio-Torregrosa, C. Echeverria, M. Seemann, D. Zerzion, J. J. Gómez Cadenas

Comments: 5 pages, 7 figures, PSMR2024 conference

Subjects: Instrumentation and Detectors (physics.ins-det); Medical Physics (physics.med-ph)

Total-body PET (TB-PET) scanners, with axial lengths exceeding 1 meter, provide significantly higher sensitivity than conventional PET scanners due to their greater acceptance of gamma pairs. However, this increased sensitivity often comes from gamma rays detected at oblique angles, leading to substantial multiple scattering along the patient's body. Additionally, the cost of TB-PET scanners scales with their extended detector length, often costing 5 to 10 times more than conventional scanners. Therefore, optimizing TB-PET performance requires crystals that enhance energy resolution and control costs.
Cesium iodide (CsI), though historically less favored for PET due to its lower stopping power and light yield compared to crystals like LYSO, shows remarkable improvement when operated at cryogenic temperatures ($\sim$100 K). Under these conditions, CsI light yield rises dramatically to about 100 photons/keV, providing excellent energy resolution and good coincidence time resolution at a lower cost - typically 3 to 5 times cheaper than other crystals at parity of radiation length.
In our study, cryogenic CsI crystals achieved an energy resolution better than 7% FWHM at 511 keV and a coincidence time resolution of less than 2 ns. These results demonstrate the potential of cryogenic CsI as a cost-effective, high-performance material for TB-PET scanners.

[69] arXiv:2406.13603 [pdf, html, other]

Title: Formation of a Magnetic Cloud from the Merging of Two Successive Coronal Mass Ejections

Chong Chen, Ying D. Liu, Bei Zhu, Huidong Hu, Rui Wang

Subjects: Space Physics (physics.space-ph); Solar and Stellar Astrophysics (astro-ph.SR)

On 2022 March 28 two successive coronal mass ejections (CMEs) were observed by multiple spacecraft and resulted in a magnetic cloud (MC) at 1 AU. We investigate the propagation and interaction properties of the two CMEs correlated with the MC using coordinated multi-point remote sensing and in situ observations from Solar Orbiter, STEREO A, SOHO, and Wind. The first CME was triggered by a filament eruption with a high inclination angle. Roughly 9 hr later, the second CME originating from the same active region erupted with a smaller tilt angle and faster speed compared to the first one. The second CME overtook the preceding CME and formed a merged front at approximately 75 \rsun{}, which developed into a complex ejecta at 1 AU. The descending speed and low proton temperature inside the complex ejecta suggest that the two CMEs have fully merged before reaching 1 AU, leading them to begin expanding rather than compressing against each other. The complex ejecta appears to have the magnetic field and plasma signatures of an MC, although there is a discontinuity in the magnetic field implying previous interactions. The cross section of the complex ejecta, reconstructed from in situ data using a Grad-Shafranov technique, exhibits a right--handed flux rope structure. These results highlight that an MC--like complex ejecta lacking interaction features could arise from the complete merging of two CMEs.

[70] arXiv:2406.13610 [pdf, other]

Title: Towards the optimization of a perovskite-based room temperature ozone sensor: A multifaceted approach in pursuit of sensitivity, stability, and understanding of mechanism

Aikaterini Argyrou, Rafaela Maria Giappa, Emmanouil Gagaoudakis, Vasilios Binas, Ioannis Remediakis, Konstantinos Brintakis, Athanasia Kostopoulou, Emmanuel Stratakis

Comments: Main document 35 pages, 6 panel figures. Support information 28 pages, 43 figures

Subjects: Chemical Physics (physics.chem-ph); Materials Science (cond-mat.mtrl-sci)

Metal halide perovskites (MHPs) have attracted significant attention owing to their simple manufacturing process and unique optoelectronic properties. Their reversible electrical or optical properties changes in response to oxidizing or reducing environments make them prospective materials for gas detection technologies. Despite advancements in perovskite-based sensor research, the mechanisms behind perovskite-gas interactions, vital for sensor performance, are still unexclusive. This work presents the first evaluation of the sensing performance and long-term stability of MHPs, considering factors such as halide composition variation and Mn doping levels. The research reveals a clear correlation between halide composition and sensing behavior, with Br-rich sensors displaying a p-type response to O3 gas, while Cl-based counterparts exhibit an n-type sensing behavior. Notably, Mn-doping significantly enhances the O3 sensing performance by facilitating the gas adsorption process, as supported by both atomistic simulations and experimental evidence. Long-term evaluation of the sensors provides valuable insights into evolving sensing behaviors, highlighting the impact of dynamic instabilities over time. Overall, this research offers insights into optimal halide combination and Mn-doping levels, representing a significant step forward in engineering room temperature perovskite-based gas sensors that are not only low-cost and high-performing but also durable, marking a new era in sensor technology.

[71] arXiv:2406.13638 [pdf, html, other]

Title: XENONnT WIMP Search: Signal & Background Modeling and Statistical Inference

XENON Collaboration: E. Aprile, J. Aalbers, K. Abe, S. Ahmed Maouloud, L. Althueser, B. Andrieu, E. Angelino, D. Antón Martin, F. Arneodo, L. Baudis, M. Bazyk, L. Bellagamba, R. Biondi, A. Bismark, K. Boese, A. Brown, G. Bruno, R. Budnik, J. M. R. Cardoso, A. P. Cimental Chávez, A. P. Colijn, J. Conrad, J. J. Cuenca-García, V. D'Andrea, L. C. Daniel Garcia, M. P. Decowski, C. Di Donato, P. Di Gangi, S. Diglio, K. Eitel, A. Elykov, A. D. Ferella, C. Ferrari, H. Fischer, T. Flehmke, M. Flierman, W. Fulgione, C. Fuselli, P. Gaemers, R. Gaior, M. Galloway, F. Gao, S. Ghosh, R. Giacomobono, R. Glade-Beucke, L. Grandi, J. Grigat, H. Guan, M. Guida, P. Gyoergy, R. Hammann, A. Higuera, C. Hils, L. Hoetzsch, N. F. Hood, M. Iacovacci, Y. Itow, J. Jakob, F. Joerg, Y. Kaminaga, M. Kara, P. Kavrigin, S. Kazama, M. Kobayashi, A. Kopec, F. Kuger, H. Landsman, R. F. Lang, L. Levinson, I. Li, S. Li, S. Liang, Y.-T. Lin, S. Lindemann, M. Lindner, K. Liu, J. Loizeau, F. Lombardi, J. Long, J. A. M. Lopes, T. Luce, Y. Ma, C. Macolino, J. Mahlstedt, A. Mancuso, L. Manenti, F. Marignetti, T. Marrodán Undagoitia, K. Martens, J. Masbou, E. Masson, S. Mastroianni, A. Melchiorre, M. Messina, A. Michael, K. Miuchi, A. Molinario, S. Moriyama, K. Morå

Comments: 20 pages, 10 figures

Subjects: Data Analysis, Statistics and Probability (physics.data-an); Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Physics - Experiment (hep-ex); Instrumentation and Detectors (physics.ins-det)

The XENONnT experiment searches for weakly-interacting massive particle (WIMP) dark matter scattering off a xenon nucleus. In particular, XENONnT uses a dual-phase time projection chamber with a 5.9-tonne liquid xenon target, detecting both scintillation and ionization signals to reconstruct the energy, position, and type of recoil. A blind search for nuclear recoil WIMPs with an exposure of 1.1 tonne-years yielded no signal excess over background expectations, from which competitive exclusion limits were derived on WIMP-nucleon elastic scatter cross sections, for WIMP masses ranging from 6 GeV/$c^2$ up to the TeV/$c^2$ scale. This work details the modeling and statistical methods employed in this search. By means of calibration data, we model the detector response, which is then used to derive background and signal models. The construction and validation of these models is discussed, alongside additional purely data-driven backgrounds. We also describe the statistical inference framework, including the definition of the likelihood function and the construction of confidence intervals.

[72] arXiv:2406.13669 [pdf, other]

Title: Micro-gap thermo-photo-thermionics: An alternative approach to harvesting thermo-photons and its comparison with thermophotovoltaics

Ehsanur Rahman, Alireza Nojeh

Comments: 35 pages, 6 figures, 3 tables

Journal-ref: Applied Thermal Engineering,224, 119993, 2023

Subjects: Applied Physics (physics.app-ph)

This work investigates an alternative to thermophotovoltaics for harvesting thermal and optical energy via photon coupling and thermionic energy conversion. In this device, a heat source is radiatively coupled to a thermionic electron emitter through a nanoscale gap and the electron emitter is coupled to collector through a microscale gap. The analysis using fluctuational electrodynamics and finite time thermodynamics shows that for identical thermal radiator and photon to electron conversion materials, the output power density in the thermionic device can be more than twice that of the thermophotovoltaic device; the thermionic mechanism can also provide more than 30 percent improvement in the energy conversion efficiency compared to the thermophotovoltaic device. Moreover, the maximum power point voltage in the thermionic device is shown to significantly exceed the band gap of conversion material, which determines the theoretical upper limit of the open circuit voltage in a thermophotovoltaic cell. Therefore, the results of this study indicate that thermionic energy harvesting via thermo-photon coupling can be a promising alternative to thermophotovoltaics.

[73] arXiv:2406.13680 [pdf, html, other]

Title: Effects of settling on inertial particle slip velocity statistics in wall bounded flows

Andrew P. Grace, David Richter, Tim Berk, Andrew D. Bragg

Subjects: Fluid Dynamics (physics.flu-dyn); Mathematical Physics (math-ph); Atmospheric and Oceanic Physics (physics.ao-ph)

Developing reduced order models for the transport of solid particles in turbulence typically requires a statistical description of the particle-turbulence interactions. In this work, we utilize a statistical framework to derive continuum equations for the moments of the slip velocity of inertial settling Lagrangian particles in a turbulent boundary layer. Using coupled Eulerian-Lagrangian direct numerical simulations, we then identify the dominant mechanisms controlling the slip velocity variance, and find that for a range of St+, Sv+, and Re, the slip variance is primarily controlled by local differences between the "seen" variance and the particle velocity variance, while terms appearing due to the inhomogeneity of the turbulence are sub-leading until Sv+ becomes large. We also consider several comparative metrics to assess the relative magnitudes of the fluctuating slip velocity and the mean slip velocity, and we find that the vertical mean slip increases rapidly with Sv+, rendering the variance relatively small -- an effect found to be most substantial for Sv+>1. Finally, we compare the results to a model of the acceleration variance Berk and Coletti (2021) based the concept of a response function described in Csanady (1963), highlighting the role of the crossing trajectories mechanism. We find that while there is good agreement for low Sv+, systematic errors remain, possibly due to implicit non-local effects arising from rapid particle settling and inhomogeneous turbulence. We conclude with a discussion of the implications of this work for modeling the transport of coarse dust grains in the atmospheric surface layer.

[74] arXiv:2406.13685 [pdf, html, other]

Title: Transverse spin and orbital angular momenta in rotating-wave structured light

Zhen-Lai Wang

Subjects: Optics (physics.optics)

Within monochromatic optical fields, we demonstrate the rotating-wave structured light with wave vortex carrying an intrinsic transverse orbital angular momentum orthogonal to the propagation direction of light. Remarkably, we find that such a rotating-wave structured light reveals highly nontrivial features of transverse spin and orbital angular momentum densities. The normalized total angular momentum density is conserved universally, suggesting a mutual conversion of the intrinsic transverse spin and orbital angular momentum in free space. Despite such mutual conversion at local level, the integral intrinsic orbital angular momentum can be well defined with the topological charge of the vortex per photon. Moreover, the orientation of transverse spin density is governed by the direction of the Poynting momentum density, manifesting a spin-momentum-locking effect in free space.

[75] arXiv:2406.13686 [pdf, html, other]

Title: A 1.8-um pitch, 47-ps jitter SPAD Array in 130nm SiGe BiCMOS Process

Feng Liu, Edoardo Charbon

Comments: journal

Subjects: Instrumentation and Detectors (physics.ins-det)

We introduce the world's first SPAD family design in 130 nm SiGe BiCMOS process. At 1.8um, we achieved the smallest pitch on record thanks to guard-ring sharing techniques, while keeping a relatively high fill factor of 24.2%. 4x4 SPAD arrays with two parallel selective readout circuits were designed to explore crosstalk and scalability. The SPAD family has a minimum breakdown voltage of 11 V, a maximum PDP of 40.6% and a typical timing jitter of 47 ps FWHM. The development of silicon SPADs in SiGe process paves the way to Ge-on-Si SPADs for SWIR applications, and to cryogenic optical interfaces for quantum applications.

[76] arXiv:2406.13766 [pdf, html, other]

Title: Nonlinear modulation of dispersive fast magnetosonic waves in an inhomogeneous rotating solar low-$\beta$ magnetoplasma

J. Turi, A. P. Misra

Comments: 14 Pages, 7 figures

Subjects: Plasma Physics (physics.plasm-ph); Solar and Stellar Astrophysics (astro-ph.SR)

We study the modulation of fast magnetosonic waves (MSWs) in rotating inhomogeneous low-$\beta$ magnetoplasmas with the effects of gravitation and the Coriolis force. By employing the standard multiple-scale reductive perturbation technique (RPT), we derive a nonlinear Schrödinger (NLS) equation that governs the evolution of slowly varying MSW envelopes. The fast MSW becomes dispersive by the effects of the Coriolis force in the fluid motion, and the magnetic field and density inhomogeneity effects favor the Jeans instability in self-gravitating plasmas in a larger domain of the wave number ($k$, below the Jeans critical wave number, $k_J$) than homogeneous plasmas. The relative influence of the Jeans frequency ($\omega_J$, associated with the gravitational force) and the angular frequency ($\Omega_0$, relating to the Coriolis force) on the Jeans carrier MSW mode and the modulational instability (MI) of the MSW envelope is studied. We show that the MSW envelope (corresponding to the unstable carrier Jeans mode with $\omega_J>2\Omega_0$ and $k<k_J$) is always unstable against the plane wave perturbation with no cut-offs for growth rates. In contrast, the stable Jeans mode with $\omega_J>2\Omega_0$ but $k>k_J$ manifests either modulational stability or MI having a finite growth rate before being cut off. We find an enhancement of the MI growth rate by the influence of magnetic field or density inhomogeneity. The case with constant gravity force (other than the self-gravity) perpendicular to the magnetic field is also briefly discussed to show that the fast magnetosonic carrier mode is always unstable, giving MI of slowly varying envelopes with no cut-offs for the growth rates. Possible applications of MI in solar plasmas, such as those in the X-ray corona, are also briefly discussed.

[77] arXiv:2406.13767 [pdf, html, other]

Title: A fully observer-covariant formulation of the fluid dynamics of simple fluids: derivation, simple examples and a generalized Orr-Sommerfeld equation

Alberto Scotti

Subjects: Fluid Dynamics (physics.flu-dyn); Mathematical Physics (math-ph)

We present a formalism to describe the motion of a fluid fully which is fully covariant with respect to arbitrary observers. To achieve fully covariance, we write prognostic equations for quantities that belong to the graded exterior algebra of the cotangent bundle of the manifold occupied by the fluid. With the new formalism, we consider problems of stability, and we derive a generalization of the Orr-Sommerfeld equation that describes the evolution of perturbations relative to an arbitrary observer. The latter is applied to cases where the observer is the Lagrangian observer comoving with the background flow.

[78] arXiv:2406.13776 [pdf, html, other]

Title: Flow and clogging of capillary droplets

Yuxuan Cheng, Benjamin F. Lonial, Shivnag Sista, David J. Meer, Anisa Hofert, Eric R. Weeks, Mark D. Shattuck, Corey S. O'Hern

Subjects: Computational Physics (physics.comp-ph); Fluid Dynamics (physics.flu-dyn)

Capillary droplets form due to surface tension when two immiscible fluids are mixed. We describe the motion of gravity-driven capillary droplets flowing through narrow constrictions and obstacle arrays in both simulations and experiments. Our new capillary deformable particle model recapitulates the shape and velocity of single oil droplets in water as they pass through narrow constrictions in microfluidic chambers. Using this experimentally validated model, we simulate the flow and clogging of single capillary droplets in narrow channels and obstacle arrays and find several important results. First, the capillary droplet speed profile is nonmonotonic as the droplet exits the narrow orifice, and we can tune the droplet properties so that the speed overshoots the terminal speed far from the constriction. Second, in obstacle arrays, we find that extremely deformable droplets can wrap around obstacles, which leads to decreased average droplet speed in the continuous flow regime and increased probability for clogging in the regime where permanent clogs form. Third, the wrapping mechanism causes the clogging probability in obstacle arrays to become nonmonotonic with surface tension $\Gamma$. At large $\Gamma$, the droplets are nearly rigid and the clogging probability is large since the droplets can not squeeze through the gaps between obstacles. With decreasing $\Gamma$, the clogging probability decreases as the droplets become more deformable. However, in the small-$\Gamma$ limit the clogging probability increases, since the droplets are extremely deformable and cause clogs as they wrap around the obstacles. The results from these studies are important for developing a predictive understanding of capillary droplet flows through complex and confined geometries.

[79] arXiv:2406.13782 [pdf, html, other]

Title: Clock-line-mediated Sisyphus Cooling

Chun-Chia Chen, Jacob L. Siegel, Benjamin D. Hunt, Tanner Grogan, Youssef S. Hassan, Kyle Beloy, Kurt Gibble, Roger C. Brown, Andrew D. Ludlow

Comments: 8 pages, 6 figures

Subjects: Atomic Physics (physics.atom-ph)

We demonstrate sub-recoil Sisyphus cooling using the long-lived $^{3}\mathrm{P}_{0}$ clock state in alkaline-earth-like ytterbium. A 1388 nm optical standing wave nearly resonant with the $^{3}\textrm{P}_{0}$$\,\rightarrow$$\,^{3}\textrm{D}_{1}$ transition creates a spatially periodic light shift of the $^{3}\textrm{P}_{0}$ clock state. Following excitation on the ultranarrow clock transition, we observe Sisyphus cooling in this potential, as the light shift is correlated with excitation to $^{3}\textrm{D}_{1}$ and subsequent spontaneous decay to the $^{1}\textrm{S}_{0}$ ground state. We observe that cooling enhances the loading efficiency of atoms into a 759 nm magic-wavelength one-dimensional (1D) optical lattice, as compared to standard Doppler cooling on the $^{1}\textrm{S}_{0}$$\,\rightarrow\,$$^{3}\textrm{P}_{1}$ transition. Sisyphus cooling yields temperatures below 200 nK in the weakly confined, transverse dimensions of the 1D optical lattice. These lower temperatures improve optical lattice clocks by facilitating the use of shallow lattices with reduced light shifts, while retaining large atom numbers to reduce the quantum projection noise. This Sisyphus cooling can be pulsed or continuous and is applicable to a range of quantum metrology applications.

[80] arXiv:2406.13789 [pdf, html, other]

Title: Death, Taxes, and Inequality. Can a Minimal Model Explain Real Economic Inequality?

John C. Stevenson

Comments: 16 pages, 6 figures, 1 table, 1 algorithm table

Subjects: Physics and Society (physics.soc-ph); Computational Finance (q-fin.CP)

Income inequalities and redistribution policies are modeled with a minimal, endogenous model of a simple foraging economy. The model is scaled to match human lifespans and overall death rates. Stochastic income distributions from the model are compared to empirical data from actual economies. Empirical data are fit to implied distributions providing necessary resolution for comparison. The impacts of redistribution policies on total wealth, income distributions, and inequality are shown to be similar for the empirical data and the model. These comparisons enable detailed determinations of population welfare beyond what is possible with total wealth and inequality metrics. Estate taxes in the model appear quite effective in reducing inequality without reducing total wealth. Significant income inequality emerges for the model for a population of equally capable individuals presented with equal opportunities. Stochastic population instability at both the high and low ends of infertility are considered.

[81] arXiv:2406.13804 [pdf, html, other]

Title: Elasticity and acoustic velocities of $\delta$-AlOOH at extreme conditions: a methodology assessment

Chenxing Luo, Yang Sun, Renata Wentzcovitch

Subjects: Computational Physics (physics.comp-ph); Materials Science (cond-mat.mtrl-sci); Geophysics (physics.geo-ph)

Hydrous phases play a fundamental role in the deep-water cycle on Earth. Understanding their stability and thermoelastic properties is essential for constraining their abundance using seismic tomography. However, determining their elastic properties at extreme conditions is notoriously challenging. The challenges stem from the complex behavior of hydrogen bonds under high pressures and temperatures (P,Ts). In this study, we evaluate how advanced molecular dynamics simulation techniques can address these challenges by investigating the adiabatic elasticity and acoustic velocities of $\delta$-AlOOH, a critical and prototypical high-pressure hydrous phase. We compared the performances of three methods to assess their viability and accuracy. The thermoelastic tensor was computed up to 140 GPa and temperatures up to 2,700 K using molecular dynamics with a DeePMD machine-learning interatomic potential based on the SCAN meta-GGA functional. The excellent agreement with ambient condition single-crystal ultrasound measurements and the correct description of velocity changes induced by H-bond disorder-symmetrization transition observed at 10 GPa in Brillouin scattering measurements underscores the accuracy and efficacy of our approach.

[82] arXiv:2406.13816 [pdf, html, other]

Title: The Dangerous Allure of Low Fertility

John C. Stevenson

Comments: 9 pages, 5 figures, 2 appendices, 1 table

Subjects: Physics and Society (physics.soc-ph); Populations and Evolution (q-bio.PE)

Stochastic population and wealth trajectories for societies as functions of fertility are modeled with a minimal, endogenous model of a simple foraging economy. The model is scaled to match human lifespans and overall death rates. Stochastic population instability at both the high and low ends of fertility are considered. Lower population levels, caused by low fertility, generate concerns on economic growth, military security, and international political power; while also seen by some as reducing ecological and environmental damage. The model shows that increasingly low fertility leads to both higher wealth and lower population levels. As society is encouraged by increasing per capita wealth to continue to decrease fertility, dangerous population regimes are reached where stochastic extinction becomes more and more likely.

[83] arXiv:2406.13832 [pdf, html, other]

Title: Poiseuille flow for a simplified pseduoplastic rheology

Chris Reese

Subjects: Fluid Dynamics (physics.flu-dyn); Soft Condensed Matter (cond-mat.soft)

Poiseuille flow in cylindrical and planar geometries with a simplified, pseudoplastic (shear thinning) rheology characterized by constant viscosity plateaus above and below a transition strain rate is considered. Analytical, steady state solutions for velocity profile and volume flux are formulated. Transient flow development is addressed numerically and compared to the theory in the steady state limit. Stationary flow is approached after the momentum diffusion timescale based on the spatially dominant kinematic viscosity. For large viscosity ratio and shear thinning region confined near the domain boundary, velocity distributions are quasi-plug like with large boundary to interior strain rate ratio.

[84] arXiv:2406.13837 [pdf, html, other]

Title: U-shaped disks in Stokes flow: Chiral sedimentation of a non-chiral particle

Christian Vaquero-Stainer, Tymoteusz Miara, Anne Juel, Draga Pihler-Puzović, Matthias Heil

Comments: 27 pages, 12 figures

Subjects: Fluid Dynamics (physics.flu-dyn)

We study the sedimentation of U-shaped circular disks in the Stokes limit of vanishing inertia. We simulate the flow past such disks using a finite-element-based solution of the 3D Stokes equations, accounting for the integrable singularities that develop along their edges. We show that the purely vertical sedimentation of such disks in their upright- [upside-down-] U orientation is unstable to perturbations about their pitching [rolling] axes. The instability is found to depend only weakly on the size of the container in which the disks sediment, allowing us to analyse their behaviour based on the resistance matrix which governs the evolution of the disk's six rigid-body degrees of freedom in an unbounded fluid. We show that the governing equations can be reduced to two ODEs which describe the disk's inclination against the direction of gravity. A phase-plane analysis, results of which are in good agreement with experiments, reveals that the two instabilities generally cause the disk to sediment along complex spiral trajectories while it alternates between pitching- and rolling-dominated motions. The chirality of the trajectories is set by the initial conditions rather than the (non-chiral) shape of the disk. For certain initial orientations, the disk retains its inclination and sediments along a perfectly helical path. The observed behaviour is fundamentally different from that displayed by flat circular disks which sediment without any reorientation. We therefore study the effect of variations in the disk's curvature to show how in the limit of vanishing curvature the behaviour of a flat disk is recovered.

[85] arXiv:2406.13838 [pdf, html, other]

Title: Potential Flow Formulation of Parker's Unsteady Solar Wind Model and Nonlinear Stability Aspects Near the Parker Sonic Critical Point

Bhimsen K. Shivamoggi

Subjects: Space Physics (physics.space-ph); Solar and Stellar Astrophysics (astro-ph.SR); Plasma Physics (physics.plasm-ph)

The purpose of this paper is to present the first ever systematic theoretical formulation to address the long-standing issue of regularization of the singularity associated with the Parker sonic critical point in the linear perturbation problem for Parker's unsteady solar wind model. This is predicated on the necessity to go outside the framework of the linear perturbation problem and incorporate the dominant nonlinearities in this dynamical system. For this purpose, a whole new theoretical formulation of Parker's unsteady solar wind model based on the potential flow theory in ideal gas dynamics is given, which provides an appropriate optimal theoretical framework to accomplish this task. The stability of Parker's steady solar wind solution is shown to extend also to the neighborhood of the Parker sonic critical point by going to the concomitant nonlinear problem.

[86] arXiv:2406.13852 [pdf, html, other]

Title: On the Dual-Phase-Lag thermal response in the Pulsed Photoacoustic effect: 1D approach

L.F. Escamilla-Herrera, J.M. Domínguez-Derramadero, J. E. Alba-Rosales, F.J. García-Rodríguez, O. M. Medina-Cázares, G. Gutiérrez-Juárez

Comments: 32 pages, 11 figures

Subjects: General Physics (physics.gen-ph); Optics (physics.optics)

The Photoacoustic (PA) effect is the mechanism to convert non-ionizing electromagnetic energy into mechanical one; its main application is PA imaging in biomedicine. In this work, and in order to consider the heat flux non-heuristically, we obtained exact solutions of a 1D boundary value problem of the Dual-Phase-Lag (DPL) heat conduction equation for a three-layer system in the frequency domain; once the thermal boundary problem was solved via the DPL model, the second derivative of temperature solutions were considered as the PA source in the respective 1D boundary value problem for the pressures, via the PA wave equation. Temperature and pressure solutions were explored by assuming two considerations; being the first one, that the characteristic thermal lag response time $\tau_{_T}$ related with the DPL heat conduction model, is a free parameter on this effective model. The second one is that for the sake of simplicity, the whole is system is assumed to have the same value for the $\tau_{_T}$, i.e., the three-layer system relax thermally in the same way. Both assumptions are made, since up to our knowledge, there are not first-principles proposals for the values of this parameter, nor experimental measurements available in the literature. By varying $\tau_{_T}$, theoretical solutions for pressure can be adjusted to reproduce experimental results accurately; we have found that under this assumption if $\tau_{_T}$ is close to the laser pulse time $\tau_p$, acoustic multiple reflections are accurately reproduced in the frequency domain and, via Fast Fourier transforms, PA pulses are also reproduced accurately in the time domain.

[87] arXiv:2406.13884 [pdf, html, other]

Title: Quasilinear drift kinetic theory of alpha particle transport by neoclassical tearing modes

Elizabeth A. Tolman, Peter J. Catto

Comments: 17 pages, 1 figure

Subjects: Plasma Physics (physics.plasm-ph)

Kinetic theory of particles near resonances is a current topic of discussion in plasma physics and astrophysics. We extend this discussion to the kinetic theory of the interaction between alpha particles (energetic particles predicted to exist in large quantities in next-generation fusion experiments) and a neoclassical tearing mode (NTM), a resistively-driven perturbation that sometimes exists in a tokamak. We develop a quasilinear treatment of the interaction between alphas and an NTM, showing why an NTM can be a source of significant passing alpha particle transport in tokamaks. The limitations on quasilinear theory constrain our theory's applicability to small amplitude NTMs, highlighting the importance of nonlinear studies.

[88] arXiv:2406.13907 [pdf, html, other]

Title: Observation of full contrast icosahedral Bose-Einstein statistics in laser desorbed, buffer gas cooled C$_{60}$

Ya-Chu Chan, Lee R. Liu, Andrew Scheck, David J. Nesbitt, Jun Ye, Dina Rosenberg

Subjects: Atomic Physics (physics.atom-ph); Chemical Physics (physics.chem-ph); Quantum Physics (quant-ph)

The quantum mechanical nature of spherical top molecules is particularly evident at low angular momentum quantum number J. Using infrared spectroscopy on the 8.4$\mu$m rovibrational band of buffer gas cooled $^{12}$C$_{60}$, we observe the hitherto unseen R(J = 0 - 29) rotational progression, including the complete disappearance of certain transitions due to the molecule's perfect icosahedral symmetry and identical bosonic nuclei. The observation of extremely weak C$_{60}$ absorption is facilitated by a laser desorption C$_{60}$ vapor source, which transfers 1000-fold less heat to the cryogenic buffer gas cell than a traditional oven source. This technique paves the way to cooling C$_{60}$ and other large gas phase molecules to much lower temperatures, providing continued advances for spectral resolution and sensitivity.

[89] arXiv:2406.13946 [pdf, other]

Title: Ferroelectric Materials for Synaptic Transistors and Their Neuromorphic Applications

Zexin Wang

Comments: 44 pages, 7 figures,

Subjects: Applied Physics (physics.app-ph); Materials Science (cond-mat.mtrl-sci); Emerging Technologies (cs.ET)

After more than a hundred years of development, ferroelectric materials have demonstrated their strong potential to people, and more and more ferroelectric materials are being used in the research of ferroelectric transistors (FeFETs). As a new generation of neuromorphic devices, ferroelectric materials have attracted people's attention due to their powerful functions and many characteristics. This article summarizes the development of ferroelectric material systems in recent years and discusses the simulation of artificial synapses. The mainstream ferroelectric materials are divided into traditional perovskite structure, fluorite structure, organic polymer, and new 2D van der Waals ferroelectricity. The principles, research progress, and optimization for brain like computers of each material system are introduced, and the latest application progress is summarized. Finally, the scope of application of different material systems is discussed, with the aim of helping people screen out different material systems based on different needs.

[90] arXiv:2406.13956 [pdf, other]

Title: Orbit symmetry breaking in MXene implements enhanced soft bioelectronic implants

Yizhang Wu, Yuan Li, Yihan Liu, Dashuai Zhu, Sicheng Xing, Noah Lambert, Hannah Weisbecker, Siyuan Liu, Brayden Davis, Lin Zhang, Meixiang Wang, Gongkai Yuan, Chris Zhoufan You, Anran Zhang, Cate Duncan, Wanrong Xie, Yihang Wang, Yong Wang, Sreya Kanamurlapudi, Garcia-Guzman Evert, Arjun Putcha, Michael D. Dickey, Ke Huang, Wubin Bai

Subjects: Applied Physics (physics.app-ph)

Bioelectronic implants with soft mechanics, biocompatibility, and excellent electrical performance enable biomedical implants to record electrophysiological signals and execute interventions within internal organs, promising to revolutionize the diagnosing, monitoring, and treatment of various pathological conditions. However, challenges remain in improving excessive impedance at the bioelectronic-tissue interface and thus the efficacy of electrophysiological signaling and intervention. Here, we devise orbit symmetry breaking in MXene (a low-cost scalability, biocompatible, and conductive 2D layered material, that we refer to as OBXene), that exhibits low bioelectronic-tissue impedance, originating from the out-of-plane charge transfer. Furthermore, the Schottky-induced piezoelectricity stemming from the asymmetric orbital configuration of OBXene facilitates interlayered charge transport in the device. In this study, we report an OBXene-based cardiac patch applied on the left ventricular epicardium of both rodent and porcine models to enable spatiotemporal epicardium mapping and pacing, while coupling the wireless and battery-free operation for long-term real-time recording and closed-loop stimulation.

[91] arXiv:2406.13958 [pdf, other]

Title: Symmetry engineering in 2D bioelectronics facilitating augmented biosensing interfaces

Yizhang Wu, Yihan Liu, Yuan Li, Ziquan Wei, Sicheng Xing, Yunlang Wang, Dashuai Zhu, Ziheng Guo, Anran Zhang, Gongkai Yuan, Zhibo Zhang, Ke Huang, Yong Wang, Guorong Wu, Ke Cheng, Wubin Bai

Subjects: Applied Physics (physics.app-ph)

Symmetry lies at the heart of 2D bioelectronics, determining material properties at the fundamental level. Breaking the symmetry allows emergent functionalities and effects. However, symmetry modulation in 2D bioelectronics and the resultant applications have been largely overlooked. Here we devise an oxidized architectural MXene, referred as OXene, that couples orbit symmetric breaking with inverse symmetric breaking to entitle the optimized interfacial impedance and Schottky-induced piezoelectric effects. The resulting OXene validates applications ranging from microelectrode arrays, gait analysis, active transistor matrix, and wireless signaling transmission, which enables highly-fidelity signal transmission and reconfigurable logic gates. Further OXene interfaces are investigated in both rodent and porcine myocardium, featuring high-quality and spatiotemporally resolved physiological recordings, while accurate differentiated predictions, enabled via various machine learning pipelines.

[92] arXiv:2406.13959 [pdf, html, other]

Title: Multifrequency-resolved Hanbury Brown-Twiss Effect

Joseph Ferrantini, Jesse Crawford, Sergei Kulkov, Jakub Jirsa, Aaron Mueninghoff, Lucas Lawrence, Stephen Vintskevich, Tommaso Milanese, Samuel Burri, Ermanno Bernasconi, Claudio Bruschini, Michal Marcisovsky, Peter Svihra, Andrei Nomerotski, Paul Stankus, Edoardo Charbon, Raphael A. Abrahao

Subjects: Optics (physics.optics); Instrumentation and Methods for Astrophysics (astro-ph.IM); Quantum Physics (quant-ph)

The Hanbury Brown-Twiss (HBT) effect holds a pivotal place in intensity interferometry and gave a seminal contribution to the development of quantum optics. To observe such an effect, both good spectral and timing resolutions are necessary. Most often, the HBT effect is observed for a single frequency at a time, due to limitations in dealing with multifrequencies simultaneously, halting and limiting some applications. Here, we report a fast and data-driven spectrometer built with a one-dimensional array of single-photon-sensitive avalanche diodes. We report observing the HBT effect for multifrequencies at the same time. Specifically, we observed the HBT for up to 5 lines of the Ne spectrum, but this can be improved even further. Our work represents a major step to make spectral binning and multifrequencies HBT more widely available. The technology we present can benefit both classical and quantum applications.

[93] arXiv:2406.13962 [pdf, html, other]

Title: Analyzing Near-Field Intensity Distribution in Subwavelength Gratings through Cylindrical Wave Decomposition

A.S. Bereza, A.E. Chernyavsky, S.V. Perminov, D.A. Shapiro

Comments: 14 pages, 8 figures, bibliography 31 item

Subjects: Optics (physics.optics)

The investigation into the scattering of plane waves by a periodic array of parallel cylinders utilizes the method of cylindrical wave decomposition, thereby reducing the problem complexity to a series of linear algebraic equations. This methodology proves particularly efficacious when the diameter of cylinders is significantly less than the wavelength of incident wave, resulting in a rapid diminution of the solution coefficients as a function of azimuth numbers. Such a reductionist approach facilitates the computation of scattered radiation intensity in near field. Subsequent cross-validation with numerical results corroborates the theoretical findings, showcasing a qualitative concordance between the two. This study underscores the efficacy of cylindrical wave decomposition in simplifying and accurately modeling wave scattering phenomena in structured media.

[94] arXiv:2406.13970 [pdf, other]

Title: Pixel-scale NIR-VIS Spectral Routers Based on 2D Mie-type Metagratings

Yifan Shao, Shuhan Guo, Rui Chen, Yongdi Dang, Yi Zhou, Yubo Wang, Junjie Zhan, Jiaqi Yu, Bing-Feng Ju, Yungui Ma

Journal-ref: Laser and Photonics Reviews 17, 2300027(2023)

Subjects: Optics (physics.optics)

The out-of-band energy loss caused by in-built color filters significantly degrades the signal-to-noise ratio and the dynamic range of conventional image sensors, which has restricted the attempt to develop ultrahigh-density imaging devices by merely shrinking the pixel size. This issue will be more serious for security cameras which need to collect visible (VIS) light and near-infrared (NIR) photons as well. The existing solutions mostly explore complex photonic nanostructures, which are often too complicated for production. In this work, we demonstrate a pixel-scale spectral router utilizing two-dimensional (2D) Si3N4 Mie scattering metagratings that can spatially divide NIR (850 nm) and VIS (400-700 nm) light to different pixels at high efficiencies. It has a minimum feature size larger than 360 nm, highly promising for massive production. Compared with the traditional filter design, our router can gain about 42% and 30% signal enhancement for NIR and VIS band, respectively. We show that it also has good polarization insensitivity and incident angle tolerance. The NIR-VIS simultaneous imaging is inspected without any complex reconstruction algorithm. Mode analysis indicates that the multipolar scattering of our Mie-type metagratings provides the necessary degrees of freedom to spatially optimize the routing functions for broadband photons.

[95] arXiv:2406.14018 [pdf, other]

Title: One-Dimensional, One-Phase and Two-Phase Eulerian Explicit Shock Tube Simulation Code

María Giselle Fernández-Godino

Comments: 72 pages, 15 figures, and 8 tables

Subjects: Fluid Dynamics (physics.flu-dyn); Computational Physics (physics.comp-ph)

In this work, a one-dimensional simulation code was developed for both single-phase and two-phase systems, focusing on time-dependent Euler equations for gas and particles. These equations, non-linear hyperbolic conservation laws, describe the dynamics of compressible materials, where body forces, viscous stresses, and heat flux are neglected. The Euler equations were discretized using the finite volume method, and the code was written in MATLAB. To test the accuracy of the computational fluid code, the Sod shock tube problem, a physical analogue of the Riemann problem, was employed. This problem models a pressure discontinuity where high and low-pressure regions are separated by a diaphragm, which breaks at t=0, creating a discontinuity in density as well. Exact solutions were used for code verification. A key focus was on modeling a curtain of particles impacted by a shock wave, relevant to multiphase heterogeneous cylindrical explosion studies by the PSAAP II project. This initiative, funded by the US Department of Energy (DOE) National Nuclear Security Administration (NNSA) Office of Advanced Simulation and Computing (ASC), involves Sandia National Laboratories and the Center for Compressible Multiphase Turbulence at the University of Florida. The propagation of uncertainties in the maximum density of the particle curtain was studied by varying initial curtain thickness and initial high density. Given the computational expense of multiple code evaluations for uncertainty propagation, a multi-fidelity surrogate model combining low and high-fidelity simulations was implemented. This model facilitated uncertainty propagation using DAKOTA, a flexible and extensible interface between analysis codes and iterative systems analysis methods.

[96] arXiv:2406.14037 [pdf, html, other]

Title: Delving into the Catalytic Mechanism of Molybdenum Cofactors: A Novel Coupled Cluster Study

Marta Gałyńska, Matheus Morato F. de Moraes, Paweł Tecmer, Katharina Boguslawski

Comments: 6 figures, 2 tables

Subjects: Chemical Physics (physics.chem-ph); Biological Physics (physics.bio-ph); Computational Physics (physics.comp-ph)

In this work, we use modern electronic structure methods to model the catalytic mechanism of different variants of the molybdenum cofactor (Moco). We investigate the dependence of various Moco model systems on structural relaxation and the importance of environmental effects for five critical points along the reaction coordinate with the DMSO and NO$_3^-$ substrates. Furthermore, we scrutinize the performance of various coupled-cluster approaches for modeling the relative energies along the investigated reaction paths, focusing on several pair coupled cluster doubles (pCCD) flavors and conventional coupled cluster approximations. Moreover, we elucidate the Mo--O bond formation using orbital-based quantum information measures, which highlight the flow of $\sigma_{\rm M-O}$ bond formation and $\sigma_{\rm N/S-O}$ bond breaking. Our study shows that pCCD-based models are a viable alternative to conventional methods and offer us unique insights into the bonding situation along a reaction coordinate. Finally, this work highlights the importance of environmental effects or changes in the core and, consequently, in the model itself to elucidate the change in activity of different Moco variants.

[97] arXiv:2406.14044 [pdf, html, other]

Title: Encoder-Decoder Neural Networks in Interpretation of X-ray Spectra

Jalmari Passilahti, Anton Vladyka, Johannes Niskanen

Subjects: Atomic and Molecular Clusters (physics.atm-clus); Machine Learning (cs.LG); Data Analysis, Statistics and Probability (physics.data-an)

Encoder-decoder neural networks (EDNN) condense information most relevant to the output of the feedforward network to activation values at a bottleneck layer. We study the use of this architecture in emulation and interpretation of simulated X-ray spectroscopic data with the aim to identify key structural characteristics for the spectra, previously studied using emulator-based component analysis (ECA). We find an EDNN to outperform ECA in covered target variable variance, but also discover complications in interpreting the latent variables in physical terms. As a compromise of the benefits of these two approaches, we develop a network where the linear projection of ECA is used, thus maintaining the beneficial characteristics of vector expansion from the latent variables for their interpretation. These results underline the necessity of information recovery after its condensation and identification of decisive structural degrees for the output spectra for a justified interpretation.

[98] arXiv:2406.14067 [pdf, other]

Title: A microwave photonic prototype for concurrent radar detection and spectrum sensing over an 8 to 40 GHz bandwidth

Taixia Shi, Dingding Liang, Lu Wang, Lin Li, Shaogang Guo, Jiawei Gao, Xiaowei Li, Chulun Lin, Lei Shi, Baogang Ding, Shiyang Liu, Fangyi Yang, Chi Jiang, Yang Chen

Comments: 18 pages, 12 figures, 1 table

Subjects: Optics (physics.optics); Signal Processing (eess.SP)

In this work, a microwave photonic prototype for concurrent radar detection and spectrum sensing is proposed, designed, built, and investigated. A direct digital synthesizer and an analog electronic circuit are integrated to generate an intermediate frequency (IF) linearly frequency-modulated (LFM) signal with a tunable center frequency from 2.5 to 9.5 GHz and an instantaneous bandwidth of 1 GHz. The IF LFM signal is converted to the optical domain via an intensity modulator and then filtered by a fiber Bragg grating (FBG) to generate only two 2nd-order optical LFM sidebands. In radar detection, the two optical LFM sidebands beat with each other to generate a frequency-and-bandwidth-quadrupled LFM signal, which is used for ranging, radial velocity measurement, and imaging. By changing the center frequency of the IF LFM signal, the radar function can be operated within 8 to 40 GHz. In spectrum sensing, one 2nd-order optical LFM sideband is selected by another FBG, which then works in conjunction with the stimulated Brillouin scattering gain spectrum to map the frequency of the signal under test to time with an instantaneous measurement bandwidth of 2 GHz. By using a frequency shift module to adjust the pump frequency, the frequency measurement range can be adjusted from 0 to 40 GHz. The prototype is comprehensively studied and tested, which is capable of achieving a range resolution of 3.75 cm, a range error of less than $\pm$ 2 cm, a radial velocity error within $\pm$ 1 cm/s, delivering clear imaging of multiple small targets, and maintaining a frequency measurement error of less than $\pm$ 7 MHz and a frequency resolution of better than 20 MHz.

[99] arXiv:2406.14105 [pdf, html, other]

Title: Barrier discharges in CO$_2$ -- optical emission spectra analysis and E/N determination from intensity ratio

Tomáš Hoder, David Prokop, Corentin Bajon, Simon Dap, Zdeněk Navrátil, Nicolas Naudé

Comments: 19 pages, 15 figures

Subjects: Plasma Physics (physics.plasm-ph)

We study barrier discharges in CO$_2$ using optical emission spectroscopy and electrical measurements. We record the spectra of weak CO$_2$ barrier discharge emission in UV-VIS-NIR range. The CO spectral bands of 3rd positive, Angstrom and Asundi systems are identified in the spectra, together with the CO+2 bands of the UV-doublet and the Fox-Duffendack-Baker systems. The effect of CO$_2$ flow rate variations on the relative intensities of the CO and CO$_2$ optical emissions is also investigated. We analyze the optical emission of selected vibrational spectral bands and attempt to determine the E/N using intensity ratio method with kinetic data available in the literature. The method, using intensities from different spectral bands, is tested on sinusoidal driven atmospheric pressure Townsend (APTD) and single-filament barrier discharges at atmospheric pressure. For APTD at different flows and known CO conversion factors, an attempt is made to use the ratio of selected CO to CO$_2$ band intensities. The technique of time-correlated single photon counting is used to obtain necessary sub-nanosecond temporal resolution and, importantly, high signal sensitivity for the single-filament experiment and its utilization gives a promising result, E/N of 330 Td in barrier discharge streamer. Nevertheless, the uncertainties coming from different kinetic data and the low sensitivity of some rate coefficient ratios complicate an easy utilisation of the method. Future steps are therefore proposed, including uncertainty quantification and sensitivity analysis of the simplified model and necessary CO+2 and CO synthetic spectra fitting.

[100] arXiv:2406.14110 [pdf, html, other]

Title: Multi-objective optimization of the magnetic wiping process in dip-coating

Fabio Pino, Benoit Scheid, Miguel Alfonso Mendez

Subjects: Fluid Dynamics (physics.flu-dyn); Optimization and Control (math.OC)

Electromagnetic wiping systems allow to pre-meter the coating thickness of the liquid metal on a moving substrate. These systems have the potential to provide a more uniform coating and significantly higher production rates compared to pneumatic wiping, but they require substantially larger amounts of energy. This work presents a multi-objective optimization accounting for (1) maximal wiping efficiency (2) maximal smoothness of the wiping meniscus, and (3) minimal Joule heating. We present the Pareto front, identifying the best wiping conditions given a set of weights for the three competing objectives. The optimization was based on a 1D steady-state integral model, whose prediction scales according to the Hartmann number (Ha). The optimization uses a multi-gradient approach, with gradients computed with a combination of finite differences and variational methods. The results show that the wiping efficiency depends solely on Ha and not the magnetic field distribution. Moreover, we show that the liquid thickness becomes insensitive to the intensity of the magnetic field above a certain threshold and that the current distribution (hence the Joule heating) is mildly affected by the magnetic field's intensity and shape.

[101] arXiv:2406.14133 [pdf, html, other]

Title: Beam shaping by nonlinear moir\'e metasurfaces

Lun Qu, Wei Wu, Di Zhang, Chenxiong Wang, Lu Bai, Chenyang Li, Wei Cai, Mengxin Ren, Andrea Alù, Jingjun Xu

Comments: 10 pages, 5 figures

Subjects: Optics (physics.optics)

This paper explores the interplay of momentum transfer and nonlinear optical processes through moiré phenomena. Momentum transfer plays a crucial role in the interaction between photons and matter. Here, we study stacked metasurfaces with tailored dispersion and rotated against each other with varying twisted angles. The stacking introduces interlayer interactions, which can be controlled by the relative angle between metasurfaces, significantly enriching the resulting response compared to the single layer counterpart. By focusing on second-harmonic generation (SHG) from these twisted metasurfaces, we delve into the realm of nonlinear moiré photonics. Through experimental observations, we unveil the emergence of intricate far-field SHG radiation patterns, showing their effective tuning by varying the twisted angles. These findings offer a fresh perspective to explore nonlinear wavefront shaping through moiré phenomena, opening new avenues for nonlinear information processing, optical steering, and nonlinear optical switching.

[102] arXiv:2406.14149 [pdf, html, other]

Title: CheMFi: A Multifidelity Dataset of Quantum Chemical Properties of Diverse Molecules

Vivin Vinod, Peter Zaspel

Comments: SI not included

Subjects: Chemical Physics (physics.chem-ph); Machine Learning (cs.LG)

Progress in both Machine Learning (ML) and conventional Quantum Chemistry (QC) computational methods have resulted in high accuracy ML models for QC properties ranging from atomization energies to excitation energies. Various datasets such as MD17, MD22, and WS22, which consist of properties calculated at some level of QC method, or fidelity, have been generated to benchmark such ML models. The term fidelity refers to the accuracy of the chosen QC method to the actual real value of the property. The higher the fidelity, the more accurate the calculated property, albeit at a higher computational cost.
Research in multifidelity ML (MFML) methods, where ML models are trained on data from more than one numerical QC method, has shown the effectiveness of such models over single fidelity methods. Much research is progressing in this direction for diverse applications ranging from energy band gaps to excitation energies. A major hurdle for effective research in this field of research in the community is the lack of a diverse multifidelity dataset for benchmarking.
Here, we present a comprehensive multifidelity dataset drawn from the WS22 molecular conformations. We provide the quantum Chemistry MultiFidelity (CheMFi) dataset consisting of five fidelities calculated with the TD-DFT formalism. The fidelities differ in their basis set choice and are namely: STO-3G, 3-21G, 6-31G, def2-SVP, and def2-TZVP. CheMFi offers to the community a variety of QC properties including vertical excitation energies, oscillator strengths, molecular dipole moments, and ground state energies. In addition to the dataset, multifidelity benchmarks are set with state-of-the-art MFML and optimized-MFML

[103] arXiv:2406.14196 [pdf, html, other]

Title: Formation of motile cell clusters in heterogeneous model tumors: the role of cell-cell alignment

Quirine J.S. Braat, Cornelis Storm, Liesbeth M.C. Janssen

Comments: 11 pages, 6 figures

Subjects: Biological Physics (physics.bio-ph)

Circulating tumor cell clusters play an important role in the metastatic cascade. These clusters can acquire a migratory and more invasive phenotype, and coordinate their motion to migrate as a collective. Before such clusters can form by collectively detaching from a primary tumor, however, the cluster must first aggregate in the tumor interior. The mechanism of this cluster formation process is still poorly understood. One of the possible ways for cells to cluster is by aligning their direction of motion with their neighboring cells. This work aims to investigate the role of this cell-cell alignment interaction on the formation of motile cell clusters inside the bulk of a tumor using computer simulations. We employ a Cellular Potts model in which we model a two-dimensional heterogeneous confluent layer containing both motile and non-motile cells. Our results indicate that the degree of clustering is governed by two distinct processes: the formation of clusters due to the presence of cell-cell alignment interactions among motile cells, and the suppression of clustering due to the presence of the dynamic cellular environment (comprised of the non-motile cells). We find that the largest motile clusters are formed for intermediate alignment strengths, contrary to what is observed for motile cells in free space (that is, unimpeded by a dense cellular environment), in which case stronger cell-cell alignment always leads to larger clustering. Our findings suggest that the presence of a densely-packed cellular environment and strong cell-cell alignment inhibits the formation of large migratory clusters within the primary tumor, providing physical insight into potential factors at play during the early stages of metastasis.

[104] arXiv:2406.14204 [pdf, other]

Title: Achieving Cooling Without Repump Lasers Through Ion Motional Heating

Yue Xiao, Yongxu Peng, Linfeng Chen, Chunhui Li, Zongao Song, Xin Wang, Tao Wang, Yurun Xie, Bin Zhao, Tiangang Yang

Subjects: Atomic Physics (physics.atom-ph); Chemical Physics (physics.chem-ph)

Laser cooling typically requires one or more repump lasers to clear dark states and enable recycling transitions. Here, we have achieved cooling of Be+ ions using a single laser beam, facilitated by one-dimensional heating through micromotion. By manipulating the displacement from the trap's nodal line, we precisely controlled the ion micromotion direction and speed, reaching up to 3144 m/s, which corresponds to a 7.1 GHz Doppler frequency shift in our experiment. This approach eliminates the necessity of a 1.25 GHz offset repump laser while keeping the Be+ ions cold in the perpendicular direction. Measurements were taken using cooling laser detuning and imaging of ion trajectories. Molecular dynamics simulations, based on machine learned time-dependent electric field E(X, Y, Z, t) inside the trap, accurately reproduced the experimental observation, illuminating the relationship between the direction of micromotion and the trapping electric filed vector. This work not only provides a robust method for managing the micromotion velocity of ions but also sheds light on laser cooling complex systems that require multiple repumping lasers. Additionally, it offers a method for controlling energy in the context of ion-molecule collision investigations.

[105] arXiv:2406.14205 [pdf, other]

Title: Understanding building blocks of photonic logic gates: Reversible, read-write-erase cycling using photoswitchable beads in micropatterned arrays

Heyou Zhang, Pankaj Dharpure, Michael Philipp, Paul Mulvaney, Mukundan Thelakkat, Jürgen Köhler

Comments: Main article: 14 pages, 4 figures. Supporting information: 13 pages, 6 figures. To be published

Subjects: Optics (physics.optics)

Using surface-templated electrophoretic deposition, we have created arrays of polymer beads (photonic units) incorporating photo-switchable DAE molecules, which can be reversibly and individually switched between high and low emission states by direct photo-excitation, without any energy or electron transfer processes within the molecular system. The micropatterned array of these photonic units is spectroscopically characterized in detail and optimized with respect to both signal contrast and cross-talk. The optimum optical parameters including laser intensity, wavelength and duration of irradiation are elucidated and ideal conditions for creating reversible on/off cycles in a micropatterned array are determined. 500 such cycles are demonstrated with no obvious on/off contrast attenuation. The ability to process binary information is demonstrated by selectively writing information to the given photonic unit, reading the resultant emissive signal pattern and finally erasing the information again, which in turn demonstrates the possibility of continuous recording. This basic study paves the way for building complex circuits using spatially well-arranged photonic units.

[106] arXiv:2406.14222 [pdf, html, other]

Title: Stress-Dependent Optical Extinction in LPCVD Silicon Nitride Measured by Nanomechanical Photothermal Sensing

Kostas Kanellopulos, Robert G. West, Stefan Emminger, Paolo Martini, Markus Sauer, Annette Foelske, Silvan Schmid

Comments: Main text: 7 pages, 3 figures, 1 table Supporting Information: 4 pages, 4 figures, 1 table

Subjects: Optics (physics.optics); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Materials Science (cond-mat.mtrl-sci); Applied Physics (physics.app-ph)

Understanding optical absorption in silicon nitride is crucial for cutting-edge technologies like photonic integrated circuits, nanomechanical photothermal infrared sensing and spectroscopy, and cavity optomechanics. Yet, the origin of its strong dependence on film deposition and fabrication process is not fully understood. This Letter leverages nanomechanical photothermal sensing to investigate optical extinction $\kappa_{\mathrm{ext}}$ at 632.8 nm wavelength in LPCVD SiN strings across a wide range of deposition-related tensile stresses ($200-850$ MPa). Measurements reveal a reduction in $\kappa_{\mathrm{ext}}$ from 10$^3$ to 10$^1$ ppm with increasing stress, correlated to variations in Si/N content ratio. Within the band-fluctuations framework, this trend indicates an increase of the energy bandgap with the stress, ultimately reducing absorption. Overall, this study showcases the power and simplicity of nanomechanical photothermal sensing for low absorption measurements, offering a sensitive, scattering-free platform for material analysis in nanophotonics and nanomechanics.

[107] arXiv:2406.14229 [pdf, html, other]

Title: Approaches to conservative Smoothed Particle Hydrodynamics with entropy

Michal Pavelka, Vaclav Klika, Ondrej Kincl

Subjects: Fluid Dynamics (physics.flu-dyn); Mathematical Physics (math-ph)

Smoothed particle hydrodynamics (SPH) is typically used for barotropic fluids, where the pressure depends only on the local mass density. Here, we show how to incorporate the entropy into the SPH, so that the pressure can also depend on the temperature, while keeping the growth of the total entropy, conservation of the total energy, and symplecticity of the reversible part of the SPH equations. The SPH system of ordinary differential equations with entropy is derived by means of the Poisson reduction and the Lagrange-Euler transformation. We present several approaches towards SPH with entropy, which are then illustrated on systems with discontinuities, on adiabatic and nonadiabatic expansion, and on the Rayleigh-Beenard convection without the Boussinesq approximation. Finally, we show how to model hyperbolic heat conduction within the SPH, extending the SPH variables with not only entropy but also a heat-flux-related vector field.

[108] arXiv:2406.14234 [pdf, html, other]

Title: Zero field active shielding

Alain de Cheveigné

Comments: 26 pages, 7 figures

Subjects: Medical Physics (physics.med-ph); Human-Computer Interaction (cs.HC); Signal Processing (eess.SP); Instrumentation and Detectors (physics.ins-det); Neurons and Cognition (q-bio.NC)

Ambient field suppression is critical for accurate magnetic field measurements, and a requirement for certain low-field sensors to operate. The difference in magnitude between noise and signal (up to 10$^9$) makes the problem challenging, and solutions such as passive shielding, post-hoc processing, and most active shielding designs do not address it completely. Zero field active shielding (ZFS) achieves accurate field suppression with a feed-forward structure in which correction coils are fed by reference sensors via a matrix found using data-driven methods. Requirements are a sufficient number of correction coils and reference sensors to span the ambient field at the sensors, and to zero out the coil-to-reference sensor coupling. The solution assumes instantaneous propagation and mixing, but it can be extended to handle convolutional effects. Precise calculations based on sensor and coil geometries are not necessary, other than to improve efficiency and usability. The solution is simulated here but not implemented in hardware.

[109] arXiv:2406.14258 [pdf, html, other]

Title: Ultrafast TACOS -- Terahertz-Assisted Chiro-Optical Spectroscopy

Justas Terentjevas, Patricia Vindel-Zandbergen, Laura Rego, Felipe Morales, Andrés Ordóñez, Olga Smirnova, David Ayuso

Subjects: Optics (physics.optics); Chemical Physics (physics.chem-ph)

We bring together the advantages of terahertz (THz) and optical spectroscopies to introduce TACOS (Terahertz-Assisted Chiro-Optical Spectroscopy), a novel approach for ultrafast and highly efficient imaging of molecular chirality and control over chiral electronic dynamics. We show how, using a THz pulse, we can induce a transient electronic orientation in a medium of randomly oriented chiral molecules that breaks the isotropy of the molecular sample. This symmetry breaking twists the nonlinear response of the medium to an ultrashort linearly polarised optical pulse in a highly enantiosensitive manner. As a result, the medium emits elliptically polarised light at new optical frequencies that records the molecular handedness via purely electric-dipole interactions. The long wavelength and period of the THz pulse enable both spatial coherence across the sample and a substantial degree of electronic orientation over the duration of the ultrashort optical pulse. TACOS does not require optical carrier-envelope phase stability or working in vacuum, and it creates exciting avenues for ultrafast and highly efficient chiral sensing and manipulation.

[110] arXiv:2406.14296 [pdf, html, other]

Title: Foundry compatible, efficient wafer-scale manufacturing of ultra-low loss, high-density Si$_3$N$_4$ photonic integrated circuits

Xinru Ji, Rui Ning Wang, Yang Liu, Johann Riemensberger, Zheru Qiu, Tobias J. Kippenberg

Comments: 2023 Conference on Lasers and Electro-Optics (CLEO). IEEE, 2023

Subjects: Optics (physics.optics); Applied Physics (physics.app-ph)

Silicon nitride (Si$_3$N$_4$) photonic integrated circuits (PICs) have shown low linear loss, negligible nonlinear loss, and high power handling over traditional silicon photonics. To achieve high-density photonic integration and high effective nonlinearity through tight optical confinement, thick stoichiometric Si$_3$N$_4$ films are indispensable. However, when using low-pressure chemical vapor deposition (LPCVD) to achieve high optical material transparency, Si$_3$N$_4$ films exhibit large tensile stress on the order of GPa. Methods for crack prevention are therefore essential. The photonic Damascene process has addressed this issue, attaining record low loss Si$_3$N$_4$ PICs, but it lacks control of the waveguide height. Conversely, precise waveguide dimension and ultra-low loss have been achieved with subtractive processing, but this method is not compatible with mass production due to the use of electron beam lithography. To date, an outstanding challenge is to attain both lithographic precision and ultra-low loss in high confinement Si$_3$N$_4$ PICs that are compatible with large-scale foundry manufacturing. Here, we present a single-step deposited, DUV-based subtractive method for producing wafer-scale ultra-low loss Si$_3$N$_4$ PICs that harmonize these necessities. By employing deep etching of densely distributed, interconnected trenches into the substrate, we effectively mitigate the tensile stress in the Si$_3$N$_4$ layer, enabling direct deposition of thick films without cracking and substantially prolonged storage duration. Lastly, we identify ultraviolet (UV) radiation-induced damage that can be remedied through rapid thermal annealing. Collectively, we develop ultra-low loss Si$_3$N$_4$ microresonators and 0.5 m-long spiral waveguides with losses down to 1.4 dB/m at 1550 nm with high production yield.

[111] arXiv:2406.14331 [pdf, html, other]

Title: Photonic and phononic modes in acoustoplasmonic toroidal nanopropellers

Beatriz Castillo López de Larrinzar, Jorge M. García, Norberto Daniel Lanzillotti-Kimura, Antonio García-Martín

Comments: 9 pages 7 figures

Subjects: Optics (physics.optics); Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Non-conventional resonances, both acoustic and photonic, are found in metallic particles with a toroidal nanopropeller geometry that is generated by sweeping a three-lobed 2D-shape along a spiral with twisting angle, ${\alpha}$. For both optical and acoustic cases, spectral location of resonances experiences a red-shift as a function of ${\alpha}$. We demonstrate that the optical case can be understood as a natural evolution of resonances as the spiral length of the toroidal nanopropeller increases with ${\alpha}$, implying a huge helicity dependent absorption cross section. In the case of acoustic response, two red-shifting breathing modes are identified. Additionally, even small ${\alpha}$ allows the appearance of new low-frequency resonances, whose spectral dispersion depends on a competition between length of the generative spiral and the pitch of the toroidal nanopropeller.

[112] arXiv:2406.14347 [pdf, other]

Title: $\nabla^2$DFT: A Universal Quantum Chemistry Dataset of Drug-Like Molecules and a Benchmark for Neural Network Potentials

Kuzma Khrabrov, Anton Ber, Artem Tsypin, Konstantin Ushenin, Egor Rumiantsev, Alexander Telepov, Dmitry Protasov, Ilya Shenbin, Anton Alekseev, Mikhail Shirokikh, Sergey Nikolenko, Elena Tutubalina, Artur Kadurin

Subjects: Chemical Physics (physics.chem-ph); Machine Learning (cs.LG); Machine Learning (stat.ML)

Methods of computational quantum chemistry provide accurate approximations of molecular properties crucial for computer-aided drug discovery and other areas of chemical science. However, high computational complexity limits the scalability of their applications. Neural network potentials (NNPs) are a promising alternative to quantum chemistry methods, but they require large and diverse datasets for training. This work presents a new dataset and benchmark called $\nabla^2$DFT that is based on the nablaDFT. It contains twice as much molecular structures, three times more conformations, new data types and tasks, and state-of-the-art models. The dataset includes energies, forces, 17 molecular properties, Hamiltonian and overlap matrices, and a wavefunction object. All calculations were performed at the DFT level ($\omega$B97X-D/def2-SVP) for each conformation. Moreover, $\nabla^2$DFT is the first dataset that contains relaxation trajectories for a substantial number of drug-like molecules. We also introduce a novel benchmark for evaluating NNPs in molecular property prediction, Hamiltonian prediction, and conformational optimization tasks. Finally, we propose an extendable framework for training NNPs and implement 10 models within it.

[113] arXiv:2406.14350 [pdf, html, other]

Title: A first-principles geometric model for dynamics of motor-driven centrosomal asters

Yuan-Nan Young, Vicente Gomez Herrera, Helena Z. Huan, Reza Farhadifar, Michael J. Shelley

Comments: 50 pages (double-spaced), eight figures in main text, and four figures in the supplemental material

Subjects: Biological Physics (physics.bio-ph); Adaptation and Self-Organizing Systems (nlin.AO); Subcellular Processes (q-bio.SC)

The centrosomal aster is a mobile cellular organelle that exerts and transmits forces necessary for nuclear migration and spindle positioning. Recent experimental and theoretical studies of nematode and human cells demonstrate that pulling forces on asters by cortical force generators are dominant during such processes. We present a comprehensive investigation of a first-principles model of aster dynamics, the S-model (S for stoichiometry), based solely on such forces. The model evolves the astral centrosome position, a probability field of cell-surface motor occupancy by centrosomal microtubules (under an assumption of stoichiometric binding), and free boundaries of unattached, growing microtubules. We show how cell shape affects the centering stability of the aster, and its transition to oscillations with increasing motor number. Seeking to understand observations in single-cell nematode embryos, we use accurate simulations to examine the nonlinear structures of the bifurcations, and demonstrate the importance of binding domain overlap to interpreting genetic perturbation experiments. We find a rich dynamical landscape, dependent upon cell shape, such as internal equatorial orbits of asters that can be seen as traveling wave solutions. Finally, we study the interactions of multiple asters and demonstrate an effective mutual repulsion due to their competition for cortical force generators. We find, amazingly, that asters can relax onto the vertices of platonic and non-platonic solids, closely mirroring the results of the classical Thomson problem for energy-minimizing configurations of electrons constrained to a sphere and interacting via repulsive Coulomb potentials. Our findings both explain experimental observations, providing insights into the mechanisms governing spindle positioning and cell division dynamics, and show the possibility of new nonlinear phenomena in cell biology.

[114] arXiv:2406.14364 [pdf, html, other]

Title: Characterization and optimization of a heterolytic Ring Laser Gyroscope

Nicolò Beverini, Giorgio Carelli, Simone Castellano, Giuseppe Di Somma, Angela D.V. Di Virgilio, Enrico Maccioni, Paolo Marsili

Subjects: Optics (physics.optics); Instrumentation and Detectors (physics.ins-det)

A characterization of Ring Laser Gyroscopes (RLGs) was performed at INFN-Pisa, and optimization is ongoing for a kind of very high sensitivity and accuracy rotation measurement device. Data quality is monitored through fringe contrast, such quantity is factorized, as it depends on single light beam values and their alignment, and on the polarization of the beams at their interference outside the cavity. Models of the alignment and polarization contributions to contrast have been implemented. In particular, the GP2 prototype at INFN-Pisa was characterized as for non-planarity, alignment, and polarization of the interfering beams. Beams interference was optimized by obtaining linearly polarized beams out of the cavity. Advantage with respect to elliptically polarized interfering beams is shown.

[115] arXiv:2406.14392 [pdf, other]

Title: An efficient singlet-triplet spin qubit to fiber interface assisted by a photonic crystal cavity

Kui Wu, Sebastian Kindel, Thomas Descamps, Tobias Hangleiter, Jan Christoph Müller, Rebecca Rodrigo, Florian Merget, Hendrik Bluhm, Jeremy Witzens

Journal-ref: The 25th European Conference on Integrated Optics, Springer Proceedings in Physics 402, pp. 365-372, 2024

Subjects: Optics (physics.optics); Quantum Physics (quant-ph)

We introduce a novel optical interface between a singlet-triplet spin qubit and a photonic qubit which would offer new prospects for future quantum communication applications. The interface is based on a 220 nm thick GaAs/Al-GaAs heterostructure membrane and features a gate-defined singlet-triplet qubit, a gate-defined optically active quantum dot, a photonic crystal cavity and a bot-tom gold reflector. All essential components can be lithographically defined and deterministically fabricated, which greatly increases the scalability of on-chip in-tegration. According to our FDTD simulations, the interface provides an overall coupling efficiency of 28.7% into a free space Gaussian beam, assuming an SiO2 interlayer filling the space between the reflector and the membrane. The performance can be further increased to 48.5% by undercutting this SiO2 interlayer below the photonic crystal.

[116] arXiv:2406.14403 [pdf, other]

Title: External Cavity 637-nm Laser with Increased RSOA-to-PIC Alignment Tolerance and a Filtered Sagnac-Loop Reflector with Single Output Waveguide

Georgios Sinatkas, Arijit Misra, Florian Merget, Jeremy Witzens

Journal-ref: The 25th European Conference on Integrated Optics, Springer Proceedings in Physics 402, pp. 8-16, 2024

Subjects: Optics (physics.optics)

The design of a 637-nm wavelength, photonic-integrated-circuit-based external cavity laser (PIC-based ECL) aimed at quantum technology applications is presented together with first experimental results. The PIC is designed to provide relaxed alignment tolerance for coupling to a reflective semiconductor optical amplifier (RSOA) gain chip. This is achieved by using a multi-mode edge coupler (MMEC) in place of the usually employed single-mode coupling schemes. A 1-dB-penalty misalignment tolerance of up to +/- 2.4 um can be achieved in the plane of the chip, creating a path towards reliable flip-chip integration at short wavelengths. The power coupled to the PIC is fed to a Sagnac-loop reflector, filtered by a pair of ring resonators operated in Vernier configuration for providing the required frequency selective optical feedback. The ring resonators are designed to have different loaded Q-factors and they are asymmetrically coupled to bus and drop waveguides with suitably engineered directional couplers to provide single output waveguide emission. Moreover, requirements for high output power and narrow linewidths are balanced. Finally, preliminary measurements strongly suggest lasing in the fabricated devices, with further performance optimization being currently carried out.

[117] arXiv:2406.14406 [pdf, other]

Title: Focusing Optical Phased Array for Optically Enabled Probing of the Retina with Subcellular Resolution

Pedram Hosseini, Prachi Agrawal, Alireza Tabatabaei Mashayekh, Sandra Johnen, Jeremy Witzens, Florian Merget

Journal-ref: The 25th European Conference on Integrated Optics, Springer Proceedings in Physics 402, pp. 168-175, 2024

Subjects: Optics (physics.optics); Applied Physics (physics.app-ph)

We present a silicon-nitride-based optical phased array with built-in focusing and steering capability, that operates at 522 nm and is aimed at complementing a micro-electrode array for joint electrical and optical probing of retinal tissue. It achieves subcellular resolution with a beam diameter of 1.4 um at a focal point located above the chip. Targeted cellular excitation can be achieved by steering the beam through a combination of wavelength tuning and simplified thermo-optical phase shifters with a single electrical input for each of transverse beam steering and selection of the focal plane.

[118] arXiv:2406.14407 [pdf, html, other]

Title: Efficient algorithms for dynamic aperture and momentum acceptance calculation

Bernard Riemann, Masamitsu Aiba, Jonas Kallestrup, Andreas Streun

Subjects: Accelerator Physics (physics.acc-ph)

New algorithms useful for the calculation of dynamic aperture and momentum acceptance in circular accelerators are developed and presented. The flood-fill tool from raster graphics inspired us to efficiently compute dynamic apertures by minimizing required trackings on stable initial coordinates, leading to several factors of speed-up with respect to standard algorithms. A novel technique for momentum acceptance calculations, Fast Touschek Tracking, is developed. Thorough benchmarking using modern accelerator codes shows that the new technique can provide one or two orders of magnitude faster computation of local momentum acceptances with only limited loss of accuracy.

[119] arXiv:2406.14413 [pdf, other]

Title: Silicon Nitride C-Band Grating Coupler with Reduced Waveguide Back-Reflection Using Adaptively Corrected Elliptical Grates

Ibrahim Ghannam, Florian Merget, Jeremy Witzens

Journal-ref: The 25th European Conference on Integrated Optics, Springer Proceedings in Physics 402, pp. 571-578, 2024

Subjects: Optics (physics.optics); Applied Physics (physics.app-ph)

We present experimental results for a fully etched C-band grating coupler with reduced back reflection fabricated in an 800 nm silicon nitride platform. Back-reflections are reduced by symmetrically interrupting the first few grates around the center axis of the propagating light. The span of the etched grates is gradually increased until they cover the full width. By interrupting the grates, light is reflected back obliquely, which leads to the excitation of higher-order modes that are scattered out of the structure. While this approach has been previously shown in silicon, it comes with a significant penalty in coupling efficiency of around 2.4 dB of extra loss in the layer stack investigated here. In this work, we present the design and measurement results of a grating coupler in which waveguide-to-waveguide back-reflections are suppressed by ~10 dB with this technique, while at the same time mitigating excess insertion losses by reshaping the grates as ellipses of varying eccentricity. This helps to compensate the phase front error induced by the interruption of the grates. This correction does not affect the level by which the back-reflection is suppressed, but reduces the insertion loss penalty from 2.4 dB to 1 dB.

[120] arXiv:2406.14423 [pdf, html, other]

Title: Double-tough and ultra-strong ceramics: leveraging multiscale toughening mechanisms through Bayesian Optimization

Francesco Aiello, Jian Zhang, Johannes C. Brouwer, Mauro Salazar, Diletta Giuntini

Subjects: Applied Physics (physics.app-ph)

We present an optimization-driven approach to creating a double-tough ceramic material with a brick-and-mortar microstructure, where the mortar is itself transformation-toughened, engineered with the goal of simultaneously achieving high strength and fracture toughness levels. Specifically, we design a material where high-strength alumina bricks are interconnected via a ceria-stabilized zirconia mortar. As the design of such a material, driven by multiscale toughening mechanisms, requires a laborious trial-and-error approach, we propose a Bayesian optimization framework as an integral part of our methodology to streamline and accelerate the design process. We use a Gaussian process to emulate the material's mechanical response and implement a cost-aware batch Bayesian optimization to efficiently identify optimal design process parameters, accounting for the cost of experimentally varying them. This approach expedites the optimization of the material's mechanical properties. As a result, we develop a bio-inspired all-ceramic composite that exhibits an exceptional balance between bending strength (704 MPa), and fracture toughness (13.6 MPa m^0.5).

[121] arXiv:2406.14433 [pdf, other]

Title: Structural and Electrical Properties of Grafted Si/GaAsSb Heterojunction

Haris Naeem Abbasi, Seunghyun Lee Hyemin Jung, Nathan Gajowski, Yi Lu, Linus Wang, Donghyeok Kim, Jie Zhou, Jiarui Gong, Chris Chae, Jinwoo Hwang, Manisha Muduli, Subramanya Nookala, Zhenqiang. Ma, Sanjay Krishna

Comments: 14 pages, 6 figures

Subjects: Applied Physics (physics.app-ph); Materials Science (cond-mat.mtrl-sci)

The short-wave infrared (SWIR) wavelength, especially 1.55 um, has attracted significant attention in various areas such as high-speed optical communication and LiDAR systems. Avalanche photodiodes (APDs) are a critical component as a receiver in these systems due to their internal gain which enhances the system performance. Silicon-based APDs are promising since they are CMOS compatible, but they are limited in detecting 1.55 um light detection. This study proposes a p-type Si on n-type GaAs0.51Sb0.49 (GaAsSb) lattice matched to InP substrates heterojunction formed using a grafting technique for future GaAsSb/Si APD technology. A p+Si nanomembrane is transferred onto the GaAsSb/AlInAs/InP substrate, with an ultrathin ALD-Al2O3 oxide at the interface, which behaves as both double-side passivation and quantum tunneling layers. The devices exhibit excellent surface morphology and interface quality, confirmed by atomic force microscope (AFM) and transmission electron microscope (TEM). Also, the current-voltage (I-V) of the p+Si/n-GaAsSb heterojunction shows ideal rectifying characteristics with an ideality factor of 1.15. The I-V tests across multiple devices confirm high consistency and yield. Furthermore, the X-ray photoelectron spectroscopy (XPS) measurement reveals that GaAsSb and Si are found to have type-II band alignment with a conduction band offset of 50 meV which is favorable for the high-bandwidth APD application. The demonstration of the GaAsSb/Si heterojunction highlights the potential to advance current SWIR PD technologies.

[122] arXiv:2406.14502 [pdf, html, other]

Title: High Bulk Modulus Pentamodes: the Three-Dimensional Metal Water

Giacomo Brambilla, Sebastiano Cominelli, Marco Verbicaro, Gabriele Cazzulani, Francesco Braghin

Comments: 13 pages, 6 figures

Subjects: Applied Physics (physics.app-ph)

Despite significant advances in the field of phononic crystals, the development of acoustic metafluids that replicate the behaviour of liquids in three dimensions remains elusive. For instance, water - the quintessential pentamode (PM) material - has a bulk modulus two orders of magnitude higher than current state-of-the-art PMs. The need for a low shear modulus inherently conflicts with the desire of high bulk modulus and density. In this letter, we shed light on the limitations of existing PM geometries and propose an innovative shape for the links that constitute the network. Inspired by the kinematics of ropes, these links are constructed from thin fibres and demonstrate the potential to create PMs with properties akin to those of liquids. As a prime example, we present the design of the first metamaterial that fully deserves the name 3D metal water, since its acoustic properties in the low frequency regime are indistinguishable with water. Additionally, we highlight a shear band gap in the lattice dispersion diagram, and illustrate the influence of geometric parameters on the dynamic properties at higher frequencies. This novel design of metafluids holds promise for applications requiring anisotropic materials such as acoustic lenses, waveguides, and cloaks.

[123] arXiv:2406.14520 [pdf, other]

Title: Energy Mapping of Existing Building Stock in Cambridge using Energy Performance Certificates and Thermal Infrared Imagery

Yinglong He, Jiayu Pan, Ramit Debnath, Ronita Bardhan, Luke Cullen, Marco Gomez Jenkins, Erik Mackie, George Hawker, Ian Parry

Subjects: Geophysics (physics.geo-ph)

Energy performance certificate (EPC) and thermal infrared (TIR) images both play a key role in the energy performance mapping of the urban building stock. In this paper, we developed parametric building archetypes using an EPC database and conducted temperature clustering on TIR images acquired through drones and satellite datasets. We evaluated 1725 EPCs of existing building stock in Cambridge, UK to generate energy consumption profiles. Drone-based TIR images of individual buildings in two Cambridge University colleges were processed using a machine learning pipeline for thermal anomaly detection and investigated the influence of two specific factors that affect the reliability of TIR for energy management applications: ground sample distance (GSD) and angle of view (AOV). The EPC-level results suggest that the construction year of the buildings influences their energy consumption. For example, modern buildings were over 30% more energy-efficient than older ones. Parallelly, older buildings were found to show almost double the energy savings potential through retrofitting than newly constructed buildings. TIR imaging results showed that thermal anomalies can only be properly identified in images with a GSD of 1m/pixel or less. A GSD of 1-6m/pixel can detect hot areas of building surfaces. We found that a GSD > 6m/pixel cannot characterise individual buildings but does help identify urban heat island effects. Additional sensitivity analysis showed that building thermal anomaly detection is more sensitive to AOV than to GSD. Our study informs newer approaches to building energy diagnostics using thermography and supports decision-making for retrofitting at a large scale.

[124] arXiv:2406.14521 [pdf, other]

Title: Photoacoustic methane detection assisted by a gas-filled anti-resonant hollow-core fiber laser

Cuiling Zhang, Jose Enrique Antonio-Lopez, Rodrigo Amezcua-Correa, Yazhou Wang, Christos Markos

Comments: 18 pages, 7 figures

Subjects: Optics (physics.optics)

Photoacoustic spectroscopys (PAS)-based methane (CH4) detectors have garnered significant attention with various developed systems using near-infrared (NIR) laser sources, which requires high-energy and narrow-linewidth laser sources to achieve high-sensitivity and low-concentration gas detection. The anti-resonant hollow-core fiber (ARHCF) lasers in the NIR and mid-infrared (MIR) spectral domain show a great potential for spectroscopy and high-resolution gas detection. In this work, we demonstrate the generation of a frequency-comb-like Raman laser with high pulse energy spanning from ultraviolet (UV) (328 nm) to NIR (2065 nm wavelength) based on a hydrogen (H2)-filled 7-ring ARHCF. The gas-filled ARHCF fiber is pumped with a custom-laser at 1044 nm with ~100 {\mu}J pulse energy and a few nanoseconds duration. Through stimulated Raman scattering process, we employ the sixth-order Stokes as case example located at ~1650 nm to demonstrate how the developed high-energy and narrow-linewidth laser source can effectively be used to detect CH4 in the NIR-II region using the photoacoustic modality. We report the efficient detection of CH4 with sensitivity as low as ~550 ppb with an integration time of ~40 s. In conclusion, the main goal of this work is to demonstrate and emphasize the potential of the gas-filled ARHCF laser technology for compact next-generation spectroscopy across different spectral regions.

[125] arXiv:2406.14522 [pdf, html, other]

Title: Learning thresholds lead to stable language coexistence

Mikhail V. Tamm, Els Heinsalu, Stefano Scialla, Marco Patriarca

Comments: 5 pages, 3 figures

Subjects: Physics and Society (physics.soc-ph); Computation and Language (cs.CL)

We introduce a language competition model that incorporates the effects of memory and learning on the language shift dynamics, using the Abrams-Strogatz model as a starting point. On a coarse grained time scale, the effects of memory and learning can be expressed as thresholds on the speakers fractions. In its simplest form, the resulting model is exactly solvable. Besides the consensus on one of the two languages, the model describes additional equilibrium states that are not present in the Abrams-Strogatz model: a stable coexistence of the two languages, if both thresholds are low enough, so that the language shift processes in the two opposite directions compensate each other, and a frozen state coinciding with the initial state, when both thresholds are too high for any language shift to take place. We show numerically that these results are preserved for threshold functions of a more general shape.

Cross submissions for Friday, 21 June 2024 (showing 54 of 54 entries )

[126] arXiv:2406.12886 (cross-list from cond-mat.mtrl-sci) [pdf, other]

Title: Bessel beam fabrication of graphitic micro electrodes in diamond using laser bursts

Akhil Kuriakose, Francesco P. Mezzapesa, Caterina Gaudiuso, Andrea Chiappini, Federico Picollo, Antonio Ancona, Ottavia Jedrkiewicz

Subjects: Materials Science (cond-mat.mtrl-sci); Optics (physics.optics)

We present the fabrication of conductive graphitic microelectrodes in diamond by using pulsed Bessel beams in the burst mode laser writing regime. The graphitic wires are created in the bulk of a 500 {\mu}m thick monocrystalline HPHT diamond (with (100) orientation) perpendicular to the sample surface, without beam scanning or sample translation. In particular, the role of different burst features in the resistivity of such electrodes is investigated for two very different sub-pulse durations namely 200 fs and 10 ps, together with the role of thermal annealing. Micro-Raman spectroscopy is implemented to investigate the laser-induced crystalline modification, and the results obtained by using two different laser repetition rates, namely 20 Hz and 200 kHz, are compared. A comparison of the micro-Raman spectra and of the resistivity of the electrodes fabricated respectively with 10 ps single pulses and with bursts (of sub-pulses) of similar total duration has also been made, and we show that the burst mode writing regime allows to fabricate more conductive micro electrodes, thanks to the heat accumulation process leading to stronger graphitization. Moreover, the microfabrication of diamond by means of the longest available bursts (~ 46.7 ps duration) featured by 32 sub-pulses of 200 fs duration, with intra-burst time delay of 1.5 ps (sub-THz bursts), leads to graphitic wires with the lowest resistivity values obtained in this work, especially at low repetition rate such as 20 Hz. Indeed, micro electrodes with resistivity on the order of 0.01 {\Omega} cm can be fabricated by Bessel beams in the burst mode regime even when the bursts are constituted by femtosecond laser sub-pulses, in contrast with the results of the standard writing regime with single fs pulses typically leading to less conductive micro electrodes.

[127] arXiv:2406.12888 (cross-list from cond-mat.mtrl-sci) [pdf, html, other]

Title: A Space Group Symmetry Informed Network for O(3) Equivariant Crystal Tensor Prediction

Keqiang Yan, Alexandra Saxton, Xiaofeng Qian, Xiaoning Qian, Shuiwang Ji

Comments: This paper has been accepted to ICML 24 as a poster. You are encouraged to cite the conference version of this paper

Subjects: Materials Science (cond-mat.mtrl-sci); Artificial Intelligence (cs.AI); Atomic Physics (physics.atom-ph)

We consider the prediction of general tensor properties of crystalline materials, including dielectric, piezoelectric, and elastic tensors. A key challenge here is how to make the predictions satisfy the unique tensor equivariance to O(3) group and invariance to crystal space groups. To this end, we propose a General Materials Tensor Network (GMTNet), which is carefully designed to satisfy the required symmetries. To evaluate our method, we curate a dataset and establish evaluation metrics that are tailored to the intricacies of crystal tensor predictions. Experimental results show that our GMTNet not only achieves promising performance on crystal tensors of various orders but also generates predictions fully consistent with the intrinsic crystal symmetries. Our code is publicly available as part of the AIRS library (this https URL).

[128] arXiv:2406.12893 (cross-list from cond-mat.mtrl-sci) [pdf, html, other]

Title: A variational method for the simulation of hydrogen diffusion in metals

Eva M. Andrés, Ignacio Romero

Subjects: Materials Science (cond-mat.mtrl-sci); Computational Physics (physics.comp-ph)

We present a new method for the approximate solution of the strongly coupled, nonlinear stress-diffusion problem that appears when modeling hydrogen transport in metals. The most salient feature of the proposed approximation is that it is fully variational, meaning that all the discrete equations are obtained from the optimality conditions of an incremental potential, even for inelastic mechanical behavior. Like other variational methods, the proposed algorithm has remarkable properties, including the symmetry of the tangent operator, making its solution extremely efficient compared to other similar methods available in the literature.

[129] arXiv:2406.12904 (cross-list from cs.LG) [pdf, html, other]

Title: Meent: Differentiable Electromagnetic Simulator for Machine Learning

Yongha Kim, Anthony W. Jung, Sanmun Kim, Kevin Octavian, Doyoung Heo, Chaejin Park, Jeongmin Shin, Sunghyun Nam, Chanhyung Park, Juho Park, Sangjun Han, Jinmyoung Lee, Seolho Kim, Min Seok Jang, Chan Y. Park

Comments: under review

Subjects: Machine Learning (cs.LG); Computational Physics (physics.comp-ph); Optics (physics.optics)

Electromagnetic (EM) simulation plays a crucial role in analyzing and designing devices with sub-wavelength scale structures such as solar cells, semiconductor devices, image sensors, future displays and integrated photonic devices. Specifically, optics problems such as estimating semiconductor device structures and designing nanophotonic devices provide intriguing research topics with far-reaching real world impact. Traditional algorithms for such tasks require iteratively refining parameters through simulations, which often yield sub-optimal results due to the high computational cost of both the algorithms and EM simulations. Machine learning (ML) emerged as a promising candidate to mitigate these challenges, and optics research community has increasingly adopted ML algorithms to obtain results surpassing classical methods across various tasks. To foster a synergistic collaboration between the optics and ML communities, it is essential to have an EM simulation software that is user-friendly for both research communities. To this end, we present Meent, an EM simulation software that employs rigorous coupled-wave analysis (RCWA). Developed in Python and equipped with automatic differentiation (AD) capabilities, Meent serves as a versatile platform for integrating ML into optics research and vice versa. To demonstrate its utility as a research platform, we present three applications of Meent: 1) generating a dataset for training neural operator, 2) serving as an environment for the reinforcement learning of nanophotonic device optimization, and 3) providing a solution for inverse problems with gradient-based optimizers. These applications highlight Meent's potential to advance both EM simulation and ML methodologies. The code is available at this https URL with the MIT license to promote the cross-polinations of ideas among academic researchers and industry practitioners.

[130] arXiv:2406.12909 (cross-list from cs.LG) [pdf, html, other]

Title: Scalable Training of Graph Foundation Models for Atomistic Materials Modeling: A Case Study with HydraGNN

Massimiliano Lupo Pasini, Jong Youl Choi, Kshitij Mehta, Pei Zhang, David Rogers, Jonghyun Bae, Khaled Z. Ibrahim, Ashwin M. Aji, Karl W. Schulz, Jorda Polo, Prasanna Balaprakash

Comments: 16 pages, 13 figures

Subjects: Machine Learning (cs.LG); Computational Physics (physics.comp-ph)

We present our work on developing and training scalable graph foundation models (GFM) using HydraGNN, a multi-headed graph convolutional neural network architecture. HydraGNN expands the boundaries of graph neural network (GNN) in both training scale and data diversity. It abstracts over message passing algorithms, allowing both reproduction of and comparison across algorithmic innovations that define convolution in GNNs. This work discusses a series of optimizations that have allowed scaling up the GFM training to tens of thousands of GPUs on datasets that consist of hundreds of millions of graphs. Our GFMs use multi-task learning (MTL) to simultaneously learn graph-level and node-level properties of atomistic structures, such as the total energy and atomic forces. Using over 150 million atomistic structures for training, we illustrate the performance of our approach along with the lessons learned on two United States Department of Energy (US-DOE) supercomputers, namely the Perlmutter petascale system at the National Energy Research Scientific Computing Center and the Frontier exascale system at Oak Ridge National Laboratory. The HydraGNN architecture enables the GFM to achieve near-linear strong scaling performance using more than 2,000 GPUs on Perlmutter and 16,000 GPUs on Frontier. Hyperparameter optimization (HPO) was performed on over 64,000 GPUs on Frontier to select GFM architectures with high accuracy. Early stopping was applied on each GFM architecture for energy awareness in performing such an extreme-scale task. The training of an ensemble of highest-ranked GFM architectures continued until convergence to establish uncertainty quantification (UQ) capabilities with ensemble learning. Our contribution opens the door for rapidly developing, training, and deploying GFMs using large-scale computational resources to enable AI-accelerated materials discovery and design.

[131] arXiv:2406.12910 (cross-list from cs.LG) [pdf, other]

Title: Human-level molecular optimization driven by mol-gene evolution

Jiebin Fang (1 and 2), Churu Mao (2), Yuchen Zhu (3), Xiaoming Chen (2), Chang-Yu Hsieh (3), Zhongjun Ma (1 and 2) ((1) Hainan Institute of Zhejiang University, (2) Institute of Marine Biology and Pharmacology, Ocean College, Zhejiang University, (3) College of Pharmaceutical Sciences and Cancer Center, Zhejiang University)

Subjects: Machine Learning (cs.LG); Artificial Intelligence (cs.AI); Neural and Evolutionary Computing (cs.NE); Chemical Physics (physics.chem-ph); Biomolecules (q-bio.BM)

De novo molecule generation allows the search for more drug-like hits across a vast chemical space. However, lead optimization is still required, and the process of optimizing molecular structures faces the challenge of balancing structural novelty with pharmacological properties. This study introduces the Deep Genetic Molecular Modification Algorithm (DGMM), which brings structure modification to the level of medicinal chemists. A discrete variational autoencoder (D-VAE) is used in DGMM to encode molecules as quantization code, mol-gene, which incorporates deep learning into genetic algorithms for flexible structural optimization. The mol-gene allows for the discovery of pharmacologically similar but structurally distinct compounds, and reveals the trade-offs of structural optimization in drug discovery. We demonstrate the effectiveness of the DGMM in several applications.

[132] arXiv:2406.12919 (cross-list from cs.LG) [pdf, html, other]

Title: Understanding active learning of molecular docking and its applications

Jeonghyeon Kim, Juno Nam, Seongok Ryu

Subjects: Machine Learning (cs.LG); Chemical Physics (physics.chem-ph); Biomolecules (q-bio.BM)

With the advancing capabilities of computational methodologies and resources, ultra-large-scale virtual screening via molecular docking has emerged as a prominent strategy for in silico hit discovery. Given the exhaustive nature of ultra-large-scale virtual screening, active learning methodologies have garnered attention as a means to mitigate computational cost through iterative small-scale docking and machine learning model training. While the efficacy of active learning methodologies has been empirically validated in extant literature, a critical investigation remains in how surrogate models can predict docking score without considering three-dimensional structural features, such as receptor conformation and binding poses. In this paper, we thus investigate how active learning methodologies effectively predict docking scores using only 2D structures and under what circumstances they may work particularly well through benchmark studies encompassing six receptor targets. Our findings suggest that surrogate models tend to memorize structural patterns prevalent in high docking scored compounds obtained during acquisition steps. Despite this tendency, surrogate models demonstrate utility in virtual screening, as exemplified in the identification of actives from DUD-E dataset and high docking-scored compounds from EnamineReal library, a significantly larger set than the initial screening pool. Our comprehensive analysis underscores the reliability and potential applicability of active learning methodologies in virtual screening campaigns.

[133] arXiv:2406.12948 (cross-list from cs.CR) [pdf, other]

Title: New Reservoir Computing Kernel Based on Chaotic Chua Circuit and Investigating Application to Post-Quantum Cryptography

Matthew John Cossins, Sendy Phang

Comments: 72 pages, 62 figures, Master of Engineering final project report

Subjects: Cryptography and Security (cs.CR); Machine Learning (cs.LG); Chaotic Dynamics (nlin.CD); Applied Physics (physics.app-ph); Classical Physics (physics.class-ph)

The aim of this project was to develop a new Reservoir Computer implementation, based on a chaotic Chua circuit. In addition to suitable classification and regression benchmarks, the Reservoir Computer was applied to Post-Quantum Cryptography, with its suitability for this application investigated and assessed. The cryptographic algorithm utilised was the Learning with Errors problem, for both encryption and decryption. To achieve this, the Chua circuit was characterised, in simulation, and by physical circuit testing. The Reservoir Computer was designed and implemented using the results of the characterisation. As part of this development, noise was considered and mitigated.
The benchmarks demonstrate that the Reservoir Computer can achieve current literature benchmarks with low error. However, the results with Learning with Errors suggest that a Chua-based Reservoir Computer is not sufficiently complex to tackle the high non-linearity in Post-Quantum Cryptography. Future work would involve researching the use of different combinations of multiple Chua Reservoir Computers in larger neural network architectures. Such architectures may produce the required high-dimensional behaviour to achieve the Learning with Errors problem.
This project is believed to be only the second instance of a Chua-based Reservoir Computer in academia, and it is the first to be applied to challenging real-world tasks such as Post-Quantum Cryptography. It is also original by its investigation of hitherto unexplored parameters, and their impact on performance. It demonstrates a proof-of-concept for a mass-producible, inexpensive, low-power consumption hardware neural network. It also enables the next stages in research to occur, paving the road for using Chua-based Reservoir Computers across various applications.

[134] arXiv:2406.12986 (cross-list from quant-ph) [pdf, other]

Title: Simulating spin biology using a digital quantum computer: Prospects on a near-term quantum hardware emulator

Pedro H. Alvarez, Farhan T. Chowdhury, Luke D. Smith, Trevor J. Brokowski, Clarice D. Aiello, Daniel R. Kattnig, Marcos C. de Oliveira

Comments: 10 pages, 9 figures

Subjects: Quantum Physics (quant-ph); Biological Physics (physics.bio-ph)

Understanding the intricate quantum spin dynamics of radical pair reactions is crucial for unraveling the underlying nature of chemical processes across diverse scientific domains. In this work, we leverage Trotterization to map coherent radical pair spin dynamics onto a digital gate-based quantum simulation. Our results demonstrated agreement between the idealized noiseless quantum circuit simulation and established master equation approaches for homogeneous radical pair recombination, identifying approximately 15 Trotter steps to be sufficient for faithfully reproducing the coupled spin dynamics of a prototypical system. By utilizing this computational technique to study the dynamics of spin systems of biological relevance, our findings underscore the potential of digital quantum simulation (DQS) of complex radical pair reactions and builds the groundwork towards more utilitarian investigations into their intricate reaction dynamics. We further investigate the effect of realistic error models on our DQS approach, and provide an upper limit for the number of Trotter steps that can currently be applied in the absence of error mitigation techniques before losing simulation accuracy to deleterious noise effects.

[135] arXiv:2406.13020 (cross-list from gr-qc) [pdf, html, other]

Title: Microscale torsion resonators for short-range gravity experiments

J. Manley, C. A. Condos, S. Schlamminger, J. R. Pratt, D. J. Wilson, W. A. Terrano

Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph); Instrumentation and Detectors (physics.ins-det)

Measuring gravitational interactions on sub-100-$\mu$m length scales offers a window into physics beyond the Standard Model. However, short-range gravity experiments are limited by the ability to position sufficiently massive objects to within small separation distances. Here we propose mass-loaded silicon nitride ribbons as a platform for testing the gravitational inverse square law at separations currently inaccessible with traditional torsion balances. These microscale torsion resonators benefit from low thermal noise due to strain-induced dissipation dilution while maintaining compact size (<100$\,\mu$g) to allow close approach. Considering an experiment combining a 40$\,\mu$g torsion resonator with a source mass of comparable size (130$\,\mu$g) at separations down to 25$\,\mu$m, and including limits from thermomechanical noise and systematic uncertainty, we predict these devices can set novel constraints on Yukawa interactions within the 1-100$\,\mu$m range.

[136] arXiv:2406.13022 (cross-list from astro-ph.SR) [pdf, html, other]

Title: Distorted Magnetic Flux Ropes within Interplanetary Coronal Mass Ejections

Andreas J. Weiss, Teresa Nieves-Chinchilla, Christian Möstl

Comments: 16 pages, 5 figures

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Space Physics (physics.space-ph)

Magnetic flux ropes within interplanetary coronal mass ejections are often characterized as simplistic cylindrical or toroidal tubes with field lines that twist around the cylinder or torus axis. Recent multi-point observations suggest that the overall geometry of these large-scale structures may be significantly more complex, so that the contemporary modeling approaches would be, in some cases, insufficient to properly understand the global structure of any interplanetary coronal mass ejection. In an attempt to partially rectify this issue, we have developed a novel magnetic flux rope model that allows for the description of arbitrary distortions of the cross-section or deformation of the magnetic axis. The distorted magnetic flux rope model is a fully analytic flux rope model, that can be used to describe significantly more complex geometries and is numerically efficient enough to be used for large ensemble simulations. To demonstrate the usefulness of our model, we focus on a specific implementation of our model and apply it to an ICME event that was observed \textit{in situ} on 2023 April 23 at the L1 point by the Wind spacecraft and also by the STEREO-A spacecraft that was $10.2^\circ$ further east and $0.9^\circ$ south in heliographic coordinates. We demonstrate that our model can accurately reconstruct each observation individual and also gives a fair reconstruction of both events simultaneously using a multi-point reconstruction approach, which results in a geometry that is not fully constistent with a cylindrical or toroidal approximation.

[137] arXiv:2406.13042 (cross-list from quant-ph) [pdf, html, other]

Title: Long-range interactions in Weyl dense atomic arrays protected from dissipation and disorder

Iñaki García-Elcano, Paloma A. Huidobro, Jorge Bravo-Abad, Alejandro González-Tudela

Comments: 15 pages, 6 figures

Subjects: Quantum Physics (quant-ph); Atomic Physics (physics.atom-ph); Optics (physics.optics)

Long-range interactions are a key resource in many quantum phenomena and technologies. Free-space photons mediate power-law interactions but lack tunability and suffer from decoherence processes due to their omnidirectional emission. Engineered dielectrics can yield tunable and coherent interactions, but typically at the expense of making them both shorter-ranged and sensitive to material disorder and photon loss. Here, we propose a platform that can circumvent all these limitations based on three-dimensional subwavelength atomic arrays subjected to magnetic fields. Our key result is to show how to design the polaritonic bands of these atomic metamaterials to feature a pair of frequency-isolated Weyl points. These Weyl excitations can thus mediate interactions that are simultaneously long-range, due to their gapless nature; robust, due to the topological protection of Weyl points; and decoherence-free, due to their subradiant character. We demonstrate the robustness of these isolated Weyl points for a large regime of interatomic distances and magnetic field values and characterize the emergence of their corresponding Fermi arcs surface states. The latter can as well lead to two-dimensional, non-reciprocal atomic interactions with no analogue in other chiral quantum optical setups.

[138] arXiv:2406.13051 (cross-list from cond-mat.mtrl-sci) [pdf, other]

Title: Size Effect of Negative Capacitance State and Subthreshold Swing in Van der Waals Ferrielectric Field-Effect Transistors

Anna N. Morozovska, Eugene A. Eliseev, Yulian M. Vysochanskii, Sergei V. Kalinin, Maksym V. Strikha

Comments: 40 pages, 6 figures, 4 Appendices

Subjects: Materials Science (cond-mat.mtrl-sci); Applied Physics (physics.app-ph)

Analytical calculations corroborated by the finite element modelling show that thin films of Van der Waals ferrielectrics covered by a 2D-semiconductor are promising candidates for the controllable reduction of the dielectric layer capacitance due to the negative capacitance (NC) effect emerging in the ferrielectric film. The NC state is conditioned by energy-degenerated poly-domain states of the ferrielectric polarization induced in the films under incomplete screening conditions in the presence of a dielectric layer. Calculations performed for the FET-type heterostructure "ferrielectric CuInP2S6 film - 2D-MoS2 single-layer - SiO2 dielectric layer" reveal the pronounced size effect of the multilayer capacitance. Derived analytical expressions for the electric polarization and multilayer capacitance allow to predict the thickness range of the dielectric layer and ferrielectric film for which the NC effect is the most pronounced in various Van der Waals ferrielectrics, and the corresponding subthreshold swing becomes much less than the Boltzmann's limit. Obtained results can be useful for the size and temperature control of the NC effect in the steep-slope ferrielectric FETs.

[139] arXiv:2406.13055 (cross-list from nucl-th) [pdf, html, other]

Title: Self-consistent strong screening applied to thermonuclear reactions

Christopher Grayson, Cheng Tao Yang, Martin Formanek, Johann Rafelski

Comments: 16 pages, 5 figures, typeset using LATEX default style in AASTeX631

Subjects: Nuclear Theory (nucl-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Plasma Physics (physics.plasm-ph)

Self-consistent strong plasma screening around light nuclei is implemented in the Big Bang nucleosynthesis (BBN) epoch to determine the short-range screening potential, $e\phi(r)/T \geq 1$, relevant for thermonuclear reactions. We numerically solve the non-linear Poisson-Boltzmann equation incorporating Fermi-Dirac statistics adopting a generalized screening mass to find the electric potential in the cosmic BBN electron-positron plasma for finite-sized $^4$He nuclei as an example. Although the plasma follows Boltzmann statistics at large distances, Fermi-Dirac statistics is necessary when work performed by ions on electrons is comparable to their rest mass energy. While strong screening effects are generally minor due to the high BBN temperatures, they can enhance the fusion rates of high-$Z>2$ elements while leaving fusion rates of lower-$Z\le 2$ elements relatively unaffected. Our results also reveal a pronounced spatial dependence of the strong screening potential near the nuclear surface. These findings about the electron-positron plasma's role refine BBN theory predictions and offer broader applications for studying weakly coupled plasmas in diverse cosmic and laboratory settings.

[140] arXiv:2406.13070 (cross-list from cond-mat.mtrl-sci) [pdf, html, other]

Title: Influence of the coating brittleness on the thermomechanical fatigue behavior of a $\beta$-NiAl coated R125 Ni-based superalloy

Capucine Billard, Damien Texier, Matthieu Rambaudon, Jean-Christophe Teissedre, Noureddine Bourhila, Dimitri Marquie, Lionel Marcin, Hugo Singer, Vincent Maurel

Subjects: Materials Science (cond-mat.mtrl-sci); Applied Physics (physics.app-ph)

The brittleness of an aluminide diffusion coating protecting a René 125 Ni-based polycrystalline superalloy was investigated over a wide range of temperatures in its as-received and thermally aged form. Isothermal and thermal cycled aging were performed on the coated system at a maximum temperature of 1100 °C. Microstructure evolutions and damage initiation within the coating were characterized. Interrupted tensile tests and thermomechanical fatigue tests were conducted to document critical stress-strain conditions leading to the coating cracking and lifetime for the case of thermo-mechanical fatigue loading. Advanced digital image correlation and acoustic emission techniques were used to detect coating cracking. Isothermal oxidation or cyclic oxidation led to improved strain-to-failure due to metallurgical evolutions and also longer fatigue life under thermomechanical fatigue conditions.

[141] arXiv:2406.13090 (cross-list from astro-ph.SR) [pdf, other]

Title: Magnetohydrodynamic simulation of the 2012-July-12 CME Event With the Fluxrope-G3DMHD Model

Chin-Chun Wu (1,a)Kan Liou (2,b)Brian Wood (1,c)Keiji Hayashi (3,d)

Comments: in press, Phys Astron Int J. 2024; 8(I):1-3.DOI:https://doi.org/10.15406/paij.2024.08.00324

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Space Physics (physics.space-ph)

Coronal mass ejections (CMEs) and their driven shocks are a major source of large geomagnetic storms due to their large and long-lasting, southward component of magnetic field in the sheath and the flux rope (e.g., magnetic cloud). Predicting the strength and arrival time of southward fields accurately thus plays a key role in space weather predictions. To address this problem, we have developed a new model, which combines the global three-dimensional, time-dependent, magnetohydrodynamic (MHD), data-driven model (G3DMHD) and a self-contained magnetic flux-rope model [1]. As a demonstration and validation, here we simulate the evolution of a Sun-Earth-directed CME that erupted on 2012-July-12. The computational domain spans from 2.5 solar radii (Rs) from the surface of the Sun, where the flux rope is injected, to 245 Rs. We compare the time profiles of the simulated MHD parameters (Density, velocity, temperature, and magnetic field) with in situ solar wind observations acquired at ~1 AU by the Wind spacecraft and the result is encouraging. The model successfully reproduces the shock, sheath, and flux rope similar to those observed by Wind.

[142] arXiv:2406.13096 (cross-list from cond-mat.mtrl-sci) [pdf, other]

Title: Electric field enhances the electronic and diffusion properties of penta-graphene nanoribbons for application in lithium-ion batteries: a first-principles study

Thi Nhan Tran, Nguyen Vo Anh Duy, Nguyen Hoang Hieu, Truc Anh Nguyen, Nguyen To Van, Viet Bac Thi Phung, Peter Schall, Minh Triet Dang

Comments: 21 pages, 5 figures

Subjects: Materials Science (cond-mat.mtrl-sci); Computational Physics (physics.comp-ph)

Enhancing the electronic and diffusion properties of lithium-ion batteries is crucial for improving the performance of the fast-growing energy storage devices. Here we use first principles methods with density functional theory and the climbing image-nudged elastic band method to evaluate the impact of an external electric field on the stability, electronic and diffusion properties of penta-graphene nanoribbons upon lithium adsorption. We show that by adsorbing a lithium atom, these semiconductor nanoribbons become metal with a formation energy of -0.22 (eV). The diffusion coefficient of this material is five orders of magnitude higher than that of a common carbon graphite layer. Under a relatively small vertical electric field, these lithium-ion systems are even more stable, and their diffusion coefficient is enhanced significantly of 711 times higher than that of the material in the absence of an applied electric field and 520 times higher than in the case of commercial graphitic carbon layers. Our results highlight the role of an external electric field as a novel switch to improve the efficiency of lithium-ion batteries with penta-graphene nanoribbon electrodes and open a new horizon for the use of more environmentally friendly pentagonal materials as electrode materials in lithium-ion battery industry.

[143] arXiv:2406.13109 (cross-list from quant-ph) [pdf, html, other]

Title: Non-hermitian Floquet perspective on high harmonic generation and above threshold ionization spectra from Photon statistics

Nimrod Moiseyev

Subjects: Quantum Physics (quant-ph); Chemical Physics (physics.chem-ph)

We present a proof based on non-hermitian Floquet theory that confirms the experimental findings of Tsatrafylis and his colleagues in 2017, demonstrating the coincidence between the high harmonic generation spectra (HGS) and the number of absorbed odd infrared (IR) photons leading to emitted extreme ultraviolet (XUV) radiation. This coincidence is achieved through post-selection of the IR photons, conserving the total energy of the absorbed odd IR photons and the emitted XUV photons. Our derivation is consistent with their results and relies on our ability to compute the HGS in ultra-high-intensity lasers using non-Hermitian quantum mechanics (NHQM), which competes with above-threshold ionization (ATI). Through our NHQM theoretical simulation, we identify the regimes where there is correspondence between the HHG and ATI spectra and annihilated pump photons (with post-selection). Additionally, we demonstrate that the photon statistics in HHG exhibit Wigner-type distributions, which reflect the quantum chaotic dynamics of electrons at the cutoff of the plateau of the HGS. We emphasize that our findings underscore a unified mechanism governing the three distinct measurements of HGS, ATI, and IR photon number distribution, none of which require the quantization of the electromagnetic field.

[144] arXiv:2406.13156 (cross-list from astro-ph.IM) [pdf, html, other]

Title: Development of RFSoC-based direct sampling highly multiplexed microwave SQUID readout for future CMB and submillimeter surveys

Chao Liu, Zeeshan Ahmed, Shawn W. Henderson, Ryan Herbst, Larry Ruckman, Thomas Satterthwaite

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Accelerator Physics (physics.acc-ph)

The SLAC Microresonator Radio Frequency (SMuRF) electronics is being deployed as the readout for the Cosmic Microwave Background (CMB) telescopes of the Simons Observatory (SO). A Radio Frequency System-on-Chip (RFSoC) based readout of microwave frequency resonator based cryogenic sensors is under development at SLAC as an upgrade path for SMuRF with simplified RF hardware, a more compact footprint, and lower total power consumption. The high-speed integrated data converters and digital data path in RFSoC enable direct RF sampling without analog up and down conversion for RF frequencies up to 6 GHz. A comprehensive optimization and characterization study has been performed for direct RF sampling for microwave SQUID multiplexers, which covers noise level, RF dynamic range, and linearity using a prototype implementation. The SMuRF firmware, including the implementation of closed-loop tone tracking, has been ported to the RFSoC platform and interfaced with the quadrature mixers for digital up and down conversion in the data converter data path to realize a full microwave SQUID multiplexer readout. In this paper, a selection of the performance characterization results of direct RF sampling for microwave SQUID multiplexer readout will be summarized and compared with science-driven requirements. Preliminary results demonstrating the read out of cryogenic sensors using the prototype system will also be presented here. We anticipate our new RFSoC-based SMuRF system will be an enabling readout for on-going and future experiments in astronomy and cosmology, which rely on large arrays of cryogenic sensors to achieve their science goals.

[145] arXiv:2406.13193 (cross-list from cs.LG) [pdf, html, other]

Title: PRESTO: Progressive Pretraining Enhances Synthetic Chemistry Outcomes

He Cao, Yanjun Shao, Zhiyuan Liu, Zijing Liu, Xiangru Tang, Yuan Yao, Yu Li

Subjects: Machine Learning (cs.LG); Artificial Intelligence (cs.AI); Computation and Language (cs.CL); Chemical Physics (physics.chem-ph)

Multimodal Large Language Models (MLLMs) have seen growing adoption across various scientific disciplines. These advancements encourage the investigation of molecule-text modeling within synthetic chemistry, a field dedicated to designing and conducting chemical reactions to synthesize new compounds with desired properties and applications. Current approaches, however, often neglect the critical role of multiple molecule graph interaction in understanding chemical reactions, leading to suboptimal performance in synthetic chemistry tasks. This study introduces PRESTO(Progressive Pretraining Enhances Synthetic Chemistry Outcomes), a new framework that bridges the molecule-text modality gap by integrating a comprehensive benchmark of pretraining strategies and dataset configurations. It progressively improves multimodal LLMs through cross-modal alignment and multi-graph understanding. Our extensive experiments demonstrate that PRESTO offers competitive results in downstream synthetic chemistry tasks. The code can be found at this https URL.

[146] arXiv:2406.13203 (cross-list from cond-mat.mes-hall) [pdf, other]

Title: Dynamical phase-field model of cavity electromagnonic systems

Shihao Zhuang, Yujie Zhu, Changchun Zhong, Liang Jiang, Xufeng Zhang, Jia-Mian Hu

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Materials Science (cond-mat.mtrl-sci); Applied Physics (physics.app-ph)

Cavity electromagnonic system, which simultaneously consists of cavities for photons, magnons (quanta of spin waves), and acoustic phonons, provides an exciting platform to achieve coherent energy transduction among different physical systems down to single quantum level. Here we report a dynamical phase-field model that allows simulating the coupled dynamics of the electromagnetic waves, magnetization, and strain in 3D multiphase systems. As examples of application, we computationally demonstrate the excitation of hybrid magnon-photon modes (magnon polaritons), Floquet-induced magnonic Aulter-Townes splitting, dynamical energy exchange (Rabi oscillation) and relative phase control (Ramsey interference) between the two magnon polariton modes. The simulation results are consistent with analytical calculations based on Floquet Hamiltonian theory. Simulations are also performed to design a cavity electro-magno-mechanical system that enables the triple phonon-magnon-photon resonance, where the resonant excitation of a chiral, fundamental (n=1) transverse acoustic phonon mode by magnon polaritons is demonstrated. With the capability to predict coupling strength, dissipation rates, and temporal evolution of photon/magnon/phonon mode profiles using fundamental materials parameters as the inputs, the present dynamical phase-field model represents a valuable computational tool to guide the fabrication of the cavity electromagnonic system and the design of operating conditions for applications in quantum sensing, transduction, and communication.

[147] arXiv:2406.13209 (cross-list from eess.IV) [pdf, html, other]

Title: Diffusion Model-based FOD Restoration from High Distortion in dMRI

Shuo Huang, Lujia Zhong, Yonggang Shi

Comments: 11 pages, 7 figures

Subjects: Image and Video Processing (eess.IV); Computer Vision and Pattern Recognition (cs.CV); Medical Physics (physics.med-ph)

Fiber orientation distributions (FODs) is a popular model to represent the diffusion MRI (dMRI) data. However, imaging artifacts such as susceptibility-induced distortion in dMRI can cause signal loss and lead to the corrupted reconstruction of FODs, which prohibits successful fiber tracking and connectivity analysis in affected brain regions such as the brain stem. Generative models, such as the diffusion models, have been successfully applied in various image restoration tasks. However, their application on FOD images poses unique challenges since FODs are 4-dimensional data represented by spherical harmonics (SPHARM) with the 4-th dimension exhibiting order-related dependency. In this paper, we propose a novel diffusion model for FOD restoration that can recover the signal loss caused by distortion artifacts. We use volume-order encoding to enhance the ability of the diffusion model to generate individual FOD volumes at all SPHARM orders. Moreover, we add cross-attention features extracted across all SPHARM orders in generating every individual FOD volume to capture the order-related dependency across FOD volumes. We also condition the diffusion model with low-distortion FODs surrounding high-distortion areas to maintain the geometric coherence of the generated FODs. We trained and tested our model using data from the UK Biobank (n = 1315). On a test set with ground truth (n = 43), we demonstrate the high accuracy of the generated FODs in terms of root mean square errors of FOD volumes and angular errors of FOD peaks. We also apply our method to a test set with large distortion in the brain stem area (n = 1172) and demonstrate the efficacy of our method in restoring the FOD integrity and, hence, greatly improving tractography performance in affected brain regions.

[148] arXiv:2406.13263 (cross-list from math.AP) [pdf, other]

Title: Well-posedness of the Euler equations in a stably stratified ocean in isopycnal coordinates

Théo Fradin (IMB)

Subjects: Analysis of PDEs (math.AP); Atmospheric and Oceanic Physics (physics.ao-ph); Fluid Dynamics (physics.flu-dyn)

This article is concerned with the well-posedness of the incompressible Euler equations describing a stably stratified ocean, reformulated in isopycnal coordinates. Our motivation for using this reformulation is twofold: first, its quasi-2D structure renders some parts of the analysis easier. Second, it closes a gap between the analysis performed in the paper by Bianchini and Duch{ê}ne in 2022 in isopycnal coordinates, with shear velocity but with a regularizing term, and the analysis performed in the paper by Desjardins, Lannes, Saut in 2020 in Eulerian coordinates, without any regularizing term but without shear velocity. Our main result is an energy estimate in Sobolev spaces on the system in isopycnal coordinates, with shear velocity, without any regularizing term. With additional assumptions, it is uniform in the shallow-water parameter. The main difficulty consists in transposing to the isopycnal reformulation the symmetric structure of the system which is more straightforward in Eulerian coordinates.

[149] arXiv:2406.13382 (cross-list from cond-mat.mtrl-sci) [pdf, other]

Title: Flexoelectricity in Amorphous Hafnium Oxide (HfO$_2$)

Daniel Moreno-Garcia, Kaitlin M. Howell, Luis Guillermo Villanueva

Subjects: Materials Science (cond-mat.mtrl-sci); Applied Physics (physics.app-ph)

Flexoelectricity, inherent in all materials, offers a promising alternative to piezoelectricity for nanoscale actuation and sensing. However, its widespread application faces significant challenges: differentiating flexoelectric effects from those of piezoelectricity and other phenomena, verifying its universality across all material structures and thicknesses, and establishing a comprehensive database of flexoelectric coefficients across different materials. This work introduces a groundbreaking methodology that accurately isolates flexoelectricity from piezoelectric, electrostrictive and electrostatic effects, with a detection threshold extending below 1 fC/m. The robustness of this method is demonstrated through its application to amorphous hafnium oxide (HfO$_2$), successfully measuring a flexoelectric coefficient of 105 $\pm$ 10 pC/m. This measurement signifies the first measurement of flexoelectricity in hafnia, as well as in any amorphous material. Additionally, the study compiles a list of published flexoelectric coefficients, revealing an important insight. The relationship between the flexoelectric coefficient and the material's relative permittivity is better approximated by a quadratic proportionality. This challenges the traditional linear assumption proposed in Kogan's work and opens new avenues for future research in flexoelectric materials.

[150] arXiv:2406.13389 (cross-list from cond-mat.soft) [pdf, html, other]

Title: Unifying Mixed Gas Adsorption in Molecular Sieve Membranes and MOFs using Machine Learning

Subhadeep Dasgupta, Amal R S, Prabal K. Maiti

Comments: Accepted in Separation and Purification Technology, on June 16, 2024. Data available at this https URL

Subjects: Soft Condensed Matter (cond-mat.soft); Materials Science (cond-mat.mtrl-sci); Machine Learning (cs.LG); Computational Physics (physics.comp-ph)

Recent machine learning models to accurately obtain gas adsorption isotherms focus on polymers or metal-organic frameworks (MOFs) separately. The difficulty in creating a unified model that can predict the adsorption trends in both types of adsorbents is challenging, owing to the diversity in their chemical structures. Moreover, models trained only on single gas adsorption data are incapable of predicting adsorption isotherms for binary gas mixtures. In this work, we address these problems using feature vectors comprising only the physical properties of the gas mixtures and adsorbents. Our model is trained on adsorption isotherms of both single and binary mixed gases inside carbon molecular sieving membrane (CMSM), together with data available from CoRE MOF database. The trained models are capable of accurately predicting the adsorption trends in both classes of materials, for both pure and binary components. ML architecture designed for one class of material, is not suitable for predicting the other class, even after proper training, signifying that the model must be trained jointly for proper predictions and transferability. The model is used to predict with good accuracy the CO2 uptake inside CALF-20 framework. This work opens up a new avenue for predicting complex adsorption processes for gas mixtures in a wide range of materials.

[151] arXiv:2406.13452 (cross-list from quant-ph) [pdf, html, other]

Title: Quantum Networks: from Multipartite Entanglement to Hypergraph Immersion

Yu Tian, Yuefei Liu, Xiangyi Meng

Comments: 8 pages, 3 figures, 1 table

Subjects: Quantum Physics (quant-ph); Discrete Mathematics (cs.DM); Social and Information Networks (cs.SI); Computational Physics (physics.comp-ph); Physics and Society (physics.soc-ph)

Multipartite entanglement, a higher-order interaction unique to quantum information, offers various advantages over bipartite entanglement in quantum network (QN) applications. Establishing multipartite entanglement across remote parties in QN requires entanglement routing, which irreversibly transforms the QN topology at the cost of existing entanglement links. Here, we address the question of whether a QN can be topologically transformed into another via entanglement routing. Our key result is an exact mapping from multipartite entanglement routing to Nash-Williams's graph immersion problem, extended to hypergraphs. This generalized hypergraph immersion problem introduces a partial order between QN topologies, permitting certain topological transformations while precluding others, offering discerning insights into the design and manipulation of higher-order network topologies in QNs.

[152] arXiv:2406.13504 (cross-list from cond-mat.stat-mech) [pdf, html, other]

Title: Self-organized transport in noisy dynamic networks

Frederic Folz, Kurt Mehlhorn, Giovanna Morigi

Comments: 12 pages, 10 figures

Subjects: Statistical Mechanics (cond-mat.stat-mech); Adaptation and Self-Organizing Systems (nlin.AO); Biological Physics (physics.bio-ph); Neurons and Cognition (q-bio.NC)

We present a numerical study of multi-commodity transport in a noisy, nonlinear network. The nonlinearity determines the dynamics of the edge capacities, which can be amplified or suppressed depending on the local current flowing across an edge. We consider network self-organization for three different nonlinear functions: For all three we identify parameter regimes where noise leads to self-organization into more robust topologies, that are not found by the sole noiseless dynamics. Moreover, the interplay between noise and specific functional behavior of the nonlinearity gives rise to different features, such as (i) continuous or discontinuous responses to the demand strength and (ii) either single or multi-stable solutions. Our study shows the crucial role of the activation function on noise-assisted phenomena.

[153] arXiv:2406.13505 (cross-list from cs.AR) [pdf, other]

Title: Demonstration of low power and highly uniform 6-bit operation in SiO2-based memristors embedded with Pt nanoparticles

G. Kleitsiotis, P. Bousoulas, S. D. Mantas, C. Tsioustas, I. A. Fyrigos, G. Sirakoulis, D. Tsoukalas

Subjects: Hardware Architecture (cs.AR); Emerging Technologies (cs.ET); Applied Physics (physics.app-ph)

In this work, an optimized method was implemented for attaining stable multibit operation with low energy consumption in a two-terminal memory element made from the following layers: Ag/Pt nanoparticles (NPs)/SiO2/TiN in a 1-Transistor-1-Memristor configuration. Compared to the reference sample where no NPs were embedded, an enlarged memory window was recorded in conjunction with reduced variability for both switching states. A comprehensive numerical model was also applied to shed light on this enhanced performance, which was attributed to the spatial confinement effect induced by the presence of the Pt NPs and its impact on the properties of the percolating conducting filaments (CFs). Although 5-bit precision was demonstrated with the application of the incremental-step-pulse-programming (ISPP) algorithm, the reset process was unreliable and the output current increased abnormally when exceeded the value of 150 uA. As a result, the multibit operation was limited. To address this issue, a modified scheme was developed to accurately control the distance between the various resistance levels and achieve highly reliable 6-bit precision. Our work provides valuable insights for the development of energy-efficient memories for applications where a high density of conductance levels is required.

[154] arXiv:2406.13512 (cross-list from quant-ph) [pdf, html, other]

Title: Managing Temperature in Open Quantum Systems Strongly Coupled with Structured Environments

Brieuc Le Dé, Amine Jaouadi, Etienne Mangaud, Alex W. Chin, Michèle Desouter-Lecomte

Comments: 24 pages, 14 figures and supplemental material

Subjects: Quantum Physics (quant-ph); Chemical Physics (physics.chem-ph)

In non-perturbative non-Markovian open quantum systems, reaching either low temperatures with the hierarchical equations of motion (HEOM) or high temperatures with the Thermalized Time Evolving Density Operator with Orthogonal Polynomials (T-TEDOPA) formalism in Hilbert space remains challenging. We compare different manners of modeling the environment. Sampling the Fourier transform of the bath correlation function, also called temperature dependent spectral density, proves to be very effective. T-TEDOPA (Tamascelli et al. Phys. Rev. Lett. 123, 090402 (2019)) uses a linear chain of oscillators with positive and negative frequencies while HEOM is based on the complex poles of an optimized rational decomposition of the temperature dependent spectral density (Xu et al. Phys. Rev. Lett. 129, 230601 (2022)). Resorting to the poles of the temperature independent spectral density and of the Bose function separately is an alternative when the problem due to the huge number of the Bose poles at low temperature is circumvented. Two examples illustrate the effectiveness of the HEOM and T-TEDOPA approaches: a benchmark pure dephasing case and a two-bath model simulating dynamics of excited electronic states coupled through a conical intersection. We show the efficiency of T-TEDOPA to simulate dynamics at a finite temperature by using either continuous spectral densities or only all the intramolecular oscillators of a linear vibronic model calibrated from ab initio data of a phenylene ethynylene dimer.

[155] arXiv:2406.13548 (cross-list from cond-mat.quant-gas) [pdf, html, other]

Title: Dynamical Instabilities of Strongly Interacting Ultracold Fermions in an Optical Cavity

Filip Marijanović, Sambuddha Chattopadhyay, Luka Skolc, Timo Zwettler, Catalin-Mihai Halati, Simon B. Jäger, Thierry Giamarchi, Jean-Philippe Brantut, Eugene Demler

Subjects: Quantum Gases (cond-mat.quant-gas); Atomic Physics (physics.atom-ph)

Recent quench experiments on ultra cold fermions in optical cavities provide a clean platform for studying how long-range interactions between fermions structure their dynamics. Motivated by these experiments, we provide a theoretical analysis of the dynamical instabilities that lead to the formation of superradiance as the hybrid system is driven across the self-organization transition. We compute the rate at which order forms and quantify the fluctuations of the pre-quench state which seed the instability. Our results quantitatively match existing experiments on free fermions and make predictions for quench experiments involving near unitary fermi gases coupled to an optical cavity. Our work suggests that the non-local nature of the photon-mediated interactions between fermions generates ordering dynamics that are qualitatively different than those observed in short-range interacting systems.

[156] arXiv:2406.13605 (cross-list from cs.CY) [pdf, html, other]

Title: Nicer Than Humans: How do Large Language Models Behave in the Prisoner's Dilemma?

Nicoló Fontana, Francesco Pierri, Luca Maria Aiello

Comments: 9 pages, 8 figures, 1 table

Subjects: Computers and Society (cs.CY); Artificial Intelligence (cs.AI); Computer Science and Game Theory (cs.GT); Physics and Society (physics.soc-ph)

The behavior of Large Language Models (LLMs) as artificial social agents is largely unexplored, and we still lack extensive evidence of how these agents react to simple social stimuli. Testing the behavior of AI agents in classic Game Theory experiments provides a promising theoretical framework for evaluating the norms and values of these agents in archetypal social situations. In this work, we investigate the cooperative behavior of Llama2 when playing the Iterated Prisoner's Dilemma against random adversaries displaying various levels of hostility. We introduce a systematic methodology to evaluate an LLM's comprehension of the game's rules and its capability to parse historical gameplay logs for decision-making. We conducted simulations of games lasting for 100 rounds, and analyzed the LLM's decisions in terms of dimensions defined in behavioral economics literature. We find that Llama2 tends not to initiate defection but it adopts a cautious approach towards cooperation, sharply shifting towards a behavior that is both forgiving and non-retaliatory only when the opponent reduces its rate of defection below 30%. In comparison to prior research on human participants, Llama2 exhibits a greater inclination towards cooperative behavior. Our systematic approach to the study of LLMs in game theoretical scenarios is a step towards using these simulations to inform practices of LLM auditing and alignment.

[157] arXiv:2406.13616 (cross-list from quant-ph) [pdf, html, other]

Title: Entangled Matter-waves for Quantum Enhanced Sensing

John Drew Wilson, Jarrod T. Reilly, Haoqing Zhang, Chengyi Luo, Anjun Chu, James K. Thompson, Ana Maria Rey, Murray J. Holland

Subjects: Quantum Physics (quant-ph); Atomic and Molecular Clusters (physics.atm-clus)

The ability to create and harness entanglement is crucial to the fields of quantum sensing andsimulation, and ultracold atom-cavity systems offer pristine platforms for this undertaking. Recently, an experiment demonstrated an effective momentum-exchange interaction between atoms in a common cavity mode. Here, we derive this interaction from a general atom-cavity model, and discuss the role of the cavity frequency shift in response to atomic motion. We show the cavity response leads to many different squeezing interactions between the atomic momentum states. Furthermore, when the atoms form a density grating, the collective motion leads to one-axis twisting, a many-body energy gap, and metrologically useful entanglement even in the presence of noise. This system offers a highly tunable, many-body quantum sensor and simulator.

[158] arXiv:2406.13625 (cross-list from cs.CV) [pdf, other]

Title: Enhance the Image: Super Resolution using Artificial Intelligence in MRI

Ziyu Li, Zihan Li, Haoxiang Li, Qiuyun Fan, Karla L. Miller, Wenchuan Wu, Akshay S. Chaudhari, Qiyuan Tian

Comments: A book chapter in Machine Learning in MRI: From methods to clinical translation. Copyright may be transferred without notice, after which this version may no longer be accessible

Subjects: Computer Vision and Pattern Recognition (cs.CV); Artificial Intelligence (cs.AI); Medical Physics (physics.med-ph)

This chapter provides an overview of deep learning techniques for improving the spatial resolution of MRI, ranging from convolutional neural networks, generative adversarial networks, to more advanced models including transformers, diffusion models, and implicit neural representations. Our exploration extends beyond the methodologies to scrutinize the impact of super-resolved images on clinical and neuroscientific assessments. We also cover various practical topics such as network architectures, image evaluation metrics, network loss functions, and training data specifics, including downsampling methods for simulating low-resolution images and dataset selection. Finally, we discuss existing challenges and potential future directions regarding the feasibility and reliability of deep learning-based MRI super-resolution, with the aim to facilitate its wider adoption to benefit various clinical and neuroscientific applications.

[159] arXiv:2406.13627 (cross-list from cs.LG) [pdf, html, other]

Title: Can AI be enabled to dynamical downscaling? Training a Latent Diffusion Model to mimic km-scale COSMO-CLM downscaling of ERA5 over Italy

Elena Tomasi, Gabriele Franch, Marco Cristoforetti

Comments: 24 pages, 14 figures

Subjects: Machine Learning (cs.LG); Atmospheric and Oceanic Physics (physics.ao-ph)

Downscaling techniques are one of the most prominent applications of Deep Learning (DL) in Earth System Modeling. A robust DL downscaling model can generate high-resolution fields from coarse-scale numerical model simulations, saving the timely and resourceful applications of regional/local models. Additionally, generative DL models have the potential to provide uncertainty information, by generating ensemble-like scenario pools, a task that is computationally prohibitive for traditional numerical simulations. In this study, we apply a Latent Diffusion Model (LDM) to downscale ERA5 data over Italy up to a resolution of 2 km. The high-resolution target data consists of results from a high-resolution dynamical downscaling performed with COSMO-CLM. Our goal is to demonstrate that recent advancements in generative modeling enable DL-based models to deliver results comparable to those of numerical dynamical downscaling models, given the same input data (i.e., ERA5 data), preserving the realism of fine-scale features and flow characteristics. The training and testing database consists of hourly data from 2000 to 2020. The target variables of this study are 2-m temperature and 10-m horizontal wind components. A selection of predictors from ERA5 is used as input to the LDM, and a residual approach against a reference UNET is leveraged in applying the LDM. The performance of the generative LDM is compared with reference baselines of increasing complexity: quadratic interpolation of ERA5, a UNET, and a Generative Adversarial Network (GAN) built on the same reference UNET. Results highlight the improvements introduced by the LDM architecture and the residual approach over these baselines. The models are evaluated on a yearly test dataset, assessing the models' performance through deterministic metrics, spatial distribution of errors, and reconstruction of frequency and power spectra distributions.

[160] arXiv:2406.13644 (cross-list from math.NA) [pdf, html, other]

Title: Kinetic Monte Carlo methods for three-dimensional diffusive capture problems in exterior domains

Alan E. Lindsay, Andrew J. Bernoff

Comments: 32 pages, 10 figures

Subjects: Numerical Analysis (math.NA); Analysis of PDEs (math.AP); Biological Physics (physics.bio-ph); Quantitative Methods (q-bio.QM)

Cellular scale decision making is modulated by the dynamics of signalling molecules and their diffusive trajectories from a source to small absorbing sites on the cellular surface. Diffusive capture problems are computationally challenging due to the complex geometry and the applied boundary conditions together with intrinsically long transients that occur before a particle is captured. This paper reports on a particle-based Kinetic Monte Carlo (KMC) method that provides rapid accurate simulation of arrival statistics for (i) a half-space bounded by a surface with a finite collection of absorbing traps and (ii) the domain exterior to a convex cell again with absorbing traps. We validate our method by replicating classical results and in addition, newly developed boundary homogenization theories and matched asymptotic expansions on capture rates. In the case of non-spherical domains, we describe a new shielding effect in which geometry can play a role in sharpening cellular estimates on the directionality of diffusive sources.

[161] arXiv:2406.13661 (cross-list from cs.LG) [pdf, html, other]

Title: Hitchhiker's guide on Energy-Based Models: a comprehensive review on the relation with other generative models, sampling and statistical physics

Davide Carbone (1 and 2) ((1) Dipartimento di Scienze Matematiche, Politecnico di Torino, Torino, Italy, (2) INFN, Sezione di Torino, Torino, Italy)

Subjects: Machine Learning (cs.LG); Mathematical Physics (math-ph); Applied Physics (physics.app-ph); Data Analysis, Statistics and Probability (physics.data-an)

Energy-Based Models (EBMs) have emerged as a powerful framework in the realm of generative modeling, offering a unique perspective that aligns closely with principles of statistical mechanics. This review aims to provide physicists with a comprehensive understanding of EBMs, delineating their connection to other generative models such as Generative Adversarial Networks (GANs), Variational Autoencoders (VAEs), and Normalizing Flows. We explore the sampling techniques crucial for EBMs, including Markov Chain Monte Carlo (MCMC) methods, and draw parallels between EBM concepts and statistical mechanics, highlighting the significance of energy functions and partition functions. Furthermore, we delve into state-of-the-art training methodologies for EBMs, covering recent advancements and their implications for enhanced model performance and efficiency. This review is designed to clarify the often complex interconnections between these models, which can be challenging due to the diverse communities working on the topic.

[162] arXiv:2406.13708 (cross-list from eess.IV) [pdf, other]

Title: Low-rank based motion correction followed by automatic frame selection in DT-CMR

Fanwen Wang, Pedro F.Ferreira, Camila Munoz, Ke Wen, Yaqing Luo, Jiahao Huang, Yinzhe Wu, Dudley J.Pennell, Andrew D. Scott, Sonia Nielles-Vallespin, Guang Yang

Comments: Accepted as ISMRM 2024 Digital poster 2141

Journal-ref: ISMRM 2024 Digital poster 2141

Subjects: Image and Video Processing (eess.IV); Medical Physics (physics.med-ph)

Motivation: Post-processing of in-vivo diffusion tensor CMR (DT-CMR) is challenging due to the low SNR and variation in contrast between frames which makes image registration difficult, and the need to manually reject frames corrupted by motion. Goals: To develop a semi-automatic post-processing pipeline for robust DT-CMR registration and automatic frame selection. Approach: We used low intrinsic rank averaged frames as the reference to register other low-ranked frames. A myocardium-guided frame selection rejected the frames with signal loss, through-plane motion and poor registration. Results: The proposed method outperformed our previous noise-robust rigid registration on helix angle data quality and reduced negative eigenvalues in healthy volunteers.

[163] arXiv:2406.13825 (cross-list from cond-mat.mes-hall) [pdf, other]

Title: Low frequency noise in nanoparticle-molecule networks and implications for in-materio reservoir computing

Cécile Huez, David Guérin, Florence Volatron, Anna Proust, Dominique Vuillaume

Comments: Full paper and supporting information

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Applied Physics (physics.app-ph)

We study the low-frequency noise (LFN), i.e. flicker noise, also referred to as 1/f noise, in 2D networks of molecularly functionalized gold nanoparticles (NMN: nanoparticle-molecule network). We examine the noise behaviors of the NMN hosting alkyl chains (octanethiol), fatty acid oleic acids (oleylamine), redox molecule switches (polyoxometalate derivatives) or photo-isomerizable molecules (azobenzene derivatives) and we compare their 1/f noise behaviors. These noise metrics are used to evaluate which molecules are the best candidates to build in-materio reservoir computing molecular devices based on NMNs.

[164] arXiv:2406.13978 (cross-list from cond-mat.mes-hall) [pdf, html, other]

Title: Topological Solitons in Square-root Graphene Nanoribbons Controlled by Electric Fields

Haiyue Huang (1), Mamun Sarker (2), Percy Zahl (3), C. Stephen Hellberg (4), Jeremy Levy (5), Ioannis Petrides (1), Alexander Sinitskii (2), Prineha Narang (1,6) ((1) Division of Physical Sciences, College of Letters and Science, University of California, Los Angeles, California, USA (2) Department of Chemistry, University of Nebraska, Lincoln, Nebraska, USA (3) Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York, USA (4) U.S. Naval Research Laboratory, Washington, District of Columbia, USA (5) Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania, USA (6) Department of Electrical and Computer Engineering, University of California, Los Angeles, California, USA)

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Materials Science (cond-mat.mtrl-sci); Computational Physics (physics.comp-ph); Quantum Physics (quant-ph)

Graphene nanoribbons (GNRs) are unique quasi-one-dimensional (1D) materials that have garnered a lot of research interest in the field of topological insulators. While the topological phases exhibited by GNRs are primarily governed by their chemical structures, the ability to externally control these phases is crucial for their potential utilization in quantum electronics and spintronics. Here we propose a class of GNRs featured by mirror symmetry and four zigzag segments in a unit cell that has unique topological properties induced and controlled by an externally applied electric field. Their band structures manifest two finite gaps which support topological solitons, as described by an effective square-root model. To demonstrate the experimental feasibility, we design and synthesize a representative partially zigzag chevron-type GNR (pzc-GNR) with the desired zigzag segments using a bottom-up approach. First-principles calculations on pzc-GNR reveal band inversions at the two finite gaps by switching the direction of the electric field, which is in accordance with predictions from the square-root Hamiltonian. We show different topological phases can be achieved by controlling the direction of the field and the chemical potential of the system in square-root GNRs. Consequently, upon adding a step-function electric field, solitons states can be generated at the domain wall. We discuss the properties of two types of soliton states, depending on whether the terminating commensurate unit cell is mirror symmetric.

[165] arXiv:2406.14030 (cross-list from cond-mat.stat-mech) [pdf, html, other]

Title: The inviscid fixed point of the multi-dimensional Burgers-KPZ equation

Liubov Gosteva, Malo Tarpin, Nicolás Wschebor, Léonie Canet

Comments: 17 pages, 5 figures

Subjects: Statistical Mechanics (cond-mat.stat-mech); Fluid Dynamics (physics.flu-dyn)

A new scaling regime characterized by a $z=1$ dynamical critical exponent has been reported in several numerical simulations of the one-dimensional Kardar-Parisi-Zhang and noisy Burgers equations. This scaling was found to emerge in the tensionless limit for the interface and in the inviscid limit for the fluid. Based on functional renormalization group, the origin of this scaling has been elucidated. It was shown to be controlled by a yet unpredicted fixed point of the one-dimensional Burgers-KPZ equation, termed inviscid Burgers fixed point. The associated universal properties, including the scaling function, were calculated. Here, we generalize this analysis to the multi-dimensional Burgers-KPZ equation. We show that the inviscid-Burgers fixed point exists in all dimensions $d$, and that it controls the large momentum behavior of the correlation functions in the inviscid limit. It turns out that it yields in all $d$ the same super-universal value $z=1$ for the dynamical exponent.

[166] arXiv:2406.14049 (cross-list from cond-mat.quant-gas) [pdf, html, other]

Title: Emergent Universal Drag Law in a Model of Superflow

M.T.M. Christenhusz, A. Safavi-Naini, H. Rubinsztein-Dunlop, T.W. Neely, M.T. Reeves

Comments: 6+2 pages, 3+2 figures, 1 table

Subjects: Quantum Gases (cond-mat.quant-gas); Fluid Dynamics (physics.flu-dyn)

Despite the fundamentally different dissipation mechanisms, many laws and phenomena of classical turbulence equivalently manifest in quantum turbulence. The Reynolds law of dynamical similarity states that two objects of same geometry across different length scales are hydrodynamically equivalent under the same Reynolds number, leading to a universal drag coefficient law. In this work we confirm the existence of a universal drag law in a superfluid wake, facilitated by the nucleation of quantized vortices. We numerically study superfluid flow across a range of Reynolds numbers for the paradigmatic classical hard-wall and the Gaussian obstacle, popular in experimental quantum hydrodynamics. In addition, we provide a feasible method for measuring superfluid drag forces in an experimental environment using control volumes.

[167] arXiv:2406.14062 (cross-list from q-bio.QM) [pdf, html, other]

Title: An agent-based model of behaviour change calibrated to reversal learning data

Roben Delos Reyes, Hugo Lyons Keenan, Cameron Zachreson

Comments: 23 pages, 5 figures

Subjects: Quantitative Methods (q-bio.QM); Biological Physics (physics.bio-ph); Computation (stat.CO)

Behaviour change lies at the heart of many observable collective phenomena such as the transmission and control of infectious diseases, adoption of public health policies, and migration of animals to new habitats. Representing the process of individual behaviour change in computer simulations of these phenomena remains an open challenge. Often, computational models use phenomenological implementations with limited support from behavioural data. Without a strong connection to observable quantities, such models have limited utility for simulating observed and counterfactual scenarios of emergent phenomena because they cannot be validated or calibrated. Here, we present a simple stochastic individual-based model of reversal learning that captures fundamental properties of individual behaviour change, namely, the capacity to learn based on accumulated reward signals, and the transient persistence of learned behaviour after rewards are removed or altered. The model has only two parameters, and we use approximate Bayesian computation to demonstrate that they are fully identifiable from empirical reversal learning time series data. Finally, we demonstrate how the model can be extended to account for the increased complexity of behavioural dynamics over longer time scales involving fluctuating stimuli. This work is a step towards the development and evaluation of fully identifiable individual-level behaviour change models that can function as validated submodels for complex simulations of collective behaviour change.

[168] arXiv:2406.14079 (cross-list from cond-mat.mtrl-sci) [pdf, other]

Title: Nano-Patterned Pt-Based Metallic Glass Electrocatalysts with In-Situ Copper Oxide Foam for Enhanced Hydrogen Evolution

Fei-Fan Cai, Baran Sarac, Adnan Akman, Juan J. Londoño, Selin Gümrükcü, Lukas Schweiger, Martin Hantusch, Jan Schroers, Andreas Blatter, Annett Gebert, Florian Spieckermann, Jürgen Eckert

Comments: 28 pages, 9 figures (including supplementary information)

Subjects: Materials Science (cond-mat.mtrl-sci); Chemical Physics (physics.chem-ph)

Hydrogen is a promising energy carrier for replacing fossil fuels, and hydrogen production via hydrogen evolution reaction (HER) is an environmentally friendly option if electrocatalysts with low overpotentials and long-term stability are used. In this work, the electrocatalytic performance of $\mathrm{Pt_{57.5}Cu_{14.7}Ni_{5.3}P_{22.5}}$ bulk metallic glass (BMG) with flat, micro-patterned, and nano-patterned surfaces for HER in 0.5 M H2SO4 is studied. The nano-patterned Pt-BMG demonstrates outstanding long-term stability and self-improving behavior with a final overpotential of 150 mV and a Tafel slope of 42 $\mathrm{mV dec^{-1}}$ after 1000 linear sweep voltammetry (LSV) cycles, which is respectively 42% and 37% lower than in the first LSV cycle. X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) indicate the formation of a layer of CuO/Cu2O foam deposited on top of the nano-patterned surface during the stability test of 1000 LSV cycles. A three-step process is proposed to explain the formation of CuxO foam via dynamic hydrogen bubble templating (DHBT) electrodeposition from Cu dissolution of the Pt-BMG without using copper salt. This work provides a method to create CuxO foams that could be used for various applications. Moreover, nano-patterned BMGs with DHBT deposition offer a feasible strategy to synthesize metal or metal-oxide foams.

[169] arXiv:2406.14113 (cross-list from quant-ph) [pdf, html, other]

Title: A differentiable quantum phase estimation algorithm

Davide Castaldo, Soran Jahangiri, Agostino Migliore, Juan Miguel Arrazola, Stefano Corni

Subjects: Quantum Physics (quant-ph); Computational Physics (physics.comp-ph)

The simulation of electronic properties is a pivotal issue in modern electronic structure theory, driving significant efforts over the past decades to develop protocols for computing energy derivatives. In this work, we address this problem by developing a strategy to integrate the quantum phase estimation algorithm within a fully differentiable framework. This is accomplished by devising a smooth estimator able to tackle arbitrary initial states. We provide analytical expressions to characterize the statistics and algorithmic cost of this estimator. Furthermore, we provide numerical evidence that the estimation accuracy is retained when an arbitrary state is considered and that it exceeds the one of standard majority rule. We explicitly use this procedure to estimate chemically relevant quantities, demonstrating our approach through ground-state and triplet excited state geometry optimization with simulations involving up to 19 qubits. This work paves the way for new quantum algorithms that combine interference methods and quantum differentiable programming.

[170] arXiv:2406.14121 (cross-list from hep-ex) [pdf, html, other]

Title: First Demonstration of a Combined Light and Charge Pixel Readout on the Anode Plane of a LArTPC

N. Anfimov, A. Branca, J. Bürgi, L. Calivers, C. Cuesta, R. Diurba, P. Dunne, D. A. Dwyer, J. J. Evans, A. C. Ezeribe, A. Gauch, I. Gil-Botella, S. Greenberg, D. Guffanti, A. Karcher, I. Kreslo, J. Kunzmann, N. Lane, S. Manthey Corchado, N. McConkey, A. Navrer-Agasson, S. Parsa, G. Ruiz Ferreira, B. Russell, A. Selyunin, S. Söldner-Rembold, A. M. Szelc, A. Tapper, F. Terranova, C. Tognina, G. V. Stenico, M. Weber, I. Xiotidis

Subjects: High Energy Physics - Experiment (hep-ex); Instrumentation and Detectors (physics.ins-det)

The novel SoLAr concept aims to extend sensitivities of liquid-argon neutrino detectors down to the MeV scale for next-generation detectors. SoLAr plans to accomplish this with a liquid-argon time projection chamber that employs an anode plane with dual charge and light readout, which enables precision matching of light and charge signals for data acquisition and reconstruction purposes. We present the results of a first demonstration of the SoLAr detector concept with a small-scale prototype detector integrating a pixel-based charge readout and silicon photomultipliers on a shared printed circuit board. We discuss the design of the prototype, and its operation and performance, highlighting the capability of such a detector design.

[171] arXiv:2406.14200 (cross-list from cond-mat.dis-nn) [pdf, html, other]

Title: Gaussian approximation of dynamic cavity equations for linearly-coupled stochastic dynamics

Mattia Tarabolo, Luca Dall'Asta

Comments: 44 pages, 5 figures (including supplemental material)

Subjects: Disordered Systems and Neural Networks (cond-mat.dis-nn); Statistical Mechanics (cond-mat.stat-mech); Data Analysis, Statistics and Probability (physics.data-an)

Stochastic dynamics on sparse graphs and disordered systems often lead to complex behaviors characterized by heterogeneity in time and spatial scales, slow relaxation, localization, and aging phenomena. The mathematical tools and approximation techniques required to analyze these complex systems are still under development, posing significant technical challenges and resulting in a reliance on numerical simulations. We introduce a novel computational framework for investigating the dynamics of sparse disordered systems with continuous degrees of freedom. Starting with a graphical model representation of the dynamic partition function for a system of linearly-coupled stochastic differential equations, we use dynamic cavity equations on locally tree-like factor graphs to approximate the stochastic measure. Here, cavity marginals are identified with local functionals of single-site trajectories. Our primary approximation involves a second-order truncation of a small-coupling expansion, leading to a Gaussian form for the cavity marginals. For linear dynamics with additive noise, this method yields a closed set of causal integro-differential equations for cavity versions of one-time and two-time averages. These equations provide an exact dynamical description within the local tree-like approximation, retrieving classical results for the spectral density of sparse random matrices. Global constraints, non-linear forces, and state-dependent noise terms can be addressed using a self-consistent perturbative closure technique. The resulting equations resemble those of dynamical mean-field theory in the mode-coupling approximation used for fully-connected models. However, due to their cavity formulation, the present method can also be applied to ensembles of sparse random graphs and employed as a message-passing algorithm on specific graph instances.

[172] arXiv:2406.14245 (cross-list from cs.CR) [pdf, html, other]

Title: On countering adversarial perturbations in graphs using error correcting codes

Saif Eddin Jabari

Subjects: Cryptography and Security (cs.CR); Data Analysis, Statistics and Probability (physics.data-an)

We consider the problem of a graph subjected to adversarial perturbations, such as those arising from cyber-attacks, where edges are covertly added or removed. The adversarial perturbations occur during the transmission of the graph between a sender and a receiver. To counteract potential perturbations, we explore a repetition coding scheme with sender-assigned binary noise and majority voting on the receiver's end to rectify the graph's structure. Our approach operates without prior knowledge of the attack's characteristics. We provide an analytical derivation of a bound on the number of repetitions needed to satisfy probabilistic constraints on the quality of the reconstructed graph. We show that the method can accurately decode graphs that were subjected to non-random edge removal, namely, those connected to vertices with the highest eigenvector centrality, in addition to random addition and removal of edges by the attacker.

[173] arXiv:2406.14256 (cross-list from cond-mat.soft) [pdf, html, other]

Title: Microscopic and stochastic simulations of chemically active droplets

Roxanne Berthin, Jacques Fries, Marie Jardat, Vincent Dahirel, Pierre Illien

Subjects: Soft Condensed Matter (cond-mat.soft); Statistical Mechanics (cond-mat.stat-mech); Biological Physics (physics.bio-ph)

Biomolecular condensates play a central role in the spatial organization of living matter. Their formation is now well understood as a form of liquid-liquid phase separation that occurs very far from equilibrium. For instance, they can be modeled as active droplets, where the combination of molecular interactions and chemical reactions result in microphase separation. However, so far, models of chemically active droplets are spatially continuous and deterministic. Therefore, the relationship between the microscopic parameters of the models and some crucial properties of active droplets (such as their polydispersity, their shape anisotropy, or their typical lifetime) is yet to be established. In this work, we address this question computationally, using Brownian dynamics simulations of chemically active droplets: the building blocks are represented explicitly as particles that interact with attractive or repulsive interactions, depending on whether they are in a droplet-forming state or not. Thanks to this microscopic and stochastic view of the problem, we reveal how driving the system away from equilibrium in a controlled way determines the fluctuations and dynamics of active emulsions.

[174] arXiv:2406.14327 (cross-list from cond-mat.stat-mech) [pdf, html, other]

Title: Application of Haldane's statistical correlation theory in classical systems

Projesh Kumar Roy

Subjects: Statistical Mechanics (cond-mat.stat-mech); Mathematical Physics (math-ph); Data Analysis, Statistics and Probability (physics.data-an); Quantum Physics (quant-ph)

This letter investigates the application of Haldane's statistical correlation theory in classical systems. A modified statistical correlation theory has been proposed by including non-linearity into the original theory of Haldane. It is shown that indistinguishability can be introduced as a form of external statistical correlation into distinguishable systems. It is proved that this modified statistical correlation theory can be used to derive classical fractional exclusion statistics (CFES) using maximum entropy methods for a self-correlating system. An extended non-linear correlation model based on power series expansion is also proposed, which can produce various intermediate statistical models.

[175] arXiv:2406.14363 (cross-list from astro-ph.SR) [pdf, html, other]

Title: Analysis of Differences between ICME catalogues and Construction of a Unified Catalogue

Anton Shiryaev (1 and 2), Ksenia Kaportseva (1 and 3) ((1) Lomonosov Moscow State University, Skobeltsyn Institute of Nuclear Physics, (2) Faculty of Information Technology, Bryansk State Technical University, (3) Lomonosov Moscow State University, Physics Faculty)

Comments: 22 pages, in Russian language, 4 figures

Journal-ref: Memoirs of the Faculty of Physics 44, 2023

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Space Physics (physics.space-ph)

Multiple magnetic and kinetic solar wind plasma parameters are used to detect coronal mass ejections (CMEs) as they travel through the heliosphere. There are various interplanetary CME (ICME) catalogues, but due to differences between their ICME identification criteria they can significantly vary. In this paper we analyze Richardson and Cane and CCMC CME Scoreboard ICME catalogues and the SRI RAS solar wind types catalogue, and propose an algorithm of merging them. A unified catalogue is constructed for 2010 to 2022. The resulting catalogue is completed with data from the OMNI database. Analysis of the unified catalogue demonstrated high accuracy when merging events present in multiple catalogues and a tendency of events defined in all three initial catalogues to demonstrate greater duration, speed and geoeffectiveness. The catalog is presented on the SINP MSU Space Weather Exchange website: this https URL

[176] arXiv:2406.14399 (cross-list from cs.LG) [pdf, html, other]

Title: WEATHER-5K: A Large-scale Global Station Weather Dataset Towards Comprehensive Time-series Forecasting Benchmark

Tao Han, Song Guo, Zhenghao Chen, Wanghan Xu, Lei Bai

Comments: 26 pages,13 figures

Subjects: Machine Learning (cs.LG); Computer Vision and Pattern Recognition (cs.CV); Atmospheric and Oceanic Physics (physics.ao-ph); Machine Learning (stat.ML)

Global Station Weather Forecasting (GSWF) is crucial for various sectors, including aviation, agriculture, energy, and disaster preparedness. Recent advancements in deep learning have significantly improved the accuracy of weather predictions by optimizing models based on public meteorological data. However, existing public datasets for GSWF optimization and benchmarking still suffer from significant limitations, such as small sizes, limited temporal coverage, and a lack of comprehensive variables. These shortcomings prevent them from effectively reflecting the benchmarks of current forecasting methods and fail to support the real needs of operational weather forecasting. To address these challenges, we present the WEATHER-5K dataset. This dataset comprises a comprehensive collection of data from 5,672 weather stations worldwide, spanning a 10-year period with one-hour intervals. It includes multiple crucial weather elements, providing a more reliable and interpretable resource for forecasting. Furthermore, our WEATHER-5K dataset can serve as a benchmark for comprehensively evaluating existing well-known forecasting models, extending beyond GSWF methods to support future time-series research challenges and opportunities. The dataset and benchmark implementation are publicly available at: this https URL.

[177] arXiv:2406.14426 (cross-list from stat.ML) [pdf, html, other]

Title: Transferable Boltzmann Generators

Leon Klein, Frank Noé

Subjects: Machine Learning (stat.ML); Machine Learning (cs.LG); Chemical Physics (physics.chem-ph); Computational Physics (physics.comp-ph)

The generation of equilibrium samples of molecular systems has been a long-standing problem in statistical physics. Boltzmann Generators are a generative machine learning method that addresses this issue by learning a transformation via a normalizing flow from a simple prior distribution to the target Boltzmann distribution of interest. Recently, flow matching has been employed to train Boltzmann Generators for small molecular systems in Cartesian coordinates. We extend this work and propose a first framework for Boltzmann Generators that are transferable across chemical space, such that they predict zero-shot Boltzmann distributions for test molecules without being retrained for these systems. These transferable Boltzmann Generators allow approximate sampling from the target distribution of unseen systems, as well as efficient reweighting to the target Boltzmann distribution. The transferability of the proposed framework is evaluated on dipeptides, where we show that it generalizes efficiently to unseen systems. Furthermore, we demonstrate that our proposed architecture enhances the efficiency of Boltzmann Generators trained on single molecular systems.

[178] arXiv:2406.14484 (cross-list from quant-ph) [pdf, html, other]

Title: A two-dimensional optomechanical crystal for quantum transduction

Felix M. Mayor, Sultan Malik, André G. Primo, Samuel Gyger, Wentao Jiang, Thiago P. M. Alegre, Amir H. Safavi-Naeini

Comments: 13 pages, 4 main figures

Subjects: Quantum Physics (quant-ph); Optics (physics.optics)

Integrated optomechanical systems are one of the leading platforms for manipulating, sensing, and distributing quantum information. The temperature increase due to residual optical absorption sets the ultimate limit on performance for these applications. In this work, we demonstrate a two-dimensional optomechanical crystal geometry, named \textbf{b-dagger}, that alleviates this problem through increased thermal anchoring to the surrounding material. Our mechanical mode operates at 7.4 GHz, well within the operation range of standard cryogenic microwave hardware and piezoelectric transducers. The enhanced thermalization combined with the large optomechanical coupling rates, $g_0/2\pi \approx 880~\mathrm{kHz}$, and high optical quality factors, $Q_\text{opt} = 2.4 \times 10^5$, enables the ground-state cooling of the acoustic mode to phononic occupancies as low as $n_\text{m} = 0.35$ from an initial temperature of 3 kelvin, as well as entering the optomechanical strong-coupling regime. Finally, we perform pulsed sideband asymmetry of our devices at a temperature below 10 millikelvin and demonstrate ground-state operation ($n_\text{m} < 0.45$) for repetition rates as high as 3 MHz. Our results extend the boundaries of optomechanical system capabilities and establish a robust foundation for the next generation of microwave-to-optical transducers with entanglement rates overcoming the decoherence rates of state-of-the-art superconducting qubits.

[179] arXiv:2406.14512 (cross-list from astro-ph.HE) [pdf, html, other]

Title: Scaling up global kinetic models of pulsar magnetospheres using a hybrid force-free-PIC numerical approach

Adrien Soudais, Benoît Cerutti, Ioannis Contopoulos

Comments: 12 pages, 7 figures, accepted for publication in A&A

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Computational Physics (physics.comp-ph); Plasma Physics (physics.plasm-ph)

The particle-in-cell approach has proven effective at modeling neutron star and black hole magnetospheres from first principles, but global simulations are plagued with an unrealistically small separation between the scales where microphysics operates and the system-size scales due to limited numerical resources. A legitimate concern is whether the scale separation currently achieved is large enough, such that results can be safely extrapolated to realistic scales. In this work, our aim is to explore the effect of scaling physical parameters up, and to check whether salient features uncovered by pure kinetic models at smaller scales are still valid, with a special emphasis on particle acceleration and high-energy radiation emitted beyond the light cylinder. To reach this objective, we develop a new hybrid numerical scheme coupling the ideal force-free and the particle-in-cell methods, to optimize the numerical cost of global models. We propose a domain decomposition of the magnetosphere based on the magnetic field topology using the flux function. The force-free model is enforced along open field lines while the particle-in-cell model is restricted to the reconnecting field line region. As a proof of concept, this new hybrid model is applied to simulate a weak millisecond pulsar magnetosphere with realistic scales using high-resolution axisymmetric simulations. Magnetospheric features reported by previous kinetic models are recovered, and strong synchrotron radiation above 100MeV consistent with the Fermi-LAT gamma-ray pulsar population is successfully reproduced. This work further consolidates the shining reconnecting current sheet scenario as the origin of the gamma-ray emission in pulsars, as well as firmly establishes pulsar magnetospheres as at least TeV particle accelerators.

Replacement submissions for Friday, 21 June 2024 (showing 77 of 77 entries )

[180] arXiv:2301.05551 (replaced) [pdf, html, other]

Title: Dynamic Basis Function Interpolation for Adaptive In Situ Data Integration in Ocean Modeling

Derek DeSantis, Ayan Biswas, Earl Lawrence, Phillip Wolfram

Subjects: Atmospheric and Oceanic Physics (physics.ao-ph); Machine Learning (cs.LG); Dynamical Systems (math.DS)

We propose a new method for combining in situ buoy measurements with Earth system models (ESMs) to improve the accuracy of temperature predictions in the ocean. The technique utilizes the dynamics \textit{and} modes identified in ESMs alongside buoy measurements to improve accuracy while preserving features such as seasonality. We use this technique, which we call Dynamic Basis Function Interpolation, to correct errors in localized temperature predictions made by the Model for Prediction Across Scales Ocean component (MPAS-O) with the Global Drifter Program's in situ ocean buoy dataset.

[181] arXiv:2304.04715 (replaced) [pdf, html, other]

Title: An unusual bifurcation scenario in a stably stratified, valley-shaped enclosure heated from below

Patrick J. Stofanak, Cheng-Nian Xiao, Inanc Senocak

Comments: 29 pages, 8 figures

Subjects: Fluid Dynamics (physics.flu-dyn)

We delineate the structure of steady laminar flows within a stably stratified, valley-shaped triangular cavity heated from below through linear stability analysis and Navier-Stokes simulations. We derive an exact solution to the quiescent conduction state, and characterize the flow via the stratification perturbation parameter, $\Pi_s$, which is a measure of the strength of the surface heat flux relative to the background stable stratification. Beyond a threshold value of $\Pi_s$, two unstable eigenmodes appear, one marked by a dominant central circulation, and the other one exhibiting dual circulations of equal strength. Through Navier-Stokes simulations, we confirm that the central-circulation eigenmode generates a pair of asymmetric steady states, whereas the dual-circulation eigenmode leads to distinct upslope and downslope symmetric steady states. Linear stability analysis and Navier-Stokes simulations jointly confirm the instability of the two symmetric steady states, both of which transition to the asymmetric steady state under a perturbation. Thus, for a given set of dimensionless parameters, the Navier-Stokes equations admit at least five possible steady-state solutions. Two of these solutions, namely the quiescent, pure conduction state and the counter-intuitive symmetric downslope state, have previously been overlooked in heated, stably stratified, valley-shaped enclosures. These five flow solutions reveal an intriguing bifurcation structure, including both a perfect pitchfork bifurcation and a nested bifurcation that gives rise to two distinct states. The inner bifurcation, while resembling a pitchfork in some respects, does not break any symmetry of the valley due to the lack of any possible horizontal axis of symmetry. The categorization of this inner bifurcation remains an unresolved matter, as it does not conform to any established descriptions of canonical bifurcations.

[182] arXiv:2306.17807 (replaced) [pdf, html, other]

Title: Surrogate Modeling of Urban Boundary-Layer Flow

Gurpreet S. Hora, Marco G. Giometto

Subjects: Fluid Dynamics (physics.flu-dyn)

Surrogate modeling is a viable solution for applications involving repetitive evaluations of expensive computational fluid dynamics models, such as uncertainty quantification and inverse problems. This study proposes a multi-layer perceptron (MLP) based machine-learning surrogate for canopy flow statistics accommodating any approaching mean-wind angle. The training and testing of the surrogate model is based on results from large-eddy simulations of open-channel flow over and within surface-mounted cubes under neutral ambient stratification. The training dataset comprises flow statistics from various approaching mean-wind angles, and the surrogate is asked to "connect between the dots," i.e., to predict flow statistics for unseen values of the approaching mean-wind angle. The MLP performance is compared against a more traditional spline-based interpolation approach for a range of training data. In terms of relative mean absolute errors on individual flow statistics, the proposed MLP surrogate consistently outperforms the spline interpolation, especially when the number of training samples is reduced. The MLP model accurately captures mean profiles and three-dimensional flow variability, offering robust predictions, even when trained with as few as four approaching wind angles. The model is $10^4 \times$ faster than large-eddy simulations, thus proving effective for multi-query tasks in the context of urban canopy flow modeling.

[183] arXiv:2307.13520 (replaced) [pdf, html, other]

Title: Using power system modelling outputs to identify weather-induced extreme events in highly renewable systems

Aleksander Grochowicz, Koen van Greevenbroek, Hannah C. Bloomfield

Journal-ref: Environmental Research Letters, Volume 19, Number 5 (2024)

Subjects: Physics and Society (physics.soc-ph); Systems and Control (eess.SY)

In highly renewable power systems the increased weather dependence can result in new resilience challenges, such as renewable energy droughts, or a lack of sufficient renewable generation at times of high demand. The weather conditions responsible for these challenges have been well-studied in the literature. However, in reality multi-day resilience challenges are triggered by complex interactions between high demand, low renewable availability, electricity transmission constraints and storage dynamics. We show these challenges cannot be rigorously understood from an exclusively power systems, or meteorological, perspective. We propose a new method that uses electricity shadow prices - obtained by a European power system model based on 40 years of reanalysis data - to identify the most difficult periods driving system investments. Such difficult periods are driven by large-scale weather conditions such as low wind and cold temperature periods of various lengths associated with stationary high pressure over Europe. However, purely meteorological approaches fail to identify which events lead to the largest system stress over the multi-decadal study period due to the influence of subtle transmission bottlenecks and storage issues across multiple regions. These extreme events also do not relate strongly to traditional weather patterns (such as Euro-Atlantic weather regimes or the North Atlantic Oscillation index). We therefore compile a new set of weather patterns to define energy system stress events which include the impacts of electricity storage and large-scale interconnection. Without interdisciplinary studies combining state-of-the-art energy meteorology and modelling, further strive for adequate renewable power systems will be hampered.

[184] arXiv:2309.07316 (replaced) [pdf, html, other]

Title: Plasma modes in QED super-strong magnetic fields of magnetars and laser plasmas

Mikhail V. Medvedev

Comments: Invited paper for the PoP Special Collection on Relativistic Plasma in Supercritical Electromagnetic Fields. 17 pages, 8 figures

Subjects: Plasma Physics (physics.plasm-ph); High Energy Astrophysical Phenomena (astro-ph.HE)

Ultra-magnetized plasmas, where the magnetic field strength exceeds the Schwinger field of about $B_{Q}\approx4\times10^{13}$~gauss, become of great scientific interest, thanks to the current advances in laser-plasma experiments and astrophysical observations of magnetar emission. These advances demand better understanding of how quantum electrodynamics (QED) effects influence collective plasma phenomena. In particular, Maxwell's equations become nonlinear in the strong-QED regime. Here we present the `QED plasma framework' which will allow one to {\em systematically} explore collective phenomena in a QED-plasma with arbitrarily strong magnetic field. Further, we illustrate the framework by exploring low-frequency modes in the ultra-magnetized, cold, electron-positron plasmas. We demonstrate that the classical picture of five branches holds in the QED regime; no new eigenmodes appear. The dispersion curves of all the modes are modified. The QED effects include the overall modification to the plasma frequency, which becomes field-dependent. They also modify resonances and cutoffs of the modes, which become both field- and angle-dependent. The strongest effects are (i) the {\em field-induced transparency of plasma} for the O-mode via the dramatic reduction of the low-frequency cutoff well below the plasma frequency, (ii) the {\em Alfven mode suppression} in the large-$k$ regime via the reduction of the Alfven mode resonance, and (iii) the {\em O-mode slowdown} via strong angle-dependent increase of the index of refraction. These results should be important for understanding of a magnetospheric pair plasma of a magnetar and for laboratory laser-plasma experiments in the QED regime.

[185] arXiv:2309.12536 (replaced) [pdf, html, other]

Title: Exceptional points in optical systems: A resonant-state expansion study

Kyle S Netherwood, Hannah Riley, Egor A Muljarov

Comments: 25 pages. 13 figures (3 in Appendix). To be published in Physical Review A. Authors: K. S. Netherwood (primary author), H. K. Riley (initial concept work), E. A. Muljarov (theme leader)

Subjects: Optics (physics.optics)

Exceptional points (EPs) in open optical systems are rigorously studied using the resonant-state expansion (RSE). A spherical resonator, specifically a homogeneous dielectric sphere in a vacuum, perturbed by two point-like defects which break the spherical symmetry and bring the optical modes to EPs, is used as a worked example. The RSE is a non-perturbative approach encoding the information about an open optical system in matrix form in a rigorous way, and thus offering a suitable tool for studying its EPs. These are simultaneous degeneracies of the eigenvalues and corresponding eigenfunctions of the system, which are rigorously described by the RSE and illustrated for perturbed whispering-gallery modes (WGMs). An exceptional arc, which is a line of adjacent EPs, is obtained analytically for perturbed dipolar WGMs. Perturbation of high-quality WGMs with large angular momentum and their EPs are found by reducing the RSE equation to a two-state problem by means of an orthogonal transformation of a large RSE matrix. WGM pairs have opposite chirality in spherically symmetric systems and equal chirality at EPs. This chirality at EPs can be observed in circular dichroism measurements, as it manifested itself in a squared-Lorentzian part of the optical spectra, which we demonstrate here analytically and numerically in the Purcell enhancement factor for the perturbed dipolar WGMs.

[186] arXiv:2309.14780 (replaced) [pdf, other]

Title: Transferring climate change knowledge

Francesco Immorlano, Veronika Eyring, Thomas le Monnier de Gouville, Gabriele Accarino, Donatello Elia, Giovanni Aloisio, Pierre Gentine

Subjects: Atmospheric and Oceanic Physics (physics.ao-ph); Artificial Intelligence (cs.AI); Machine Learning (cs.LG)

Accurate and precise climate projections are required for climate adaptation and mitigation, but Earth system models still exhibit great uncertainties. Several approaches have been developed to reduce the spread of climate projections and feedbacks, yet those methods cannot capture the non-linear complexity inherent in the climate system. Using a Transfer Learning approach, we show that Machine Learning can be used to optimally leverage and merge the knowledge gained from Earth system models simulations and historical observations to more accurately project global surface air temperature fields in the 21st century. We reach an uncertainty reduction of more than 50% with respect to state-of-the-art approaches. We give evidence that our novel method provides narrower projection uncertainty together with more accurate mean climate projections, urgently required for climate adaptation.

[187] arXiv:2310.00028 (replaced) [pdf, html, other]

Title: Fundamental scaling limits and bandwidth shaping of frequency-modulated combs

Mithun Roy, Zhenyang Xiao, Sadhvikas Addamane, David Burghoff

Comments: 24 pages, 5 figures

Subjects: Optics (physics.optics); Applied Physics (physics.app-ph)

Frequency-modulated (FM) combs based on active cavities like quantum cascade lasers have recently emerged as promising light sources in many spectral regions. Unlike passive modelocking, which uses amplitude modulation to generate amplitude modulation, FM combs use phase modulation to generate phase modulation. They can therefore be regarded as a phase-domain version of passive modelocking. However, while the ultimate scaling laws of passive modelocking have long been known -- Haus showed in 1975 that pulses have a bandwidth proportional to effective gain bandwidth -- the limits of FM combs have been much less clear. Here, we show that FM combs are governed by the same fundamental limits, producing combs whose bandwidths are linear in the effective gain bandwidth. Not only do we show theoretically that the diffusive effect of gain curvature limits comb bandwidth, we also show experimentally how this limit can be increased. By adding carefully designed resonant-loss structures that are evanescently coupled to the cavity of a terahertz laser, we reduce the curvature and increase the effective gain bandwidth of the laser, demonstrating bandwidth enhancement. Our results give a new degree of freedom for the creation of active chip-scale combs and can be applied to a wide array of cavity geometries.

[188] arXiv:2310.03287 (replaced) [pdf, html, other]

Title: Single-Subject Deep-Learning Image Reconstruction with a Neural Optimization Transfer Algorithm for PET-enabled Dual-Energy CT Imaging

Siqi Li, Yansong Zhu, Benjamin A. Spencer, Guobao Wang

Subjects: Medical Physics (physics.med-ph)

Combining dual-energy computed tomography (DECT) with positron emission tomography (PET) offers many potential clinical applications but typically requires expensive hardware upgrades or increases radiation doses on PET/CT scanners due to an extra X-ray CT scan. The recent PET-enabled DECT method allows DECT imaging on PET/CT without requiring a second X-ray CT scan. It combines the already existing X-ray CT image with a 511 keV \gamma-ray CT (gCT) image reconstructed from time-of-flight PET emission data. A kernelized framework has been developed for reconstructing gCT image but this method has not fully exploited the potential of prior knowledge. Use of deep neural networks may explore the power of deep learning in this application. However, common approaches require a large database for training, which is impractical for a new imaging method like PET-enabled DECT. Here, we propose a single-subject method by using neural-network representation as a deep coefficient prior to improving gCT image reconstruction without population-based pre-training. The resulting optimization problem becomes the tomographic estimation of nonlinear neural-network parameters from gCT projection data. This complicated problem can be efficiently solved by utilizing the optimization transfer strategy with quadratic surrogates. Each iteration of the proposed neural optimization transfer algorithm includes: PET activity image update; gCT image update; and least-square neural-network learning in the gCT image domain. This algorithm is guaranteed to monotonically increase the data likelihood. Results from computer simulation, real phantom data and real patient data have demonstrated that the proposed method can significantly improve gCT image quality and consequent multi-material decomposition as compared to other methods.

[189] arXiv:2310.07337 (replaced) [pdf, html, other]

Title: On Penrose's Analogy between Curved Spacetime Regions and Optical Lenses

Dennis Lehmkuhl, Christian Röken, Juliusz Doboszewski

Comments: 30 pages, 2 figures, minor correction, reference removed (published version)

Journal-ref: Philosophy of Physics, 2(1), id.4, 2024

Subjects: History and Philosophy of Physics (physics.hist-ph); General Relativity and Quantum Cosmology (gr-qc)

We present a detailed analysis of Penrose's gravito-optical analogy between the focusing effects of particular families of Ricci- and Weyl-curved spacetime regions on the one hand, and anastigmatic and astigmatic optical lenses on the other. We put the analogy in its historical context, investigate its underlying assumptions, its range of validity, its proof of concept, and its application in Penrose's study of the notion of energy flux in general relativity. Finally, we examine the analogy within the framework of Norton's material theory of induction.

[190] arXiv:2310.12624 (replaced) [pdf, html, other]

Title: Poles, Shocks and Tygers: The Time-reversible Burgers equation

Arunava Das, Pinaki Dutta, Vishwanath Shukla

Comments: 25 pages, 18 figures

Subjects: Fluid Dynamics (physics.flu-dyn); Statistical Mechanics (cond-mat.stat-mech); Chaotic Dynamics (nlin.CD)

We construct a formally time-reversible, one-dimensional forced Burgers equation by imposing a global constraint of energy conservation, wherein the constant viscosity is modified to a fluctuating state-dependent dissipation coefficient. The system exhibits dynamical properties which bear strong similarities with those observed for the Burgers equation and can be understood using the dynamics of the poles, shocks, and truncation effects, such as tygers. A complex interplay of these give rise to interesting statistical regimes ranging from hydrodynamic behavior to a completely thermalized warm phase. The end of the hydrodynamic regime is associated with the appearance of a shock in the solution and a continuous transition leading to a truncation-dependent state. Beyond this, the truncation effects such as tygers and the appearance of secondary discontinuity at the resonance point in the solution strongly influence the statistical properties. These disappear at the second transition, at which the global quantities exhibit a jump and attain values that are consistent with the establishment of a quasiequilibrium state characterized by energy equipartition among the Fourier modes. Our comparative analysis shows that the macroscopic statistical properties of the formally time-reversible system and the Burgers equation are equivalent in all the regimes, irrespective of the truncation effects, and this equivalence is not just limited to the hydrodynamic regime, thereby further strengthening the Gallavotti's equivalence conjecture. The properties of the system are further examined by inspecting the complex space singularities in the velocity field of the Burgers equation. Furthermore, an effective theory is proposed to describe the discontinuous transition.

[191] arXiv:2311.06253 (replaced) [pdf, html, other]

Title: Advancing Parsimonious Deep Learning Weather Prediction using the HEALPix Mesh

Matthias Karlbauer, Nathaniel Cresswell-Clay, Dale R. Durran, Raul A. Moreno, Thorsten Kurth, Boris Bonev, Noah Brenowitz, Martin V. Butz

Comments: Submitted to Journal of Advances in Modeling Earth Systems (JAMES)

Subjects: Atmospheric and Oceanic Physics (physics.ao-ph); Machine Learning (cs.LG)

We present a parsimonious deep learning weather prediction model to forecast seven atmospheric variables with 3-h time resolution for up to one-year lead times on a 110-km global mesh using the Hierarchical Equal Area isoLatitude Pixelization (HEALPix). In comparison to state-of-the-art (SOTA) machine learning (ML) weather forecast models, such as Pangu-Weather and GraphCast, our DLWP-HPX model uses coarser resolution and far fewer prognostic variables. Yet, at one-week lead times, its skill is only about one day behind both SOTA ML forecast models and the SOTA numerical weather prediction model from the European Centre for Medium-Range Weather Forecasts. We report several improvements in model design, including switching from the cubed sphere to the HEALPix mesh, inverting the channel depth of the U-Net, and introducing gated recurrent units (GRU) on each level of the U-Net hierarchy. The consistent east-west orientation of all cells on the HEALPix mesh facilitates the development of location-invariant convolution kernels that successfully propagate weather patterns across the globe without requiring separate kernels for the polar and equatorial faces of the cube sphere. Without any loss of spectral power after the first two days, the model can be unrolled autoregressively for hundreds of steps into the future to generate realistic states of the atmosphere that respect seasonal trends, as showcased in one-year simulations.

[192] arXiv:2311.14987 (replaced) [pdf, other]

Title: Reconstruction of a Long-term spatially Contiguous Solar-Induced Fluorescence (LCSIF) over 1982-2022

Jianing Fang, Xu Lian, Youngryel Ryu, Sungchan Jeong, Chongya Jiang, Pierre Gentine

Subjects: Geophysics (physics.geo-ph); Instrumentation and Methods for Astrophysics (astro-ph.IM)

Satellite-observed solar-induced chlorophyll fluorescence (SIF) is a powerful proxy for diagnosing the photosynthetic characteristics of terrestrial ecosystems. Despite the increasing spatial and temporal resolutions of these satellite retrievals, records of SIF are primarily limited to the recent decade, impeding their application in detecting long-term dynamics of ecosystem function and structure. In this study, we leverage the two surface reflectance bands (red and near-infrared) available both from Advanced Very High-Resolution Radiometer (AVHRR, 1982-2022) and MODerate-resolution Imaging Spectroradiometer (MODIS, 2001-2022). Importantly, we calibrate and orbit-correct the AVHRR bands against their MODIS counterparts during their overlapping period. Using the long-term bias-corrected reflectance data, a neural network is then built to reproduce the Orbiting Carbon Observatory-2 SIF using AVHRR and MODIS, and used to map SIF globally over the entire 1982-2022 period. Compared with the previous MODIS-based CSIF product relying on four reflectance bands, our two-band-based product has similar skill but can be advantageously extended to the bias-corrected AVHRR period. Further comparison with three widely used vegetation indices (NDVI, kNDVI, NIRv; all based empirically on red and near-infrared bands) shows a higher or comparable correlation of LCSIF with satellite SIF and site-level GPP estimates across vegetation types, ensuring a greater capacity of LCSIF for representing terrestrial photosynthesis. Globally, LCSIF-AVHRR shows an accelerating upward trend since 1982, with an average rate of 0.0025 mW m-2 nm-1 sr-1 per decade during 1982-2000 and 0.0038 mW m-2 nm-1 sr-1 per decade during 2001-2022. Our LCSIF data provide opportunities to better understand the long-term dynamics of ecosystem photosynthesis and their underlying driving processes.

[193] arXiv:2312.00128 (replaced) [pdf, html, other]

Title: Low latency optical-based mode tracking with machine learning deployed on FPGAs on a tokamak

Yumou Wei, Ryan F. Forelli, Chris Hansen, Jeffrey P. Levesque, Nhan Tran, Joshua C. Agar, Giuseppe Di Guglielmo, Michael E. Mauel, Gerald A. Navratil

Comments: The following article has been submitted to/accepted by Review of Scientific Instruments. After it is published, it will be found at this https URL

Subjects: Plasma Physics (physics.plasm-ph); Hardware Architecture (cs.AR); Machine Learning (cs.LG); Instrumentation and Detectors (physics.ins-det)

Active feedback control in magnetic confinement fusion devices is desirable to mitigate plasma instabilities and enable robust operation. Optical high-speed cameras provide a powerful, non-invasive diagnostic and can be suitable for these applications. In this study, we process fast camera data, at rates exceeding 100kfps, on $\textit{in situ}$ Field Programmable Gate Array (FPGA) hardware to track magnetohydrodynamic (MHD) mode evolution and generate control signals in real-time. Our system utilizes a convolutional neural network (CNN) model which predicts the $n$=1 MHD mode amplitude and phase using camera images with better accuracy than other tested non-deep-learning-based methods. By implementing this model directly within the standard FPGA readout hardware of the high-speed camera diagnostic, our mode tracking system achieves a total trigger-to-output latency of 17.6$\mu$s and a throughput of up to 120kfps. This study at the High Beta Tokamak-Extended Pulse (HBT-EP) experiment demonstrates an FPGA-based high-speed camera data acquisition and processing system, enabling application in real-time machine-learning-based tokamak diagnostic and control as well as potential applications in other scientific domains.

[194] arXiv:2401.12169 (replaced) [pdf, html, other]

Title: My Understanding for Static and Dynamic Light Scattering

Yong Sun

Comments: The results obtained using my computing program are consistent with the values obtained twenty years ago. It also makes me believe that how to obtain particle size information using the Light Scattering technique needs to be reconsidered. arXiv admin note: text overlap with arXiv:1110.1703

Subjects: Chemical Physics (physics.chem-ph)

The results obtained using my computing program are consistent with the values obtained twenty years ago. It also makes me believe that how to obtain particle size information using the Light Scattering technique needs to be reconsidered.
Static Light Scattering (SLS) and Dynamic Light Scattering (DLS) are very important techniques to study the characteristics of nano-particles in dispersion. The data of SLS is determined by the optical characteristic and the measured values of DLS are determined by optical and hydrodynamic characteristics of different size nano-particles in dispersion. Then considering the optical characteristic of nano-particles and using the SLS technique further, the size distribution can be measured accurately and is also consistent with the results measured using the TEM technique. Based on the size distribution obtained using the SLS or TEM technique and the relation between the static and hydrodynamic radii, all the expected and measured values of $g^{\left( 2\right) }\left( \tau \right) $ investigated are very well consistent. Since the data measured using the DLS technique contains the information of the optical and hydrodynamic properties of nano-particles together, therefore the accurate size distribution cannot be obtained from the experimental data of
$g^{\left( 2\right) }\left( \tau \right) $ for an unknown sample. The traditional particle information: apparent hydrodynamic radius and polydispersity index measured using the DLS technique are determined by the optical and hydrodynamic characteristics and size distribution together. They cannot represent a number distribution of nano-particles in dispersion. Using the light scattering technique not only can measure the size distribution accurately but also can provide a method to understand the optical and hydrodynamic characteristics of nano-particles.

[195] arXiv:2401.13372 (replaced) [pdf, html, other]

Title: Influence of resonant plasmonic nanoparticles on optically accessing the valley degree of freedom in 2D semiconductors

Tobias Bucher (1, 2, 3), Zlata Fedorova (1, 2, 3), Mostafa Abasifard (2, 1, 3), Rajeshkumar Mupparapu (2), Matthias J. Wurdack (4, 1, 2, 3), Emad Najafidehaghani (5), Ziyang Gan (5), Heiko Knopf (6, 2, 3), Antony George (5, 3), Falk Eilenberger (6, 2, 3, 7), Thomas Pertsch (2, 3, 6, 7), Andrey Turchanin (5, 3, 8), Isabelle Staude (1, 2, 3, 7) ((1) Institute of Solid State Physics, Friedrich Schiller University Jena, Germany (2) Institute of Applied Physics, Friedrich Schiller University Jena, Germany (3) Abbe Center of Photonics, Friedrich Schiller University Jena, Germany (4) ARC Centre of Excellence in Future Low-Energy Electronics Technologies and Department of Quantum Science and Technology, Research School of Physics, The Australian National University, Canberra, Australia (5) Institute of Physical Chemistry, Friedrich Schiller University Jena, Germany (6) Fraunhofer Institute for Applied Optics and Precision Engineering IOF, Jena, Germany (7) Max Planck School of Photonics, Germany (8) Jena Center for Soft Matter (JCSM), Jena, Germany)

Comments: Tobias Bucher and Zlata Fedorova contributed equally to this work. 29 pages, 6 figures

Subjects: Optics (physics.optics); Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

The valley degree of freedom is one of the most intriguing properties of atomically thin transition metal dichalcogenides. Together with the possibility to address this degree of freedom by valley-contrasting optical selection rules, it has the potential to enable a completely new class of future electronic and optoelectronic devices. Resonant optical nanostructures emerge as promising tools for interacting with and controlling the valley degree of freedom at the nanoscale. However, a critical understanding gap remains in how nanostructures and their nearfields affect the circular polarization properties of valley-selective emission hindering further developments in this field. In order to address this issue, our study delves into the experimental investigation of a hybrid model system where valley-specific emission from a monolayer of molybdenum disulfide is interacting with a resonant plasmonic nanosphere. Contrary to the simple intuition suggesting that a centrosymmetric nanoresonator preserves the degree of circular polarization in the forward scattered farfield by angular momentum conservation, our cryogenic photoluminescence microscopy reveals that the light emitted from the nanoparticle position is largely unpolarized, i.e. we observe depolarization. We rigorously study the nature of this phenomenon numerically considering the monolayer-nanoparticle interaction at different levels including excitation and emission. In doing so, we find that the farfield degree of polarization strongly reduces in the hybrid system when including excitons emitting from outside of the system's symmetry point, which in combination with depolarisation at the excitation level causes the observed effect. Our results highlight the importance of considering spatially distributed emitters for precise predictions of polarization responses in these hybrid systems.

[196] arXiv:2402.01542 (replaced) [pdf, html, other]

Title: Learning Collective Variables with Synthetic Data Augmentation through Physics-inspired Geodesic Interpolation

Soojung Yang, Juno Nam, Johannes C. B. Dietschreit, Rafael Gómez-Bombarelli

Subjects: Chemical Physics (physics.chem-ph); Machine Learning (cs.LG); Biomolecules (q-bio.BM)

In molecular dynamics simulations, rare events, such as protein folding, are typically studied using enhanced sampling techniques, most of which are based on the definition of a collective variable (CV) along which acceleration occurs. Obtaining an expressive CV is crucial, but often hindered by the lack of information about the particular event, e.g., the transition from unfolded to folded conformation. We propose a simulation-free data augmentation strategy using physics-inspired metrics to generate geodesic interpolations resembling protein folding transitions, thereby improving sampling efficiency without true transition state samples. This new data can be used to improve the accuracy of classifier-based methods. Alternatively, a regression-based learning scheme for CV models can be adopted by leveraging the interpolation progress parameter.

[197] arXiv:2402.04047 (replaced) [pdf, html, other]

Title: Does $E=mc^2$ Require Relativity?

Tony Rothman

Comments: 33 pages, 3 figures. Moderate line-editing on previous version. A few derivations slightly trimmed/simplified. "Victorian" thought experiment in Sec. 7 simplified by going to two masses instead of three

Subjects: History and Philosophy of Physics (physics.hist-ph); Classical Physics (physics.class-ph); Physics Education (physics.ed-ph)

It is universally believed that with his 1905 paper "Does the inertia of a body depend on its energy content?" Einstein first demonstrated the equivalence of mass and energy by making use of his special theory of relativity. In the final step of that paper, however, Einstein equates the kinetic energy of a body to its Newtonian value, indicating that his result is at best a low-velocity approximation. Today, several characters debate whether a mid-nineteenth century physicist, employing only physics available at the time, could plausibly arrive at the celebrated result. In other words, is Einsteinian relativity necessary to derive ${\mc E}=mc^2$?

[198] arXiv:2402.07121 (replaced) [pdf, html, other]

Title: Quasidiscrete spectrum Cherenkov radiation by a charge moving inside a dielectric waveguide

A. A. Saharian, S. B. Dabagov, H. F. Khachatryan, L. Sh. Grigoryan

Comments: 11 pages, 2 figures, Discussions added

Journal-ref: JINST 19 (2024) C06017

Subjects: Optics (physics.optics)

We investigate the Cherenkov radiation by a charge uniformly moving inside a dielectric cylindrical channel in a homogeneous medium. The expressions for the Fourier components of the electric and magnetic fields are derived by using the electromagnetic field Green tensor. The spectral distribution of the Cherenkov radiation intensity in the exterior medium is studied for the general case of frequency dispersion of the interior and exterior dielectric functions. It is shown that, under certain conditions on the dielectric permittivities, strong narrow peaks appear in the spectral distribution. The spectral locations of those peaks are specified and their heights and widths are estimated analytically on the base of the dispersion equation for the electromagnetic eigenmodes of the cylinder.

[199] arXiv:2402.10120 (replaced) [pdf, html, other]

Title: Dopant concentration effects on Si$_{1-x}$Ge$_{x}$ crystals for emerging light-source technologies: A molecular dynamics study

Matthew D. Dickers, Gennady B. Sushko, Andrei V. Korol, Nigel J. Mason, Felipe Fantuzzi, Andrey V. Solov'yov

Journal-ref: Eur. Phys. J. D 78, 77 (2024)

Subjects: Atomic Physics (physics.atom-ph)

In this study, we conduct atomistic-level molecular dynamics simulations on fixed-sized silicon-germanium (Si$_{1-x}$Ge$_{x}$) crystals to elucidate the effects of dopant concentration and temperature on the crystalline inter-planar distances. Our calculations consider a range of Ge dopant concentrations between pure Si (0%) and 15%, and for both the optimised system state and a temperature of 300 K. We observe a linear relationship between Ge concentration and inter-planar distance and lattice constant, in line with the approximation of Vegard's Law, and other experimental and computational results. These findings will be employed in conjunction with future studies to establish precise tolerances for use in crystal growth, crucial for the manufacture of crystals intended for emerging gamma-ray crystal-based light source technologies.

[200] arXiv:2402.12553 (replaced) [pdf, html, other]

Title: Triglobal resolvent-analysis-based control of separated flows around low-aspect-ratio wings

Jean Hélder Marques Ribeiro, Kunihiko Taira

Subjects: Fluid Dynamics (physics.flu-dyn)

We perform direct numerical simulations (DNS) of actively controlled laminar separated wakes around low-aspect-ratio wings with two primary goals: (i) reducing the size of the separation bubble and (ii) attenuating the wing tip vortex. Instead of preventing separation, we modify the three-dimensional ($3$-D) dynamics to exploit wake vortices for aerodynamic enhancements. A direct wake modification is considered using optimal harmonic forcing modes from triglobal resolvent analysis. For this study, we consider wings at angles of attack of $14^\circ$ and $22^\circ$, taper ratios $0.27$ and $1$, and leading edge sweep angles of $0^\circ$ and $30^\circ$, at a mean-chord-based Reynolds number of $600$. The wakes behind these wings exhibit $3$-D reversed-flow bubble and large-scale vortical structures. For tapered swept wings, the diversity of wake vortices increases substantially, posing a challenge for flow control. To achieve the first control objective for an untapered unswept wing, root-based actuation at the shedding frequency is introduced to reduce the reversed-flow bubble size by taking advantage of the wake vortices to significantly enhance the aerodynamic performance of the wing. For both untapered and tapered swept wings, root-based actuation modifies the stalled flow, reduces the reversed-flow region, and enhances aerodynamic performance by increasing the root contribution to lift. For the goal of controlling the tip vortex, we demonstrate the effectiveness of actuation with high-frequency perturbations near the tip. This study shows how insights from resolvent analysis for unsteady actuation can enable global modification of $3$-D separated wakes and achieve improved aerodynamics of wings.

[201] arXiv:2402.16711 (replaced) [pdf, html, other]

Title: Action potential propagation properties of 4D, 3D and 2D Hodgkin-Huxley type models

Lízia Branco, Rui Dilão

Comments: 8 pages, 12 figures

Subjects: Biological Physics (physics.bio-ph); Neurons and Cognition (q-bio.NC)

We explore the relationship between sodium (Na$^+$) and potassium (K$^+$) gating variables in the 4-dimensional (4D) Hodgkin-Huxley (HH) electrophysiology model and reduce its complexity by deriving new 3D and 2D models that retain the original model's dynamic properties. The new 3D and 2D models are based on the relationship $h \simeq c - n$ between the gating variables $h$ and $n$ of the 4D HH model, where $c$ is a constant, which suggests an interdependence between the dynamics of Na$^+$ and K$^+$ transmembrane voltage-gated channels. We derive the corresponding cable equations for the three HH-type models and demonstrate that the action potential propagates along the axon at a speed described by $v(R, C_m) = \alpha / (C_m R^{\beta}) = \gamma D^{\beta}$, where $\alpha > 0$, $0 < \beta < 1$, and $\gamma$ are constants independent of the local stimulus intensity, $D$ is the diffusion coefficient of the electric signal along the axon, $C_m$ is the axon transmembrane capacitance, and $R$ is the axon conducting resistivity. The width $w$ of the action potential spikes is inversely related to the resistivity of the axon, with $w = \alpha_2 / R^{\beta_2}$, where $\alpha_2 > 0$ and $\beta_2 > 0$.

[202] arXiv:2402.18681 (replaced) [pdf, other]

Title: Aging effects in the COMPASS hybrid GEM-Micromegas pixelized detectors

Damien Neyret, Philippe Abbon, Marc Anfreville, Vincent Andrieux, Yann Bedfer, Dominique Durand, Sébastien Herlant, Nicole d'Hose, Fabienne Kunne, Stephane Platchkov, Florian Thibaud, Michel Usseglio, Maxence Vandenbroucke

Comments: 9 pages, 9 figures, proceedings to the 3rd International Conference on Detector Stability and Aging Phenomena in Gaseous Detectors, CERN, November 6-10 2023, will be published in the NIMA journal Proceedings Section

Journal-ref: Nucl.Instrum.Meth.A 1065 (2024) 169511

Subjects: Instrumentation and Detectors (physics.ins-det)

Large-size hybrid and pixelized GEM-Micromegas gaseous detectors (40x40 cm$^2$ active area) were developed and installed in 2014 and 2015 for the COMPASS2 physics program which started at the same time. That program involved in particular two full years of Drell-Yan studies using a high-intensity pion beam on a thick polarized target. Although the detectors were placed behind a thick absorber, they were exposed to an important flux of low energy neutrons and photons. The detectors were designed to drastically reduce the discharge rate, a major issue for non-resistive Micromegas in high hadron flux, by a factor of more than 100 compared to the former ones. A hybrid solution was chosen where a pre-amplifying GEM foil is placed 2 mm above the micromesh electrode. A pixelized readout was also added in the center of the detector, where the beam is going through, in order to track particles scattered at very low angles. The combination of the hybrid structure and the pixelized central readout allowed the detector to be operated in an environment with particle flux above 10 MHz/cm$^2$ with very good detection efficiencies and spatial resolution. The performance has remained stable since 2015 in terms of gain and resolution, showing the interest of hybrid structures associating a GEM foil to a Micromegas board to protect gaseous detectors against discharges and aging effects

[203] arXiv:2403.00289 (replaced) [pdf, html, other]

Title: Optimization of array encoding for ultrasound imaging

Jacob Spainhour, Korben Smart, Stephen Becker, Nick Bottenus

Comments: 31 pages, 12 figures

Journal-ref: Phys. Med. Biol. 69 125024 (2024)

Subjects: Medical Physics (physics.med-ph); Machine Learning (cs.LG); Optimization and Control (math.OC)

Objective: The transmit encoding model for synthetic aperture imaging is a robust and flexible framework for understanding the effects of acoustic transmission on ultrasound image reconstruction. Our objective is to use machine learning (ML) to construct scanning sequences, parameterized by time delays and apodization weights, that produce high-quality B-mode images. Approach: We use a custom ML model in PyTorch with simulated RF data from Field II to probe the space of possible encoding sequences for those that minimize a loss function that describes image quality. This approach is made computationally feasible by a novel formulation of the derivative for delay-and-sum beamforming. Main Results: When trained for a specified experimental setting (imaging domain, hardware restrictions, etc.), our ML model produces optimized encoding sequences that, when deployed in the REFoCUS imaging framework, improve a number of standard quality metrics over conventional sequences including resolution, field of view, and contrast. We demonstrate these results experimentally on both wire targets and a tissue-mimicking phantom. Significance: This work demonstrates that the set of commonly used encoding schemes represent only a narrow subset of those available. Additionally, it demonstrates the value for ML tasks in synthetic transmit aperture imaging to consider the beamformer within the model, instead of purely as a post-processing step.

[204] arXiv:2403.03137 (replaced) [pdf, other]

Title: Enhanced beam-beam modeling to include longitudinal variation during weak-strong simulation

Derong Xu, Vasiliy S. Morozov, David Sagan, Yue Hao, Yun Luo

Comments: 11 pages, 4 figures

Subjects: Accelerator Physics (physics.acc-ph)

Beam-beam interactions pose substantial challenges in the design and operation of circular colliders, significantly affecting their performance. In particular, the weak-strong simulation approach is pivotal for investigating single-particle dynamics during the collider design phase. This paper evaluates the limitations of existing models in weak-strong simulations, noting that while they accurately account for energy changes due to slingshot effects, they fail to incorporate longitudinal coordinate changes ($z$-variation). To address this gap, we introduce two novel transformations that enhance Hirata's original framework by including both $z$-variation and slingshot effect-induced energy changes. Through rigorous mathematical analysis and extensive weak-strong simulation studies, we validate the efficacy of these enhancements in achieving a more precise simulation of beam-beam interactions. Our results reveal that although $z$-variation constitutes a higher-order effect and does not substantially affect the emittance growth rate within the specific design parameters of the Electron-Ion Collider (EIC), the refined model offers improved accuracy, particularly in scenarios involving the interaction between beam-beam effects and other random diffusion processes, as well as in simulations incorporating realistic lattice models.

[205] arXiv:2403.08366 (replaced) [pdf, other]

Title: Amplified linear and nonlinear chiral sensing assisted by anapole modes in hybrid metasurfaces

Guillermo Serrera, Javier González-Colsa, Pablo Albella

Comments: This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Appl. Phys. Lett. 124, 251701 (2024) and may be found at https://doi.org/10.1063/5.0212393. Copyright (2024) Authors. This article is distributed under a Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International (CC BY-NC-ND) License

Journal-ref: Appl. Phys. Lett. 124, 251701 (2024)

Subjects: Optics (physics.optics); Materials Science (cond-mat.mtrl-sci); Applied Physics (physics.app-ph)

The interaction between chiral molecules and circularly polarized light is largely influenced by the local optical chirality density. This interaction prompts substantial demand of the design of nanophotonic platforms capable of enhancing such effects across large and accessible volumes. Such a magnification requires nanostructures that provide strong electric and magnetic field enhancements while preserving the phase relation of circular light. Dielectric nanostructures, particularly those able to support resonances, are ideal candidates for this task due to their capacity for high electric and magnetic field enhancements. On the other hand, efficient third harmonic generation calls for strong electric field resonances within dielectric materials, a feature often boosted by incorporating plasmonic materials into hybrid systems. In this work, we numerically propose a coupled silicon disk-gold ring system that can exploit the anapole-induced field confinement to provide a broadband magnified circular dichroism under realistic conditions, reaching values up to a 230-fold enhancement. We also demonstrate that this structure can be employed as an efficient third harmonic generator which, when integrated with chiral media, enables an 800-fold enhancement in circular dichroism. Furthermore, we show that pulsed illumination at intensities up to 10 GW/cm2 does not induce temperature increments that could potentially damage the samples. These findings suggest that this system can be a promising and versatile approach towards ultrasensitive chiral sensing.

[206] arXiv:2403.10277 (replaced) [pdf, html, other]

Title: Delayed interactions in the noisy voter model through the periodic polling mechanism

Aleksejus Kononovicius, Rokas Astrauskas, Marijus Radavičius, Feliksas Ivanauskas

Comments: submitted; 22 pages, 11 figures, 54 references

Subjects: Physics and Society (physics.soc-ph); Statistical Mechanics (cond-mat.stat-mech)

We investigate the effects of delayed interactions on the stationary distribution of the noisy voter model. We assume that the delayed interactions occur through the periodic polling mechanism and replace the original instantaneous two-agent interactions. In our analysis, we require that the polling period aligns with the delay in announcing poll outcomes. As expected, when the polling period is relatively short, the model with delayed interactions is almost equivalent to the original model. As the polling period increases, oscillatory behavior emerges, but the model with delayed interactions still converges to stationary distribution. The stationary distribution resembles a Beta-binomial distribution, with its shape parameters scaling with the polling period. The observed scaling behavior is non-monotonic. Namely, the shape parameters peak at some intermediate polling period.

[207] arXiv:2403.14417 (replaced) [pdf, html, other]

Title: A two-dimensional vertex model for curvy cell-cell interfaces at the subcellular scale

Kyungeun Kim, J. M. Schwarz, Martine Ben Amar

Comments: 18 pages, 16 figures

Subjects: Biological Physics (physics.bio-ph); Soft Condensed Matter (cond-mat.soft)

Cross-sections of cell shapes in a tissue monolayer typically resemble a tiling of convex polygons. Yet, examples exist where the polygons are not convex with curved cell-cell interfaces, as seen in the adaxial epidermis. To date, two-dimensional vertex models predicting the structure and mechanics of cell monolayers have been mostly limited to convex polygons. To overcome this limitation, we introduce a framework to study curvy cell-cell interfaces at the subcellular scale within vertex models by using a parameterized curve between vertices that is expanded in a Fourier series and whose coefficients represent additional degrees of freedom. This extension to non-convex polygons allows for cells with same shape index, or dimensionless perimeter, to be, for example, either elongated or globular with lobes. In the presence of applied, anisotropic stresses, we find that local, subcellular curvature, or buckling, can be energetically more favorable than larger scale deformations involving groups of cells. Inspired by recent experiments, we also find that local, subcellular curvature at cell-cell interfaces emerges in a group of cells in response to the swelling of additional cells surrounding the group. Our framework, therefore, can account for a wider array of multi-cellular responses to constraints in the tissue environment.

[208] arXiv:2404.01193 (replaced) [pdf, html, other]

Title: Enhancing capabilities of particle image/tracking velocimetry with physics-informed neural networks

Vladimir Parfenyev, Mark Blumenau, Ilia Nikitin

Subjects: Fluid Dynamics (physics.flu-dyn); Data Analysis, Statistics and Probability (physics.data-an)

Solving inverse problems, which means obtaining model parameters from observed data, using conventional computational fluid dynamics solvers is prohibitively expensive. Here we employ machine learning algorithms to overcome the challenge. As an example, we consider a moderately turbulent fluid flow, excited by a stationary force and described by a two-dimensional Navier-Stokes equation with linear bottom friction. Given sparse and probably noisy data for the velocity and the general form of the model, we reconstruct the dense velocity and pressure fields in the observation domain, infer the driving force, and determine the unknown fluid viscosity and friction coefficient. Our approach involves training a physics-informed neural network by minimizing the loss function, which penalizes deviations from the provided data and violations of the Navier-Stokes equation. The suggested technique extracts additional information from experimental and numerical observations, potentially enhancing the capabilities of particle image/tracking velocimetry.

[209] arXiv:2404.05437 (replaced) [pdf, other]

Title: Mapping finite-fault slip with spatial correlation between seismicity and point-source Coulomb failure stress change

Anthony Lomax (ALomax Scientific)

Comments: 41 pages, 12 figures; for supplementary movies, see this https URL ; presented at 2024 Annual Meeting, Seismological Society of America, 29 April-3 May, Anchorage, Alaska. v2: updated synthetic fault slip analysis, minor text changes

Subjects: Geophysics (physics.geo-ph)

Most earthquake energy release arises during fault slip many kilometers below the Earth's surface. Understanding earthquakes and their hazard requires mapping the geometry and distribution of this slip. Such finite-fault maps are typically derived from surface phenomena, such as seismic and geodetic ground motions. Here we introduce an imaging procedure for mapping finite-fault slip directly from seismicity and aftershocks - phenomena occurring at depth around an earthquake rupture. For specified source and receiver faults, we map source-fault slip in 3D by correlation of point-source Coulomb failure stress change (${\Delta}$CFS) kernels across the distribution of seismicity around an earthquake. These seismicity-stress maps show relative, static fault slip compatible with the surrounding seismicity given the physics of ${\Delta}$CFS; they can aid other slip inversions and aftershock forecasting, and be obtained for early instrumental earthquakes. We verify this procedure recovers synthetic fault slip, and matches independent estimates of slip for the 2004 Mw 6.0 Parkfield and 2021 Mw 6.0 Antelope Valley California earthquakes. For the 2018 Mw 7.1 Anchorage Alaska intra-slab earthquake, seismicity-stress maps, combined with multi-scale precise hypocenter relocation, resolve the enigma of which mainshock faulting plane ruptured (the gently east-dipping plane), and clarify slab structures activated in the energetic aftershock sequence.

[210] arXiv:2404.12885 (replaced) [pdf, html, other]

Title: Testbeam results of irradiated SiGe BiCMOS monolithic silicon pixel detector without internal gain layer

T. Moretti, M. Milanesio, R. Cardella, T. Kugathasan, A. Picardi, I. Semendyaev, M. Elviretti, H. Rücker, K. Nakamura, Y. Takubo, M. Togawa, F. Cadoux, R. Cardarelli, L. Cecconi, S. Débieux, Y. Favre, C. A. Fenoglio, D. Ferrere, S. Gonzalez-Sevilla, L. Iodice, R. Kotitsa, C. Magliocca, M. Nessi, A. Pizarro-Medina, J. Sabater Iglesias, J. Saidi, M. Vicente Barreto Pinto, S. Zambito, L. Paolozzi, G. Iacobucci

Subjects: Instrumentation and Detectors (physics.ins-det)

Samples of the monolithic silicon pixel ASIC prototype produced in 2022 within the framework of the Horizon 2020 MONOLITH ERC Advanced project were irradiated with 70 MeV protons up to a fluence of 1 x 1016 neq/cm2, and then tested using a beam of 120 GeV/c pions. The ASIC contains a matrix of 100 \mu m pitch hexagonal pixels, readout out by low noise and very fast frontend electronics produced in a 130 nm SiGe BiCMOS technology process. The dependence on the proton fluence of the efficiency and the time resolution of this prototype was measured with the frontend electronics operated at a power density between 0.13 and 0.9 W/cm2. The testbeam data show that the detection efficiency of 99.96% measured at sensor bias voltage of 200 V before irradiation becomes 96.2% after a fluence of 1 x 1016 neq/cm2. An increase of the sensor bias voltage to 300 V provides an efficiency to 99.7% at that proton fluence. The timing resolution of 20 ps measured before irradiation rises for a proton fluence of 1 x 1016 neq/cm2 to 48 and 44 ps at HV = 200 and 300 V, respectively.

[211] arXiv:2404.13231 (replaced) [pdf, html, other]

Title: Relativistic coupled cluster with completely renormalized and perturbative triples corrections

Stephen H. Yuwono, Run R. Li, Tianyuan Zhang, Kshitijkumar A. Surjuse, Edward F. Valeev, Xiaosong Li, A. Eugene DePrince III

Subjects: Chemical Physics (physics.chem-ph)

We have implemented noniterative triples corrections to the energy from coupled-cluster with single and double excitations (CCSD) within the 1-electron exact two-component (1eX2C) relativistic framework. The effectiveness of both the CCSD(T) and the completely renormalized (CR) CC(2,3) approaches are demonstrated by performing all-electron computations of the potential energy curves and spectroscopic constants of copper, silver, and gold dimers in their ground electronic states. Spin-orbit coupling effects captured via the 1eX2C framework are shown to be crucial for recovering the correct shape of the potential energy curves, and the correlation effects due to triples in these systems changes the dissociation energies by about 0.1--0.2 eV or about 4--7\%. We also demonstrate that relativistic effects and basis set size and contraction scheme are significantly more important in Au$_2$ than in Ag$_2$ or Cu$_2$.

[212] arXiv:2404.14505 (replaced) [pdf, html, other]

Title: Reformulation of Time-Dependent Density Functional Theory for Non-Perturbative Dynamics: The Rabi Oscillation Problem Resolved

Davood B. Dar, Anna Baranova, Neepa T. Maitra

Subjects: Chemical Physics (physics.chem-ph); Atomic Physics (physics.atom-ph); Computational Physics (physics.comp-ph)

Rabi oscillations have long been thought to be out of reach in simulations using time-dependent density functional theory (TDDFT), a prominent symptom of the failure of the adiabatic approximation for non-perturbative dynamics. We present a reformulation of TDDFT which requires response quantities only, thus enabling an adiabatic approximation to predict such dynamics accurately because the functional is evaluated on a density close to the ground-state, instead of on the fully non-perturbative density. Our reformulation applies to it any real-time dynamics, redeeming TDDFT far from equilibrium. Examples of a resonantly-driven local excitation in a model He atom, and charge-transfer in the LiCN molecule are given.

[213] arXiv:2404.16503 (replaced) [pdf, other]

Title: Characteristics of FEL-generated THz waves using planar and helical undulators

A. A. Molavi Choobini, S. S. Ghaffari-Oskooei, F. Farahi, F. M. Aghamir

Subjects: Accelerator Physics (physics.acc-ph); Plasma Physics (physics.plasm-ph)

Emission of terahertz waves in free electron lasers (FELs) with both planar (linear) and helical undulators has been explored. The analysis employs Lienard-Wiechert fields to characterize FEL radiation within the THz region. Specifically, the study delves into the analytical examination of radiation pattern of THz waves, which provides insight into the angular distribution of radiation energy. The variations of radiation pattern for various parameters such as different harmonics, Lorentz factor, magnetic parameter, and total number of periods of planar and helical undulators were investigated. The Fourier transform of free electron laser electric field is showcased across four distinct sets of FEL parameters. The interplay between electron beam and undulators parameters sheds light on how these factors influence the directionality of THz waves. Simulation results indicate that planar undulators often produce radiation with noticeable side lobes, especially at higher harmonics, while helical undulators typically exhibit reduced side lobes, resulting in a more focused main radiation peak. However, the radiation pattern of THz waves tends to concentrate predominantly in the forward direction and the polarization of the emitted radiation is determined by the properties of the undulator and electron beam, rather than the specific undulator geometry. The study underscores that an optimal selection of undulator and beam parameters can effectively maximize the angular distribution of emitted radiation.

[214] arXiv:2404.19022 (replaced) [pdf, other]

Title: Mobility and Threshold Voltage Extraction in Transistors with Gate-Voltage-Dependent Contact Resistance

Robert K. A. Bennett, Lauren Hoang, Connor Cremers, Andrew J. Mannix, Eric Pop

Comments: Corrected values tabulated in Figure 2d (surrounding discussion/conclusions unchanged); updated discussion surrounding Monte Carlo approach for error propagation; corrected typos

Subjects: Applied Physics (physics.app-ph); Other Condensed Matter (cond-mat.other)

The mobility of emerging (e.g., two-dimensional, oxide, organic) semiconductors is commonly estimated from transistor current-voltage measurements. However, such devices often experience contact gating, i.e., electric fields from the gate modulate the contact resistance during measurements, which can lead conventional extraction techniques to estimate mobility incorrectly even by a factor >2. This error can be minimized by measuring transistors at high gate-source bias, |$V_\mathrm{gs}$|, but this regime is often inaccessible in emerging devices that suffer from high contact resistance or early gate dielectric breakdown. Here, we propose a method of extracting mobility in transistors with gate-dependent contact resistance that does not require operation at high |$V_\mathrm{gs}$|, enabling accurate mobility extraction even in emerging transistors with strong contact gating. Our approach relies on updating the transfer length method (TLM) and can achieve <10% error even in regimes where conventional techniques overestimate mobility by >2$\times$.

[215] arXiv:2405.01721 (replaced) [pdf, html, other]

Title: Symmetry breaking of rotating convection due to Non-Oberbeck-Boussinesq effects

Shuang Wang, Wanying Kang

Subjects: Fluid Dynamics (physics.flu-dyn); Atmospheric and Oceanic Physics (physics.ao-ph)

The non-Oberbeck-Boussinesq (NOB) effects arising from variations in thermal expansivity are theoretically and numerically studied in the context of rotating Rayleigh-Bénard convection under two-dimensional (2D) configuration. The thermal expansivity increases with pressure (depth), and its variation is measured by a dimensionless factor $\epsilon$. Utilizing an asymptotic expansion with weak nonlinearity, we derive an amplitude equation, revealing that NOB effects amplify the magnitude of convection. An order-$\epsilon^2$ NOB correction leads to a symmetry breaking about the horizontal mid-plane, manifested in the strengthening of convection near the bottom and its weakening near the top, forming a bottom-heavy profiles. At order $\epsilon^3$, the conjunction of NOB effects and nonlinear advection leads to a horizontal symmetry breaking. The downward cold plumes become stronger and more concentrated compared to the upward warm plumes. Numerical simulations validate the theoretical analyses in the weak nonlinear regime and confirm robust horizontal asymmetry and stronger downward plumes at very large Rayleigh numbers. This work advances our understanding of hydrothermal plumes in some winter lakes on Earth, and in the subglacial oceans on icy moons as well as tracer transport from the seafloor to the ice shell.

[216] arXiv:2405.02138 (replaced) [pdf, html, other]

Title: XtalOpt Version 13: Multi-Objective Evolutionary Search for Novel Functional Materials

Samad Hajinazar, Eva Zurek

Subjects: Computational Physics (physics.comp-ph); Materials Science (cond-mat.mtrl-sci)

Version 13 of XtalOpt, an evolutionary algorithm for crystal structure prediction, is now available for download from the CPC program library or the XtalOpt website, this https URL. In the new version of the XtalOpt code, a general platform for multi-objective global optimization is implemented. This functionality is designed to facilitate the search for (meta)stable phases of functional materials through minimization of the enthalpy of a crystalline system coupled with the simultaneous optimization of any desired properties that are specified by the user. The code is also able to perform a constrained search by filtering the parent pool of structures based on a user-specified feature, while optimizing multiple objectives. Here, we present the implementation and various technical details, and we provide a brief overview of additional improvements that have been introduced in the new version of XtalOpt.

[217] arXiv:2405.16972 (replaced) [pdf, html, other]

Title: Chip-Scale Point-Source Sagnac Interferometer by Phase-Space Squeezing

Yiftach Halevy, Yali Cina, Omer Feldman, David Groswasser, Yonathan Japha, Ron Folman

Subjects: Atomic Physics (physics.atom-ph); Instrumentation and Detectors (physics.ins-det); Quantum Physics (quant-ph)

Matter-wave interferometry is essential to both science and technology. Phase-space squeezing has been shown to be an advantageous source of atoms, whereby the spread in momentum is decreased. Here, we show that the opposite squeezing may be just as advantageous. As an exemplification, we analyze the effect of such a source on point source atom interferometry (PSI), which enables rotation sensing. We describe how a squeezed PSI (SPSI) increases the sensitivity and dynamic range while facilitating short cycle times and high repetition rates. We present regions in parameter space for which the figures of merit are improved by orders of magnitude and show that under some definition of compactness, the SPSI is superior by more than four orders of magnitude. The SPSI thus enables either enhancing the performance for standard size devices or maintaining the performance while miniaturizing to a chip-scale device, opening the door to real-life applications.

[218] arXiv:2406.01754 (replaced) [pdf, html, other]

Title: Validating Automated Resonance Evaluation with Synthetic Data

Oleksii Zivenko, Noah A. W. Walton, William Fritsch, Jacob Forbes, Amanda M. Lewis, Aaron Clark, Jesse M. Brown, Vladimir Sobes

Comments: 39 pages, 12 figures; As a follow-up to arXiv:2303.09698 and arXiv:2402.14122

Subjects: Computational Physics (physics.comp-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th); Medical Physics (physics.med-ph)

The integrity and precision of nuclear data are crucial for a broad spectrum of applications, from national security and nuclear reactor design to medical diagnostics, where the associated uncertainties can significantly impact outcomes. A substantial portion of uncertainty in nuclear data originates from the subjective biases in the evaluation process, a crucial phase in the nuclear data production pipeline. Recent advancements indicate that automation of certain routines can mitigate these biases, thereby standardizing the evaluation process, reducing uncertainty and enhancing reproducibility. This article contributes to developing a framework for automated evaluation techniques testing, emphasizing automated fitting methods that do not require the user to provide any prior information. This approach simplifies the process and reduces the manual effort needed in the initial evaluation stage. It highlights the capability of the framework to validate and optimize subroutines, targeting the performance analysis and optimization of the fitting procedure using high-fidelity synthetic data (labeled experimental data) and the concept of a fully controlled computational experiment. An error metric is introduced to provide a clear and intuitive measure of the fitting quality by quantifying the accuracy and performance across the specified energy. This metric sets a scale for comparison and optimization of routines or hyperparameter selection, improving the entire evaluation process methodology and increasing reproducibility and objectivity.

[219] arXiv:2406.03863 (replaced) [pdf, other]

Title: Topological Materials for Near-Field Radiative Heat Transfer

Azadeh Didari-Bader, Seonyeong Kim, Heejin Choi, Sunae Seo, Piyali Biswas, Heejeong Jeong, Chang-Won Lee

Subjects: Optics (physics.optics); Quantum Physics (quant-ph)

Topological materials provide a platform that utilizes the geometric characteristics of structured materials to control the flow of waves, enabling unidirectional and protected transmission that is immune to defects or impurities. The topologically designed photonic materials can carry quantum states and electromagnetic energy, benefiting nanolasers or quantum photonic systems. This article reviews recent advances in the topological applications of photonic materials for radiative heat transfer, especially in the near field. When the separation distance between media is considerably smaller than the thermal wavelength, the heat transfer exhibits super-Planckian behavior that surpasses Planck's blackbody predictions. Near-field thermal radiation in subwavelength systems supporting surface modes has various applications, including nanoscale thermal management and energy conversion. Photonic materials and structures that support topological surface states show immense potential for enhancing or suppressing near-field thermal radiation. We present various topological effects, such as periodic and quasi-periodic nanoparticle arrays, Dirac and Weyl semimetal-based materials, structures with broken global symmetries, and other topological insulators, on near-field heat transfer. Also, the possibility of realizing near-field thermal radiation in such topological materials for alternative thermal management and heat flux guiding in nano-scale systems is discussed based on the existing technology.

[220] arXiv:2406.05579 (replaced) [pdf, html, other]

Title: Omnidirectional Energetic Electron Fluxes from 150 km to 20,000 km: an ELFIN-Based Model

Emile Saint-Girons, Xiao-Jia Zhang, Didier Mourenas, Anton V. Artemyev, Vassilis Angelopoulos

Subjects: Space Physics (physics.space-ph); Plasma Physics (physics.plasm-ph)

The strong variations of energetic electron fluxes in the Earth's inner magnetosphere are notoriously hard to forecast. Developing accurate empirical models of electron fluxes from low to high altitudes at all latitudes is therefore useful to improve our understanding of flux variations and to assess radiation hazards for spacecraft systems. In the present work, energy- and pitch-angle-resolved precipitating, trapped, and backscattered electron fluxes measured at low altitude by Electron Loss and Fields Investigation (ELFIN) CubeSats are used to infer omnidirectional fluxes at altitudes below and above the spacecraft, from 150 km to 20,000 km, making use of adiabatic transport theory and quasi-linear diffusion theory. The inferred fluxes are fitted as a function of selected parameters using a stepwise multivariate optimization procedure, providing an analytical model of omnidirectional electron flux along each geomagnetic field line, based on measurements from only one spacecraft in low Earth orbit. The modeled electron fluxes are provided as a function of $L$-shell, altitude, energy, and two different indices of past geomagnetic activity, computed over the preceding 4 hours or 3 days, potentially allowing to disentangle impulsive processes (such as rapid injections) from cumulative processes (such as inward radial diffusion and wave-driven energization). The model is validated through comparisons with equatorial measurements from the Van Allen Probes, demonstrating the broad applicability of the present method. The model indicates that both impulsive and time-integrated geomagnetic activity partly control electron fluxes in the outer radiation belt and in the plasma sheet.

[221] arXiv:2406.06063 (replaced) [pdf, html, other]

Title: Enabling Large-Scale and High-Precision Fluid Simulations on Near-Term Quantum Computers

Zhao-Yun Chen, Teng-Yang Ma, Chuang-Chao Ye, Liang Xu, Ming-Yang Tan, Xi-Ning Zhuang, Xiao-Fan Xu, Yun-Jie Wang, Tai-Ping Sun, Yong Chen, Lei Du, Liang-Liang Guo, Hai-Feng Zhang, Hao-Ran Tao, Tian-Le Wang, Xiao-Yan Yang, Ze-An Zhao, Peng Wang, Sheng Zhang, Chi Zhang, Ren-Ze Zhao, Zhi-Long Jia, Wei-Cheng Kong, Meng-Han Dou, Jun-Chao Wang, Huan-Yu Liu, Cheng Xue, Peng-Jun-Yi Zhang, Sheng-Hong Huang, Peng Duan, Yu-Chun Wu, Guo-Ping Guo

Comments: 31 pages, 10 figures

Subjects: Computational Physics (physics.comp-ph); Quantum Physics (quant-ph)

Quantum computational fluid dynamics (QCFD) offers a promising alternative to classical computational fluid dynamics (CFD) by leveraging quantum algorithms for higher efficiency. This paper introduces a comprehensive QCFD method, including an iterative method "Iterative-QLS" that suppresses error in quantum linear solver, and a subspace method to scale the solution to a larger size. We implement our method on a superconducting quantum computer, demonstrating successful simulations of steady Poiseuille flow and unsteady acoustic wave propagation. The Poiseuille flow simulation achieved a relative error of less than $0.2\%$, and the unsteady acoustic wave simulation solved a 5043-dimensional matrix. We emphasize the utilization of the quantum-classical hybrid approach in applications of near-term quantum computers. By adapting to quantum hardware constraints and offering scalable solutions for large-scale CFD problems, our method paves the way for practical applications of near-term quantum computers in computational science.

[222] arXiv:2406.07064 (replaced) [pdf, html, other]

Title: Modeling fibrous tissue in vascular fluid-structure interaction: a morphology-based pipeline and biomechanical significance

Yujie Sun, Jiayi Huang, Qingshuang Lu, Xinhai Yue, Xuanming Huang, Wei He, Yun Shi, Ju Liu

Subjects: Medical Physics (physics.med-ph); Biological Physics (physics.bio-ph); Fluid Dynamics (physics.flu-dyn)

We propose a suite of technologies for analyzing the interaction between anisotropic arterial walls and blood flow for subject-specific geometries. Utilizing an established lumen modeling strategy, we present a comprehensive pipeline for generating the thick-walled artery models. Through a specialized mesh generation procedure, we obtain the meshes for the arterial lumen and wall with mesh continuity across the interface ensured. Exploiting the centerline information, a series of procedures is introduced for generating local basis vectors within the arterial wall. The procedures are tailored to handle thick-walled and, in particular, aneurysmatic tissues in which the basis vectors may exhibit transmural variations. Additionally, we propose methods to accurately identify the centerline in multi-branched vessels and bifurcating regions. The developed fiber generation method is evaluated against the strategy using linear elastic analysis, demonstrating that the proposed approach yields satisfactory fiber definitions in the considered benchmark. Finally, we examine the impact of anisotropic arterial wall models on the vascular fluid-structure interaction analysis through numerical examples. For comparison purposes, the neo-Hookean model is considered. The first case involves an idealized curved geometry, while the second case studies an image-based abdominal aorta model. The numerical results reveal that the deformation and stress distribution are critically related to the constitutive model of the wall, while the hemodynamic factors are less sensitive to the wall model. This work paves the way for more accurate image-based vascular modeling and enhances the prediction of arterial behavior under physiologically realistic conditions.

[223] arXiv:2406.09471 (replaced) [pdf, other]

Title: Nowcasting Earthquakes with QuakeGPT: Methods and First Results

John B. Rundle, Geoffrey Fox, Andrea Donnellan, Lisa Grant Ludwig

Comments: 25 Pages, 10 Figures

Subjects: Geophysics (physics.geo-ph)

Earthquake nowcasting has been proposed as a means of tracking the change in large earthquake potential in a seismically active area. The method was developed using observable seismic data, in which probabilities of future large earthquakes can be computed using Receiver Operating Characteristic (ROC) methods. Furthermore, analysis of the Shannon information content of the earthquake catalogs has been used to show that there is information contained in the catalogs, and that it can vary in time. Here we discuss a new method for earthquake nowcasting that uses an AI-enhanced deep learning model "QuakeGPT" that is based on an attention-based science transformer adapted for time series forecasting. Such dot product attention-based transformers were introduced by Vaswani et al. (2017), and are the basis for the new large language models such as ChatGPT. To use these science transformers, they must first be trained on a large corpus of data. A problem is that the existing history of reliable earthquake catalog data extends back in time only a few decades, which is almost certainly too short to train a model for reliable nowcasting/forecasting. As a result, we turn to earthquake simulations to train the transformer model. Specifically we discuss a simple stochastic earthquake simulation model "ERAS" that has recently been introduced. The ERAS model is similar to the more common "ETAS" models, the difference being that the ERAS model has only 2 novel, adjustable parameters, rather than the 6-8 adjustable parameters that characterize most ETAS models. Using this ERAS model, we then define a transformer model and train it using a long catalog of ERAS simulations, then apply it to an ERAS validation dataset with the transformer model. In this paper, we describe this new method and assess the applicability to observed earthquake catalogs for use in nowcasting/forecasting.

[224] arXiv:2406.09544 (replaced) [pdf, html, other]

Title: No more gap-shifting: Stochastic many-body-theory based TDHF for accurate theory of polymethine cyanine dyes

Nadine C. Bradbury, Barry Y. Li, Tucker Allen, Justin R. Caram, Daniel Neuhauser

Comments: 5 pages, 4 figures

Subjects: Chemical Physics (physics.chem-ph)

We introduce an individually fitted screened-exchange interaction for the time-dependent Hartree-Fock (TDHF) method and show that it resolves the missing binding energies in polymethine organic dye molecules compared to time-dependent density functional theory (TDDFT). The interaction kernel, which can be thought as a dielectric function, is generated by stochastic fitting to the screened-Coulomb interaction of many-body perturbation theory (MBPT), specific to each system. We test our method on the flavylium (Flav) and indocyanine green (ICG) dye families with a modifiable length of the polymethine bridge, leading to excitations ranging from the visible to short-wave infrared (SWIR). Our approach validates earlier observations on the importance of inclusion of medium range exchange for the exciton binding energy. Our resulting method, TDHF@$v_W$, also achieves a mean absolute error on par with MBPT at a computational cost on par with local-functional TDDFT.

[225] arXiv:2406.09934 (replaced) [pdf, other]

Title: Generation of THz waves through interaction of the wakefield of two-color laser pulses with magnetized plasma

A. A. Molavi Choobini, F. M. Aghamir

Subjects: Plasma Physics (physics.plasm-ph); Accelerator Physics (physics.acc-ph)

The present study explores radiation in THz spectrum region through the interaction of the wakefield of two-color laser pulses with magnetized plasma. The interaction of the two-color laser with plasma electrons induces transverse nonlinear current in two dimensions, resulting in generation of a wakefield and a forward wave. The investigation revealed that during the non-relativistic regime of laser-plasma interaction, interdependence exists between the electric fields of the forward wave and the wake. Conversely, in the relativistic regime, the dynamic of interaction changes, and plasma electrons are influenced not only by the electric field of the laser pulse but also by relativistic effects like Lorentz contraction, responding to both the electric and magnetic field components. This leads to generation of wake and forward wave radiations. The interplay between various laser and plasma parameters is analyzed, shedding light on the conditions leading to radiation angular distribution patterns in the forward and backward directions. The impact of spatial laser profile, a DC external magnetic field, polarization states, and plasma interaction length on the generated wake and forward wave patterns has been investigated. Through systematic variation of these parameters, the objective is to elucidate the controlled directional features of the resulting fields and radiation patterns.

[226] arXiv:2406.11491 (replaced) [pdf, html, other]

Title: Freely Decaying Saffman Turbulence Experimentally Generated by Magnetic Stirrers

Jean-Baptiste Gorce, Eric Falcon

Subjects: Fluid Dynamics (physics.flu-dyn)

We investigate experimentally the decay of three-dimensional hydrodynamic turbulence, initially generated by the erratic motions of centimeter-size magnetic stirrers in a closed container. Such zero-mean-flow homogeneous isotropic turbulence is well suited to test Saffman's model and Batchelor's model of freely decaying turbulence. Here, we report a consistent set of experimental measurements (temporal decay of the turbulent kinetic energy, of the energy dissipation rate, and growth of the integral scale) strongly supporting the Saffman model. We also measure the conservation of the Saffman invariant at early times of the decay and show that the energy spectrum scales as $k^{2}$ at large scales and keeps its self-similar shape during the decay. This letter thus presents the first experimental evidence of the validity of the connection between the Saffman invariant and the $k^{2}$-energy spectrum of the large scales. The final decay regime closely corresponds to Saffman's model when the container size is sufficiently large.

[227] arXiv:2204.01426 (replaced) [pdf, html, other]

Title: Empirical adequacy of the time operator canonically conjugate to a Hamiltonian generating translations

Ovidiu Cristinel Stoica

Comments: Accepted version. The mathematical results are unchanged, but I added substantial explanations of the physical significance. Phys. Scr. (2024)

Subjects: Quantum Physics (quant-ph); Mathematical Physics (math-ph); History and Philosophy of Physics (physics.hist-ph)

To admit a canonically conjugate time operator, the Hamiltonian has to be a generator of translations (like the momentum operator generates translations in space), so its spectrum must be unbounded. But the Hamiltonian governing our world is thought to be bounded from below. Also, judging by the number of fields and parameters of the Standard Model, the Hamiltonian seems much more complicated.
In this article I give examples of worlds governed by Hamiltonians generating translations. They can be expressed as a partial derivative operator just like the momentum operator, but when expressed in function of other observables they can exhibit any level of complexity. The examples include any quantum world realizing a standard ideal measurement, any quantum world containing a clock or a free massless fermion, the quantum representation of any deterministic time-reversible dynamical system without time loops, and any quantum world that cannot return to a past state.
Such worlds are as sophisticated as our world, but they admit a time operator. I show that, despite having unbounded Hamiltonian, they do not decay to infinite negative energy any more than any quantum or classical world. Since two such quantum systems of the same Hilbert space dimension are unitarily equivalent even if the physical content of their observables is very different, they are concrete counterexamples to Hilbert Space Fundamentalism (HSF). Taking the observables into account removes the ambiguity of HSF and the clock ambiguity problem attributed to the Page-Wootters formalism, also caused by assuming HSF. These results provide additional motivations to restore the spacetime symmetry in the formulation of Quantum Mechanics and for the Page-Wootters formalism.

[228] arXiv:2305.19519 (replaced) [pdf, html, other]

Title: Two applications of stochastic thermodynamics to hydrodynamics

Kohei Yoshimura, Sosuke Ito

Comments: 5+4 pages, 2 figures

Journal-ref: Phys. Rev. Research 6, L022057 (2024)

Subjects: Statistical Mechanics (cond-mat.stat-mech); Fluid Dynamics (physics.flu-dyn)

Recently, the theoretical framework of stochastic thermodynamics has been revealed to be useful for macroscopic systems. However, despite its conceptual and practical importance, the connection to hydrodynamics has yet to be explored. In this Letter, we reformulate the thermodynamics of compressible and incompressible Newtonian fluids so that it becomes comparable to stochastic thermodynamics and unveil their connections; we obtain the housekeeping--excess decomposition of entropy production rate (EPR) for hydrodynamic systems and find a lower bound on EPR given by relative fluctuation similar to the thermodynamic uncertainty relation. These results not only prove the universality of stochastic thermodynamics but also suggest the potential extensibility of the thermodynamic theory of hydrodynamic systems.

[229] arXiv:2307.05125 (replaced) [pdf, html, other]

Title: Linearizing Binary Optimization Problems Using Variable Posets for Ising Machines

Kentaro Ohno, Nozomu Togawa

Comments: 22 pages. This article has been accepted for publication in IEEE Transactions on Emerging Topics in Computing

Subjects: Optimization and Control (math.OC); Statistical Mechanics (cond-mat.stat-mech); Emerging Technologies (cs.ET); Applied Physics (physics.app-ph)

Ising machines are next-generation computers expected to efficiently sample near-optimal solutions of combinatorial optimization problems. Combinatorial optimization problems are modeled as quadratic unconstrained binary optimization (QUBO) problems to apply an Ising machine. However, current state-of-the-art Ising machines still often fail to output near-optimal solutions due to the complicated energy landscape of QUBO problems. Furthermore, the physical implementation of Ising machines severely restricts the size of QUBO problems to be input as a result of limited hardware graph structures. In this study, we take a new approach to these challenges by injecting auxiliary penalties preserving the optimum, which reduces quadratic terms in QUBO objective functions. The process simultaneously simplifies the energy landscape of QUBO problems, allowing the search for near-optimal solutions, and makes QUBO problems sparser, facilitating encoding into Ising machines with restriction on the hardware graph structure. We propose linearization of QUBO problems using variable posets as an outcome of the approach. By applying the proposed method to synthetic QUBO instances and to multi-dimensional knapsack problems, we empirically validate the effects on enhancing minor-embedding of QUBO problems and the performance of Ising machines.

[230] arXiv:2307.05257 (replaced) [pdf, html, other]

Title: Right On Time: Ultrafast Charge Separation Before Hybrid Exciton Formation

Lukas Gierster, Olga Turkina, Jan-Christoph Deinert, Sesha Vempati, Elsie Baeta, Yves Garmshausen, Stefan Hecht, Claudia Draxl, Julia Stähler

Subjects: Materials Science (cond-mat.mtrl-sci); Soft Condensed Matter (cond-mat.soft); Chemical Physics (physics.chem-ph); Computational Physics (physics.comp-ph)

Organic/inorganic hybrid systems offer great potential for novel solar cell design combining the tunability of organic chromophore absorption properties with high charge carrier mobilities of inorganic semiconductors. However, often such material combinations do not show the expected performance: while ZnO, for example, basically exhibits all necessary properties for a successful application in light-harvesting, it was clearly outpaced by TiO$_2$ in terms of charge separation efficiency. The origin of this deficiency has long been debated. This study employs femtosecond time-resolved photoelectron spectroscopy and many-body ab initio calculations to identify and quantify all elementary steps leading to the suppression of charge separation at an exemplary organic/ZnO interface. We demonstrate that charge separation indeed occurs efficiently on ultrafast (350 fs) timescales, but that electrons are recaptured at the interface on a 100 ps timescale and subsequently trapped in a strongly bound (0.7 eV) hybrid exciton state with a lifetime exceeding 5 $\mu$s. Thus, initially successful charge separation is followed by delayed electron capture at the interface, leading to apparently low charge separation efficiencies. This finding provides a sufficiently large timeframe for counter-measures in device design to successfully implement specifically ZnO and, moreover, invites material scientists to revisit charge separation in various kinds of previously discarded hybrid systems.

[231] arXiv:2308.08421 (replaced) [pdf, html, other]

Title: Transport and Energetics of Bacterial Rectification

Satyam Anand, Xiaolei Ma, Shuo Guo, Stefano Martiniani, Xiang Cheng

Comments: 27 pages, 11 figures

Subjects: Soft Condensed Matter (cond-mat.soft); Statistical Mechanics (cond-mat.stat-mech); Biological Physics (physics.bio-ph)

Randomly moving active particles can be herded into directed motion by asymmetric geometric structures. Although such a rectification process has been extensively studied due to its fundamental, biological, and technological relevance, a comprehensive understanding of active matter rectification based on single particle dynamics remains elusive. Here, by combining experiments, simulations, and theory, we study the directed transport and energetics of swimming bacteria navigating through funnel-shaped obstacles -- a paradigmatic model of rectification of living active matter. We develop a microscopic parameter-free model for bacterial rectification, which quantitatively explains experimental and numerical observations and predicts the optimal geometry for the maximum rectification efficiency. Furthermore, we quantify the degree of time irreversibility and measure the extractable work associated with bacterial rectification. Our study provides quantitative solutions to long-standing questions on bacterial rectification and establishes a generic relationship between time irreversibility, particle fluxes, and extractable work, shedding light on the energetics of non-equilibrium rectification processes in living systems.

[232] arXiv:2309.08666 (replaced) [pdf, html, other]

Title: Variational Embeddings for Many Body Quantum Systems

Stefano Barison, Filippo Vicentini, Giuseppe Carleo

Comments: 15 pages, 7 figures. The framework has been extended to include embeddings of classical variational methods

Subjects: Quantum Physics (quant-ph); Other Condensed Matter (cond-mat.other); Computational Physics (physics.comp-ph)

We propose a variational scheme to represent composite quantum systems using multiple parameterized functions of varying accuracies on both classical and quantum hardware. The approach follows the variational principle over the entire system, and is naturally suited for scenarios where an accurate description is only needed in a smaller subspace. We show how to include quantum devices as high-accuracy solvers on these correlated degrees of freedom, while handling the remaining contributions with a classical device. We demonstrate the effectiveness of the protocol on spin chains and small molecules and provide insights into its accuracy and computational cost.

[233] arXiv:2310.05227 (replaced) [pdf, html, other]

Title: Physics-aware Machine Learning Revolutionizes Scientific Paradigm for Machine Learning and Process-based Hydrology

Qingsong Xu, Yilei Shi, Jonathan Bamber, Ye Tuo, Ralf Ludwig, Xiao Xiang Zhu

Comments: 33 pages, 6 figures

Subjects: Machine Learning (cs.LG); Artificial Intelligence (cs.AI); Fluid Dynamics (physics.flu-dyn)

Accurate hydrological understanding and water cycle prediction are crucial for addressing scientific and societal challenges associated with the management of water resources, particularly under the dynamic influence of anthropogenic climate change. Existing reviews predominantly concentrate on the development of machine learning (ML) in this field, yet there is a clear distinction between hydrology and ML as separate paradigms. Here, we introduce physics-aware ML as a transformative approach to overcome the perceived barrier and revolutionize both fields. Specifically, we present a comprehensive review of the physics-aware ML methods, building a structured community (PaML) of existing methodologies that integrate prior physical knowledge or physics-based modeling into ML. We systematically analyze these PaML methodologies with respect to four aspects: physical data-guided ML, physics-informed ML, physics-embedded ML, and physics-aware hybrid learning. PaML facilitates ML-aided hypotheses, accelerating insights from big data and fostering scientific discoveries. We first conduct a systematic review of hydrology in PaML, including rainfall-runoff hydrological processes and hydrodynamic processes, and highlight the most promising and challenging directions for different objectives and PaML methods. Finally, a new PaML-based hydrology platform, termed HydroPML, is released as a foundation for hydrological applications. HydroPML enhances the explainability and causality of ML and lays the groundwork for the digital water cycle's realization. The HydroPML platform is publicly available at this https URL.

[234] arXiv:2310.09082 (replaced) [pdf, html, other]

Title: From Maximum of Intervisit Times to Starving Random Walks

L. Régnier, M. Dolgushev, O. Bénichou

Comments: 6 pages, 3 figures + 16 pages, 11 figures

Journal-ref: Phys. Rev. Lett. 132, 127101 (2024)

Subjects: Statistical Mechanics (cond-mat.stat-mech); Mathematical Physics (math-ph); Data Analysis, Statistics and Probability (physics.data-an)

Very recently, a fundamental observable has been introduced and analyzed to quantify the exploration of random walks: the time $\tau_k$ required for a random walk to find a site that it never visited previously, when the walk has already visited $k$ distinct sites. Here, we tackle the natural issue of the statistics of $M_n$, the longest duration out of $\tau_0,\dots,\tau_{n-1}$. This problem belongs to the active field of extreme value statistics, with the difficulty that the random variables $\tau_k$ are both correlated and non-identically distributed. Beyond this fundamental aspect, we show that the asymptotic determination of the statistics of $M_n$ finds explicit applications in foraging theory and allows us to solve the open $d$-dimensional starving random walk problem, in which each site of a lattice initially contains one food unit, consumed upon visit by the random walker, which can travel $\mathcal{S}$ steps without food before starving. Processes of diverse nature, including regular diffusion, anomalous diffusion, and diffusion in disordered media and fractals, share common properties within the same universality classes.

[235] arXiv:2310.20309 (replaced) [pdf, html, other]

Title: Tensor formalism for predicting synaptic connections with ensemble modeling or optimization

Tirthabir Biswas, Tianzhi Lambus Li, James E. Fitzgerald

Comments: 31 pages, 6 figures, 2 tables

Subjects: Neurons and Cognition (q-bio.NC); Disordered Systems and Neural Networks (cond-mat.dis-nn); Biological Physics (physics.bio-ph)

Theoretical neuroscientists often try to understand how the structure of a neural network relates to its function by focusing on structural features that would either follow from optimization or occur consistently across possible implementations. Both optimization theories and ensemble modeling approaches have repeatedly proven their worth, and it would simplify theory building considerably if predictions from both theory types could be derived and tested simultaneously. Here we show how tensor formalism from theoretical physics can be used to unify and solve many optimization and ensemble modeling approaches to predicting synaptic connectivity from neuronal responses. We specifically focus on analyzing the solution space of synaptic weights that allow a threshold-linear neural network to respond in a prescribed way to a limited number of input conditions. For optimization purposes, we compute the synaptic weight vector that minimizes an arbitrary quadratic loss function. For ensemble modeling, we identify synaptic weight features that occur consistently across all solutions bounded by an arbitrary ellipsoid. We derive a common solution to this suite of nonlinear problems by showing how each of them reduces to an equivalent linear problem that can be solved analytically. Although identifying the equivalent linear problem is nontrivial, our tensor formalism provides an elegant geometrical perspective that allows us to solve the problem approximately in an analytical way or exactly using numeric methods. The final algorithm is applicable to a wide range of interesting neuroscience problems, and the associated geometric insights may carry over to other scientific problems that require constrained optimization.

[236] arXiv:2311.13663 (replaced) [pdf, html, other]

Title: Simulation tools, first results and experimental status of the MURAVES experiment

Andrea Giammanco, Yanwen Hong, Marwa Al Moussawi, Fabio Ambrosino, Antonio Anastasio, Samip Basnet, Lorenzo Bonechi, Massimo Bongi, Diletta Borselli, Alan Bross, Antonio Caputo, Roberto Ciaranfi, Luigi Cimmino, Vitaliano Ciulli, Raffaello D'Alessandro, Mariaelena D'Errico, Catalin Frosin, Flora Giudicepietro, Sandro Gonzi, Giovanni Macedonio, Vincenzo Masone, Massimo Orazi, Andrea Paccagnella, Rosario Peluso, Anna Pla-Dalmau, Amrutha Samalan, Giulio Saracino, Giovanni Scarpato, Paolo Strolin, Michael Tytgat, Enrico Vertechi, Lorenzo Viliani

Subjects: High Energy Physics - Experiment (hep-ex); Instrumentation and Detectors (physics.ins-det)

The MUon RAdiography of VESuvius (MURAVES) project aims at the study of Mt. Vesuvius, an active and hazardous volcano near Naples, Italy, with the use of muons freely and abundantly produced by cosmic rays. In particular, the MURAVES experiment intends to perform muographic imaging of the internal structure of the summit of Mt. Vesuvius. The challenging measurement of the rock density distribution in its summit by muography, in conjunction with data from other geophysical techniques, can help model possible eruption dynamics. The MURAVES apparatus consists of an array of three independent and identical muon trackers, with a total sensitive area of 3 square meters. In each tracker, a sequence of 4 XY tracking planes made of plastic scintillators is complemented by a 60 cm thick lead wall inserted between the two downstream planes to improve rejection of background from low energy muons. The apparatus is currently acquiring data. This paper presents preliminary results from the analysis of the first data samples acquired with trackers pointing towards Mt. Vesuvius, including the first relative measurement of the density projection of two flanks of the volcano at three different altitudes; we also present the workflow of the simulation chain of the MURAVES experiment and its ongoing developments.

[237] arXiv:2311.15779 (replaced) [pdf, html, other]

Title: Scale invariance of a spherical unitary Fermi gas

Lu Wang, Xiangchuan Yan, Jing Min, Dali Sun, Xin Xie, Shi-Guo Peng, Mingsheng Zhan, Kaijun Jiang

Comments: 15 pages and 10 figurs

Journal-ref: Phys. Rev. Lett. 132, 243403 (2024), Editors' Suggestion

Subjects: Quantum Gases (cond-mat.quant-gas); Atomic Physics (physics.atom-ph)

A unitary Fermi gas in an isotropic harmonic trap is predicted to show scale and conformal symmetry that have important consequences in its thermodynamic and dynamical properties. By experimentally realizing a unitary Fermi gas in an isotropic harmonic trap, we demonstrate its universal expansion dynamics along each direction and at different temperatures. We show that as a consequence of SO(2,1) symmetry, the measured release energy is equal to that of the trapping energy. We further observe the breathing mode with an oscillation frequency twice the trapping frequency and a small damping rate, providing the evidence of SO(2,1) symmetry. In addition, away from resonance when scale invariance is broken, we determine the effective exponent $\gamma$ that relates the chemical potential and average density along the BEC-BCS crossover, which qualitatively agrees with the mean field predictions. This work opens the possibility of studying non-equilibrium dynamics in a conformal invariant system in the future.

[238] arXiv:2312.06071 (replaced) [pdf, html, other]

Title: Precipitation Downscaling with Spatiotemporal Video Diffusion

Prakhar Srivastava, Ruihan Yang, Gavin Kerrigan, Gideon Dresdner, Jeremy McGibbon, Christopher Bretherton, Stephan Mandt

Subjects: Computer Vision and Pattern Recognition (cs.CV); Machine Learning (cs.LG); Atmospheric and Oceanic Physics (physics.ao-ph); Machine Learning (stat.ML)

In climate science and meteorology, high-resolution local precipitation (rain and snowfall) predictions are limited by the computational costs of simulation-based methods. Statistical downscaling, or super-resolution, is a common workaround where a low-resolution prediction is improved using statistical approaches. Unlike traditional computer vision tasks, weather and climate applications require capturing the accurate conditional distribution of high-resolution given low-resolution patterns to assure reliable ensemble averages and unbiased estimates of extreme events, such as heavy rain. This work extends recent video diffusion models to precipitation super-resolution, employing a deterministic downscaler followed by a temporally-conditioned diffusion model to capture noise characteristics and high-frequency patterns. We test our approach on FV3GFS output, an established large-scale global atmosphere model, and compare it against six state-of-the-art baselines. Our analysis, capturing CRPS, MSE, precipitation distributions, and qualitative aspects using California and the Himalayas as examples, establishes our method as a new standard for data-driven precipitation downscaling.

[239] arXiv:2312.14885 (replaced) [pdf, html, other]

Title: Full Record Statistics of 1d Random Walks

Léo Régnier, Maxim Dolgushev, Olivier Bénichou

Comments: 16 pages, 5 figures

Journal-ref: Phys. Rev. E 109, 064101 (2024)

Subjects: Statistical Mechanics (cond-mat.stat-mech); Mathematical Physics (math-ph); Data Analysis, Statistics and Probability (physics.data-an)

We develop a comprehensive framework for analyzing full record statistics, covering record counts $M(t_1), M(t_2), \ldots$, and their corresponding attainment times $T_{M(t_1)}, T_{M(t_2)}, \ldots$, as well as the intervals until the next record. From this multiple-time distribution, we derive general expressions for various observables related to record dynamics, including the conditional number of records given the number observed at a previous time and the conditional time required to reach the current record, given the occurrence time of the previous one. Our formalism is exemplified by a variety of stochastic processes, including biased nearest-neighbor random walks, asymmetric run-and-tumble dynamics, and random walks with stochastic resetting.

[240] arXiv:2401.03427 (replaced) [pdf, html, other]

Title: Deep FBSDE Neural Networks for Solving Incompressible Navier-Stokes Equation and Cahn-Hilliard Equation

Yangtao Deng, Qiaolin He

Subjects: Numerical Analysis (math.NA); Fluid Dynamics (physics.flu-dyn)

Efficient algorithms for solving high-dimensional partial differential equations (PDEs) has been an exceedingly difficult task for a long time, due to the curse of dimensionality. We extend the forward-backward stochastic neural networks (FBSNNs) which depends on forward-backward stochastic differential equation (FBSDE) to solve incompressible Navier-Stokes equation. For Cahn-Hilliard equation, we derive a modified Cahn-Hilliard equation from a widely used stabilized scheme for original Cahn-Hilliard equation. This equation can be written as a continuous parabolic system, where FBSDE can be applied and the unknown solution is approximated by neural network. Also our method is successfully developed to Cahn-Hilliard-Navier-Stokes (CHNS) equation. The accuracy and stability of our methods are shown in many numerical experiments, specially in high dimension.

[241] arXiv:2401.16177 (replaced) [pdf, html, other]

Title: Iterative assembly of $^{171}$Yb atom arrays with cavity-enhanced optical lattices

M.A. Norcia, H. Kim, W.B. Cairncross, M. Stone, A. Ryou, M. Jaffe, M.O. Brown, K. Barnes, P. Battaglino, T.C. Bohdanowicz, A. Brown, K. Cassella, C.-A. Chen, R. Coxe, D. Crow, J. Epstein, C. Griger, E. Halperin, F. Hummel, A.M.W. Jones, J.M. Kindem, J. King, K. Kotru, J. Lauigan, M. Li, M. Lu, E. Megidish, J. Marjanovic, M. McDonald, T. Mittiga, J.A. Muniz, S. Narayanaswami, C. Nishiguchi, T. Paule, K.A. Pawlak, L.S. Peng, K.L. Pudenz, D. Rodriguez Perez, A. Smull, D. Stack, M. Urbanek, R.J.M. van de Veerdonk, Z. Vendeiro, L. Wadleigh, T. Wilkason, T.-Y. Wu, X. Xie, E. Zalys-Geller, X. Zhang, B.J. Bloom

Comments: 8 pages, 6 figures

Subjects: Quantum Physics (quant-ph); Atomic Physics (physics.atom-ph)

Assembling and maintaining large arrays of individually addressable atoms is a key requirement for continued scaling of neutral-atom-based quantum computers and simulators. In this work, we demonstrate a new paradigm for assembly of atomic arrays, based on a synergistic combination of optical tweezers and cavity-enhanced optical lattices, and the incremental filling of a target array from a repetitively filled reservoir. In this protocol, the tweezers provide microscopic rearrangement of atoms, while the cavity-enhanced lattices enable the creation of large numbers of optical traps with sufficient depth for rapid low-loss imaging of atoms. We apply this protocol to demonstrate near-deterministic filling (99% per-site occupancy) of 1225-site arrays of optical traps. Because the reservoir is repeatedly filled with fresh atoms, the array can be maintained in a filled state indefinitely. We anticipate that this protocol will be compatible with mid-circuit reloading of atoms into a quantum processor, which will be a key capability for running large-scale error-corrected quantum computations whose durations exceed the lifetime of a single atom in the system.

[242] arXiv:2402.10031 (replaced) [pdf, html, other]

Title: Tomographic Imaging of Orbital Vortex Lines in Three-Dimensional Momentum Space

T. Figgemeier, M. Ünzelmann, P. Eck, J. Schusser, L. Crippa, J. N. Neu, B. Geldiyev, P. Kagerer, J. Buck, M. Kalläne, M. Hoesch, K. Rossnagel, T. Siegrist, L.-K. Lim, R. Moessner, G. Sangiovanni, D. Di Sante, F. Reinert, H. Bentmann

Subjects: Strongly Correlated Electrons (cond-mat.str-el); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Optics (physics.optics)

We report the experimental discovery of orbital vortex lines in the three-dimensional (3D) band structure of a topological semimetal. Combining linear and circular dichroism in soft x-ray angle-resolved photoemission (SX-ARPES) with first-principles theory, we image the winding of atomic orbital angular momentum, thereby revealing - and determining the location of - lines of vorticity in full 3D momentum space. Our observation of momentum-space vortex lines with quantized winding number establishes an analogue to real-space quantum vortices, for instance, in type-II superconductors and certain non-collinear magnets. These results establish multimodal dichroism in SX-ARPES as an approach to trace 3D orbital textures. Our present findings particularly constitute the first imaging of non-trivial quantum-phase winding at line nodes and may pave the way to new orbitronic phenomena in quantum materials

[243] arXiv:2402.14475 (replaced) [pdf, html, other]

Title: DynGMA: a robust approach for learning stochastic differential equations from data

Aiqing Zhu, Qianxiao Li

Subjects: Machine Learning (cs.LG); Numerical Analysis (math.NA); Computational Physics (physics.comp-ph)

Learning unknown stochastic differential equations (SDEs) from observed data is a significant and challenging task with applications in various fields. Current approaches often use neural networks to represent drift and diffusion functions, and construct likelihood-based loss by approximating the transition density to train these networks. However, these methods often rely on one-step stochastic numerical schemes, necessitating data with sufficiently high time resolution. In this paper, we introduce novel approximations to the transition density of the parameterized SDE: a Gaussian density approximation inspired by the random perturbation theory of dynamical systems, and its extension, the dynamical Gaussian mixture approximation (DynGMA). Benefiting from the robust density approximation, our method exhibits superior accuracy compared to baseline methods in learning the fully unknown drift and diffusion functions and computing the invariant distribution from trajectory data. And it is capable of handling trajectory data with low time resolution and variable, even uncontrollable, time step sizes, such as data generated from Gillespie's stochastic simulations. We then conduct several experiments across various scenarios to verify the advantages and robustness of the proposed method.

[244] arXiv:2402.15921 (replaced) [pdf, html, other]

Title: Pretraining Strategy for Neural Potentials

Zehua Zhang, Zijie Li, Amir Barati Farimani

Subjects: Machine Learning (cs.LG); Chemical Physics (physics.chem-ph)

We propose a mask pretraining method for Graph Neural Networks (GNNs) to improve their performance on fitting potential energy surfaces, particularly in water systems. GNNs are pretrained by recovering spatial information related to masked-out atoms from molecules, then transferred and finetuned on atomic forcefields. Through such pretraining, GNNs learn meaningful prior about structural and underlying physical information of molecule systems that are useful for downstream tasks. From comprehensive experiments and ablation studies, we show that the proposed method improves the accuracy and convergence speed compared to GNNs trained from scratch or using other pretraining techniques such as denoising. On the other hand, our pretraining method is suitable for both energy-centric and force-centric GNNs. This approach showcases its potential to enhance the performance and data efficiency of GNNs in fitting molecular force fields.

[245] arXiv:2403.01716 (replaced) [pdf, html, other]

Title: Dynamics of a Generalized Dicke Model for Spin-1 Atoms

Ofri Adiv, Scott Parkins

Comments: 16 pages, 12 figures

Subjects: Quantum Physics (quant-ph); Quantum Gases (cond-mat.quant-gas); Atomic Physics (physics.atom-ph)

The Dicke model is a staple of theoretical cavity Quantum Electrodynamics (cavity QED), describing the interaction between an ensemble of atoms and a single radiation mode of an optical cavity. It has been studied both quantum mechanically and semiclassically for two-level atoms, and demonstrates a rich variety of dynamics such as phase transitions, phase multistability, and chaos. In this work we explore an open, spin-1 Dicke model with independent co- and counter-rotating coupling terms as well as a quadratic Zeeman shift enabling control over the atomic energy-level structure. We investigate the stability of operator and moment equations under two approximations and show the system undergoes phase transitions. To compliment these results, we relax the aforementioned approximations and investigate the system semiclassically. We show evidence of phase transitions to steady-state and oscillatory superradiance in this semiclassical model, as well as the emergence of chaotic dynamics. The varied and complex behaviours admitted by the model highlights the need to more rigorously map its dynamics.

[246] arXiv:2403.01922 (replaced) [pdf, html, other]

Title: FlowPrecision: Advancing FPGA-Based Real-Time Fluid Flow Estimation with Linear Quantization

Tianheng Ling, Julian Hoever, Chao Qian, Gregor Schiele

Comments: 6 pages, 3 figures, The 22nd International Conference on Pervasive Computing and Communications (PerCom 2024), PerConAI Workshop

Subjects: Machine Learning (cs.LG); Fluid Dynamics (physics.flu-dyn)

In industrial and environmental monitoring, achieving real-time and precise fluid flow measurement remains a critical challenge. This study applies linear quantization in FPGA-based soft sensors for fluid flow estimation, significantly enhancing Neural Network model precision by overcoming the limitations of traditional fixed-point quantization. Our approach achieves up to a 10.10% reduction in Mean Squared Error and a notable 9.39% improvement in inference speed through targeted hardware optimizations. Validated across multiple data sets, our findings demonstrate that the optimized FPGA-based quantized models can provide efficient, accurate real-time inference, offering a viable alternative to cloud-based processing in pervasive autonomous systems.

[247] arXiv:2403.14482 (replaced) [pdf, html, other]

Title: Assessing exchange-correlation functionals for heterogeneous catalysis of nitrogen species

Honghui Kim, Neung-Kyung Yu, Nianhan Tian, Andrew J. Medford

Comments: 44 pages, 20 figures. Figure 4 (MIL-125) data is changed. Relevant contents (texts, tables, figures, SI) are changed. VASP data is shared with accessible Zenodo link

Subjects: Materials Science (cond-mat.mtrl-sci); Chemical Physics (physics.chem-ph)

Increasing interest in sustainable synthesis of ammonia, nitrates, and urea has led to an increase in studies of catalytic conversion between nitrogen-containing compounds using heterogeneous catalysts. Density functional theory (DFT) is commonly employed to obtain molecular-scale insight into these reactions, but there have been relatively few assessments of the exchange-correlation functionals that are best suited for heterogeneous catalysis of nitrogen compounds. Here, we assess a range of functionals ranging from the generalized gradient approximation (GGA) to the random phase approximation (RPA) for the formation energies of gas-phase nitrogen species, the lattice constants of representative solids from several common classes of catalysts (metals, oxides, and metal-organic frameworks (MOFs)), and the adsorption energies of a range of nitrogen-containing intermediates on these materials. The results reveal that the choice of exchange-correlation functional and van der Waals correction can have a surprisingly large effect and that increasing the level of theory does not always improve the accuracy for nitrogen-containing compounds. This suggests that the selection of functionals should be carefully evaluated on the basis of the specific reaction and material being studied.

[248] arXiv:2403.14878 (replaced) [pdf, html, other]

Title: Offline tagging of radon-induced backgrounds in XENON1T and applicability to other liquid xenon detectors

E. Aprile, J. Aalbers, K. Abe, S. Ahmed Maouloud, L. Althueser, B. Andrieu, E. Angelino, J. R. Angevaare, D. Antón Martin, F. Arneodo, L. Baudis, A. L. Baxter, M. Bazyk, L. Bellagamba, R. Biondi, A. Bismark, E. J. Brookes, A. Brown, G. Bruno, R. Budnik, T. K. Bui, J. M. R. Cardoso, A. P. Cimental Chavez, A. P. Colijn, J. Conrad, J. J. Cuenca-García, V. D'Andrea, L. C.Daniel Garcia, M. P. Decowski, C. Di Donato, P. Di Gangi, S. Diglio, K. Eitel, A. Elykov, A. D. Ferella, C. Ferrari, H. Fischer, T. Flehmke, M. Flierman, W. Fulgione, C. Fuselli, P. Gaemers, R. Gaior, M. Galloway, F. Gao, S. Ghosh, R. Glade-Beucke, L. Grandi, J. Grigat, H. Guan, M. Guida, R. Hammann, A. Higuera, C. Hils, L. Hoetzsch, N. F. Hood, M. Iacovacci, Y. Itow, J. Jakob, F. Joerg, A. Joy, Y. Kaminaga, M. Kara, P. Kavrigin, S. Kazama, M. Kobayashi, A. Kopec, F. Kuger, H. Landsman, R. F. Lang, L. Levinson, I. Li, S. Li, S. Liang, Y. T. Lin, S. Lindemann, M. Lindner, K. Liu, J. Loizeau, F. Lombardi, J. Long, J. A. M. Lopes, T. Luce, Y. Ma, C. Macolino, J. Mahlstedt, A. Mancuso, L. Manenti, F. Marignetti, T. Marrodán Undagoitia, K. Martens, J. Masbou, E. Masson, S. Mastroianni, A. Melchiorre, M. Messina, A. Michael, K. Miuchi, A. Molinario, S. Moriyama

Comments: 17 pages, 19 figures

Subjects: High Energy Physics - Experiment (hep-ex); Instrumentation and Detectors (physics.ins-det)

This paper details the first application of a software tagging algorithm to reduce radon-induced backgrounds in liquid noble element time projection chambers, such as XENON1T and XENONnT. The convection velocity field in XENON1T was mapped out using $^{222}\text{Rn}$ and $^{218}\text{Po}$ events, and the root-mean-square convection speed was measured to be $0.30 \pm 0.01$ cm/s. Given this velocity field, $^{214}\text{Pb}$ background events can be tagged when they are followed by $^{214}\text{Bi}$ and $^{214}\text{Po}$ decays, or preceded by $^{218}\text{Po}$ decays. This was achieved by evolving a point cloud in the direction of a measured convection velocity field, and searching for $^{214}\text{Bi}$ and $^{214}\text{Po}$ decays or $^{218}\text{Po}$ decays within a volume defined by the point cloud. In XENON1T, this tagging system achieved a $^{214}\text{Pb}$ background reduction of $6.2^{+0.4}_{-0.9}\%$ with an exposure loss of $1.8\pm 0.2 \%$, despite the timescales of convection being smaller than the relevant decay times. We show that the performance can be improved in XENONnT, and that the performance of such a software-tagging approach can be expected to be further improved in a diffusion-limited scenario. Finally, a similar method might be useful to tag the cosmogenic $^{137}\text{Xe}$ background, which is relevant to the search for neutrinoless double-beta decay.

[249] arXiv:2404.08122 (replaced) [pdf, html, other]

Title: Cavity engineered phonon-mediated superconductivity in MgB$_2$ from first principles quantum electrodynamics

I-Te Lu, Dongbin Shin, Mark Kamper Svendsen, Hannes Hübener, Umberto De Giovannini, Simone Latini, Michael Ruggenthaler, Angel Rubio

Comments: 30 pages, 3 figures

Subjects: Superconductivity (cond-mat.supr-con); Materials Science (cond-mat.mtrl-sci); Applied Physics (physics.app-ph); Computational Physics (physics.comp-ph)

Strong laser pulses can control superconductivity, inducing non-equilibrium transient pairing by leveraging strong-light matter interaction. Here we demonstrate theoretically that equilibrium ground-state phonon-mediated superconductive pairing can be affected through the vacuum fluctuating electromagnetic field in a cavity. Using the recently developed ab initio quantum electrodynamical density-functional theory approximation, we specifically investigate the phonon-mediated superconductive behavior of MgB$_2$ under different cavity setups and find that in the strong light-matter coupling regime its superconducting transition temperature can be, in principles, enhanced by $\approx 73\%$ ($\approx 40\%$) in an in-plane (out-of-plane) polarized cavity. However, in a realistic cavity, we expect the T$_{\rm{c}}$ of MgB$_2$ can increase, at most, by $5$ K via photon vacuum fluctuations. The results highlight that strong light-matter coupling in extended systems can profoundly alter material properties in a non-perturbative way by modifying their electronic structure and phononic dispersion at the same time. Our findings indicate a pathway to the experimental realization of light-controlled superconductivity in solid-state materials at equilibrium via cavity-material engineering.

[250] arXiv:2404.19589 (replaced) [pdf, html, other]

Title: Acceptance Tests of more than 10 000 Photomultiplier Tubes for the multi-PMT Digital Optical Modules of the IceCube Upgrade

R. Abbasi, M. Ackermann, J. Adams, S. K. Agarwalla, J. A. Aguilar, M. Ahlers, J.M. Alameddine, N. M. Amin, K. Andeen, C. Argüelles, Y. Ashida, S. Athanasiadou, L. Ausborm, S. N. Axani, X. Bai, A. Balagopal V., M. Baricevic, S. W. Barwick, S. Bash, V. Basu, R. Bay, J. J. Beatty, J. Becker Tjus, J. Beise, C. Bellenghi, C. Benning, S. BenZvi, D. Berley, E. Bernardini, D. Z. Besson, E. Blaufuss, L. Bloom, S. Blot, F. Bontempo, J. Y. Book Motzkin, C. Boscolo Meneguolo, S. Böser, O. Botner, J. Böttcher, J. Braun, B. Brinson, J. Brostean-Kaiser, L. Brusa, R. T. Burley, D. Butterfield, M. A. Campana, I. Caracas, K. Carloni, J. Carpio, S. Chattopadhyay, N. Chau, Z. Chen, D. Chirkin, S. Choi, B. A. Clark, A. Coleman, G. H. Collin, A. Connolly, J. M. Conrad, P. Coppin, R. Corley, P. Correa, D. F. Cowen, P. Dave, C. De Clercq, J. J. DeLaunay, D. Delgado, S. Deng, A. Desai, P. Desiati, K. D. de Vries, G. de Wasseige, T. DeYoung, A. Diaz, J. C. Díaz-Vélez, P. Dierichs, M. Dittmer, A. Domi, L. Draper, H. Dujmovic, K. Dutta, M. A. DuVernois, T. Ehrhardt, L. Eidenschink, A. Eimer, P. Eller, E. Ellinger, S. El Mentawi, D. Elsässer, R. Engel, H. Erpenbeck, J. Evans, P. A. Evenson, K. L. Fan, K. Fang, K. Farrag, A. R. Fazely, A. Fedynitch, N. Feigl, S. Fiedlschuster

Comments: 24 pages, 19 figures, 2 tables, submitted to JINST

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Physics - Experiment (hep-ex); Instrumentation and Detectors (physics.ins-det)

More than 10,000 photomultiplier tubes (PMTs) with a diameter of 80 mm will be installed in multi-PMT Digital Optical Modules (mDOMs) of the IceCube Upgrade. These have been tested and pre-calibrated at two sites. A throughput of more than 1000 PMTs per week with both sites was achieved with a modular design of the testing facilities and highly automated testing procedures. The testing facilities can easily be adapted to other PMTs, such that they can, e.g., be re-used for testing the PMTs for IceCube-Gen2. Single photoelectron response, high voltage dependence, time resolution, prepulse, late pulse, afterpulse probabilities, and dark rates were measured for each PMT. We describe the design of the testing facilities, the testing procedures, and the results of the acceptance tests.

[251] arXiv:2405.06212 (replaced) [pdf, other]

Title: Realized Stable BP-N at Ambient Pressure by Phosphorus Doping

Guo Chen, Chengfeng Zhang, Yuanqin Zhu, Bingqing cao, Jie Zhang, Xianlong Wang

Comments: 27 pages, 6 figures

Subjects: Materials Science (cond-mat.mtrl-sci); Chemical Physics (physics.chem-ph)

Black phosphorus nitrogen (BP-N) is an attractive high-energy-density material. However, high-pressure synthesized BP-N will decompose at low-pressure and cannot be quenched to ambient conditions. Finding a method to stabilize it at 0 GPa is of great significance for its practical applications. However, unlike cg-N, LP-N, and HLP-N, it is always a metastable phase at high-pressure up to 260 GPa, and decomposes into chains at 23 GPa. Here, based on the first-principles simulations, we find that P atom doping can effectively reduce the synthesis pressure of BP-N and maintain its stability at 0 GPa. Uniform distribution of P atom dopants within the layer helps maintain the structural stability of BP-N layer at 0 GPa, while interlayer electrostatic interaction induced by N-P dipoles enhances its dynamic stability by eliminating interlayer slipping. Furthermore, pressure is conducive to enhancing the stability of BP-N and its doped forms by suppressing N-chain dissociation. For the configuration with 12.5% doping concentration, a gravimetric energy density of 8.07 kJ/g can be realized, which is nearly two times higher than TNT.

[252] arXiv:2405.08414 (replaced) [pdf, html, other]

Title: ICO learning as a measure of transient chaos in PT-symmetric Li\'enard systems

J. P. Deka, A. Govindarajan, A. K. Sarma

Comments: 9 pages, 12 figures

Subjects: Adaptation and Self-Organizing Systems (nlin.AO); Chaotic Dynamics (nlin.CD); Computational Physics (physics.comp-ph)

In this article, we investigate the implications of the unsupervised learning rule known as Input-Correlations (ICO) learning in the nonlinear dynamics of two linearly coupled PT-symmetric Liénard oscillators. The fixed points of the oscillator have been evaluated analytically and the Jacobian linearization is employed to study their stability. We find that on increasing the amplitude of the external periodic drive, the system exhibits period-doubling cascade to chaos within a specific parametric regime wherein we observe emergent chaotic dynamics. We further notice that the system indicates an intermittency route to chaos in the chaotic regime. Finally, in the period-4 regime of our bifurcation analysis, we predict the emergence of transient chaos which eventually settles down to a period-2 oscillator response which has been further validated by both the maximal Finite-Time Lyapunov Exponent (FTLE) using the well-known Gram-Schmidt orthogonalization technique and the Hilbert Transform of the time-series. In the transiently chaotic regime, we deploy the ICO learning to analyze the time-series from which we identify that when the chaotic evolution transforms into periodic dynamics, the synaptic weight associated with the time-series of the loss oscillator exhibits stationary temporal evolution. This signifies that in the periodic regime, there is no overlap between the filtered signals obtained from the time-series of the coupled PT-symmetric oscillators. In addition, the temporal evolution of the weight associated with the stimulus mimics the behaviour of the Hilbert transform of the time-series.

[253] arXiv:2405.15253 (replaced) [pdf, other]

Title: Seeing the World through an Antenna's Eye: Reception Quality Visualization Using Incomplete Technical Signal Information

Leif Bergerhoff

Comments: 5 pages, to be published in the conference proceedings of the European Signal Processing Conference (EUSIPCO) 2024, camera-ready version adding information on the space and time complexity, as well as the dataset size

Subjects: Computer Vision and Pattern Recognition (cs.CV); Numerical Analysis (math.NA); Data Analysis, Statistics and Probability (physics.data-an)

We come up with a novel application for image analysis methods in the context of direction dependent signal characteristics. For this purpose, we describe an inpainting approach adding benefit to technical signal information which are typically only used for monitoring and control purposes in ground station operations. Recalling the theoretical properties of the employed inpainting technique and appropriate modeling allow us to demonstrate the usefulness of our approach for satellite data reception quality assessment. In our application, we show the advantages of inpainting products over raw data as well as the rich potential of the visualization of technical signal information.

[254] arXiv:2405.18419 (replaced) [pdf, html, other]

Title: Exploring the Evolution of Altruistic Punishment with a PDE Model of Cultural Multilevel Selection

Daniel B. Cooney

Comments: 79 pages, 17 figures v2; Updated version of Section 5 with corrected versions of Figures 5.1 and 5.5, as well as new subsection and figure added to describe multilevel dynamics for Tullock contest function (Figure 5.5 in Section 5.3)

Subjects: Populations and Evolution (q-bio.PE); Physics and Society (physics.soc-ph)

Two mechanisms that have been used to study the evolution of cooperative behavior are altruistic punishment, in which cooperative individuals pay additional costs to punish defection, and multilevel selection, in which competition between groups can help to counteract individual-level incentives to cheat. Boyd, Gintis, Bowles, and Richerson have used simulation models of cultural evolution to suggest that altruistic punishment and pairwise group-level competition can work in concert to promote cooperation, even when neither mechanism can do so on its own. In this paper, we formulate a PDE model for multilevel selection motivated by the approach of Boyd and coauthors, modeling individual-level birth-death competition with a replicator equation based on individual payoffs and describing group-level competition with pairwise conflicts based on differences in the average payoffs of the competing groups. Building off of existing PDE models for multilevel selection with frequency-independent group-level competition, we use analytical and numerical techniques to understand how the forms of individual and average payoffs can impact the long-time ability to sustain altruistic punishment in group-structured populations. We find several interesting differences between the behavior of our new PDE model with pairwise group-level competition and existing multilevel PDE models, including the observation that our new model can feature a non-monotonic dependence of the long-time collective payoff on the strength of altruistic punishment. Going forward, our PDE framework can serve as a way to connect and compare disparate approaches for understanding multilevel selection across the literature in evolutionary biology and anthropology.

[255] arXiv:2406.09849 (replaced) [pdf, html, other]

Title: Steady Contiguous Vortex-Patch Dipole Solutions of the 2D Incompressible Euler Equation

De Huang, Jiajun Tong

Comments: 41 pages, 6 figures

Subjects: Analysis of PDEs (math.AP); Fluid Dynamics (physics.flu-dyn)

We rigorously construct the first steady traveling wave solutions of the 2D incompressible Euler equation that take the form of a contiguous vortex-patch dipole, which can be viewed as the vortex-patch counterpart of the well-known Lamb-Chaplygin dipole. Our construction is based on a novel fixed-point approach that determines the patch boundary as the fixed point of a certain nonlinear map. Smoothness and other properties of the patch boundary are also obtained.

[256] arXiv:2406.10184 (replaced) [pdf, html, other]

Title: Hyperbolic embedding of brain networks as a tool for epileptic seizures forecasting

Martin Guillemaud, Louis Cousyn, Vincent Navarro, Mario Chavez

Subjects: Neurons and Cognition (q-bio.NC); Data Analysis, Statistics and Probability (physics.data-an)

The evidence indicates that intracranial EEG connectivity, as estimated from daily resting state recordings from epileptic patients, may be capable of identifying preictal states. In this study, we employed hyperbolic embedding of brain networks to capture non-trivial patterns that discriminate between connectivity networks from days with (preictal) and without (interictal) seizure. A statistical model was constructed by combining hyperbolic geometry and machine learning tools, which allowed for the estimation of the probability of an upcoming seizure. The results demonstrated that representing brain networks in a hyperbolic space enabled an accurate discrimination (85%) between interictal (no-seizure) and preictal (seizure within the next 24 hours) states. The proposed method also demonstrated excellent prediction performances, with an overall accuracy of 87% and an F1-score of 89% (mean Brier score and Brier skill score of 0.12 and 0.37, respectively). In conclusion, our findings indicate that representations of brain connectivity in a latent geometry space can reveal a daily and reliable signature of the upcoming seizure(s), thus providing a promising biomarker for seizure forecasting.