Physics and Society · Cross-listed from cs.SI
The Power of Network Pluralism: Multi-Perspective Modeling of Heterogeneous Legal Document Networks
Titus Pünder and Corinna Coupette
Insights are relative - influenced by a range of factors such as assumptions, scopes, or methods that together define a research perspective. In normative and empirical fields alike, this insight has led to the conclusion that no single perspective can generate complete knowledge. As a response, epistemological pluralism mandates that researchers consider multiple perspectives simultaneously to obtain a holistic understanding of their phenomenon under study. Translating this mandate to network science, our work introduces Network Pluralism as a conceptual framework that leverages multi-perspectivity to yield more complete, meaningful, and robust results. We develop and demonstrate the benefits of this approach via a hands-on analysis of complex legal systems, constructing a network space from references across documents from different branches of government as well as including organizational hierarchy above and fine-grained structure below the document level. Leveraging the resulting heterogeneity in a multi-network analysis, we show how complementing perspectives can help contextualize otherwise high-level findings, how contrasting several networks derived from the same data enables researchers to learn by difference, and how relating metrics to perspectives may increase the transparency and robustness of network-analytical results. To analyze a space of networks as perspectives, researchers need to map dimensions of variation in a given domain to network-modeling decisions and network-metric parameters. While this remains a challenging and inherently interdisciplinary task, our work acts as a blueprint to facilitate the broader adoption of Network Pluralism in domain-driven network research.
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Plasma Physics
Fast electrostatic microinstability evaluation in arbitrary toroidal magnetic geometry using a variational approach
M.C.L. Morren, P. Mulholland, J.H.E. Proll et al. (+5 more)
Small-scale
turbulence originating from microinstabilities limits the energy confinement time in
magnetic confinement fusion. Here we develop a semi-analytical dispersion relation based on lowest-order solutions to the gyrokinetic equations in an asymptotic expansion in the ratio of transit (bounce) frequency to the mode frequency for ions (electrons), capable of describing two common instabilities: the ion temperature gradient (ITG) mode and trapped-electron mode (TEM), in the electrostatic limit. The dispersion relation, which is valid in arbitrary toroidal geometry, takes into account resonances with the
magnetic ion and bounce-averaged electron drifts, incorporates non-local effects along the
magnetic field line, is valid for arbitrary sign of the growth rate and
magnetic curvature, and is shown to satisfy a variational property. Several common approximation models are introduced for both the
magnetic drift and finite Larmor radius (FLR) damping, with the Padé approximation for FLR effect in particular resulting in remarkable agreement with the baseline dispersion relation model at significantly reduced costs. The baseline model is verified by comparing solutions of the dispersion relation model to high-fidelity linear gyrokinetic simulations, where the exact eigenfunction of the electrostatic potential from simulations is used as a trial function, showing good quantitative agreement for ITGs and TEMs in (shaped) tokamaks as well as low-
magnetic-shear stellarators.
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All authors M.C.L. Morren, P. Mulholland, J.H.E. Proll, M.J. Pueschel, L. Podavini, D.D. Kiszkiel, J.A. Schuurmans, A. Zocco
Geophysics
EA-ERT: a new ensemble approach to convert time-lapse ERT data to soil water content
B. Loiseau, S.D. Carrière, N.K. Martin-StPaul et al. (+8 more)
Electrical Resistivity
Tomography (ERT) is increasingly used to study subsurface hydrological processes. It shows promising potential for estimating soil water content, a key but challenging property to quantify. However, converting the resistivity signal into water content is complex. This encourages developing approaches to increase the robustness of estimates while facilitating the evaluation of uncertainties. In this paper, we propose an innovative method, called the Ensemble Approach ERT (EA-ERT), to build an ensemble model of electrical resistivity calibrated from field data and then to convert it into a spatial distribution of water content. This approach combines time-lapse ERT data with point-based in-situ soil water content measurements. It enables i) circumventing inversion parameter choice by evaluating the performance of a large number of models, ii) estimating uncertainty in the final model by calculating the coefficient of variation among the models composing the ensemble, and iii) converting electrical resistivity models to water content. The method was tested at two dissimilar field sites in southern France. For each site, an ensemble model, built from multiple inversions, was selected and converted into soil water content. The calculated values showed a good fit, with small differences compared to in-situ measurements. Areas of high uncertainty were identified, providing complementary information to the more classical indicators from the inversion code. EA-ERT provides a robust and automatable method to convert ERT data to related parameters, contributing to improved monitoring and understanding processes in the subsurface.
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All authors B. Loiseau, S.D. Carrière, N.K. Martin-StPaul, R. Clément, C. Champollion, V. Mercier, J. Thiesson, S. Pasquet, C. Doussan, T. Hermans, D. Jougnot
Biological Physics
A Frenet frame analysis of protein geometry: hints for secondary structure assignments
M. Prados, M.D. Hernández de la Torre and F. de Soto
This paper deepens into the analysis of the
protein secondary structure using Frenet frame to describe the
curvature and torsion of the discrete curve formed by the
protein $\alpha$-carbons. We show how a simple criterion based on the evaluation of the
curvature and torsion of the discrete curve can be useful to pinpoint the presence of some secondary and supersecondary structures in
proteins. Moreover, the description of
proteins as fixed points of an effective action inspired by an $U(1)$ gauge model is strongly supported by the
curvature and torsion observed over a large
dataset of
proteins in the
Protein Data Bank.
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Fluid Dynamics
Uncertainty Growth in Stably Stratified Turbulence
Mrinal Jyoti Powdel and Samriddhi Sankar Ray
We investigate uncertainty growth and chaotic dynamics in statistically steady, stably stratified three-dimensional
turbulence. Using direct numerical simulations of the Boussinesq equations, we quantify the divergence of initially infinitesimal perturbations via twin simulations and decorrelator diagnostics. At short times, perturbations exhibit exponential growth, allowing us to define a (largest) Lyapunov exponent. We systematically examine how this exponent depends on stratification strength, quantified by the Brunt–Väisälä frequency and the Froude number, in a parameter regime relevant to oceanic flows. We find that increasing stratification leads to a monotonic reduction of the Lyapunov exponent, indicating suppressed chaoticity. Despite this reduction, uncertainty growth retains the universal temporal sequence observed in homogeneous isotropic
turbulence – initial decay, exponential growth, and saturation. The growth phase is characterized by self-similar decorrelator spectra, but exhibits strong anisotropy: uncertainty spreads much more slowly along the stratification direction than horizontally, with the disparity increasing with stratification strength. An analysis of the decorrelator
evolution equation reveals that the suppression of chaos arises primarily from strain-mediated
alignment dynamics rather than direct buoyancy coupling. Our results provide a quantitative characterization of predictability and uncertainty growth in stratified
turbulence and highlight the utility of decorrelator-based methods for anisotropic geophysical flows.
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Chemical Physics
Characteristics of mono-, di-, and trivalent cations in electric double layers: a molecular dynamic investigation
Bowen Ai, Zekun Gong, Long Ma et al. (+3 more)
Ionic behaviors, including ion distributions and hydration characteristics at solid-
liquid interfaces, are important research interests in many important applications, such as electric double-layer capacitors and water lubrication. Here, we systematically investigated the concentration distributions, hydration numbers, and screening properties of Li+, Na+, K+, Ca2+, Mg2+, and La3+ ions inside electric double layers (EDLs) at various charge densities. For the surface charge density weaker than -0.16 C m-2, monovalent cations mainly accumulate in the outer Helmholtz plane (OHP). As the charge density magnitude increases, monovalent cations start to dehydrate and migrate to the inner Helmholtz plane (IHP), following the order of K+, Na+, and Li+. This size-dependent behavior arises from the lower hydration energy of larger ions. While for the di- and trivalent ions, no obvious IHP appears. Based on ion distributions, the screening effect of counterions on surface charges is evaluated by analyzing the net charge distributions. As the charge density changes from 0 to -0.32 C m-2, due to the stronger accumulation of cations in EDLs, the location of the neutral plane changes from ~1.2 to ~0.4 nm. When the charge density reaches a threshold, excessive accumulation of cations can induce charge inversion. The threshold value and the maximum reversed charge are found to correlate with the ion size, cation valence, and concentration.
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All authors Bowen Ai, Zekun Gong, Long Ma, Hongwen Zhang, Tianyi Sui, Yinghua Qiu
Chemical Physics
Modulation of Electroosmotic Flow through Short Nanopores by Charged Exterior Surfaces
Chao Zhang, Xiaomei Zhang, Hongwen Zhang et al. (+4 more)
Electroosmotic flow (EOF) through nanoporous membranes has broad applications in micro- and nanofluidic systems, particularly in biomedical diagnostics and chemical analysis. The use of short nanopores enables high fluid flux, and the presence of exterior surface charges can further enhance ion flux through short nanopores. Here, systematic simulations are conducted to explore the modulation of EOF by exterior surface charges. Our results indicate that charged exterior surfaces can provide an additional effective pathway for fluid flow, significantly increasing both the EOF velocity and output pressure. By analyzing the dependence of EOF velocity on the area of the charged exterior surface, we derive the effective width (Lcs_eff) of the charged ring region extending beyond the pore boundary. This parameter is quantitatively examined under various nanopore configurations and applied conditions. Lcs_eff is found to be proportional to the pore diameter, surface charge density, and applied voltage, while inversely proportional to pore length and salt concentration. These findings provide valuable insights into the modulation of EOF by exterior surface charges and offer theoretical guidance for optimizing the structural and functional properties of nanoporous membranes in practical applications of EOF.
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All authors Chao Zhang, Xiaomei Zhang, Hongwen Zhang, Zekun Gong, Xiuhua Ren, Mengnan Guo, Yinghua Qiu
Chemical Physics · Cross-listed from cond-mat.stat-mech
The geometric control of boundary-catalytic branching processes
Denis S. Grebenkov and Yilin Ye
Boundary-catalytic branching processes describe a broad class of natural phenomena where the population of diffusing particles grows due to their spontaneous binary branching (e.g., division, fission or splitting) on a catalytic boundary located in a complex environment. We investigate the possibility of the
geometric control of the population growth by compensating the proliferation of particles due to catalytic branching events by their absorptions in the bulk or on absorbing regions of the boundary. We identify an appropriate Steklov spectral problem to obtain the phase diagram of this out-of-
equilibrium stochastic process. The principal
eigenvalue determines the critical line that separates an exponential growth of the population from its extinction in a bounded domain. In other words, we establish a powerful tool for calculating the growth-regulating absorption rate that equilibrates the opposite effects of branching and absorption events and thus results in steady-state behavior of this
diffusion-reaction system. Moreover, we show the existence of a critical catalytic rate above which no compensation is possible, so that the population cannot be controlled and keeps growing exponentially. The proposed framework opens promising perspectives for better understanding, modeling and control of various boundary-catalytic branching processes, with applications in physics, chemistry, and life sciences.
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Optics
Irene La Penna, Tecla Gabbrielli, Borislav Hinkov et al. (+8 more)
Noise characteristics of state-of-the art light sources are crucial parameters in understanding their limitations towards
quantum applications. This work describes a method to study the electrical noise transfer of current driver sources to the intensity noise of mid-infrared emission by commercial
quantum and interband cascade
lasers (QCLs and ICLs, respectively). A current driver with sub-shot electrical noise in a specific frequency range (up to 10 dB below the shot noise level) was developed for this purpose. This enables testing the performance of mid-infrared
lasers when driven via such a quiet pump source. By using this novel current driver, we identify the fundamental noise of a QCL and an ICL, that is the
laser intensity noise resulting solely from the internal dynamics of the
laser under test. The proposed methodology allows us to retrieve the noise transfer function from current to light, showing that the main limitations in observing the
quantum properties of the emitted
photons come from
laser excess noise and poor matching between
laser and detection system in terms of bandwidth and optical power. From the analysis of the measured parameters, we highlight current technological limitations and suggest which key features should be optimized in mid-infrared systems for matching the performance required by
quantum applications.
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All authors Irene La Penna, Tecla Gabbrielli, Borislav Hinkov, Robert Weih, Naota Akikusa, Lorenzo Mischi, Alessio Montori, Simone Borri, Luigi Consolino, Francesco Cappelli, Paolo De Natale
Chemical Physics
Modulation of Ionic Current Rectification in Short Unipolar Nanopores
Hongwen Zhang, Long Ma, Di Liu et al. (+3 more)
With controlled ionic current rectification (ICR) achieved through a strategically designed non-uniform surface charge distribution, short unipolar nanopores exhibit promising applications in nanofluidic sensors, ionic
circuits, and ion amplifiers. By systematically investigating how the charged length on inner pore walls modulates ion transport, we found that both the maximum ICR degree and the corresponding charged-length proportion were influenced by nanopore parameters and simulation conditions. For 100 nm-long unipolar nanopores, the highest ICR degree is obtained at a charged-length proportion of ~0.3, due to the corresponding most significant ion enrichment and depletion inside the nanopore under opposite biases. This charged-length proportion of ~0.3 consistently appears as a characteristic value across most considered cases. For short unipolar nanopores, the presence of exterior surface charges significantly enhances the ICR degree by facilitating ion transport through nanopores. The effective widths of charged regions beyond nanopore borders on outer surfaces exhibit direct proportionality to the pore diameter, surface charge density, and applied voltage, and inverse proportionality to the pore length and salt concentration. Our research may provide useful guidance for the design of unipolar nanopores and porous membranes incorporating such charge configurations.
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All authors Hongwen Zhang, Long Ma, Di Liu, Tianyi Sui, Zuzanna S. Siwy, Yinghua Qiu
Atomic Physics · Cross-listed from quant-ph
Squeezing Classical Antiferromagnets into Quantum Spin Liquids via Global Cavity Fluctuations
Charlie-Ray Mann, Mark A. Oehlgrien, Błażej Jaworowski et al. (+4 more)
Cavity
quantum electrodynamics with atomic ensembles is typically associated with collective
spin phenomena, such as superradiance and
spin squeezing, in which the atoms evolve collectively as a macroscopic
spin ($S\sim N/2$) on the Bloch sphere. Surprisingly, we show that the tendency toward a collective
spin description need not imply collective
spin phenomena; rather, it can be exploited to generate new forms of strongly correlated
quantum matter. The key idea is to use uniform cavity-mediated interactions to energetically project the system into the total-
spin singlet sector ($S=0$) - a highly entangled subspace where the physics is governed entirely by cavity fluctuations. Focusing on Rydberg atom arrays coupled to a single-mode cavity, we show that global cavity fluctuations can effectively squeeze classical antiferromagnets into
quantum spin liquids, characterized by non-local
entanglement, fractionalized excitations, and emergent gauge fields. This work suggests that cavity QED can be a surprising resource for inducing strongly correlated phenomena, which could be explored in the new generation of hybrid tweezer-cavity platforms.
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All authors Charlie-Ray Mann, Mark A. Oehlgrien, Błażej Jaworowski, Giuseppe Calajó, Jamir Marino, Kyung S. Choi, Darrick E. Chang
Medical Physics
Fate of gadolinium in inflamed mouse brain: Release and phosphate interaction post-contrast agent administration
Lina Anderhalten, Nicole Höfer, Daria Dymnikova et al. (+6 more)
Mounting evidence for markedly increased cerebellar Gd retention under neuroinflammatory conditions after repeated linear gadolinium-based contrast
agents (GBCA) administration in vivo, makes necessary a discrimination between Gd retained within the GBCA complex and forms dissociated form the complex and to characterize the chemical environment of the released Gd$^{3+}$. We employed electron paramagnetic resonance (EPR) and electron
nuclear double resonance (ENDOR) spectroscopy, which enable direct detection of Gd$^{3+}$ release and evaluation of its molecular surroundings in intact cerebellar tissue from inflamed and non-inflamed
brain sections exposed to either linear or macrocyclic GBCAs. The experiments were performed on sub-mm
brain samples taken after administration of linear gadopentetate and macrocyclic gadobutrol in vivo in a murine multiple sclerosis model and ex vivo in organotypic hippocampal slice cultures under inflammatory conditions. EPR detected {\mu}M range Gd levels in intact cerebellar biopsies and slices and distinguished between complex-bound and released Gd following linear GBCA administration in vivo. In biopsies, we detected by ENDOR phosphorus-containing molecules in the microenvironment of released Gd. Complementary mass spectrometry (MS) and MRI calibration experiments on Gd-spiked homogenized mouse
brain tissue were used to assess the relaxation-active fraction of retained Gd evidencing binding to inorganic ligands. Our findings demonstrate inflammation-promoted Gd retention, underscore the importance of integrating in vivo and ex vivo analyses to unravel mechanisms of long-term Gd retention, and suggest that conventional MRI may underestimate the true extent of Gd accumulation, especially under neuroinflammatory conditions.
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All authors Lina Anderhalten, Nicole Höfer, Daria Dymnikova, Julia Hahndorf, Matthias Taupitz, Heike Traub, Christian Teutloff, Carmen Infante-Duarte, Robert Bittl
Applied Physics · Cross-listed from cond-mat.mtrl-sci
Prussian Blue and Prussian Blue Analogs as Emerging Memristive Materials
L.B. Avila
Prussian blue analogues (PBAs) and related organic materials are promising platforms for next-generation
memory and energy-storage technologies due to their redox activity, ionic mobility, and compatibility with low-cost and scalable fabrication. Electrodeposited Prussian Blue (PB) and Prussian White (PW) thin films show robust resistive switching with ON/OFF ratios from one to three orders of magnitude in both bipolar and unipolar modes. Structural and spectroscopic analyses reveal homogeneous films with well-defined grain boundaries and ionic pathways that enable filamentary conduction. Current-voltage measurements, impedance spectroscopy, and
quantum transport modeling indicate switching mechanisms governed by ohmic or space-charge-limited conduction, driven by potassium-ion migration and reversible redox processes. PB-based devices also exhibit conductance quantization with discrete steps at integer and half-integer multiples of G0, consistent with ballistic electron transport through atomic-scale channels. Complementary studies on perylene-based
liquid crystals and FeHCF on
graphene oxide highlight the versatility of PBAs for
memory and supercapacitor applications. Together, these results demonstrate the multifunctionality and scalability of PBAs for future ReRAM, neuromorphic computing, multilevel
memory, cryptographic hardware, and high-performance energy-storage devices.
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Fluid Dynamics
Development of Rheological Constitutive Modeling Method Using a Sparse Identification Algorithm: A Case Study for Extensional Flows
Takeshi Sato, Souta Miyamoto and Shota Kato
Deriving constitutive models (CMs) from numerical data has been an attractive approach as a systematic CM building method. One recent study is Rheo-SINDy, which extended the sparse identification of nonlinear dynamics (SINDy) method to rheology. Although the Rheo-SINDy framework discovered an approximate CM from numerical data under shear flow, its versatility has not been investigated. To clarify its applicability to other types of flows, this study applied Rheo-SINDy to numerically generated data under extensional flow conditions. As baseline tests for extensional flow, we considered two problems: (i) whether the Rheo-SINDy framework can reproduce the famous Giesekus model from data generated by that model, and (ii) whether it can derive an approximate CM from data generated by a dumbbell model with a finite extensible nonlinear elastic (FENE) spring. For problem (i), we confirmed that Rheo-SINDy can identify the exact expression of the Giesekus model under extensional flow. For problem (ii), the Rheo-SINDy framework discovered a relatively simple expression of the approximate CM by manually designing the library
matrix based on rheological knowledge. The identified approximate CM can reasonably predict extensional rheological properties of the FENE dumbbell model, including an extrapolation region. These findings demonstrate the fundamental validity of using Rheo-SINDy under extensional flow.
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Classical Physics
Thermal performance and environmental impact of a wood frame wall enhanced with clay-based plaster: an experimental and simulation analysis
Z Boutayeb, M Labat, C Oms et al. (+1 more)
This study evaluates the thermal performance and environmental impact of wooden frame walls with clay-based plaster by using the complementary properties of both materials. Clay's moderate density and high thermal capacity enhance the thermal behaviour of wood structures, making it a valuable addition to lightweight constructions. At the material scale, the thermal properties of clay-based plaster were experimentally characterized and integrated into thermal dynamic simulations to assess the influence of internal and external wall configurations on the indoor temperature in the framework of overheating in summer. A life cycle assessment was conducted to compare the environmental impact of three walls: one made of concrete, a wooden frame wall, and another using wood frame wall with clay-based plaster.
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All authors Z Boutayeb, M Labat, C Oms, S Ginestet
Instrumentation and Detectors
Design and Performance of a 96-channel Resistive PICOSEC Micromegas Detector for ENUBET
A. Kallitsopoulou, S.Aune, Y.Angelis et al. (+54 more)
The PICOSEC-Micromegas (PICOSEC-MM) detector is a fast gaseous detector that achieves picosecond-level timing by coupling a Cherenkov radiator, typically an MgF2
crystal, to a Micromegas-based photodetector with a photocathode. This configuration allows the fast photoelectron-induced signal to suppress the intrinsic time jitter of gaseous detectors, enabling sub-20 ps timing precision while preserving the robustness and scalability of micro-pattern gaseous detector technologies. The 96-pad PICOSEC-MM detector is a large-area demonstrator optimized for precision timing in high-energy physics, building on research and development insights from earlier 7-pad resistive prototypes to validate scalability, uniformity, and robustness for the ENUBET project. It employs a 2.5 nm diamond-like carbon photocathode and a Micromegas board with a surface resistivity of 10 megaohms per square, and was characterized using 150 GeV/c
muons at the CERN SPS beamline, with one-third of the active area instrumented per run. A dedicated
alignment procedure for multi-pad PICOSEC-MM systems was used to reconstruct pad centers and merge measurements across regions, yielding a timing resolution of 43 ps and uniform signal arrival time distributions over the tested area. Mechanical flatness was identified as a key factor, with planarity tolerances within 10 micrometers required to maintain good timing resolution, and the successful operation of the 96-pad demonstrator confirms the scalability of the PICOSEC-MM concept toward robust, high-granularity, picosecond-level gaseous timing detectors for monitored
neutrino beam experiments such as ENUBET.
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All authors A. Kallitsopoulou, S.Aune, Y.Angelis, R. Aleksan, A. Bonenfant, J. Bortfeldt, F. Brunbauer, M. Brunoldi, J. Datta, D. Desforge, G. Fanourakis, D. Fiorina, K. J. Floethner, M. Gallinaro, F. Garcia, I. Giomataris, K. Gnanvo, F.J. Iguaz, D. Janssens, F. Jeanneau, M.Kebbiri, M. Kovacic, B. Kross, P. Legou, M. Lisowska, J. Liu, C.Loiseau, M. Lupberger, I. Maniatis, J. McKisson, B.Moreno, Y. Meng, H. Muller, E. Oliveri, G. Orlandini, A. Pandey, T. Papaevangelou, M. Pomorski, E.F.Ribas, L. Ropelewski, D. Sampsonidis, L. Scharenberg, T. Schneider, E. Scorsone, L. Sohl, M. van Stenis, Y. Tsipolitis, S.E. Tzamarias, A. Utrobicic, I. Vai, R. Veenhof, P. Vitulo, X. Wang, S. White, W. Xi, Z. Zhang, Y. Zhou
Optics · Cross-listed from cond-mat.other
Plasmascopy of ultrafast hot charge carriers
Dmitry A. Zimin, Raja Sen, Muhammad Qasim et al. (+2 more)
We demonstrate an electric-field-resolved approach for probing ultrafast dynamics of photoinjected charge carriers in solids. Direct access to the electric field of few cycle pulses enables us to measure a broadband response of a medium with associated
plasma frequency. We prepare an ensemble of hot charge carriers with energies sufficient to trigger impact ionization and establish a framework to measure its dynamics. Our time-resolved study reveals the short-lived ultrafast dynamics consistent with impact ionization and carrier trapping. This approach provides a promising route for studying ultrafast many-body physics in photoexcited solids, with predictions from advanced theoretical models.
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All authors Dmitry A. Zimin, Raja Sen, Muhammad Qasim, Jelena Sjakste, Vladislav S. Yakovlev
Classical Physics
Homogenization of architected materials incorporating shearable beams
Matteo Franzoi, Davide Bigoni and Andrea Piccolroaz
Two-dimensional architected materials are often realized as periodic grids of elastic beams. Conventional homogenization methods represent these structures as equivalent elastic solids but neglect shear deformation in the constituent beams. This article addresses this limitation by incorporating shear deformability through Timoshenko beam theory, enabling accurate modeling of stubby beams. Moreover, shearable beams with extreme mechanical characteristics can be obtained through the design of appropriate microstructures. Introducing shearable beams into the grid expands the design space, allowing, for instance, the control of the effective Poisson's ratio beyond the limits achievable with slender beams.
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Optics
Metasurface-based all-optical diffractive convolutional neural networks
Zhijiang Liang, Chenxuan Xiang, Shuyuan Xiao et al. (+5 more)
The escalating energy demands and parallel-processing bottlenecks of electronic neural networks underscore the need for alternative computing paradigms. Optical neural networks, capitalizing on the inherent parallelism and speed of light propagation, present a compelling solution. Nevertheless, physically realizing convolutional neural network (CNN) components all-optically remains a significant challenge. To this end, we propose a metasurface-based all-optical diffractive convolutional neural network (MAODCNN) for computer
vision tasks. This architecture synergistically integrates metasurface-based optical convolutional layers, which perform parallel convolution on the optical field, with cascaded diffractive neural networks acting as all-optical decoders. This co-design facilitates layer-wise feature extraction and optimization directly within the optical domain. Numerical simulations confirm that the fusion of convolutional and diffractive layers markedly enhances classification accuracy, a performance that scales with the number of diffractive layers. The MAODCNN framework establishes a viable foundation for practical all-optical CNNs, paving the way for high-efficiency, low-power optical computing in advanced pattern recognition.
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All authors Zhijiang Liang, Chenxuan Xiang, Shuyuan Xiao, Jumin Qiu, Jie Li, Qiegen Liu, Chengjun Zou, Tingting Liu
Biological Physics
Towards an active matter theory of plant morphogenesis
Hadrien Oliveri, Christophe Godin and Ibrahim Cheddadi
Plant morphogenesis relies on dynamic growth deformations at the
cell and tissue scales driven by osmotic fluxes. A mechanistic understanding of this phenomenon demands a physical framework that integrates
cell imbibition, tissue mechanics, and water fluxes, as well as their biophysical and molecular regulations, within a theory of plant active matter capturing the open-system and out-of-
equilibrium properties of tissues. Building on historical insights into growth geometry, physics, and mechanics, combined with recent experimental results, we outline the key challenges in modelling plant growth and propose steps towards a unified physical theory of plant morphogenesis, in which biological regulation, mechanical forces, and water fluxes interact to shape biological form through the fundamental principles of living matter.
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Optics
How to measure laser chirp rate at single-emitter excitation energies
Timothée Mounier, Moritz Kaiser, Mert Tuncel et al. (+8 more)
We present a simple and direct method for measuring
laser chirp rate, i.e., group delay dispersion (GDD) of ultrashort
laser pulses at power levels compatible with single-
quantum-emitter excitation. Traditional pulse characterization techniques rely on nonlinear optical processes that require high peak powers, making them unsuitable for the attojoule-to-femtojoule regime relevant to
quantum photonics. Our approach utilizes a wavelength-to-time mapping method in which the arrival times of spectrally filtered components of a broadband pulse are recorded using a superconducting nanowire single-
photon detector and correlated via a high-resolution time-tagging system. The resulting linear relationship between wavelength and arrival time directly yields the dispersion parameter and, subsequently, the GDD. Beyond single-emitter excitation, this technique can be applied in areas such as single-
photon spectroscopy, ultralow-power optical communications, and time-domain
quantum control, where linear and non-destructive dispersion characterization is essential.
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All authors Timothée Mounier, Moritz Kaiser, Mert Tuncel, Iker Avila Arenas, René Schwarz, Ria G. Krämer, Stefan Nolte, Florian Kappe, Yusuf Karli, Gregor Weihs, Vikas Remesh
Instrumentation and Detectors
CryoDE: a Digital Cryogenic Detector Emulator for Microwave SQUID Multiplexed Systems
Timo Muscheid, Daniel Crovo, Robert Gartmann et al. (+4 more)
Simultaneous readout of large-scale cryogenic detector arrays relies on multiplexing schemes such as the FDM (Frequency-Division Multiplexing) with microwave SQUID multiplexers and highly customized readout electronics. In traditional detector systems, where mixed-signal ASICs are used in detector front-ends and typically provide a digital interface, HIL (Hardware-in-the-Loop) testing can be readily implemented by reusing the existing digital logic of the front-end for emulation purposes. Such straightforward emulation is not possible for FDM low-temperature detectors, where the sensor signal is encoded in a high-frequency microwave carrier via a two-stage modulation scheme depending on the cryogenic resonators and the SQUID response. To address this challenge, we present CryoDE, a digital cryogenic-detector emulator for microwave SQUID multiplexed detector systems. CryoDE generates the encoded detector signals, including realistic pulse responses, enabling full HIL testing of the room-temperature DAQ system without requiring the cryogenic hardware. This resource-efficient FPGA-based detector twin integrates seamlessly into existing DAQ systems and allows experiment-specific adjustment of detector-signal parameters. We describe the internal architecture and capabilities of CryoDE within our custom HIL framework and demonstrate its use in evaluating the performance of real-time signal processing firmware optimized for different microwave SQUID multiplexed cryogenic-detector experiments.
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All authors Timo Muscheid, Daniel Crovo, Robert Gartmann, Eduardo Gerlein, Oliver Sander, Sebastian Kempf, Luis E. Ardila-Perez
Optics · Cross-listed from cond-mat.soft
Electrically Tunable Heliconical Smectic Superstructure in Polar Fluids
Hiroya Nishikawa, Dennis Kwaria, Atsuko Nihonyanagi et al. (+3 more)
The ferroelectric nematic (NF) phase and related polar
liquid-crystalline phases form a new class of strongly polarized yet fluid soft matter. Well-recognized heliconical ferroelectric phases such as NTBF and SmC_P^H exist, but their electro-optic functionality in smectic systems has been largely unexplored. Here, we report a newly designed single-component achiral molecule exhibiting a hierarchical polar phase sequence: SmAF-NTBF-HEC-SmC_P^H. The key feature of the SmC_P^H phase is its ability to form a stable macroscopic orientation without any
alignment layers and to enable continuous, reversible pitch modulation over a wide spectral range at ultralow electric fields, approximately one-third of those required for conventional heliconical nematics. The system exhibits characteristic electro-optic properties in the sub-kilohertz range, differentiating it from heliconical materials controlled by dielectric-elastic balance at higher frequencies. In addition, the SmC_P^H phase's polar heliconical smectic structure facilitates enhanced second-harmonic generation via favorable phase matching, thereby establishing a simple and robust platform for low-voltage photonic applications.
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All authors Hiroya Nishikawa, Dennis Kwaria, Atsuko Nihonyanagi, Koki Sano, Hiroyuki Yoshida, Fumito Araoka
Optics
Hertz-Integral-Linewidth Lasers based on Portable Solid-state Microresonators
Xing Jin, Xuanyi Zhang, Fangxing Zhang et al. (+3 more)
Optical reference resonators serve as a cornerstone in various scientific fields. In recent years, there has been an increasing demand for compact ultrastable reference resonators capable of operating in ambient environments, enabling applications beyond the laboratory, such as
navigation, portable optical clocks, and remote sensing. Here, we present a compact ultrastable whispering-gallery-mode \ce{MgF2} reference resonator with a high loaded quality factor of $2.24\times 10^9$. The device is packaged in a compact form of 50$\times$77$\times$90 mm and supports stable optical coupling with polarization-maintaining fiber, which enables robust operation under ambient conditions.
Laser stabilization using this resonator yields a phase noise of -105 dBc/Hz at a 10 kHz offset frequency, an integral linewidth of 4 Hz, and a fractional frequency stability of $2.5\times 10^{-14}$ at a 10 ms averaging time. With the high performance and rapid manufacturability, our work offers a promising solution for ultrastable optical frequency references beyond laboratory settings.
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All authors Xing Jin, Xuanyi Zhang, Fangxing Zhang, Zhenyu Xie, Shui-Jing Tang, Qi-Fan Yang
Computational Physics
Beyond Adam: Disentangling Optimizer Effects in the Fine-Tuning of Atomistic Foundation Models
Xiaoqing Liu, Yangshuai Wang and Teng Zhao
Atomistic foundation models constitute a paradigm shift in computational materials science by providing universal machine-learned interatomic potentials with broad transferability across chemical spaces. Although fine-tuning is essential for adapting these pretrained models to specific target systems, the influence of the optimization
algorithm on this process remains insufficiently characterized. In this work, we perform a rigorous
benchmark of seven first-order optimizers, including Adam, AdamW, RAdam, SGD, LAMB, Ranger, and ScheduleFree, for the fine-tuning of foundation models across molecular, crystalline, and
liquid regimes. We evaluate these
algorithms based on energy and force accuracy for both in-distribution and out-of-distribution configurations, as well as their impact on downstream physical properties such as elastic
moduli,
phonon spectra, and interfacial dynamics. We interpret these empirical results through a preconditioning framework that views each optimizer as a data-dependent linear transformation of the gradient. This analysis clarifies how different update rules impose specific spectral filters on the effective loss Hessian. Across all regimes, AdamW and ScheduleFree achieve superior
curvature conditioning and force accuracy, whereas
stochastic gradient descent exhibits slow convergence and instability. Furthermore, we demonstrate that a brief second-order refinement stage reduces residual anisotropy in the loss landscape and enhances the fidelity of physical observables without increasing inference costs. These findings provide conceptual insight and practical guidance for selecting and designing optimizers to ensure the stable and efficient fine-tuning of universal interatomic potentials.
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Applied Physics · Cross-listed from cond-mat.mes-hall
Quantum geometry and $X$-wave magnets with $X=p,d,f,g,i$
Motohiko Ezawa
Quantum geometry is a differential geometry based on
quantum mechanics. It is related to various transport and optical properties in condensed matter physics. The Zeeman
quantum geometry is a generalization of
quantum geometry including the
spin degrees of freedom. It is related to electromagnetic cross responses.
Quantum geometry is generalized to non-Hermitian systems and density
matrices. Especially, the latter is
quantum information geometry, where the
quantum Fisher information naturally arises as
quantum metric. We apply these results to the $X$-wave magnets, which include $d$% -wave, $g$-wave and $i$-wave altermagnets as well as $p$-wave and $f$-wave magnets. They have universal physics for anomalous
Hall conductivity, tunneling magneto-resistance and planar
Hall effect. We also study magneto-optical conductivity,
magnetic circular dichroism and Friedel oscillations in the $X$-wave magnets. Various analytic formulas are derived in the case of two-band
Hamiltonians. This paper presents a review of recent progress together with some original results.
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Atomic Physics
Analysis of collision shift assessments in ion-based clocks
M. D. Barrett and K. J. Arnold
We consider back-ground gas collision shifts in ion-based clocks. We give both a classical and
quantum description of a collision between an ion and a polarizable particle with a simple hard-sphere repulsion. Both descriptions give consistent results, which shows that a collision shift bound is determined by the classical Langevin collision rate reduced by a readily calculated factor describing the decoupling of the clock
laser from the ion due to the
recoil motion. We also show that the result holds when using a more general Lennard-Jones potential to describe the interaction between the ion and its collision partner. This leads to a simple bound for the collision shift applicable to any single ion clock without resorting to large-scale Monte-Carlo simulations or determination of molecular potential energy curves describing the collision. It also provides a relatively straightforward means to measure the relevant collision rate.
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Applied Physics
Kirigami Film Reflector for Deployable Space Antennas
Gulzhan Aldan, Henry Love, Matthew Campbell et al. (+2 more)
We propose a low-pretension reflective kirigami film as a material for the reflective surfaces of large deployable space reflector
antennas with an operating frequency around 10 GHz. The kirigami cut pattern is based on the well-known rotating squares pattern but is augmented with diagonal cuts to enhance stretchability and allow control over the effective Poisson's ratio. Using finite element simulations, we analyzed how the
geometric parameters of this pattern affected the reflectance of the film and the pretension required to resist thermal deformations. Tensile testing of selected designs, which are approximately half the weight of traditional metallic meshes, demonstrated a substantial reduction in the needed pretension to ~0.5 N/m and as low as ~0.1 N/m. Such low pretension represents an order-of-magnitude improvement over traditional metallic mesh reflectors and could enable the use of lighter
antenna trusses. Free-space reflectance measurements also show that these perforated films can maintain power reflectance exceeding 90% at 10 GHz under the strains expected in the deployed configuration.
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All authors Gulzhan Aldan, Henry Love, Matthew Campbell, Firooz Aflatouni, Igor Bargatin
Biological Physics
Near-infrared fluorescent nanoprobes for irreversibility in nonequilibrium actomyosin networks
Adi Hendler-Neumark, Itamar Magar, Shirel Kleiner et al. (+2 more)
Actomyosin networks operate far from
equilibrium, yet detecting the onset of motor-driven irreversible dynamics remains challenging. Here, we embed near-infrared (NIR) fluorescent single-walled carbon nanotubes (SWCNTs) within reconstituted actin networks, and use their nonphotobleaching emission to optically report ATP-powered myosin contractile activity. G-actin-dispersed SWCNTs are incorporated into polymerized F-actin without perturbing network assembly, enabling long-term, single-emitter fluorescence monitoring. Upon myosin addition, the NIR fluorescence levels of individual SWCNTs exhibit enhanced temporal fluctuations, and population-level statistics reveal deviations from
equilibrium behaviour. The index of dispersion (IOD) distributions shift and broaden relative to
equilibrium baselines, and the Kullback-Leibler divergence between IOD distributions systematically increases with increasing motor activity. Stationarity analysis further shows a dose-dependent increase in the fraction of nonstationary fluorescence traces, indicating the emergence of irreversible, time-evolving dynamics. These results establish SWCNTs as minimally invasive optical probes of irreversibility in nonequilibrium actomyosin assemblies, with broad applicability to other active biopolymer systems.
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All authors Adi Hendler-Neumark, Itamar Magar, Shirel Kleiner, Geffen Rosenberg, Gili Bisker
Chemical Physics
Spin Polarization from Circularly Polarized Light Induced Charge Transfer
Sindhana Pannir-Sivajothi and David T. Limmer
We show how a
spin polarization can be generated through the photo-induced electron transfer of an achiral donor-acceptor complex following
chiral light excitation. In particular, we illustrate the basic energetic and
symmetry requirements for chirality induced
spin selectivity where the chirality emerges from the electronic degrees of freedom following excitation with circularly polarized light. We study this effect in a simple model of a metalloporphyrin complex with an axial acceptor ligand using
quantum mechanical rate theories and numerical simulations. We find that the
spin polarization emerges due to the selective excitation of a ring current within the porphryin, breaking the degeneracy of the two degenerate
spin states. The resultant
spin polarization increases with the
spin orbit coupling between the metal in the porphyrin and the axial ligand, and is transient, with a lifetime dependent on the rate of dephasing from the Jahn-Teller distortion mode. This proposed effect should be observable in
spin-resolved photoemission spectroscopy.
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