Peer Revenue Play credits. Real papers.

Papers

Fresh from arXiv, typeset properly. Highlighted words trade on the market.

Physics Physics

physics Watch Physics

Monday 5 January

Optics · Cross-listed from quant-ph

Quantum Interaction Between Free Electrons and Light Involving First-order and Second-order Process

Hongteng Lin, Xiaotong Xiong, Junjie Liu et al. (+2 more)

Photon-induced Near-field Electron Microscopy (PINEM) effect has revealed the quantum interaction between free electrons and optical near filed, which demonstrated plenty of novel phenomena of manipulating free electron wave packet and detecting/shaping quantum photonic states. However, free electrons generally only absorb/emit one photon at a time, while the physical mechanism and phenomena of free electron-two-photon interaction have not been studied yet. Moreover, the relationship between PINEM and Kapitza-Dirac (KD) effect and nonlinear Compton scattering is still unclear. Here we develop the full quantum theory of electron-photon interaction considering the two-photon process. It is revealed that the emission/absorption of two photons by electrons can be greatly enhanced by manipulating the electric field component of optical near field, and the quantum interference between single-photon and two-photon processes can occur in some circumstances, which affects the photon number state, electron energy states and electron-photon entanglement. Meanwhile, it is found that the KD effect (elastic electron-photon scattering) and nonlinear Compton scattering (inelastic electron-photon scattering) are also a kind of two-photon process and the distribution of electrons can be deduced analytically based on the full quantum theory. Our work uncovers the possible abundant phenomena when free electron interacting with two photons, paves the way for more in-depth studies of nonlinear processes in electron-photon quantum interactions in the future.
Read the full abstract

All authors Hongteng Lin, Xiaotong Xiong, Junjie Liu, Yidong Huang, Fang Liu

Optics · Cross-listed from quant-ph

Photon blockade effect from synergistic optical parametric amplification and driving force in Kerr-medium single-mode cavity

Zhang Zhiqiang

This work investigates photon blockade control in a hybrid quantum system containing a Kerr-nonlinear cavity coupled to an optical parametric amplifier (OPA). The dynamics are governed by a master equation derived from an effective Hamiltonian that includes cavity decay. To obtain analytical solutions, the system's quantum state is expanded in the Fock basis up to the two-photon level. Solving the steady-state Schrodinger equation yields probability amplitudes and the analytical conditions for optimal photon blockade. Results confirm that photon blockade is achievable with suitable parameters. Excellent agreement is found between the analytical solutions and numerical simulations for the steady-state, equal-time second-order correlation function, validating both the analytical method and the blockade effect. Numerically, the average intracavity photon number increases significantly under resonance, providing a theoretical pathway for enhancing single-photon source brightness. Furthermore, the driving phase is shown to regulate the optimal blockade region: it shifts the parabolic region within the two-dimensional parameter space of driving strength and OPA nonlinearity and can even reverse its opening direction. The influence of Kerr nonlinearity is also examined. Photon blockade remains robust across a wide range of Kerr strengths. Physical analysis attributes the effect to destructive quantum interference between two distinct excitation pathways that suppress two-photon states. While Kerr nonlinearity shifts the system's energy levels, it does not disrupt this interference mechanism, explaining the effect's stability over a broad parameter range.
Read the full abstract

Fluid Dynamics

Bridging Filtering and Point-Splitting Approaches for Variable-Density Flows

Hridey Narula and Prasad Perlekar

Energy transfer in turbulent flows is typically described either through correlation functions, via the Kármán-Howarth-Monin relation, or through a scale-by-scale budget of the filtered energy (Frisch 1995). For constant-density homogeneous and isotropic turbulence, the equivalence between these two descriptions is well understood. In compressible turbulence, however, several definitions of filtered energy exist, and for most definitions the associated formulation in terms of correlation functions is unclear. We develop a general empirical framework, supported by theoretical arguments and numerical simulations, to determine the multipoint correlation functions corresponding to any filtered energy. We then show that the Favre filtered energy – defined as the ratio of the squared filtered momentum to the filtered density – corresponds to an infinite series of multipoint correlation functions. This is achieved by expanding the Favre velocity as a power series in local density fluctuations. The expansion reveals the contributions of the subgrid-scale fluctuations of velocity and density to the Favre velocity. We verify the proposed expansion for the buoyancy and pressure contributions for three-dimensional buoyancy-driven bubbly flows with a large density contrast ($10^2$) between the liquid and the bubble phase.
Read the full abstract

Optics

Deep-Subwavelength Plasmon Polariton Atomic Cavity Detector for Frequency- and Polarization-Sensitive Terahertz Detection and Imaging

Shaojing Liu, Hongjia Zhu, Ximiao Wang et al. (+8 more)

Room-temperature, miniaturized, polarization-resolved terahertz (THz) detection of high speed is vital for high-resolution imaging in radar, remote sensing, and semiconductor inspection, and is essential for large-scale THz focal plane arrays. However, miniaturization below deep-subwavelength scales (< 1/50 wavelength) remain challenging due to weak light-matter interaction, which degrades responsivity and polarization sensitivity. Here, we present a graphene plasmon polariton atomic cavity (PPAC) monolithic detector that overcomes this limitation by maintaining and even enhancing performance at a deep-subwavelength channel length of just 2 micrometers (1/60 wavelength). The device integrates graphene rectangle PPAC arrays with dissimilar metal contacts, where graphene functions as both absorber and conductor, simplifying the architecture. Exploiting plasmon polariton resonances and the photothermoelectric (PTE) effect, the detector achieves polarization-sensitive, frequency-selective, and fast THz detection spanning 0.53 to 4.24 THz with a polarization ratio of 93, featuring a responsivity (RV) of 1007 V/W, a noise-equivalent power (NEP) of 16 pW/Hz^0.5, a specific detectivity (D*) of 2.9 x 10^7 Jones, and a response time of 230 ps. We further demonstrate monolithic integration for polarization imaging and non-destructive semiconductor chip inspection, advancing room-temperature, compact, and polarization-sensitive THz technologies.
Read the full abstract

All authors Shaojing Liu, Hongjia Zhu, Ximiao Wang, Runli Li, Hai Ou, Shangdong Li, Yanlin Ke, Runze Zhan, Ningsheng Xu, Huanjun Chen, Shaozhi Deng

Fluid Dynamics

Data-driven modeling and decomposition for nanoscale liquid-film dynamics: Application to superspreading nanofluid droplets

Kai Fukami and Eita Shoji

Understanding ultrathin liquid-film dynamics is crucial for unraveling complex interfacial phenomena, yet deriving governing equations directly from experimental observations remains challenging. This study proposes a data-driven approach to model droplet dynamics, capturing liquid-film thickness on the nanometer scale in the form of a partial differential equation. As a challenging test case, we examine the superspreading wetting of surfactant-free nanofluids, a phenomenon whose physical mechanism defies standard theoretical explanations. We apply a sparse identification algorithm to spatiotemporal film-thickness profiles resolved at the nanometer scale using phase-shifting imaging ellipsometry. For a pure solvent, the discovered governing equation recovers classical lubrication physics driven by disjoining pressure and evaporation. In contrast, the nanofluid dynamics necessitates an additional, unique transport term scaling with the gradient of the inverse film thickness. Theoretical scaling analysis suggests this term represents a nanoparticle-induced bias flux, consistent with a hypothesized capillary wicking mechanism within the precursor film. The identification of the current nanofluid-specific term underscores the efficacy of integrating high-precision experimental measurements with data-driven modeling to discover hidden physics and generate testable hypotheses in complex wetting dynamics.
Read the full abstract

Biological Physics

An AI-guided mechanotyping instrument for fully automated oocyte quality assessment

Yining Guo, Wenshuo Zhao, Xueying Sun et al. (+5 more)

The mechanical properties of oocytes are regarded as important indicators of their developmental potential. During fertilization, deviations from the normal mechanical range can hinder sperm penetration, ultimately reducing fertilization efficiency and compromising embryo quality. However, current methods for measuring oocyte mechanics often suffer from serious cellular damage, low automation levels, and large measurement errors. To address these limitations, we developed an AI-guided micronewton-scale mechanical measurement system for safe and automated oocyte quality assessment. The system integrates voice interaction with automated experimental workflows to control a magnetically actuated microgripper, which applies defined loading forces to induce micron-scale compressive deformation of the oocyte. Combined with AI-assisted object detection and image segmentation algorithms, the system captures cellular deformation in real time, enabling precise calculation of the oocyte's compressive modulus. This measurement system enables automated, quantitative, and non-destructive evaluation of oocyte mechanical properties, providing an effective approach for oocyte quality screening in in vitro fertilization (IVF) and other assisted reproductive technologies (ART).
Read the full abstract

All authors Yining Guo, Wenshuo Zhao, Xueying Sun, Jing Huang, Xi Chen, Xinyu Lu, Yuan Liu, Haifeng Xu

Biological Physics

Is There Elliptic Distortion in the Light Harvesting Complex 2 of Purple Bacteria?

Seogjoo J. Jang, Robert J. Silly, Ralf Kunz et al. (+2 more)

Single molecule spectroscopy (SMS) revealed unusually large gap between two major exciton peaks of the B850 unit of light harvesting complex 2 (LH2), which could be explained assuming elliptic distortion or k=2 symmetry modulation in the site excitation energy. On the basis of extensive simulation of the SMS data and ensemble lineshape, we found that uniform modulation of k=2 symmetry cannot explain the dependence of intensity ratios on the gap of the two major peaks, which are available from SMS, nor the ensemble lineshape. Alternative models of disorder with k=1 and k=2 symmetry correlation are shown to reproduce these data reasonably well and can even explain the gap distribution when it is assumed that the lower major peak in the SMS lineshape is an intensity weighted average of k=1- and k=0 states.
Read the full abstract

All authors Seogjoo J. Jang, Robert J. Silly, Ralf Kunz, Clemens Hofmann, Jürgen Köhler

Chemical Physics · Cross-listed from cond-mat.mtrl-sci

Charge Hopping Dynamics along a Disordered Chain in Quantum Environments: Comparative Study of Different Rate Kernels

Seogjoo J. Jang and Andres Montoya-Castillo

This work presents a computational study of charge hopping dynamics along a one dimensional chain with Gaussian site energy disorder and linearly coupled quantum bath. Time dependent square displacements are calculated directly from numerical solutions of Pauli master equations, for five different rate kernels: exact Fermi golden rule (FGR) rate expression, stationary phase interpolation (SPI) approximation, semiclassical (SC) approximation, classical Marcus rate expression, and Miller-Abrahams expression. All results demonstrate diffusive behavior in the steady state limit. The results based on the FGR rate expression show that the charge transport in quantum bath can be much more sensitive to the disorder than the prediction from the classical Marcus expression. While the SPI approximation captures this general trend reasonably well, the SC approximation tends to be unreliable at both quantitative and qualitative levels, and becomes even worse than the classical Marcus expression under certain conditions. These results offer useful guidance in the choice of approximate rate kernels for larger scale simulations, and also demonstrate significant but fragile positive effects of quantum environments on the charge hopping dynamics.
Read the full abstract

Optics

Subsymmetry-protected compact edge states

Ruoqi Cheng, Domenico Bongiovanni, Ziteng Wang et al. (+6 more)

Sub-symmetry (SubSy) protected topological states represent a concept that goes beyond the conventional framework of symmetry-protected topological (SPT) phases, demonstrating that topological boundary states can remain robust even when the pertinent symmetry holds only in a subset of Hilbert space. Typical SPT and SubSy boundary states decay exponentially into the bulk, which means they are not confined in just few lattice sites close to the boundary. Here, we introduce topologically compact edge states protected by SubSy, featuring extreme two-site localization at boundaries of a lattice, without any decay into the bulk. The compactness arises from local destructive interference at the boundary, while topological protection is ensured by SubSy, characterized by quantized winding numbers. Experimentally, we observe compact edge states in laser-written photonic lattices with engineered rhombic-like unit cells, confirming their robustness against perturbations under both chiral symmetry and SubSy conditions. Our results highlight the potential of SubSy protection for achieving topological confinement of light, paving the way for applications in compact waveguides, lasers, and high-sensitivity photonic sensors.
Read the full abstract

All authors Ruoqi Cheng, Domenico Bongiovanni, Ziteng Wang, Zhichan Hu, Liqin Tang, Daohong Song, Roberto Morandotti, Hrvoje Buljan, Zhigang Chen

Optics

Phase Transitions and Topological Protection in Anyonic-PT-Symmetric Lattices

Ruiying Zhang, Ziteng Wang, Daohong Song et al. (+3 more)

Parity-time (PT) symmetry and anti-PT symmetry have attracted extensive interest for their non-Hermitian spectral properties, particularly the emergence of purely real and imaginary eigenvalues in their symmetry-unbroken regime, respectively. Recently, these two scenarios have been unified under a more general framework known as anyonic-PT symmetry, yet its physical implications in waveguide platforms and corresponding topological features in extended lattice systems remain largely unexplored. Here, the phase transitions and topological protection in anyonic-PT-symmetric systems are systematically investigated in waveguide lattices. In the symmetry-unbroken regime, the arguments of all bulk eigenvalues are constrained to two discrete values separated by {\pi}, leading to distinctive oscillatory propagation dynamics accompanied by controlled amplification or dissipation. In the case of one-dimensional lattice, the energy bands exhibit a gap closing and reopening during phase transition. Moreover, in the symmetry-unbroken regime, the topological edge states emerge within the bulk gap and are protected by a generalized pseudo-anyonic-Hermiticity (PAH) symmetry. Our results establish anyonic-PT symmetry as a new tunable degree of freedom for non-Hermitian waveguide systems, where the eigenvalue argument provides a natural quantity for information encoding. This work broadens the conceptual foundation of topological protection under generalized non-Hermitian symmetries.
Read the full abstract

All authors Ruiying Zhang, Ziteng Wang, Daohong Song, Liqin Tang, Konstantinos G. Makris, Zhigang Chen

Optics

Controllable Lateral Optical Forces on Janus Particles in Fluid Media

Ziheng Xiu, Yue Chai, Pengyu Wen et al. (+7 more)

Optical forces - studied since the earliest days of laser physics - continue to reveal rich dynamics and enable powerful tools for manipulation of objects on micro- and nanoscales, and even individual atoms. Lateral optical forces, which act perpendicular to the direction of beam propagation, are particularly intriguing but have largely been restricted to interface geometries such as air - water boundaries. Here, we realize tunable lateral optical force entirely within a fluid environment by using Janus particles: dielectric microspheres half-coated with gold. We show that the lateral optical force arises from scattering asymmetry induced by the asymmetric structure of the particles; it can be tuned by adjusting the polarization angle of a linearly polarized beam, but also particle parameters including their size and orientation. Experimentally, we directly observe fully reversible lateral propulsion of Janus particles in water merely by rotating the polarization direction, in excellent agreement with theoretical predictions. These results establish a new mechanism for programmable, polarization-controlled optical manipulation, with promising implications for biophotonics, microfluidics, and active soft-matter systems.
Read the full abstract

All authors Ziheng Xiu, Yue Chai, Pengyu Wen, Chun Meng, Min-Cheng Zhong, Yu-Xuan Ren, Daohong Song, Hrvoje Buljan, Liqin Tang, Zhigang Chen

Applied Physics · Cross-listed from cond-mat.mes-hall

Two-Qubit Module Based on Phonon-Coupled Ge Hole-Spin Qubits: Design, Fabrication, and Readout at 1-4 K

D.-M. Mei, S. A. Panamaldeniya, K.-M. Dong et al. (+2 more)

We present a device-level design study for a two-qubit module based on phonon-coupled germanium (Ge) hole-spin qubits targeted for operation at $1$–$4~\mathrm{K}$. Building on prior theoretical modeling of phonon-engineered Ge qubits and phononic-crystal (PnC) cavities, we translate those modeling results into a fabrication-oriented two-qubit layout that integrates two gate-defined hole-spin qubits in a strained Ge quantum well with a GHz PnC defect mode intended to mediate a coherent phonon-based interaction. We specify the SiGe/Ge heterostructure, electrostatic gate layout, PnC cavity geometry, and a compatible nanofabrication pathway, including gate-stack formation, membrane patterning and release, RF/DC wiring, and process-risk mitigation. We further develop a readout architecture combining spin-to-charge conversion with RF reflectometry on a proximal charge sensor, and we provide a link-budget estimate that states the assumed system noise temperature, RF signal contrast, and integration-time requirements for single-shot readout at elevated cryogenic temperatures. Finally, we outline a stepwise benchmarking program for charge stability, single-qubit control, phonon-bandgap modification of relaxation, and resolvable phonon-mediated two-qubit coupling. The manuscript does not report experimental device data; rather, it provides an experimentally actionable bridge from prior modeling to future fabrication and measurement of phonon-coupled Ge hole-spin modules.
Read the full abstract

All authors D.-M. Mei, S. A. Panamaldeniya, K.-M. Dong, S. Bhattarai, A. Prem

Sunday 4 January

Optics

Towards precision quantitative measurement of radiation reaction within the classical radiation-dominated regime

Minghao Ma, Ke Liu, Ge Zhou et al. (+9 more)

Radiation reaction (RR) is a fundamental yet incompletely validated process in laser-particle interactions, since it lacks quantitatively definitive experimental verifications, especially the transition from classical to quantum regime. Herein, we propose a novel experimental scenario for investigating radiation RR within the classical radiation-dominated regime (CRDR), via the collision of a high-intensity petawatt-class laser with a tens-of-MeV electron beam from a LINAC. This approach enables access to a distinct parameter regime wherein RR dominates electron dynamics while quantum effects remain modest. Numerical simulations demonstrate that three key observables exist for identifying the RR within this CRDR regime: (i) quantitative measurement of energy spectra to validate the quantum correction factor; (ii) control of the collision time delay with charge-counting to map intensity dependence of RR; and (iii) verification of large angle ($90^\circ$) photon emission under the recoil condition $2\gamma \gtrsim a_0$. These experimental measurements will establish the benchmarks for RR models spanning the classical-to-quantum regime, thereby providing critical insights into fundamental strong-field quantum electrodynamics.
Read the full abstract

All authors Minghao Ma, Ke Liu, Ge Zhou, Zhida Yang, Yulin Xin, Jiadong Yang, Pengfei Zhu, Yipeng Wu, Min Chen, Tongpu Yu, Wenchao Yan, Jie Zhang

Computational Physics · Cross-listed from math.OC

Thrust Regulation in a Solid Fuel Ramjet using Dynamic Mode Adaptive Control

Parham Oveissi, Gohar T. Khokhar, Kyle Hanquist et al. (+1 more)

This paper presents the application of a novel data-driven adaptive control technique, called dynamic mode adaptive control (DMAC), for regulating thrust in a solid fuel ramjet (SFRJ). A high-fidelity computational model incorporating compressible flow theory and equilibrium chemistry is used to simulate the combustion dynamics. An adaptive tracking controller is designed using the DMAC framework, which leverages dynamic mode decomposition to approximate the local system behavior, followed by a tracking controller synthesized around the identified model. Simulation results demonstrate that DMAC provides an effective and reliable approach for thrust regulation in SFRJs. In addition, a systematic hyperparameter sensitivity study is conducted by varying the tuning parameters over several orders of magnitude. The resulting responses show that the closed-loop performance and tracking error remain stable across wide parameter variations, indicating that DMAC exhibits strong robustness to hyper parameter tuning.
Read the full abstract

All authors Parham Oveissi, Gohar T. Khokhar, Kyle Hanquist, Ankit Goel

Optics

Quantum Nonlinearity for Optical Neural Computing

Qingyi Zhou, Jungmin Kim, Yutian Tao et al. (+4 more)

The rapid scaling of deep neural networks comes at the cost of unsustainable power consumption. While optical neural networks offer an alternative, their capabilities remain constrained by the lack of efficient optical nonlinearities. To address this, we propose an optical neural computing architecture by embedding quantum emitters in inverse-designed nanophotonic structures. Due to their saturability, quantum emitters exhibit exceptionally strong nonlinearity compared with conventional materials. Using physics-aware training, we numerically demonstrate that the proposed architecture can solve complex tasks, including nonlinear classification and reinforcement learning, within all-optical neural networks. To enable fair comparison across different platforms, we introduce a framework that quantitatively links nonlinearity to a network's expressive power. Analysis shows that our quantum activation operates at $\text{nW}/\mu\text{m}^2$ intensity, which is seven orders of magnitude below the nonlinearity threshold of conventional optical materials. Looking ahead to large language models, we estimate the nonlinearity-limited optical power, which scales sublinearly with model size. Our results indicate that quantum nanophotonics may provide a route toward sustainable AI inference.
Read the full abstract

All authors Qingyi Zhou, Jungmin Kim, Yutian Tao, Guoming Huang, Ming Zhou, Zewei Shao, Zongfu Yu

Plasma Physics

Partially Ionized Plasma Physics and Technological Applications

Igor Kaganovich and Michael Tendler

Partially ionized plasma physics has attracted a lot of attention recently due to numerous technological applications made possible by the increased sophistication of computer modelling, the depth of the theoretical analysis, and the technological applications to a vast field of the manufacturing for computer components. The partially ionized plasma is characterized by a significant presence of neutral particles in contrast to fully ionized plasma. The theoretical analysis is based upon solutions of the kinetic Boltzmann equation yielding the non-Maxwellian electron energy distribution function (EEDF) thereby emphasizing the difference with a fully ionized plasma. The impact of the effect on discharges in inert and molecular gases is described in detail yielding the complex nonlinear phenomena in plasma self-organization. A few examples of such phenomena are given including the non-monotonic EEDFs in the discharge afterglow in mixture of argon with the molecular gas NF3; the explosive generation of cold electron populations in capacitive discharges, hysteresis of EEDF in inductively coupled plasmas. Recently, highly advanced computer codes were developed in order to address the outstanding problems of plasma technology. These developments are briefly described in general terms.
Read the full abstract

Optics

An Ingestible Light Source for Deep Photoacoustic Imaging

David C. Garrett and Lihong V. Wang

Photoacoustic tomography leverages ultrasound's deep tissue penetration to retrieve optical absorption contrast well beyond the optical diffusion limit. Conventional photoacoustic systems rely on externally delivered light and are therefore constrained by optical attenuation, limiting imaging depths to several centimeters. Here, we overcome this constraint using a compact, acoustically powered device that provides optical excitation directly from within the target medium. By exploiting the weak attenuation of low-MHz ultrasound, acoustic energy is transmitted through tissue to wirelessly power a pulsed laser diode. The emitted light pulses generate photoacoustic signals that encode local optical absorption at clinically relevant depths, which could enable imaging in regions such as the gastrointestinal tract that are inaccessible to surface-based illumination. We demonstrate this approach by imaging through a 12 cm thick phantom, establishing a pathway toward deep-tissue photoacoustic imaging.
Read the full abstract

Plasma Physics

Excess energy of strongly coupled one-component plasma from variational approach

S. A. Khrapak and A. G. Khrapak

The excess energy of the one-component plasma fluid is calculated using the variational approach combined with different variants of the excess entropy of the hard-sphere fluid, which is used as a reference system. Our comparison with recent Monte Carlo results for the excess energy of the one-component plasma identifies the Percus-Yevick virial entropy as the most accurate entropy to be used in the variational calculation of this kind. The reason for this and potential developments of the present analysis are briefly discussed. We demonstrate that the original Rosenfeld-Tarazons scaling of the thermal component of the excess energy of the one-component plasma fluid is in excellent agreement with recent Monte Carlo results.
Read the full abstract

Atomic Physics · Cross-listed from quant-ph

Design and Characterization of Compact Acousto-Optic-Deflector Individual Addressing System for Trapped-Ion Quantum Computing

Jiyong Yu, Kavyashree Ranawat, Andrew Van Horn et al. (+4 more)

We present a compact design for a beam-steering system based on acousto-optic-deflectors (AODs) used as an individual addressing system for trapped-ion quantum computing. The design targets to minimize the optomechanical degrees of freedom and the optical beam paths to improve optical stability, and we successfully implemented a solution with a compact footprint of less than 1 square foot. The system characterization results show that we achieve clean Gaussian beams at 355nm wavelength with a beam steering range of $\sim$50 times the beam diameter, and an intensity crosstalk of $< 9 \times 10^{-4}$ at all neighboring ions in a five-ion chain. Based on these capabilities, we experimentally demonstrate individual addressing of a 30-ion chain. We estimate the beam switching time of the AOD to be $\sim$240 ns. The compact system design is expected to provide high optical stability, providing the potential for high-fidelity trapped-ion quantum computing with long ion chains.
Read the full abstract

All authors Jiyong Yu, Kavyashree Ranawat, Andrew Van Horn, Jacob Whitlow, Seunghyun Baek, Junki Kim, Jungsang Kim

Chemical Physics · Cross-listed from cond-mat.stat-mech

Variation on the theme of Jarzynski's inequality

Dani R. Castellanos and Petr Jizba

The Jarzynski equality, which relates equilibrium free-energy difference to an average of non-equilibrium work, plays a central role in modern non-equilibrium statistical thermodynamics. In this paper, we study a weaker consequence of this relation, known as Jarzynski's inequality, which can be formally obtained from the Jarzynski equality via Jensen's inequality. We identify and analyze several extensions of Jarzynski's inequality that go beyond its direct derivation from the Jarzynski equality. In particular, we consider chemical systems both in the linear-response regime and away from linear thermodynamics. Furthermore, by employing functional-integral techniques, we extend Jarzynski's inequality to many-body statistical systems described by quantum field theory. Salient issues, such as connections of the Jarzynski inequality with the maximum work theorem and the Landau–Lifshitz theory of fluctuations, are also discussed.
Read the full abstract

Computational Physics

Ab initio quantum embedding at finite temperature with density matrix embedding theory

Laurence Giordano, Y. Stanley Tan, Zhi-Hao Cui et al. (+1 more)

We present a finite-temperature extension of density matrix embedding theory (FT-DMET) for realistic crystalline systems. We describe a practical framework for constructing extended bath orbitals, solving the embedding problem, and performing DMET self-consistency at finite temperature. To reduce computational cost, we introduce strategies based on mutual-information-guided bath truncation, controlled treatment of the thermal electron number without explicit optimization, and the use of low-temperature impurity solvers and one-shot FT-DMET in the low-temperature regime. We apply this approach to periodic hydrogen chains and square lattices to characterize their finite-temperature phases. We observe the Pomeranchuk-like effect in one dimension and enhanced stability of long-range order in two dimensions.
Read the full abstract

All authors Laurence Giordano, Y. Stanley Tan, Zhi-Hao Cui, Chong Sun

Instrumentation and Detectors

Simourg2.0 – Geant4 application for simulation of nuclear detectors with simple geometries

D. S. Kovalenko, V. V. Kobychev, L. M. Kobycheva et al. (+1 more)

Simourg is a software based on the Geant4 toolkit and provides the Monte Carlo simulation of nuclear spectrometric setups with simple geometries for such applications as nuclear decay research, radiation safety, and nuclear medicine. With just a few command lines, users can define simple geometries, materials, and radiation sources to obtain reliable approximations for typical experimental setups. Simourg version 2.0, currently in its prerelease stage, introduces extended functionality for data extraction, geometry configuration, debugging, and visualization.
Read the full abstract

All authors D. S. Kovalenko, V. V. Kobychev, L. M. Kobycheva, O. V. Zueva

Instrumentation and Detectors

Common Iron Passive Magnetic Shielding for Scintillator Array Photomultiplier Tubes

T. Atovullaev, S. Cherepanov, A. Atovullaeva et al. (+13 more)

In accelerator-based experiments, detector arrays constructed from organic plastic scintillators are widely used for measurements of particle timing, hit position, and energy loss. These detectors are often operated in proximity to magnetic spectrometers, where the associated photomultiplier tubes (PMTs) are exposed to fringe magnetic fields. The standard approach to mitigate magnetic interference involves individually shielding each PMT. In this work, we present a combined passive shielding solution consisting of a common iron enclosure for a row of PMTs, supplemented with individual mu-metal cylinders. This configuration was deployed during a 2022 experiment at JINR. Performance evaluations show that the proposed shielding effectively preserves PMT gain and timing resolution, demonstrating its viability for future applications in similar experimental environments.
Read the full abstract

All authors T. Atovullaev, S. Cherepanov, A. Atovullaeva, J. Kahlbow, M. Patsyuk, O. Hen, G. Johansson, I. Kruglova, B. Meirovich, S. Nepochatykh, E. Piasetzky, S. Piyadin, A. Salamatin, S. Sedykh, S. Segev, Y. Zhang

Optics

Variational treatment of the electromagnetic field in an optical cavity with a moving mirror

Francesco Lorenzi, Maria Guglielmina Pelizzo and Luca Salasnich

Optical cavities with moving mirrors provide a versatile platform for exploring radiation-matter interactions and optically mediated mechanical effects, whose control has wide technological implications. However, capturing the coupled dynamics of the electromagnetic field and of the mirror within a consistent theoretical framework remains challenging. We analyze the problem of the coupling between classical electromagnetic fields in a cavity and a movable mirror, considering both nonrelativistic and relativistic regimes of motion. Starting from the equations of motion for a mirror subject to a generic external potential, we provide a variational formulation of the mirror-radiation interaction. Within this framework, a single-mode variational approximation is introduced, which captures the essential dynamical features of the coupled system. In the special case of a mirror undergoing free motion, the variational method yields an exact solution. This unified treatment highlights the connection between different dynamical regimes and provides a basis for analyzing applications ranging from precision interferometry to relativistic radiation-pressure effects.
Read the full abstract

Plasma Physics

Hybrid PIC-fluid model for numerical simulation of laser-plasma interaction

Andrey Sladkov

A hybrid PIC-fluid model is proposed for three dimensional numerical simulation of laser-plasma interaction. Ions are treated kinetically, electrons as a ten-moment fluid, capturing ion-scale dynamics, pressure anisotropy, and non-Maxwellian distributions efficiently. A laser-envelope model handles energy deposition and ponderomotive heating without resolving optical oscillations. Collisional and ionisation processes ensure self-consistent evolution of energy and charge states. The model is implemented in the AKAM code, providing a scalable framework that bridges fully kinetic and fluid approaches for high-energy-density and laboratory plasma applications.
Read the full abstract

Computational Physics

Learning Stiff Dynamical Operators: Scaling, Fast-Slow Excitation, and Eigen-Consistent Neural Models

Mauro Valorani

Stiff dynamical systems represent a central challenge in multi scale modeling across combustion, chemical kinetics, and nonlinear dynamical systems. Neural operator learning has recently emerged as a promising approach to approximate dynamical generators from data, yet stiffness imposes severe obstacles: training errors concentrate on slow manifold states, collapse of fast dynamics occurs, and the learned operator may fail to reproduce the true eigenstructure. We demonstrate three key advances enabling accurate learning of stiff operators and preserving spectral fidelity: (i) stiffness aware scaling of time derivatives, (ii) fast direction excitation via local trajectory cloud bursts, and (iii) autograd-based Jacobian diagnostics ensuring eigenstructure fidelity. Applied to the Davis-Skodje system, the approach recovers both slow and fast modes across stiffness regimes, reducing fast eigenvalue error by an order of magnitude while improving rollout fidelity. These results argue that spectral fidelity - not trajectory accuracy alone - should be a first-class target in data driven learning of stiff operators.
Read the full abstract

Atomic Physics · Cross-listed from quant-ph

Quantum simulation with Rydberg ions in a Penning trap

Wilson S. Martins, Markus Hennrich, Ferdinand Schmidt-Kaler et al. (+1 more)

Quantum simulation of interacting many-body spin systems is routinely performed with cold trapped ions, and systems with hundreds of spins have been studied in one and two dimensions. In the most common realizations of these platforms, spin degrees of freedom are encoded in low-lying electronic levels, and interactions among the spins are mediated through crystal vibrations. Here we propose a new approach which enables the quantum simulation of two-dimensional spin systems with interaction strengths that are increased by orders of magnitude. This, together with the unprecedented longevity of trapped ions, opens an avenue for the exploration of phenomena that take place on long timescales, e.g., slow and collective relaxation in frustrated and kinetically constrained systems. Our platform makes use of the strong dipolar interactions among electronic Rydberg states and planar confinement provided by a Penning trap. We investigate how the strong electric and magnetic fields that form this trap affect the properties of the Rydberg states and show that spin-spin interaction strengths on the order of MHz are achievable under experimentally realistic conditions. As a brief illustration of the capabilities of this quantum simulator, we study the entanglement in a frustrated spin system realized by three ions.
Read the full abstract

All authors Wilson S. Martins, Markus Hennrich, Ferdinand Schmidt-Kaler, Igor Lesanovsky

Optics · Cross-listed from quant-ph

Generation of circular polarized high-order harmonics from single color quantum light

Lidija Petrovic, Philipp Stammer, Maciej Lewenstein et al. (+1 more)

The atomic response to an ultra-intense driving field produces a characteristic high-harmonic spectrum featuring a rapid drop in intensity for the lower harmonics, followed by a plateau and a sharp cutoff. This response vanishes for circularly polarized classical drivers – a limitation that can be overcome by introducing quantum features into the driving field. In this work, we show that squeezed highly elliptically polarized drivers not only enable the high-harmonic generation (HHG) process in classically forbidden regimes of large ellipticity, but also yield highly elliptical harmonic radiation with pronounced super-Poissonian photon statistics. Moreover, we show that the HHG spectral features encode information about the quantum nature of the driving field, revealing the presence of its squeezed field fluctuations. By analyzing the HHG spectral intensity dependence as a function of the driver's ellipticity and squeezing orientation, we identify a means to probe the driving field's quantum properties that intrinsically lie in the high-photon number regime.
Read the full abstract

All authors Lidija Petrovic, Philipp Stammer, Maciej Lewenstein, Javier Rivera-Dean

Chemical Physics

Effects of Edge Atoms and Channel Width on Charge Storage in Nanoporous Carbon Supercapacitors

Koushik Sarkar and Muhammad Anisuzzaman Talukder

The amorphous structure of nanoporous carbon electrodes in supercapacitors complicates the establishment of clear links between electrode geometry and capacitance. In this work, we examine how specific structural features govern charge storage and explain capacitance variations among carbide-derived carbon (CDC) electrodes. Two key methodological and mechanistic advances are introduced. First, we propose a physically motivated, electric-field-based definition of the ion sphere of influence, which avoids the ambiguity of radial distribution function-based cutoffs and enables a more reliable characterization of local ion–electrode interactions. Second, we introduce an ion-resolved channel-width descriptor that quantifies pore accessibility by identifying the narrowest passage a counter-ion must traverse to enter a pore, directly linking accessibility to ion decoordination. Using atomistic molecular dynamics simulations of supercapacitors comprising realistic CDC electrodes and a room-temperature ionic liquid electrolyte under applied potentials, we show that carbon atoms located at the edges of graphitic sheets consistently accumulate higher charge than basal-plane atoms across all electrode types. The fraction of edge atoms increases with structural disorder and correlates with enhanced capacitance, in agreement with recent experimental findings linking disorder to charge storage. Furthermore, analysis of pore size and channel width reveals that ion decoordination is governed primarily by channel width rather than pore size alone. Together, these results establish edge atom concentration and pore channel width as decisive structural descriptors controlling charge accumulation in nanoporous carbon supercapacitors, providing clear design guidelines for optimizing electrode architectures.
Read the full abstract

Fluid Dynamics · Cross-listed from nlin.CD

Identifying recurrent flows in high-dimensional dissipative chaos from low-dimensional embeddings

Pierre Beck and Tobias M. Schneider

Unstable periodic orbits (UPOs) are the non-chaotic, dynamical building blocks of spatio-temporal chaos, motivating a first-principles based theory for turbulence ever since the discovery of deterministic chaos. Despite their key role in the ergodic theory approach to fluid turbulence, identifying UPOs is challenging for two reasons: chaotic dynamics and the high-dimensionality of the spatial discretization. We address both issues at once by proposing a loop convergence algorithm for UPOs directly within a low-dimensional embedding of the chaotic attractor. The convergence algorithm circumvents time-integration, hence avoiding instabilities from exponential error amplification, and operates on a latent dynamics obtained by pulling back the physical equations using automatic differentiation through the learned embedding function. The interpretable latent dynamics is accurate in a statistical sense, and, crucially, the embedding preserves the internal structure of the attractor, which we demonstrate through an equivalence between the latent and physical UPOs of both a model PDE and the 2D Navier-Stokes equations. This allows us to exploit the collapse of high-dimensional dissipative systems onto a lower dimensional manifold, and identify UPOs in the low-dimensional embedding.
Read the full abstract