Applied Physics · Cross-listed from cond-mat.mtrl-sci
Machine learning based prediction of optical properties in two-dimensional Mo-W-S-Se-Te transition-metal dichalcogenide alloys through physics-informed sampling
Vivek Chowdhury, Tarvir Anjum Aditto, Md. Samrat et al. (+2 more)
Two-dimensional transition-metal dichalcogenide (TMD)
alloys provide a compositionally tunable platform for controlling the optical and electronic properties. However, systematic prediction of their dielectric response across multicomponent
alloy spaces remains challenging owing to the combinatorial cost of first-principles calculations. In this work, we combined ab initio optical-property calculations with a tabular foundation-model regression to predict the real and imaginary components of the frequency-dependent dielectric function for Mo-W-S-Se-Te TMD
alloys. A
dataset of 99
alloy structures spanning binary, ternary, quaternary, and quinary compositions was generated using density functional theory (DFT). The resulting polarization-dependent dielectric spectra were used to train a tabular prior-fitted network (TabPFN) and evaluated against the conventional Extra Trees and XGBoost models. To accommodate the in-context capacity limit of TabPFN, we introduced a non-uniform, physics-informed energy subsampling strategy that concentrates sampling in the optically active region above the band gap, where interband absorption is strongest. Trained solely on quaternary
alloys, our TabPFN reconstructed the dielectric spectra of held-out quaternary compositions with an R2 > 0.98 and a mean absolute error below 0.10 for all four dielectric components, outperforming both baselines while requiring no gradient-based training or hyperparameter tuning. Our model further predicted derived optical quantities, including refractive index, extinction coefficient, and absorption coefficient. Additionally, our model generalized in a zero-shot manner to binary, ternary, and quinary
alloys absent from the training set, with quinary predictions achieving an R2 > 0.97.
Read the full abstract ▾
All authors Vivek Chowdhury, Tarvir Anjum Aditto, Md. Samrat, Hafiz Imtiaz, Ahmed Zubair
Atomic Physics
Plasma screening and configuration interaction effects induced large enhancement on L-shell photoionization cross sections and opacity
Fuyang Zhou, Shengbo Niu, Simei Lu et al. (+5 more)
An opacity model that incorporates improved treatments of both
plasma screening and configuration interaction (CI) effects is proposed, and a 25-30% enhancement on the iron L-shell opacity is predicted at
solar interior temperatures. It is originated from the
plasma screening induced 14-17% enhancement on the photoionization cross sections and the CI induced 10-20% enhancement on photoexcitation and photoionization cross sections for open L-shell ions. These explain the long-standing discrepancy between theoretical and experimental iron opacity [Nature 517, 56], and the relatively weaker enhancements on chromium and nickel opacity [Phys. Rev. Lett. 122, 235001] due to the sensitivity of these effects to the different L-shell electron population and
plasma temperature/density. This letter provides the systematic interpretation of L-shell opacity measurements at
solar interior temperatures, and advances the accurate simulation of opacity and radiative transport in high-energy-density
plasma.
Read the full abstract ▾
All authors Fuyang Zhou, Shengbo Niu, Simei Lu, Chuangying Li, Xiang Gao, Yong Wu, Yizhi Qu, Jianguo Wang
Chemical Physics
Determination of fundamental properties of nitrogen from first principles. II. Potential energy curve and spectroscopic properties of N$_2$
Jakub Lang, Michał Przybytek and Michał Lesiuk
This work is the second part of the series devoted to first-principles determination of the fundamental properties of nitrogen. In this part, we calculate the potential energy curve for the electronic ground state of N$_2$. The potential is divided into three components: short-, medium-, and long-range, and a different computational protocol is applied to each component, based on a composite coupled cluster approach, genuine multireference methods, and asymptotic expansion of the interaction energy. A particular focus is on the short-range part, as the accuracy of this component is critical from the point of view of metrological applications, including the temperature dependence of many properties of nitrogen gas. Uncertainties of the theoretical data, originating both from basis set incompleteness and applied theoretical method, are rigorously analyzed and provided at $2\sigma$ level, i.e. expanded ($k=2$) uncertainties. The developed potential energy curve is used to calculate the spectroscopic parameters of the N$_2$ ground state and the results are compared with the available theoretical and experimental data.
Read the full abstract ▾
Chemical Physics
Determination of fundamental properties of nitrogen from first principles. I. Atomic polarizabilities and long-range dispersion coefficients
Michał Przybytek, Jakub Lang and Michał Lesiuk
This work is the first in a series of papers in which we perform theoretical calculations of various fundamental properties of nitrogen relevant for gas thermometry experiments. In this part we focus on the properties of nitrogen atom, namely dynamic polarizabilities and dispersion coefficients that describe interaction between two nitrogen atoms at large internuclear separations. These quantities are calculated using a composite scheme based on coupled cluster and full configuration interaction methods and large Gaussian basis sets optimized specifically for the purposes of this work. The dispersion coefficients, $C_n$ with $n=6,8,10$, are obtained using Casimir–Polder formulas by numerical integration over dipole, quadrupole, and octuple polarizabilities for imaginary frequencies represented analytically by Padé approximants. Special
attention is paid to careful error control and uncertainty estimation of the calculated quantities.
Read the full abstract ▾
Fluid Dynamics
A physics-assisted deep neural network-based closure framework for velocity gradient dynamics in compressible flows with vibrational non-equilibrium
Deep Shikha and Sawan S Sinha
In this study, we propose a dynamical model for the
evolution of velocity gradients in compressible turbulent flows with vibrational non-
equilibrium effects, using physics-assisted deep neural networks. Such models provide a powerful framework for understanding the nonlinear physics associated with small-scale structures. In compressible flows, the influence of thermodynamic fields on velocity-gradient dynamics is represented through thermodynamic gradient field (TGF) tensor. The TGF tensor is one of the primary unclosed terms in velocity-gradient
evolution equations. The TGF tensor comprises contributions from the pressure-Hessian tensor, $\rho\boldsymbol{H}$, and the baroclinic tensor, $\boldsymbol{B}$. Accordingly, the proposed framework incorporates closures for both $\boldsymbol{H}$ and $\boldsymbol{B}$ tensor dynamics. Building upon existing phenomenological closures for the $\boldsymbol{H}$ tensor governing mechanisms, we develop a neural-network-based closure for the inviscid mechanism responsible for generating the $\boldsymbol{B}$ tensor. Unlike the other recently used tensor bases, the presented work employs a novel tensor basis allowing for the inclusion of non-symmetric features in the model. The framework also incorporates a data-driven closure for vibrational non-
equilibrium effects.The resulting framework combines phenomenological and data-driven representations of various $\boldsymbol{H}$ and $\boldsymbol{B}$ tensors governing mechanisms, termed as the hybrid enhanced homogenized Euler equation (H-EHEE) model. Model predictions are evaluated across a range of turbulent Mach numbers and compared against direct numerical simulation (DNS) data and existing compressible velocity-gradient models. The H-EHEE model exhibits close agreement with DNS statistics and provides significant improvements over existing models, particularly in highly compressible flow regimes.
Read the full abstract ▾
Computational Physics
Matrix-free phase-field modeling of fracture in micromechanical testing simulations of inelastic materials
Fabio Di Gioacchino, Rezgar Shakeri, Zachary Atkins et al. (+4 more)
Resolving steep damage gradients across diffuse cracks in the phase-field modeling of fracture favors the use of high-order finite elements, for which
matrix-free methods can provide superior performance and scalability. Here, we implement the Peric & Dettmer constitutive framework for visco-elastoplastic materials in an open source solid mechanics library supporting
matrix-free operators for high-order finite elements with p-multigrid preconditioning on GPUs. We introduce a rheological fracture element assembled in series with the Peric & Dettmer block, keeping fracture and inelastic material properties mutually independent. We conduct numerical simulations of tensile and compressive quasistatic tests on synthetic particle-
matrix microstructures using an El Capitan high-performance computing prototype. The results reproduce representative inelastic responses and fracture patterns, including X-shaped cracking observed in
polymer-bonded explosives and cup-and-cone fracture in ductile metals.
Read the full abstract ▾
All authors Fabio Di Gioacchino, Rezgar Shakeri, Zachary Atkins, Karen Stengel, Layla Ghaffari, Jeremy Thompson, Jed Brown
Optics · Cross-listed from cond-mat.mes-hall
Exceptional-Point Geometry of Weak Topological Boundary States
Rafael A. Molina, Kevin González and Pedro A. Orellana
In this article, we demonstrate that weak
topology can be formulated geometrically in terms of exceptional singularities of an analytically continued Bloch
Hamiltonian. A general plaquette
chiral model in two dimensions serves as a minimal realization of dual weak
topology, possessing two independent families of weak topological invariants, one for each spatial direction. The weak-topological edge states correspond to exceptional points in complex momentum space, while corner zero modes emerge from exceptional curves obtained by complexifying both momenta. Compact localized states arise when the exceptional roots collapse to the origin. This framework provides a unified complex-momentum description of edge, corner, and compact localization.
Read the full abstract ▾
Instrumentation and Detectors
Single event effects in the HCCStar ASICs for ITk strip upgrade
Shaogang Peng, Jeff Dandoy, Bruce Gallop et al. (+12 more)
Triple Modular Redundancy (TMR) technology has been implemented in the design of the HCCStar to reduce digital state changes and ensure reliable operation. We tested the effectiveness of the protection by placing HCCStar chips in a
proton beam. We studied corrected bit flips in registers and actual single event effects in the LCB and LP paths under different
proton energies. Our estimate is that the LP data-loss fraction relative to the 400 kHz readout is $O(10^{-10})$ during normal operation and there will be $O(10)$ corrected bit flips per HCCStar bit per year at the HL-LHC.
Read the full abstract ▾
All authors Shaogang Peng, Jeff Dandoy, Bruce Gallop, Hantao Jing, Jaya John John, Paul Keener, Pedro Leitao, Qiang Li, Weiguo Lu, Godwin Mayers, Mitch Newcomer, Peter Phillips, Zhixin Tan, Matt Warren, Yan Zhou
Optics
Phase singularity enabled polarization switchable analog spatial differentiation in an atomic MoS$_2$ planar Fabry-Pérot cavity
Zhonglin Li, Yingying Wang, Jiawei Kang et al. (+3 more)
Reconfigurable analog optical computing requires rapid and efficient switching between core mathematical operations, such as first- and second-order spatial differentiation. Here, we demonstrate a monolayer MoS$_2$ integrated a planar Fabry-Pérot (F-P) cavity that performs polarization switchable analog spatial differentiation under oblique incidence. By exploiting polarization dependent phase singularities, the device satisfies distinct optical transfer functions for different-order differentiation at the same operating condition. As a result, first-order and second-order derivatives of input images are experimentally realized by simply switching the incident polarization. These results establish the planar cavity as a compact reconfigurable spatial differentiator, whose computational order is controlled solely by light polarization. This approach provides a fast, convenient, and integration friendly strategy for tunable optical computing, and enables polarization switchable edge detection for image processing, with potential applications in real-time object recognition, feature extraction, and optical data compression.
Read the full abstract ▾
All authors Zhonglin Li, Yingying Wang, Jiawei Kang, Yangyang Zhang, Wenjun Liu, Zexiang Shen
Fluid Dynamics
A One-Dimensional Integral Equation for a Porous Horizontal Disc under Water Waves
Luiz Fernando de Moraes Campos Filho, Leandro Farina and Juliana Sartori Ziebell
Wave scattering by a thin, porous circular plate submerged in deep water is investigated. The problem is formulated as a second-kind hypersingular Fredholm integral equation over the unit disk, solved numerically using the Boundary Element Method. The analysis focuses on calculating hydrodynamic forces, specifically added mass (real part) and damping coefficient (imaginary part). Results demonstrate the influence of the porosity parameter G: less porous plates (G real) increase added mass and hydrodynamic force, while more porous plates (G imaginary) reduce these effects but increase the damping coefficient. The proposed formulation is validated, showing excellent agreement with established literature.
Read the full abstract ▾
Atomic Physics
Reassessment of line profile asymmetry in measurements of the 1s-2s energy interval in hydrogen
D. Solovyev, A. Anikin, T. Zalialiutdinov et al. (+1 more)
Experiments to determine transition frequencies in the hydrogen atom represent some of the most precise spectroscopic measurements and are at a higher level among simple atomic systems. The most persistent measured value in hydrogen is the energy interval corresponding to the $1s-2s$ two-
photon transition. The achieved experimental precision is several parts of $10^{-15}$ and has not changed over the last two decades. Although repeated experiments in 2011 and 2013 have improved the accuracy by several times, the frequency value has not changed significantly. On this basis, the frequency of the $1s-2s$ transition holds pivotal for determining physical quantities such as the Rydberg constant and the
proton charge radius. Theoretical efforts to study in detail the effects that might influence such precise measurements have not revealed significant contributions. The present work revises the theoretical analysis of the line contour asymmetry and its influence on the determination of the two-
photon absorption transition frequency, taking into account the theoretical achievements of recent years in this direction. It is shown that the asymmetry of the observed profile can lead to a $1s-2s$ transition frequency shift at the level of modern experimental accuracy. The found frequency shift is consistent with the line shape model contribution that forms the error budget of the experimental measurements. Adjustment can be carried out on the basis of the asymmetric profile that has become standard in recent years.
Read the full abstract ▾
All authors D. Solovyev, A. Anikin, T. Zalialiutdinov, L. Labzowsky
Optics · Cross-listed from quant-ph
Picosecond-resolved entanglement distribution over an urban free-space channel
Alessandro Laneve, Fabrizio Cienzo, Santiago Gomez et al. (+18 more)
Time-evolving entangled states describe
quantum particles whose correlations evolve in time according to a well-defined dynamics. Such states can be generated in a variety of physical systems and are promising resources for several
quantum technologies, ranging from
quantum clock synchronization to
quantum communication. However, their full potential is currently limited by the fact that the
entanglement dynamics often occur on timescales comparable to the achievable synchronization precision, especially in experiments aimed at distributing
entanglement through noisy urban channels. In this context, accurate timing is not merely a technical detail, but a fundamental requirement for faithfully observing and exploiting the underlying
quantum correlations. Here, we demonstrate the faithful distribution of a fast-evolving entangled state over a 270 m free-space channel connecting two buildings in the center of Rome. The developed system incorporates a synchronization device capable of achieving sub-50 ps timing accuracy between the two ends of the link while simultaneously supporting channel stabilization. Our results demonstrate that time-evolving
entanglement can be reliably transmitted through a noisy urban free-space channel, representing an important
benchmark toward long-distance free-space
quantum communication and the future implementation of time-correlated entangled states in demanding scenarios such as satellite-based
quantum networks.
Read the full abstract ▾
All authors Alessandro Laneve, Fabrizio Cienzo, Santiago Gomez, Paolo Barigelli, Philip Menz, Mattia Beccaceci, Giuseppe Ronco, Giorgia Grossi, Ievgen Brytavskyi, Thomas Oberleitner, Markus Wiener, Christian Weidinger, Tobias M. Krieger, Ailton Garcia Jr., Saimon Filipe Covre da Silva, Michele B. Rota, Nicolò Spagnolo, Henning Weier, Fabio Sciarrino, Armando Rastelli, Rinaldo Trotta
Optics
Design and Optimization of Metasurfaces for Silicon Photonics: PhD Thesis
Mathys Le Grand
Metasurfaces, two-dimensional arrangements of subwavelength nanopillars, provide local control over the phase of light, enabling flat optical functions beyond conventional refractive components. Their inverse design, finding the pillar distribution producing a target response, faces two obstacles: the immense dimensionality of the design space and the prohibitive cost of rigorous electromagnetic simulations, precluding exhaustive exploration at device scale. This thesis addresses the challenge in three stages. The first assesses the reliability of rigorous Maxwell solvers: comparing three implementations of Li's factorization rules for RCWA shows that spectral convergence does not guarantee physical fidelity, as these rules implicitly distort the simulated permittivity, most severely in the plasmonic regime. FDTD, immune to such artifacts, is retained as ground truth throughout. The second stage removes the computational bottleneck: a local phase-approximation model, then fully convolutional surrogates trained on FDTD simulations of large pillar metasurfaces, predict the near field almost instantaneously. Exploiting problem
symmetries quadruples the training database, and the surrogates generalize to much larger apertures while remaining differentiable. The third stage
benchmarks three strategies under a common FDTD protocol ($R^2$ between realized and target far fields): Gerchberg-Saxton
retrieval and Local Model ($R^2\approx0.925$), surrogate-based and heuristic-initialized gradient descent ($R^2\approx0.975$), and a generative framework based on
diffusion models and Schrödinger bridges. Hybrid posterior sampling and amplitude constraints restore scale-invariant fidelity on surfaces over 230 times larger than training, with diverse, fabrication-tolerant designs. Database enhancement lifts every approach to $R^2\approx0.97$.
Read the full abstract ▾
Physics and Society · Cross-listed from econ.GN
Accelerating fossil gas independence in Europe
Lukas Franken, Iegor Riepin and Tom Brown
Recent price shocks have prompted calls to curb Europe's dependence on fossil gas imports, but the cost of this goal, and the consumer protection it affords, remain uncertain. Here we address this gap by imposing constraints on fossil gas supply in a European energy system model that co-optimises abatement across all gas uses at high spatio-temporal resolution. Cutting import reliance proves economically compelling: through savings in power generation and low-temperature heat in industry and buildings, Europe can halve its natural gas consumption for 16bnEUR/a, aligning demand with the continent's production capacity of 200 bcm. This extra system cost is comparable to what consumers spend today on a 2 EUR/MWh rise in gas import prices. However, this sovereignty alone does not shield consumers from global gas price
volatility: we find that, even at a small share of the mix, gas remains dominant in shaping the marginal electricity price, leaving consumers exposed without additional policy measures.
Read the full abstract ▾
Fluid Dynamics
Effect of free-stream turbulence on a moderate adverse pressure gradient turbulent boundary layer developing over an airfoil
Tomek Jaroslawski and Francesco Scarano
Turbulent boundary layers (TBLs) subjected to adverse pressure gradients (APGs) are common to industrial aerodynamic applications, yet the effect of freestream
turbulence (FST) on TBLs developing under moderate APGs remains insufficiently understood. Wind-tunnel experiments were conducted to investigate the effects of FST on a developing TBL over a NACA 0015 airfoil. Varying the angle of attack (2 and 4$^\circ$) adjusted the pressure gradient, and hotwire anemometry measured boundary layer properties at different chordwise positions ($x/c$ = 0.400–0.625, with $\beta = \delta^*/\tau_0 dP/dx$ = 0.2-1.5). The FST level was increased using static grids, resulting in levels ranging from 0.15 to 6$\%$. The chord-based Reynolds number was kept constant at around 250,000 for all configurations. The results show that increasing FST systematically modifies the mean-flow development of the APG boundary layer. Higher FST levels reduce the shape factor and partially suppress the APG-induced wake in the mean velocity profile, while increasing the skin-friction coefficient towards values closer to canonical ZPG behaviour. The streamwise velocity variance is amplified in both the inner and outer regions, and spectral analysis shows that this increase is associated with energetic large-scale motions introduced by the freestream
turbulence, with characteristic wavelengths of order $\lambda_x/\delta \approx 13$. These large scale structures penetrate into the boundary layer and contribute to the near-wall variance, with a stronger effect observed as the adverse pressure gradient increases. The results show that FST is a governing parameter in developing APG TBLs over airfoils and that its influence is amplified by the pressure gradient. It must therefore be considered when interpreting mean-flow
evolution,
turbulence statistics, and scale interactions in realistic aerodynamic environments.
Read the full abstract ▾
Optics
Structured Cavity Quantum Electrodynamics
Shunfa Liu, Jiantao Ma, Hanqing Liu et al. (+9 more)
A cavity
quantum electrodynamics (cQED) system consisting of a confined single
photon and a single
quantum emitter serves as a fundamental block for
quantum optics and photonic
quantum technologies. The canonical optical mode employed in the conventional cavity
quantum electrodynamics features a uniform polarization distribution, leading to the scalar light-matter interaction in most existing experiments. Despite the rapid progress in the generation of structured light with spatially varied polarizations, the structured light-matter interaction, especially at the single quanta level, is highly intriguing yet largely unexplored. Here, we present the structured light-matter interaction at the single-
photon level in a
semiconductor cavity
quantum electrodynamics system. Four distinct structured cavity modes that are spectrally close to each other are constructed in a micropillar cavity. By spatially locating a single epitaxial
quantum dot (QD) at the periphery of a
semiconductor micropillar cavity and spectrally tuning the QD emission wavelength into the resonances of the structured cavity modes, cavity-enhanced single-
photon emissions with
spin-locked
chiral orbital angular momentum (OAM) and engineerable
spin-orbit entanglements are achieved within a single wavelength-scale device. Our work opens an unexplored paradigm of structured
quantum light-matter interactions and may further advance
chiral quantum optics and high-dimensional photonic
quantum technology.
Read the full abstract ▾
All authors Shunfa Liu, Jiantao Ma, Hanqing Liu, Yangpeng Wang, Xueshi Li, Haiqiao Ni, Zhichuan Niu, Kai Zou, Yun Meng, Xiaolong Hu, Xuehua Wang, Jin Liu
Data Analysis and Statistics
A framework for general discrete probability calculations
Kacper Topolnicki and Roman Skibiński
Probability follows a simple and concise set of rules. In practice, however, reason- ing about probability may be highly unintuitive and this leads to the possibility of miscalculations even for simple problems. We present an approach to facilitate the correct description of systems governed by discrete probability. The methods described in this paper allow making general statements about the values of prob- ability. This information can next be used to calculate any probability related to the system described by the statements. In case there are too few statements to provide a unique answer,
entropy maximization is used to fill in the miss- ing information. The approach has wide potential applications that range from experimental physics to natural
language analysis. The theoretical framework described here is also the basis of a software implementation that is designed to be straightforward to extend and requires only popular python libraries, numpy, torch, sympy, and scipy.
Read the full abstract ▾
Atomic Physics · Cross-listed from quant-ph
A Quantum Interface Between Neutral-Atoms and Trapped-Ions Quantum Registers
Ayelet Hasson, Gal Dekel, Ehud Shahar et al. (+2 more)
Hybrid
quantum systems combining neutral atoms and trapped ions offer the prospect of integrating the scalability of atom arrays with the high-fidelity control available in trapped-ion platforms. Here we propose and analyze a
quantum interface between individually trapped neutral atoms and a trapped-ion
crystal. In our scheme, a neutral 88Sr atom trapped in optical tweezers interacts with a small 88Sr+ ion
crystal, and by exciting the atom to a Rydberg state, the atom-ion polarization interaction is strongly enhanced, resulting in a state-dependent modification of the ions' collective motional modes. We show that this shift enables conditional control of a MS gate, allowing the neutral atom to act as a control
qubit for an entangling operation between two ions. We investigate the feasibility of the scheme by analyzing Rydberg trapping in the combined optical tweezers and Paul trap potentials, identifying negative-polarizability Rydberg states as particularly favorable for stable confinement. We further evaluate the relevant trapping conditions, Rydberg lifetimes, and coherence requirements, and show that the proposed interface is compatible with realistic experimental parameters. These results establish a practical route toward deterministic atom-ion hybrid
quantum gates and
quantum interfaces.
Read the full abstract ▾
All authors Ayelet Hasson, Gal Dekel, Ehud Shahar, Nitzan Akerman, Roee Ozeri
Geophysics · Cross-listed from cs.CV
Latent Variable-Mediated Cross-Learning for Few-Shot Acoustic Impedance Imaging
Junheng Peng, Yong Li, Mingwei Wang et al. (+1 more)
Acoustic impedance imaging is a fundamental yet severely ill-posed problem in subsurface analysis: the seismic wavelet is unknown, observations are band-limited, and labeled well-log samples are extremely scarce (typically <1% of all traces). Existing semi-supervised deep learning methods mitigate few-shot problem by incorporating forward modeling, yet they either rely on inaccurate prior wavelet assumptions or introduce auxiliary networks, leading to unstable optimization and degraded performance. We propose RD-SCL, a novel framework that integrates regularized deconvolution with semi-supervised cross-learning. At its core lies a differentiable, closed-form first-order Tikhonov deconvolution operator that dynamically estimates the latent wavelet in the frequency domain during training, providing stable physics-guided feedback without explicit auxiliary networks and fixed wavelet priors. Building on this operator, we design a symmetric cross-learning that enforces consistency between predictions on labeled and unlabeled data, thereby effectively exploiting abundant unlabeled traces. Extensive experiments on the SEAM and Marmousi 2
benchmarks demonstrate that RD-SCL consistently outperforms state-of-the-art supervised and semi-supervised methods, achieving substantial gains with lower computational cost. With only 56.5k learnable parameters and competitive runtime, RD-SCL offers a practical, physically consistent, and efficient solution for acoustic impedance imaging.
Read the full abstract ▾
All authors Junheng Peng, Yong Li, Mingwei Wang, Yi Bao
Classical Physics · Cross-listed from nlin.SI
Lax pairs and $r$-matrices for some two-dimensional isotropic oscillators
Govind S. Krishnaswami, Garima Rajpoot and Srividya N. Vaidya
This paper concerns Lax pairs for circularly symmetric harmonic, Fock-Darwin-type and quartic anharmonic oscillators in two dimensions. Although the 2d isotropic harmonic oscillator is bi-
Hamiltonian, its recursion operator does not lead to a Lax pair, nor do we obtain such a pair by taking a limit of the harmonic Calogero model. On the other hand, we show that this superintegrable harmonic oscillator admits a $4 \times 4$ block-form Lax pair with spectral parameter giving two conserved mode energies in involution and a corresponding dynamical $r$-
matrix. Interestingly, we also find $2 \times 2$ Lax pairs with spectral parameter that give all three independent conserved quantities satisfying a nonabelian Poisson
algebra, thereby providing a simple example of a Lax pair whose conserved quantities are not all in involution. Next, we construct a family of $su(2)$ Lax pairs and $r$-
matrices for the quadratic+quartic isotropic anharmonic oscillator. This is then extended to an isotropic oscillator with a rotational energy, which may be viewed as the Fock-Darwin oscillator with a quartic potential. With a change of variables, these Lax pairs and $r$-
matrices also apply to the Rajeev-Ranken model, although its noncanonical Poisson structure is distinct from that of the anharmonic oscillator.
Read the full abstract ▾
Optics
Polarization vector conjugation in a photonic integrated circuit
Anna J. Miller, Carson G. Valdez, Anne R. Kroo et al. (+5 more)
We show how to perform polarization conjugation of light in a simple apparatus without any nonlinear optical materials, based on self-configuring Mach-Zehnder interferometers fed by a polarization splitter. This allows us to completely and automatically remove the polarization variations on a single beam or mode propagating through an optical system with arbitrary birefringence, such as a conventional optical fiber, and compensate polarization variations experienced in the forward direction by propagating the conjugated beam back through the system and recreating the original polarization at the source. We demonstrate this polarization conjugation in an optical fiber setup in different orientations with a measured polarization extinction ratio of -30 dB for the returned beam.
Read the full abstract ▾
All authors Anna J. Miller, Carson G. Valdez, Anne R. Kroo, Marko Šimić, Marek Vlk, Charles Roques-Carmes, David A.B. Miller, Olav Solgaard
Fluid Dynamics
Fractal Scaling of Moffatt Vortices in Triangular Cavity Flow
Rathindra Nath Basak, Sougata Biswas and Jiten C. Kalita
This study examines the formation, quantification, and fractal characterization of corner
vortices in slow viscous incompressible flow within a triangular cavity. The governing Navier-Stokes equations are solved numerically using a pressure-based coupled solver, and the resulting
vortex cascade is analyzed through the size and intensity ratios of successive eddies in the spirit of Moffatt's theory of corner
vortices. The fractal properties of the
vortex sequence are then investigated using the area-perimeter method. An empirical relation is proposed to estimate the fractal dimension of any successive
vortex in the cascade for arbitrary grid resolution. The results demonstrate that the corner
vortices possess non-integer fractal dimensions between 1 and 2, and that this dimension is systematically linked to
vortex size and intensity. The influence of Reynolds number on the fractal scaling is also examined. Finally, a comparative analysis of self-similarity in triangular and square cavities confirms that the observed corner-
vortex cascade exhibits robust fractal behavior across geometries and flow regimes.
Read the full abstract ▾
Optics
Statistical Analysis of Speckle Fields
Ian D. Min-Roberts, Wojciech Rozmus and Pierre A. Michel
Speckles, or
laser hot spots, are the intensity maxima of optically smoothed
laser beams that seed instabilities, making a quantitative statistical description of speckles of interest. Earlier statistical theories estimated the number of speckles above an intensity level set for optically smoothed beams produced by random phase plates, using an ansatz that relates intensity maxima to the maxima of the real and imaginary components of the underlying complex Gaussian electric field. Here, we count speckles directly from the
laser intensity field, treating it as a $\chi_2^2$ random field and imposing the local maximum conditions without a single-component ansatz. We evaluate the theory for square, circular, annular, and Gaussian aperture spectra, and include induced spatial incoherence as a temporal smoothing mechanism. Monte Carlo simulations confirm the theory and show improved accuracy relative to the earlier ansatz-based formulation. Applications include a simple SBS reflectivity model using the resulting speckle statistics, and a comparison between speckle-driven and thermal noise density-fluctuation spectra.
Read the full abstract ▾
Optics
Monolithic Magneto-Optical Mach-Zehnder Isolator Using Laser-Annealed Iron Garnet on a Silicon Waveguide
Tomoya Sugita, Reona Motoji, Yuki Yoshihara et al. (+5 more)
Stable silicon photonic
circuits require monolithically integrated optical isolators based on magneto-optical garnet. However, crystallizing the garnet by conventional furnace annealing exposes the entire chip to high temperature and degrades the silicon waveguides and the metal electrodes. Here we avoid this degradation by using local
laser annealing in
vacuum to crystallize cerium-substituted yttrium iron garnet (Ce:YIG), deposited by ion beam sputtering without a seed layer, directly within a silicon-based Mach-Zehnder interferometer. A 915 nm beam heats only the garnet region confined in micrometer-scale trenches, leaving the surrounding
circuit and electrodes intact. The device achieves an isolation ratio of 13.6 dB at a wavelength of 1540 nm, corresponding to a Faraday rotation of 0.092$\deg$/$\mu$m, with an insertion loss of 20.4 dB and a propagation loss of 9.5 dB. Transmission electron microscopy reveals the crystallized Ce:YIG and a ~10 nm boundary region at the interface with the Si waveguide. These results demonstrate that thermally sensitive silicon photonic devices and magneto-optical thin films requiring high-temperature processing can be integrated by a high-throughput technique compatible with mass production.
Read the full abstract ▾
All authors Tomoya Sugita, Reona Motoji, Yuki Yoshihara, Dan Maeda, Hiroki Yamamoto, Hibiki Miyashita, Kazushi Ishiyama, Taichi Goto
Physics and Society
Topological measures in weighted hypergraphs
Ekaterina Vasilyeva, Liubov Tupikina, Daniil Musatov et al. (+3 more)
Higher-order interactions introduce an additional structural dimension to complex networks, requiring consistent generalizations of classical topological measures. In hypergraphs, the definition of distance between nodes is not unique: beyond the conventional measure derived from clique projection, an alternative formulation that explicitly incorporates the sizes of hyperedges, those of their intersection and their weights has been recently proposed. Here, we generalize three distance-based topological measures, namely closeness centrality, betweenness centrality and node eccentricity, using this new hypergraph distance. Trough tractable illustrative examples, we demonstrate that the differences between results obtained with the two distances are systematic and arise from structurally meaningful features of the higher-order networks. Also, analyzing a series of real-world
datasets, we show that hypergraphs can be divided into three distinct classes, corresponding to the possible dominance of specific orders of interaction over their general metric structure. This provides practical guidance on the possibility of limiting the analysis to only some specific interaction orders, reducing its complexity while maintaining the full information of the system.
Read the full abstract ▾
All authors Ekaterina Vasilyeva, Liubov Tupikina, Daniil Musatov, Andrei M. Raigorodskii, Charo. I. del Genio, Stefano Boccaletti
Optics
Enhanced abrupt autofocusing and depth-of-focus of circular Airy derivative beams via controlled asymmetry
Anita Kumari and Vishwa Pal
We demonstrate simultaneous enhancement of abrupt autofocusing and depth-of-focus (DOF) in circular Airy derivative beams through controlled asymmetry. The controlled asymmetry enables multiple discrete autofocusing events to merge into a single elongated focal region, thereby enhancing both the autofocusing ability and the DOF. The DOF is extended by up to 400% with a 32% improvement in autofocusing ability and a ~ 32 {\mu}m focal spot size, whereas the autofocusing ability can be further enhanced by up to 193% with a ~ 56 {\mu}m focal spot size, while maintaining nearly the same DOF. Experimental results show good agreement with numerical simulations. The resulting asymmetric circular Airy derivative beams (ACADBs), combining strong abrupt autofocusing with extreme DOF, offer promising applications in optical trapping, optical communications, microfabrication, and biomedical imaging
Read the full abstract ▾
Chemical Physics · Cross-listed from quant-ph
An Analytically Trained Variational Surrogate for Quantum Phase Estimation on NISQ Hardware
Mousumi Kundu, Ashish Kumar Patra, Anurag K. S. V. et al. (+4 more)
Quantum Phase Estimation (QPE) is a foundational
algorithm for molecular ground-state energy estimation, but its deep
circuit requirements make direct hardware execution impractical on Noisy Intermediate-Scale
Quantum (NISQ) devices. We present an analytically grounded variational surrogate framework in which a shallow Variational
Quantum Circuit (VQC) is trained to reproduce the QPE measurement distribution without any
quantum circuit simulation. The training target is computed entirely classically via the Dirichlet kernel, evaluated directly from the Full Configuration Interaction (FCI) ground-state energy, the ancilla
qubit count, and the time
evolution parameter, eliminating the exponentially scaling simulation bottleneck of prior surrogate approaches. We apply this framework to the hydrogen molecule (H$_2$) with a
symmetry-tapered
Hamiltonian, conducting a four-stage experimental investigation on IBM
Quantum hardware. Stage 1 compares linear and full entangler
topologies for the $R_Y$-$R_Z$-$CZ$ ansatz, with and without XpXm Dynamical Decoupling (DD), across four distributional metrics (Hellinger distance, fidelity error, total variation distance, Jensen-Shannon divergence), identifying the linear entangler as optimal. Stage 2 varies VQC layers ($p=1$ to $5$) for the linear-entangler ansatz, identifying single-layer depth as optimal under hardware noise. Stage 3 applies this configuration to the reduced $R_Y$-$CZ$ ansatz, comparing ideal and noisy simulator-trained parameters. A supplementary noise analysis at $p \in \{8,64\}$ characterizes the depth-dependent interplay between
circuit depth and DD effectiveness. The framework enables faithful QPE mimicry using a linearly scaling VQC, recovering the ground-state energy within the chemical accuracy threshold (1 kcal/mol), constituting a scalable, hardware-efficient paradigm for QPE-based molecular energy estimation on NISQ devices.
Read the full abstract ▾
All authors Mousumi Kundu, Ashish Kumar Patra, Anurag K. S. V., Ruchika Bhat, Sai Shankar P., Alok Shukla, Jaiganesh G
Atomic Physics · Cross-listed from quant-ph
Generation of bright quantum high-order harmonic driven by combined coherent and bright squeezed vacuum light
Wentao Wang, Yaoshun Sun, Liyuan Wang et al. (+6 more)
Attosecond
quantum light, formed by the superposition of high-order harmonics driven by intense
quantum light, opens new routes to probe
quantum-mechanical correlations in matter. In this study, we have investigated the macroscopic propagation effects of
quantum high-order harmonics generated by the combination of strong coherent and weak bright squeezed
vacuum (BSV)
lasers interacting with atomic gas. Our results reveal that the pressure-dependent intensity of harmonics arising from absorbing or emitting BSV
photons differs from that of harmonics generated using only strong coherent pulses. Macroscopic propagation simulations indicate that the action phase of harmonics is perturbed by the weak BSV pulses. This perturbation modulates the phase mismatch of sub-cycle attosecond bursts and affects their
quantum properties when the gas pressure varies. The ability to generate bright
quantum high-order harmonics lays a foundation for the establishment and application of attosecond
quantum spectroscopy.
Read the full abstract ▾
All authors Wentao Wang, Yaoshun Sun, Liyuan Wang, Lingrui Hu, Dajun Ding, Xiangyu Tang, Mingxuan Li, Jianmin Yuan, Sizuo Luo
Atomic Physics
Measurement of the reduced dipole matrix element in Ba$^+$
N. Jayjong, M. D. K. Lee, K. J. Arnold et al. (+1 more)
We present a high-precision measurement of the reduced electric-dipole
matrix element $\langle P_{1/2}\|r\|S_{1/2}\rangle$ in $^{138}\mathrm{Ba}^+$. By comparing off-resonant scattering rates with dispersive Stark-shift measurements, we determine the
matrix element to be $3.322\,7(12)$, corresponding to a $P_{1/2}$ excited-state radiative lifetime of $7.866\,3(56)$~ns. Combining our experimental results with a prior model for the differential scalar polarizability $\Delta\alpha_0(\omega)$, we extract the static value $\Delta\alpha_0(0) = -73.09(12)$a.u. This determination directly improves the evaluation of the blackbody radiation (BBR) shift, minimizing a prominent systematic limitation in room-temperature $\mathrm{Ba}^+$ optical clock error budgets. These results provide a stringent
benchmark for atomic-structure calculations and advance high-precision applications in
quantum metrology and tests of fundamental physics.
Read the full abstract ▾
All authors N. Jayjong, M. D. K. Lee, K. J. Arnold, M. D. Barrett
Biological Physics · Cross-listed from q-bio.PE
Evolutionary Le Chatelier's Principle: Phenotypic Plasticity and Genetic Assimilation via Timescale Separation in the Price Equation
Tetsuhiro S. Hatakeyama
Phenotypic plasticity and genetic assimilation play key roles in adaptive
evolution, yet their underlying mechanism has lacked a unified physical description. A major theoretical difficulty lies in the fundamental difference in timescales, as phenotypic plasticity occurs rapidly within a generation whereas genetic changes accumulate slowly across generations. Here, we formalize these processes by bridging the continuous-time Price equation, a foundational equation of evolutionary dynamics, with the physical concept of timescale separation. A sudden environmental change induces a fast plastic displacement of the phenotype relative to the slow genotypic variable. Through genotype–phenotype coupling, this displacement generates an internal genetic stress. We demonstrate that genetic assimilation is a dynamical relaxation process in which the genotype evolves to resolve this self-generated stress. These evolutionary dynamics mathematically realize Le Chatelier's principle, where the slow genetic response naturally amplifies the initial plastic shift in the same direction. The theory predicts that a weaker restoring force, which can manifest as larger clonal phenotypic fluctuations, requires a longer evolutionary timescale for assimilation. In the ideal limit of cost-free, perfectly adaptive plasticity, the relaxation time diverges, so assimilation effectively stalls. This formulation provides a macroscopic physical mechanism for genetic assimilation, offering a universal response law for evolutionary systems in which rapid phenotypic responses precede slower genetic change.
Read the full abstract ▾