Physics and Society · Cross-listed from cs.SI
Information is localized in growing network models
Till Hoffmann and Jukka-Pekka Onnela
Mechanistic network models can capture salient characteristics of empirical networks using a small set of domain-specific, interpretable mechanisms. Yet inference remains challenging because the likelihood is often intractable. We show that, for a broad class of growing network models, information about model parameters is localized in the network, i.e., the likelihood can be expressed in terms of small subgraphs. We take a
Bayesian perspective to inference and develop neural density
estimators (NDEs) to approximate the posterior distribution of model parameters using graph neural networks (GNNs) with limited receptive size, i.e., the GNN can only "see" small subgraphs. We characterize nine growing network models in terms of their localization and demonstrate that localization predictions agree with NDEs on simulated data. Even for non-localized models, NDEs can infer high-fidelity posteriors matching model-specific inference methods at a fraction of the cost. Our findings establish information localization as a fundamental property of network growth, theoretically justifying the analysis of local subgraphs embedded in larger, unobserved networks and the use of GNNs with limited receptive field for likelihood-free inference.
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Chemical Physics · Cross-listed from cond-mat.soft
Predicting random close packing of binary hard-disk mixtures via third-virial-based parameters
Andrés Santos and Mariano López de Haro
We propose a simple and accurate approach to estimate the random close packing (RCP) fraction of binary hard-disk mixtures. By introducing a parameter based on the mixture's reduced third virial coefficient – which effectively captures three-body correlations and excluded-area constraints – we show that the RCP fraction depends nearly linearly on this parameter, leading to a near-universal collapse of simulation data over a wide range of size ratios and compositions. Comparisons with previous models by Brouwers and Zaccone indicate that the present approach provides more accurate and consistent predictions. The method can be naturally extended to polydisperse mixtures with continuous size distributions and is structurally consistent with the surplus equation-of-state formulation, offering a compact framework for understanding the near universality of RCP in hard-disk systems.
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Instrumentation and Detectors
High-resolution 3D-printed plastic scintillators with tertiary dye
Chandler Moore, Michael Febbraro, Juan Manfredi et al. (+5 more)
Additive manufacturing offers efficient production of plastic scintillators with nontrivial geometries using vat polymerization, allowing fabrication of geometries which would be difficult or even impossible to produce using conventional subtractive manufacturing. This work presents a novel photocurable scintillator formula that includes coumarin 450 as a tertiary dye to enable high-resolution 3D printing via the manipulation of the 405 nm cure light. Bulk photocured and 3D printed (with and without tertiary dye) samples were compared through observational assessment and spectral response. All samples showed pulse shape discrimination between
neutron and gamma events. Inclusion of the tertiary dye has minimal impact on emission spectrum and light output, but significant impact on print resolution as shown by comparison of printed high-complexity geometries and feature resolution test objects. With the use of a cure-limiting dye, unsupported features, such as freestanding pillars, were resolvable down to 0.7 mm. Even finer resolution at or below 0.1 mm was achieved in fully supported, integrated structures printed with off-the-shelf 405 nm desktop 3D printer. Scintillators demonstrated a light output up to 50% of EJ-200 with a PSD figure of merit up to 1.35 at 0.9-1.1 MeVee.
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All authors Chandler Moore, Michael Febbraro, Juan Manfredi, Allen Wood, Daniel Rutstrom, Thomas Ruland, Brennan Hackett, Paul Hausladen
Fluid Dynamics
Three-dimensional modelling of serrated trailing-edge noise based on the Wiener-Hopf technique
Sicheng Zhang and Benshuai Lyu
In this paper, a semi-analytical model based on the Wiener-
Hopf technique is developed to predict the turbulent boundary layer trailing edge noise from serrated edges, aiming to account for the correct three-dimensional noise source and propagation effects. The scattered surface pressure over a semi-infinite flat plate is first obtained using the Green's function developed for the acoustic scattering by a serrated edge. A radiation integral over the flat plate of a finite size is subsequently performed to obtain the far-field noise using Amiet's approach, capturing the correct three-dimensional source and propagation effects. The model is subsequently validated by comparing it against the two-dimensional Wiener-
Hopf-based model under various serration sizes and frequencies. Far-field spectral predictions show close agreement between the three- and two-dimensional models at moderate observer distances around $r/c=1$, where $r$ and $c$ represent the observer distance and the chord length, respectively. However, unlike the two-dimensional model, the present model successfully captures the far-field $1/r$ decay in noise amplitudes. In addition, the predicted directivity agrees well with the two-dimensional model at most observer angles, but also captures the correct dipolar behaviour at upstream angles and additional high-frequency lobes due to interference patterns induced by the finite flat plate. Compared to the previous three-dimensional serrated models, the present model is based on the Wiener-
Hopf technique and achieves a speed-up ratio of two orders of magnitude. It is hoped that such a model may be used to enable an efficient numerical optimisation of the serration shape in realistic applications.
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Computational Physics
MultiAtomLiouvilleEquationGenerator: A Mathematica package for Liouville superoperators and master equations of multilevel atomic systems
Pablo Yanes-Thomas, Rocío Jáuregui-Renaud, Santiago F. Caballero-Benítez et al. (+2 more)
MulAtoLEG (Multi-Atom Liouville Equation Generator) is an open-source Mathematica package for generating Liouville superoperators and Liouville equations, specialized for multilevel atomic systems comprising an arbitrary number of atoms. This scheme is based on an extension to multilevel atomic systems, originally developed by Lehmberg [R. H. Lehmberg, Phys. Rev. A 2, 883 (1970)] as an adjoint master equation for ensembles of two-level emitters and later reformulated by Genes [M. Reitz, C. Sommer and C. Genes, PRX
Quantum 3, 010201 (2022)] as a master equation. The package facilitates the generation of equations for complex transition configurations in alkali atoms. Although primarily designed for atomic systems, it can also generate the master and adjoint master equations for general
Hamiltonians and Lindbladians. In addition, it includes functionalities to construct the differential equations in the dressed-state basis, where, in many cases, the non-
unitary evolution operator can be determined explicitly. To maximize computational efficiency, the package leverages Mathematica's vectorization and sparse linear
algebra capabilities. Since MulAtoLEG produces exact equations without approximations, the feasible system size is naturally limited by the available computational resources.
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All authors Pablo Yanes-Thomas, Rocío Jáuregui-Renaud, Santiago F. Caballero-Benítez, Daniel Sahagún Sánchez, Alejandro Kunold
Classical Physics
New approach to approximate analytical solutions for a harmonic oscillator subject to combined linear and nonlinear damping
Karlo Lelas and Robert Pezer
We introduce a new approach to deriving approximate analytical solutions of a harmonic oscillator damped by purely nonlinear, or combinations of linear and nonlinear damping forces. Our approach is based on choosing a suitable trial solution, i.e. an ansatz, which is the product of the time-dependent amplitude and the oscillatory (trigonometric) function with a reduced frequency (due solely to linear damping) and an initial phase shift (due to both linear and nonlinear damping) compared to the undamped case. We derive the amplitude decay equation using the connection of the energy dissipation rate with the power of the total damping force. By matching our ansatz to the initial conditions, we obtain equations for its initial amplitude and initial phase. We demonstrate the validity of our approach for quadratic damping, a combination of linear and quadratic damping, and finally a combination of linear, quadratic, and Coulomb damping. For pure quadratic damping and for a combination of linear and quadratic damping, we compare our approximate analytical solutions with the corresponding numerical solutions and find that they describe the oscillator dynamics well in the regime of weak to moderately strong damping. For the combination of all three types of damping, our solutions agree well with the numerical solutions until the last half-period or the last few half-periods of the motion (primarily depending on the strength of the Coulomb damping). In addition, we show how to use our solutions to determine damping constants from given displacement vs. time data, demonstrating that they can be applied to the analysis of experiments.
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Computational Physics · Cross-listed from cond-mat.mtrl-sci
The Fundamental Lemma of Altermagnetism: Emergence of Alterferrimagnetism
Chanchal K. Barman, Bishal Das, Alessio Filippetti et al. (+2 more)
Recent years have seen a proliferation in investigations on Altermagnetism due to its exciting prospects both from an applications perspective and theoretical standpoint. Traditionally, altermagnets are distinguished from collinear antiferromagnets using the central concept of halving subgroups within the
spin space group formalism. In this work, we propose the Fundamental Lemma of Altermagnetism (FLAM) deriving the exact conditions required for the existence of altermagnetic phase in a
magnetic material on the basis of site-
symmetry groups and halving subgroups for a given crystallographic space group. The
spin group formalism further clubs ferrimagnetism with ferromagnetism since the same-
spin and opposite-
spin sublattices lose their meaning in the presence of multiple
magnetic species. As a consequence of FLAM, we further propose a class of fully compensated ferrimagnets, termed as Alterferrimagnets (AFiMs), which can show alternating momentum-dependent
spin-polarized non-relativistic electronic bands within the first Brillouin zone. We show that alterferrimagnetism is a generalization of traditional collinear altermagnetism where multiple
magnetic species are allowed to coexist forming fully compensated
magnetic-sublattices, each with individual up-
spin and down-
spin sublattices.
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All authors Chanchal K. Barman, Bishal Das, Alessio Filippetti, Aftab Alam, Fabio Bernardini
Applied Physics · Cross-listed from cond-mat.soft
Exploring phase transitions and thermal dynamics in nanoconfined liquid crystals using liquid-phase TEM
Olga Kaczmarczyk, Konrad Cyprych, Dominika Benkowska-Biernacka et al. (+6 more)
Nanoconfined
liquid crystals (LCs) and their nanocomposites are driving the next generation of photonic applications. Consequently, deepening our understanding of mesophase stability, defect
topology, and the dynamic response of LCs at the nanoscale requires the development of novel characterization approaches. This motivates us to perform in situ observations on model 4'-octyl-4-cyanobiphenyl (8CB) LC using
liquid-phase scanning transmission electron microscopy (LP-STEM). We find that the electron beam induced consecutive phase changes from smectic A to nematic (SmA-N) and from nematic to isotropic (N-I). The kinetic dependence of the phase transition on dose rate shows that the time between SmA-N and N-I shortens with increasing rate, revealing the hypothesis that a higher electron dose rate increases the energy dissipation rate, leading to substantial heat generation in the sample. We report on the spontaneous formation of disclinations, ordering effects, and complete process reversibility. Radiolytic effects of the electron beam are discussed in detail, and additional experiments with external heating indicate that the observed phenomena are mainly thermal in nature. The results are supported by calculations of heat
diffusion, suggesting the nanoconfined 8CB differs significantly in thermal properties compared to the bulk one. This is the first detailed study of LC phase transitions using LP-STEM, which paves the way for further studies of nanoconfined LCs and for the development of the technique for advanced LC materials research.
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All authors Olga Kaczmarczyk, Konrad Cyprych, Dominika Benkowska-Biernacka, Rafał Kowalczyk, Katarzyna Matczyszyn, Hanglong Wu, Frances M. Ross, Andrzej Miniewicz, Andrzej Żak
Optics
Low loss switchable topological photonic crystal enabled by submicron-scale patterning and phase-change of Sb2Se3
Takahiro Uemura, Yuto Moritake, Eiichi Kuramochi et al. (+3 more)
Photonic topological
insulators (PTIs) offer robust platforms for light manipulation, but reconfigurable control of their topological properties without degrading performance remains a major challenge. While phase-change materials (PCMs) provide large refractive index modulation, widely used materials such as Ge2Sb2Te5 (GST) have been successfully deployed in commercial applications including optical data storage. However, they exhibit significant optical absorption in their crystalline state, which poses a challenge for transmissive photonic devices such as PTIs where high transparency is essential. Here, we overcome this fundamental limitation by integrating the ultra-low-loss PCM antimony triselenide (Sb2Se3) onto a silicon-based 2D PTI. We achieve submicron-scale selective patterning of Sb2Se3 on a photonic
crystal for the first time, and demonstrate a topological phase transition induced by the material phase change. Owing to the transparency of Sb2Se3 in both its amorphous and crystalline states, a high Q-factor on the order of 10^3 is preserved-representing nearly an order-of-magnitude improvement over previous GST-based devices. This work resolves the absorption-loss bottleneck in reconfigurable PTIs and paves the way for practical, low-loss, tunable topological photonic devices.
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All authors Takahiro Uemura, Yuto Moritake, Eiichi Kuramochi, Masaaki Ono, Hisashi Sumikura, Masaya Notomi
Optics
A NEAT Approach to Evolving Neural-Network-based Optimization of Chiral Photonic Metasurfaces: Application of a Neuro-Evolution Pipeline
Davide Filippozzi and Arash Rahimi-Iman
The design of
chiral metasurfaces with tailored optical properties remains a central challenge in nanophotonics due to the highly nonlinear relationship between geometry and chiroptical response. Machine-learning-assisted optimization pipelines have recently emerged as efficient tools to accelerate this process, yet their performance strongly depends on the choice of neural-network (NN) architecture. In this work, we integrate the NeuroEvolution of Augmenting
Topologies (NEAT)
algorithm into an established deep-learning optimization framework for dielectric
chiral metasurfaces. NEAT autonomously evolves both network
topology and connection weights, enabling task-specific architectures without manual tuning, whereas the reinforcement-learning strategy in our framework evolves knowledge of the solution space and fine-tunes a model's weights in parallel. Using a pipeline-produced
dataset of 9,600 simulated GaP metasurface geometries, we evaluate NEAT under varying input dimensionalities, feature-scaling methods, and data sizes. With standardized feature scaling yielding the most consistent performance for both examined output dimensionalities, the relatively compact NEAT-evolved NN models, when integrated into the full optimization pipeline, achieve similar or improved predictive accuracy and generalization compared to initially employed dense few-layer perceptrons. Accordingly, these resource-efficient models successfully perform inference of metasurfaces exhibiting strong circular dichroism in the visible spectrum, allowing for transfer learning between simulated and experimental data. This approach demonstrates a scalable path toward adaptive, self-configuring machine-learning frameworks for automated photonic design both standalone and as building block for agentic artificial intelligence (AI).
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Instrumentation and Detectors · Cross-listed from gr-qc
The new generation lunar gravitational wave detectors: sky map resolution and joint analysis
Xiaolin Zhang, Chengye Yu, Haoran Li et al. (+3 more)
Lunar-based gravitational-wave interferometry is a fascinating endeavor, and was proposed as a promising approach to bridge the observational gap between space-borne and ground-based detectors. In this work, we adopt the Fisher-
matrix method to examine the angular-resolution performance of the newly proposed Crater Interferometry Gravitational-wave Observatory (CIGO) on the lunar crater rim near the north pole, together with TianQin and LISA, for monochromatic sources in the 0.1-10 Hz band. We find that above 0.1 Hz, CIGO achieves better localization accuracy than the other two space-based missions and dominates the combined detector network's performance, provided that lunar noise mitigation is achieved in the 0.1-2.87 Hz frequency range. We further explore an upgraded Tetrahedron configuration, TCIGO, with a fourth station at the bottom of a crater, which forms a regular tetrahedral constellation on the lunar surface. The result shows that TCIGO yields a five-fold improvement in angular-resolution capability over CIGO and gets better sky coverage across the target frequency band.
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All authors Xiaolin Zhang, Chengye Yu, Haoran Li, Sobhan Kazempour, Mingqiu Li, Sichun Sun
Medical Physics
Physical Limits of Proximal Tumor Detection via MAGE-A Extracellular Vesicles
A. Sila Okcu, M. Etem Bas and Ozgur B. Akan
Early cancer detection relies on invasive tissue biopsies or
liquid biopsies limited by biomarker dilution. In contrast, tumour-derived extracellular vesicles (EVs) carrying biomarkers like melanoma-associated antigen-A (MAGE-A) are highly concentrated in the peri-tumoral interstitial space, offering a promising near-field target. However, at micrometre scales, EV transport is governed by
stochastic diffusion in a low copy number regime, increasing the risk of false negatives. We theoretically assess the feasibility of a smart-needle sensor detecting MAGE-A-positive microvesicles near a tumour. We use a hybrid framework combining particle-based Brownian dynamics (Smoldyn) to quantify
stochastic arrival and false negative probabilities, and a reaction-
diffusion PDE for mean concentration profiles. Formulating detection as a threshold-based binary hypothesis test, we find a maximum feasible detection radius of approximately 275 micrometers for a 6000 s sensing window. These results outline the physical limits of proximal EV-based detection and inform the design of minimally invasive peri-tumoral sensors.
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Biological Physics · Cross-listed from q-bio.QM
An integrated quantitative single-objective light-sheet microscope for subcellular dynamics in embryos and cultured multicellular systems
Armin Shoushtarizadeh, Michele Cerminara, Corinne Chureau et al. (+3 more)
Quantitative imaging of subcellular processes in living embryos, stem-
cell systems, and organoid models requires microscopy platforms that combine high spatial resolution, fast volumetric acquisition, long-term stability, and minimal phototoxicity. Single-objective light-sheet approaches based on oblique plane microscopy (OPM) are well suited for live imaging in standard sample geometries, but most existing implementations lack the optical calibration, timing precision, and end-to-end integration required for reproducible quantitative measurements. Here we present a fully integrated and quantitatively characterized OPM platform engineered for dynamic studies of transcription and
nuclear organization in embryos, embryonic stem
cells, and three-dimensional culture systems. The system combines high numerical aperture remote refocusing with tilt-invariant light-sheet scanning and hardware-timed synchronization of
laser excitation, galvo scanning, and camera readout. We provide a comprehensive characterization of the optical performance, including point spread function, sampling geometry, usable field of view, and system stability, establishing a well-defined framework for quantitative volumetric imaging. To support high-throughput operation, we developed a unified acquisition and reconstruction pipeline that enables real time volumetric imaging at hardware-limited rates while preserving deterministic timing and reproducible geometry. Using this platform, we demonstrate quantitative three-dimensional imaging of MS2-labeled transcription sites in living Drosophila embryos, cultured mouse embryonic stem
cells, and mESC-derived gastruloids, enabling extraction of transcriptional intensity traces across diverse biological contexts. This work establishes OPM as a robust and quantitatively calibrated single-objective light-sheet platform for transcription imaging in complex living systems.
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All authors Armin Shoushtarizadeh, Michele Cerminara, Corinne Chureau, Leah Friedman, Deepthi Kailash, Thomas Gregor
Optics
Fisher Information as an Operational Metric for Structured Optical Beams
J.Sumaya-Martinez and J. Mulia-Rodriguez
Structured optical beams possess rich spatial features that are commonly characterized using entropic measures of field complexity. However, such measures do not directly quantify the operational usefulness of optical structure for parameter estimation and sensing. Here we introduce Fisher information as an operational metric to assess the metrological content of structured optical fields. By treating the measured intensity distribution as a statistical object, we define Fisher information with respect to physically relevant parameters, such as transverse displacement. We demonstrate that optical modes with comparable Shannon
entropy can exhibit markedly different Fisher information, revealing sensitivity features associated with nodal structure and local
curvature. Using Hermite–Gaussian modes as minimal test cases, we show that increasing modal order systematically enhances Fisher information. We then extend the analysis to two widely used families in structured light: Laguerre–Gaussian
vortex beams and finite-energy Bessel–Gauss beams. Across these representative families, Fisher information provides a unified and experimentally accessible criterion for comparing structured optical fields in sensing applications.
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Biological Physics
Ambiguous signals and efficient codes
Marianne Bauer and William Bialek
In many biological networks the responses of individual elements are ambiguous. We consider a scenario in which many sensors respond to a shared signal, each with limited information capacity, and ask that the outputs together convey as much information as possible about an underlying relevant variable. In a low noise limit where we can make analytic progress, we show that individually ambiguous responses optimize overall information transmission.
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Optics
Deformation enduring conveyance of structured light through multimode waveguides and its exploitation for flexible hair-thin endoscopes
Sergey Turtaev, Tomáš Tyc, Ulf Poßner et al. (+6 more)
The remarkable advancements in our capacity to synthesise structured light have facilitated the generation of any desired optical landscapes and even controlling the spatial distribution of light propagating through optically complex media such as multimode fibres. The availability of precisely defined structured light at the extremity of an exceedingly narrow and flexible cable holds the potential to stimulate a diverse range of highly sought-after applications, encompassing rapid communication,
quantum computing, and, notably, imaging. What we lack in reaching these aspirations is the resilience of such light transport to deformations of the waveguide. Although recent theoretical investigations have delineated the attributes of ideal multimode fibres capable of deformation-enduring conveyance of structured light, tangible fibres possessing this indispensable trait to a practical extent remain elusive. Our study takes a deep dive into the precision of commercially available multimode fibres with the highest probability of demonstrating the phenomenon. We identified minuscule imperfections in their refractive index distribution, examined how these affect light transport when the fibre is deformed, and studied their implications for imaging applications. Our investigation has confirmed that these imperfections are indeed responsible for the undesirable alterations introduced into the output structured light fields during bending. Finally, as an alternative to standard graded-index fibres, manufactured by drawing silica-based preforms, we present narrow multimode waveguides in which the refractive-index profile has been established by ion exchange. These waveguides indeed exhibit previously unseen resilience of structured light transport even under severe deformation conditions and aptly fulfil the requirements of imaging applications.
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All authors Sergey Turtaev, Tomáš Tyc, Ulf Poßner, Tina Eschrich, Torsten Poßner, Yang Du, André Gomes, Bernhard Messerschmidt, Tomáš Čižmár
Medical Physics
Incorporating Tissue Composition Information in Total-Body PET Metabolic Quantification of Bone Marrow through Dual-Energy CT
Siqi Li, Benjamin A. Spencer, Yiran Wang et al. (+7 more)
Bone marrow (BM) metabolic quantification with 18F-fluorodeoxyglucose (FDG) positron emission
tomography (PET) is of broad clinical significance for accurate assessment of BM at staging and follow-up, especially when immunotherapy is involved. However, current methods of quantifying BM may be inaccurate because the volume defined to measure bone marrow may also consist of a fraction of trabecular bone in which 18F-FDG activity is negligible, resulting in a potential underestimation of true BM uptake. In this study, we demonstrate this bone-led tissue composition effect and propose a bone fraction correction (BFC) method using X-ray dual-energy computed
tomography (DECT) material decomposition. This study included ten scans from five cancer patients who underwent baseline and follow-up dynamic 18F-FDG PET and DECT scans using the uEXPLORER total-body PET/CT system. The voxel-wise bone volume fraction was estimated from DECT and then incorporated into the PET measurement formulas for BFC. The standardized uptake value (SUV), 18F-FDG delivery rate K1, and net influx rate Ki values in BM regions were estimated with and without BFC and compared using the statistical analysis. The results first demonstrated the feasibility of performing voxel-wise material decomposition using DECT for metabolic BM imaging. With BFC, the SUV, K1, and Ki values significantly increased by an average of 13.28% in BM regions compared to those without BFC (all P<0.0001), indicating the impact of BFC for BM quantification. Parametric imaging with BFC further confirmed regional analysis. Our study using DECT suggests current SUV and kinetic quantification of BM are likely underestimated in PET due to the presence of a significant bone volume fraction. Incorporating tissue composition information through BFC may improve BM metabolic quantification.
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All authors Siqi Li, Benjamin A. Spencer, Yiran Wang, Yasser G. Abdelhafez, Heather Hunt, J. Anthony Seibert, Simon R. Cherry, Ramsey D. Badawi, Lorenzo Nardo, Guobao Wang
Optics · Cross-listed from quant-ph
Cavity-Free $\Delta$-Type Coherent Population Trapping for Microwave Sensing
Ido Fridman, Shemuel Sternklar and Eliran Talker
We investigated experimentally and theoretically a cavity-free microwave field that couples the two ground states of a {\Lambda}-type atomic system, thereby forming a closed {\Delta} configuration. In this regime, the absence of cavity-imposed phase matching leads to a strong sensitivity of the ground-state coherence to the microwave field parameters. We observe that the coherent population trapping (CPT) resonance exhibits a pronounced dependence on the microwave power and detuning, resulting in measurable changes in resonance contrast, linewidth, and center frequency. To explain these effects, we develop a numerical density-
matrix model in which the ground-state coherence explicitly incorporates the microwave coupling strength, capturing the essential physics of this no-phase-matching {\Delta} system. The excellent agreement between theory and experiment establishes a simple and robust framework for microwave control of cavity-free {\Delta}-type atomic systems, with direct implications for compact atomic clocks and
quantum-enhanced
quantum sensing platforms.
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Optics
Accelerated Topological Pumping in Photonic Waveguides Based on Global Adiabatic Criteria
Kai-Heng Xiao, Shi-Lei Su, Xiang Ni et al. (+8 more)
Adiabatic topological pumping enables robust transport of energy and information, yet its operational speed is fundamentally constrained by the instantaneous adiabatic condition, which necessitates prohibitively slow parameter variations. Here, we propose a paradigm shift from instantaneous to global adiabaticity. We derive a global adiabatic criterion (GAC) that establishes an absolute fidelity bound by controlling the root-mean-square nonadiabaticity. Building on this framework, we introduce a fluctuation-suppression acceleration criterion to minimize spatial inhomogeneity, allowing for a safe increase in mean nonadiabaticity without compromising fidelity. We experimentally demonstrate this principle in femtosecond-
laser-written photonic Su-Schrieffer-Heeger waveguide arrays via scalable power-law coupling modulation. Our accelerated topological pumping achieves a fidelity of >0.95 with a fivefold reduction in device length compared to conventional schemes, exhibits the predicted linear scaling with system size, and maintains robust performance across a bandwidth exceeding 400 nm. This GAC framework provides a universal design rule for fast, compact, and robust adiabatic devices across both
quantum and classical topological platforms.
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All authors Kai-Heng Xiao, Shi-Lei Su, Xiang Ni, Yi-Ke Sun, Jin-Kang Guo, Zhi-Yong Hu, Xu-Lin Zhang, Jia Li, Jin-Lei Wu, Zhen-Nan Tian, Qi-Dai Chen
Applied Physics
Adaptive Fusion Graph Network for 3D Strain Field Prediction in Solid Rocket Motor Grains
Jiada Huang, Hao Ma, Zhibin Shen et al. (+2 more)
Local high strain in solid rocket motor grains is a primary cause of structural failure. However, traditional numerical simulations are computationally expensive, and existing surrogate models cannot explicitly establish
geometric models and accurately capture high-strain regions. Therefore, this paper proposes an adaptive graph network, GrainGNet, which employs an adaptive pooling dynamic node selection mechanism to effectively preserve the key mechanical features of structurally critical regions, while concurrently utilising feature fusion to transmit deep features and enhance the model's representational capacity. In the joint prediction task involving four sequential conditions–curing and cooling, storage, overloading, and ignition–GrainGNet reduces the mean squared error by 62.8% compared to the baseline graph U-Net model, with only a 5.2% increase in parameter count and an approximately sevenfold improvement in training efficiency. Furthermore, in the high-strain regions of debonding seams, the prediction error is further reduced by 33% compared to the second-best method, offering a computationally efficient and high-fidelity approach to evaluate motor structural safety.
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All authors Jiada Huang, Hao Ma, Zhibin Shen, Yizhou Qiao, Haiyang Li
Plasma Physics
Non-equilibrium classical recombination in the expanding ultracold plasmas
Yurii V. Dumin, Ludmila M. Svirskaya and Eugen S. Savinykh
The efficiency of recombination is of crucial importance for the existence of ultracold
plasmas (UCP), particularly, the ones formed in the magneto-optical traps. Unfortunately, the
equilibrium thermodynamic treatment of the ionization-recombination processes is inappropriate for the evolving UCP clouds, while the straightforward kinetic simulation encounters the problem of huge difference in the spatial and temporal scales for free and bound motion of the electrons. As a result, only the "virtual" electron-ion pairs are usually reproduced in such modeling, and it is necessary to employ some heuristic criteria to identify them with the recombined atoms. It is the aim of this paper to present the first successful ab initio simulation of the non-
equilibrium recombination in the evolving UCP
plasmas. We employed a special
algorithm, which is based on using the "scalable" reference frame, co-moving with the expanding substance. Then, the recombination events are identified by a series of sharp equidistant peaks in the kinetic and/or potential energies, which are caused by the captured electrons passing near the pericenters of their orbits; and this is confirmed by a detailed inspection of their trajectories. Thereby, we were able to trace the real - rather than "virtual" - electron-ion pairs, and the total efficiency of their formation was found to be about 20%, which is in agreement with the laboratory measurements.
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Applied Physics
High-Efficiency Octave Bandwidth Rectifier for Electromagnetic Energy Harvesting
Haoming He, Yilin Zhou, Zhongqi He et al. (+2 more)
This letter presents the design and implementation of a compact high-efficiency octave microwave rectifier. A key highlight is the novel segmented impedance matching method, a unique approach that expands the rectifier bandwidth. The diode reactance is initially regulated by a series short-ended microstrip line. Impedance-compensated structures, characterized by varying admittance properties across an extensive frequency range, partition the operating frequency band into two segments based on the input impedance, thereby minimizing impedance variation. Ultimately, the input impedance is matched by a novel triple-band matching network. An octave rectifier was fabricated and measured. Results demonstrate that the rectifier achieves over 50% efficiency over 1.3-2.55 GHz fractional bandwidth 64.9% at 0-dBm RF input power. Even with a decrease in input power to -10 dBm, the rectifier maintains over 30% efficiency.
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All authors Haoming He, Yilin Zhou, Zhongqi He, Yuhao Feng, Changjun Liu
Computational Physics
PINNs for Electromagnetic Wave Propagation
Nilufer K. Bulut
Physics-Informed Neural Networks (PINNs) solve physical systems by incorporating governing partial differential equations directly into neural network training. In electromagnetism, where well-established methodologies such as FDTD and FEM already exist, new methodologies are expected to provide clear advantages to be accepted. Despite their mesh-free nature and applicability to inverse problems, PINNs can exhibit deficiencies in accuracy and energy metrics compared to FDTD. This study demonstrates that hybrid training strategies can bring PINNs closer to FDTD-level accuracy and energy consistency. A hybrid methodology addressing common challenges in wave propagation is presented. Causality collapse in time-dependent PINN training is addressed via time marching and causality-aware weighting. To mitigate discontinuities introduced by time marching, a two stage interface continuity loss is applied. To suppress cumulative energy drift in electromagnetic waves, a local Poynting-based regularizer is developed. In the developed PINN model, high field accuracy is achieved with an average 0.09% NRMSE and 1.01% $L^2$ error over time. Energy conservation is achieved with only a 0.02% relative energy mismatch in the 2D PEC cavity scenario. Training is performed without labeled field data, using only physics-based residual losses; FDTD is used solely for post-training evaluation. The results demonstrate that PINNs can achieve competitive results with FDTD in canonical electromagnetic examples and are a viable alternative.
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Optics
Electro-optical modulation of light polarization in a nonlocal lithium niobate metasurface
Agostino Di Francescantonio, Alessandra Sabatti, Eleni Prountzou et al. (+6 more)
We report the experimental realization of a LiNbO3 metasurface for electro-optic modulation of light polarization in the telecommunication band. High-Q quasi-bound states in the continuum are emploied to enhance the modulation of amplitude and phase of an impinging beam by a driving electric field, leading to efficient polarization rotation and conversion. We quantified modulation effects under a CMOS-compatible bias at 1 MHz frequency, achieving a variation of 5% in the Stokes parameters and a variation of the polarization ellipse angles of about 3{\deg} for the transmitted light. These results demonstrate that dynamic polarization and phase modulation can be attained in a compact platform, highlighting the potential of high-Q resonant LiNbO3 metasurfaces for enhanced light-matter interaction in subwavelength electro-optic devices.
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All authors Agostino Di Francescantonio, Alessandra Sabatti, Eleni Prountzou, Maria Antonietta Vincenti, Luca Carletti, Attilio Zilli, Michele Celebrano, Rachel Grange, Marco Finazzi
Geophysics · Cross-listed from cs.LG
Diffusion priors enhanced velocity model building from time-lag images using a neural operator
Xiao Ma, Mohammad Hasyim Taufik and Tariq Alkhalifah
Velocity model building serves as a crucial component for achieving high precision subsurface imaging. However, conventional velocity model building methods are often computationally expensive and time consuming. In recent years, with the rapid advancement of deep learning, particularly the success of generative models and neural operators, deep learning based approaches that integrate data and their statistics have attracted increasing
attention in addressing the limitations of traditional methods. In this study, we propose a novel framework that combines generative models with neural operators to obtain high resolution velocity models efficiently. Within this workflow, the neural operator functions as a forward mapping operator to rapidly generate time lag reverse time migration (RTM) extended images from the true and migration velocity models. In this framework, the neural operator is acting as a surrogate for modeling followed by migration, which uses the true and migration velocities, respectively. The trained neural operator is then employed, through automatic differentiation, to gradually update the migration velocity placed in the true velocity input channel with high resolution components so that the output of the network matches the time lag images of observed data obtained using the migration velocity. By
embedding a generative model, trained on a high-resolution velocity model distribution, which corresponds to the true velocity model distribution used to train the neural operator, as a regularizer, the resulting predictions are cleaner with higher resolution information. Both synthetic and field data experiments demonstrate the effectiveness of the proposed generative neural operator based velocity model building approach.
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Optics · Cross-listed from cond-mat.mes-hall
Soliton formation in a bound state in the continuum GaN waveguide polariton laser
V. Develay, O. Bahrova, I. Septembre et al. (+11 more)
We study polaritonic bound states in the continuum (BIC) created in GaN waveguides. The existence of
symmetry-protected BICs is confirmed by the suppression of light emission and the observation of a polarization
vortex in momentum space. Upon increasing the pumping, polariton population accumulates at the BIC and we observe polariton lasing from the blueshifted BIC states. The assessment of the polariton BIC emission energy and of its real and momentum space wavefunctions as a function of pumping power, i.e. of polariton density, indicates the formation of a bright
soliton above the lasing threshold.
Soliton formation at the BIC is induced by the combination of negative mass BIC and of repulsive polariton-polariton and polariton-reservoir interactions.
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All authors V. Develay, O. Bahrova, I. Septembre, D. Bobylev, C. Brimont, L. Doyennette, B. Alloing, H. Souissi, E. Cambril, S. Bouchoule, J. Zúñiga-Pérez, D. Solnyshkov, G. Malpuech, T. Guillet
Fluid Dynamics · Cross-listed from cond-mat.soft
An elasto-viscoplastic thixotropic model for fresh concrete capturing flow-rest transition
Jidu Yu, Bodhinanda Chandra, Christopher Wilkes et al. (+2 more)
The flow properties of fresh concrete are critical in the construction industry, as they directly affect casting quality and the durability of the final structure. Although non-Newtonian fluid models, such as the Bingham model, are widely used to model these flow properties, they often fail to capture key phenomena, including flow stoppage, and frequently rely on ad hoc, non-physical regularization or stabilization techniques to mitigate numerical instabilities at low shear rates. To address these limitations, this study proposes an elasto-viscoplastic constitutive model within the continuum mechanics framework, which treats fresh concrete as a solid-like material with a rate-dependent yield stress. The model inherently captures the transition from elastic response to viscous flow following Bingham rheology, and vice versa, enabling accurate prediction of flow cessation without ad hoc criteria. Additionally, a thixotropy
evolution law is incorporated to account for the time-dependent behavior resulting from physical flocculation and shear-induced deflocculation. The proposed model is implemented within the Material Point Method (MPM), whose Lagrangian formulation facilitates tracking of history-dependent variables and robust simulation of large deformation flows. Numerical examples demonstrate the model's effectiveness in reproducing a range of typical concrete flow scenarios, offering a more physically consistent numerical tool for optimizing concrete construction processes and minimizing defects.
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All authors Jidu Yu, Bodhinanda Chandra, Christopher Wilkes, Jidong Zhao, Kenichi Soga
Fluid Dynamics
Elliptical liquid jets in a supersonic cross-flow: Influence of J on atomization mechanism and unsteadiness
Chandrasekhar Medipati, Sivakumar Deivandren and Raghuraman N Govardhan
In our previous study [Medipati et al., (2025) J. Fluid Mech. 1014, A34] \cite{medipati2025
elliptic}, a detailed experimental investigation is performed on the elliptical
liquid jets in a supersonic cross-flow ($M_{\infty}$ = 2.5), focusing on the effect of orifice aspect ratio ($AR$ = spanwise dimension/streamwise dimension) on the atomization mechanism for a fixed momentum flux ratio ($J$). In this paper, we present experimental studies that show the influence of $J$ on the jet breakup mechanism, shock structures, and unsteady interactions for each $AR$. A wide range of $J$ values (1.5 to 9.7) and three $AR$ cases (0.3, 1, and 3.3) are chosen for the study. We find that in the case of lower $J$, the jet exhibits large unsteadiness, with larger wavelength Rayleigh-Taylor (RT) waves on the windward surface. In contrast, as the $J$ increases, the unsteadiness decreases, smaller and more regular RT wavelength is formed due to the enhanced drag resulting from the reduced jet deflection. However, irrespective of $J$, in the case of $AR$ = 0.3 and 1, the primary atomization mechanism is due to the formation of Kelvin-Helmholtz instabilities (KHI) on the lateral surfaces. Furthermore, in the case of lower $J$, the shock waves formed upstream of the jet are highly corrugated with significant variations in time. The intense interaction of the
liquid jet with the oncoming boundary layer streaks, in the case of lower $J$, is the primary source of large-scale unsteadiness. These findings highlight the significance of $J$ on the atomization mechanism in supersonic cross-flow.
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Computational Physics
A space-time extension of a conservative two-fluid cut-cell method for moving diffusion problems
Louis Libat, Can Selçuk, Eric Chénier et al. (+1 more)
We present a space-time extension of a conservative Cartesian cut-
cell finite-volume method for two-phase
diffusion problems with prescribed interface motion. The formulation follows a two-fluid approach: one scalar field is solved in each phase with discontinuous material properties, coupled by sharp interface conditions enforcing flux continuity and jump laws. To handle moving boundaries on a fixed Cartesian grid, the discrete balance is written over phase-restricted space-time control volumes, whose
geometric moments (swept volumes and apertures) are used as weights in the finite-volume operators. This construction naturally accounts for the creation and destruction of cut
cells (fresh/dead-
cell events) and yields strict discrete conservation. The resulting scheme retains the algebraic structure of the static cut-
cell formulation while incorporating motion through local
geometric weights and interface coupling operators. A series of verification and validation tests in two and three dimensions demonstrate super-linear accuracy in space, robust behavior under repeated
topology changes and conservation across strong coefficient jumps and moving interfaces. The proposed space-time cut-
cell framework provides a conservative building block for multiphase transport in evolving geometries and a foundation for future free-boundary extensions such as Stefan-type phase change.
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All authors Louis Libat, Can Selçuk, Eric Chénier, Vincent Le Chenadec
Atomic Physics
Magic wavelengths and triple magic trapping conditions for $5s^2~^1\!S_0$ and $5s5p~^3\!P_{0,2}$ states of Sr atoms
Yan-Min Wang, Qing-Yi Liu, Yong-Bo Tang et al. (+4 more)
The static and dynamic electric dipole polarizabilities of the $5s^2~^1\!S_0$ and $5s5p~^3\!P_{0,2}$ states of Sr atoms are calculated using the relativistic configuration interaction plus the many-body perturbation theory (RCI+MBPT) method. Magic wavelengths are determined for the transitions $5s^2~^1\!S_0\rightarrow 5s5p~^3\!P_{0}$, $5s^2~^1\!S_0\rightarrow 5s5p~^3\!P_{2}$, and $5s5p~^3\!P_0\rightarrow 5s5p~^3\!P_{2}$. A comprehensive study is conducted on the dependence of magic wavelengths on the angle between the
laser polarization and the
magnetic field. Furthermore, the conditions for realizing triple magic trapping at 813.4~nm for the $5s^2~^1\!S_0$, $5s5p~^3\!P_{0}$ and $5s5p~^3\!P_{2}$ states are investigated. In the case of linearly polarized light, when the angle ($\theta_p$) between the
laser polarization direction and the
magnetic field is $79.1(0.7)^\circ$, triple magic trapping for the $5s^2~^1\!S_0$, $5s5p~^3\!P_{0}$, and $5s5p~^3\!P_{2}~M=0$ states can be achieved. This result agrees well with the recent experimental measurement (78.49(3)$^\circ$)[Phys. Rev. Lett. 135, 143401 (2025)]. Meanwhile, triple magic trapping involving the $5s5p~^3\!P_{2}~M=2$ state can be achieved when $\theta_p= 37.4(0.3)^\circ$. The conditions for achieving triple magic trapping with circularly and arbitrarily elliptically polarized light are also presented.
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All authors Yan-Min Wang, Qing-Yi Liu, Yong-Bo Tang, Lei Wu, Deng-Hong Zhang, Chen-Zhong Dong, Jun Jiang