Optics
Thickness-dependence of Linear and Nonlinear Optical Properties of Multilayer 3R-MoS2
Fatemeh Abtahi, Alen Shaji, Gia Quyet Ngo et al. (+4 more)
3R-MoS2, a MoS2 polytype with broken inversion
symmetry, enables unique light-matter interactions and is promising for linear and nonlinear integrated photonics beyond the monolayer limit. Yet, systematic studies of its thickness-dependent reflectivity and its impact on harmonic generation are still lacking. . Yet, systematic studies of its thickness-dependent reflectivity and its impact on harmonic generation are still lacking. Here, we introduce a non-destructive optical method to determine the thickness of 3r-MoS2 flakes from reflectivity measurements, offering AFM-like precision with a mean bias of less than 2 nm range, while being much faster and applicable to non-solid substrates such as PDMS, in the 3-200 nm range. Nonlinear characterization further reveals distinct thickness-dependent maxima in second- and third-harmonic generation (SHG/THG), with the first clear peak at ~200 nm. These maxima arise from Fabry-Pérot-type phase matching conditions mediated by the film thickness and can further be shaped by absorption. This work thus provides both a practical thickness metrology and new insights for exploiting thickness-dependent 3R-MoS2 nonlinearities in scalable photonic technologies.
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All authors Fatemeh Abtahi, Alen Shaji, Gia Quyet Ngo, Benjamin Laudert, Hossein Esfandiar, Sebastian W. Schmitt, Falk Eilenberger
Optics
3D printed waveguides for optogenetics applications: design optimization and optical characterization
Giorgio Scordo, Kostas Kanellopulos, Surangrat Thongkorn et al. (+8 more)
Optogenetics has emerged as a powerful tool for disease modeling, enabling precise control of cellular activities through light stimulation and providing a valuable insights into disease mechanisms and therapeutic possibilities. Innovative materials and technologies such as micro-LEDs, optical fibers and micro/nano probes have been developed to allow precise spatial and temporal control of light delivery to target
cells. Recent advances in 3D printing have further enhanced optogenetic applications by enabling the fabrication of implantable, customizable, and miniaturized light stimulation systems with high spatial resolution. In this study, we introduce a novel concept of a 3D printed light delivery system for
brain organoid stimulation exploring the capabilities of projection microstereolithography (P$\mu$SL). We characterized the optical properties of the high-resolution acrylate-based 3D print resin, i.e., refractive index and extinction coefficient, to evaluate if the light transmission efficiency might limit the performance of the optogenetic stimulation systems. Finite element method simulations were employed to optimize the 3D printed design. An optogenetic setup was developed for optimal light delivery, and initial tests with optogenetically modified
cells showed light-induced dopamine release with a stimulation efficiency of 2.8%, confirming the 3D printed waveguide functionality and guiding future optimization. Our results demonstrate that this light stimulation tool offers strong potential for advancing customizable optogenetic applications.
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All authors Giorgio Scordo, Kostas Kanellopulos, Surangrat Thongkorn, Samuel Tavares da Silva Maraschin, Kambiz Ghaseminasab, Evgeniy Shkondin, Deepshika Arasu, Stephan Sylvest Keller, Arto Rainer Heiskanen, Marta Perez Pereira, Jenny Emnéus
History and Philosophy of Physics · Cross-listed from gr-qc
On the action principle as a guide to substantive general covariance
Ward Struyve
While Einstein was guided by the principle of general covariance in formulating general relativity, Kretschmann later argued that this principle lacks physical significance, since any space-time theory can be reformulated in a generally covariant form. This critique has prompted an ongoing debate over how to distinguish substantive general covariance from mere formal general covariance. Some proposals for defining substantive general covariance are based on the requirement that a theory be derivable from a diffeomorphism-invariant action. The present work aims to critically assess these proposals by examining canonical examples of Kretschmannian formulations of special relativistic theories. It will be shown that these formulations – which seem merely formally generally covariant – can always be derived from a diffeomorphism-invariant action. Although these actions involve auxiliary variables, these variables are trivial in the sense that they are either pure gauge or dynamically fixed by the other variables. Consequently, the theories described by these actions are arguably equivalent to the original Kretschmannian formulations. This stands in contrast to the actions proposed by Rosen and Sorkin, which include non-trivial auxiliary variables and hence seem to describe distinct physical theories. More recently, Freidel and Teh have suggested an additional criterion for substantial general covariance, namely that the action should also yield a non-trivial corner charge associated to diffeomorphism invariance. However, this too appears insufficient, since such actions can always be constructed.
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Optics
Large field-of-view, distortion-corrected off-axis parabolic mirror relay microscope
Meimei Liu, Yuqi Zhu and Giorgio Gratta
Off-axis
parabolic mirrors (OAPs) are occasionally desirable for specialized applications, but are known to introduce field-dependent astigmatic aberrations. In an experiment where optical tweezers are formed by OAPs, another OAP is added to form a relay configuration with an optional microscope, resulting in near diffraction-limited performance, with a resolution of $2.19$ $\mu m$. The severe radially non-uniform distortion incurred by this configuration, with a long path length and a large field of view, requires software corrections for the microscopic image. To avoid overfitting given the limited features available for calibration at the tweezers focal plane, a distortion model with a reduced set of parameters is selected based on simulation data. Applying the model to experimental data, an average residual error of $3.60$ $\mu m$ ($1.33$ $\mu m$) is achieved in object space after the simple relay (adding a $5 \times$ microscope) over a field of approximately $1$ $\mu m$ $\times$ $1$ $\mu m$ ($200$ $\mu m$ $\times$ $200$ $\mu m$). The residual errors are likely dominated by diffraction artifacts in the features used for correction.
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Atomic Physics · Cross-listed from cond-mat.mtrl-sci
Mechanistic study of mixed lithium halides solid state electrolytes
Davide Tisi, Sergey Pozdnyakov and Michele Ceriotti
Lithium halides with the general formula Li$_x$M$_y$X$_6$, where M indicates metal ions and X halide anions are very actively studied as solid-state electrolytes, because of relatively low cost, high stability and Li conductivity. The structure and properties of these halide-based solid electrolytes (HSE) can be tuned by alloying, e.g. using different halides and/or transition metals simultaneously. The large chemical space is difficult to sample by experiments, making simulations based on broadly applicable machine-learning interatomic potentials (MLIPs) a promising approach to elucidate structure-property relations, and facilitate the design of better-performing compositions. Here we focus on the Li$_3$YCl$_{6x}$Br$_{6(1-x)}$ system, for which reliable experimental data exists, and use the recently-developed PET-MAD universal MLIP to investigate the structure of the
alloy, the interplay of crystalline
lattice, volume and chemical composition, and its effect on Li conductivity. We find that the distribution of Cl and Br atoms is only weakly correlated, and that the primary effect of alloying is to modulate the
lattice parameter – although it can also trigger transition between different
lattice symmetries. By comparing constant-volume and constant-pressure simulations, we disentangle the effect of
lattice parameter and chemical composition on the conductivity, finding that the two effects compensate each other, reducing the overall dependency of conductivity on
alloy composition. An extended study of the effect of metal substitution, enabled by the semi-quantitative accuracy of the universal model, shows that the effect of metal-site alloying is small, indicating that alloying can be used to optimize cost, or electrochemical stability, without major impact on bulk conductivity.
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Atomic Physics
Comprehensive Assessment of $\mathrm{Th}^{3+}$ Properties for Nuclear Clock and Fundamental Physics Applications
A. Chakraborty and B. K. Sahoo
By employing singles, doubles, and triples excitations within the relativistic coupled-cluster framework, we perform comprehensive calculations of a wide range of atomic properties for the Th$^{3+}$ ion. These properties are essential for advancing
nuclear clock technology and probing fundamental physics. Combining our isotope shift parameters with experimental data, we estimate highly accurate values of the differential
nuclear charge radii for $^{232,229}$Th and $^{229m,229}$Th. Additionally, we determine the
nuclear magnetic dipole and electric quadrupole moments for both the ground and isomeric states of $^{229}$Th by combining measured hyperfine structure constants with our theoretical calculations. Our precise evaluations of electric dipole polarizabilities and hyperfine-induced quadrupole moments are critical for assessing systematic uncertainties in $^{229}$Th$^{3+}$-based
nuclear clock. Notably, we observe unexpectedly significant contributions from higher-order relativistic effects and excitations involving orbitals with higher angular momentum, which markedly influence the energies of the ground state and its fine-structure partner. These results highlight the substantial challenges in achieving highly accurate predictions for these properties.
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Medical Physics
On phase aberration estimation using common mid-angle speckle correlations
Naiara Korta Martiartu and Michael Jaeger
Phase aberrations, despite degrading ultrasound images, also encode valuable information about the spatial distribution of the speed of sound in tissue. In pulse-echo ultrasound, we can quantify them by exploiting speckle correlations. Among existing strategies, correlations between steered acquisitions that share a common mid-angle have proven particularly effective for inferring the speed of sound. Their phases can be linearly related to the phase aberrations undergone by both the incident and reflected wavefronts. This relationship has so far been demonstrated only through
geometric arguments based on point reflectors. Here, we develop a rigorous theoretical formalism that extends this relationship to the speckle regime, completing the previously established linear model and clarifying its underlying assumptions. More importantly, we build on this formalism to analyze correlation-phase fluctuations arising from aberration-induced speckle decorrelation. The analysis reveals that phase variance is governed by the relative loss of coherence, which increases approximately linearly with the square of the correlation phases. Local correlation-phase estimates therefore become increasingly uncertain as their magnitude grows. Experimental measurements in a uniform tissue-mimicking phantom show excellent agreement with the predicted variance. Beyond providing a theoretical basis for advancing speed-of-sound imaging, this formalism establishes the accuracy limit of common-mid-angle correlation phases, offering a
benchmark for evaluating more advanced aberration-estimation techniques.
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Applied Physics
Observation of gigantic orbital mixing conductance
Yuejie Zhang, Jinjun Ding, Tao Liu et al. (+4 more)
We report that due to the orbital
Hall effect, orbital pumping effects can occur in materials with weak
spin-orbit coupling. Moreover, there is a positive correlation between the strength of the orbital
Hall effect and the size of
spin-pumping. During the
spin-pumping, with the enhancement of the orbital
Hall effect, the resonant absorption of orbital current and the damping of the
ferromagnetic layer also increase. Especially, when the thickness of Ti reaches 60 nm, the orbital -mixing conductance of Ti/Co is an order of magnitude higher than
spin-mixing conductance of heavy metal/Co, reaching 474.1 3 ^18 m^(-2). The results indicate that the orbital current is more easily transmitted across the interface
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All authors Yuejie Zhang, Jinjun Ding, Tao Liu, Xiaofei Yang, Taoyuan Ouyang, Shi Chen, Yongqing Peng
Physics and Society · Cross-listed from cs.SI
Opinion Dynamics Models for Sentiment Evolution in Weibo Blogs
Yulong He, Anton V. Proskurnikov and Artem Sedakov
Online social media platforms enable influencers to distribute content and quickly capture audience reactions, significantly shaping their promotional strategies and advertising agreements. Understanding how sentiment dynamics and emotional contagion unfold among followers is vital for influencers and marketers, as these processes shape engagement, brand perception, and purchasing behavior. While sentiment analysis tools effectively track sentiment fluctuations, dynamical models explaining their
evolution remain limited, often neglecting network structures and interactions both among blogs and between their topic-focused follower groups. In this study, we tracked influential tech-focused Weibo bloggers over six months, quantifying follower sentiment from text-mined feedback. By treating each blogger's audience as a single "macro-
agent", we find that sentiment trajectories follow the principle of iterative averaging – a foundational mechanism in many dynamical models of opinion formation, a theoretical framework at the intersection of social network analysis and dynamical systems theory. The sentiment
evolution aligns closely with opinion-dynamics models, particularly modified versions of the classical French-DeGroot model that incorporate delayed perception and distinguish between expressed and private opinions. The inferred influence structures reveal interdependencies among blogs that may arise from homophily, whereby emotionally similar users subscribe to the same blogs and collectively shape the shared sentiment expressed within these communities.
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Optics · Cross-listed from quant-ph
Calibration of single-photon cameras using radioluminescent light sources
Radek Machulka, Václav Michálek, Ondřej Haderka et al. (+1 more)
In this paper, we address the calibration of the
quantum efficiency of single-
photon cameras using radioluminescent light sources. The proposed methods are subsequently compared with absolute calibration techniques based on the detection of correlated
photon pairs. Furthermore, we propose a method for transferring absolute calibration using the aforementioned radioluminescent emitters.
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All authors Radek Machulka, Václav Michálek, Ondřej Haderka, Jan Peřina
Computational Physics · Cross-listed from quant-ph
Tensor-network approach to quantum optical state evolution beyond the Fock basis
Nikolay Kapridov, Egor Tiunov and Dmitry Chermoshentsev
Understanding the
quantum evolution of light in nonlinear media is central to the development of next-generation
quantum technologies. Yet, modeling these processes remains computationally demanding, as the required resources grow rapidly with
photon number and phase-space resolution. Here, we introduce a tensor-network approach that efficiently captures the dynamics of nonlinear optical systems in a continuous-variable representation. Using the
matrix product state (MPS) formalism, both
quantum states and operators are encoded in a highly compressed form, enabling direct numerical integration of the Schrödinger equation. We demonstrate the method by simulating degenerate spontaneous parametric down-conversion (SPDC) and show that it accurately reproduces established theoretical
benchmarks - energy conservation, pump depletion, and quadrature squeezing - even in regimes where conventional Fock-basis simulations become infeasible. For high-intensity pump fields $(\alpha=100)$, the MPS representation achieves compression ratios below $3\times10^{-4}$ while preserving physical fidelity. This framework opens a scalable route to modeling multimode
quantum light and nonlinear optical phenomena beyond the reach of traditional methods.
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Computational Physics
jaxFMM: An Adaptive, GPU-Parallel Implementation of the Fast Multipole Method in JAX
Robert Kraft, Florian Bruckner, Dieter Suess et al. (+1 more)
We introduce jaxFMM, an open-source, adaptive, highly parallel point-charge Fast Multipole Method implementation for the Laplace kernel written in JAX. It is based on a non-uniform refinement strategy with on-the-fly rotation-based transforms tailored around JAX's just-in-time compiler, which results in extremely concise and simple code.
Benchmarks show that the
algorithm performs well at moderate accuracies, even for highly non-uniform charge distributions. JaxFMM already massively speeds up stray-field computations in micromagnetics and with JAX features like autodiff, novel applications such as inverse-design problems and machine-learning tasks can be tackled with ease in the future.
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All authors Robert Kraft, Florian Bruckner, Dieter Suess, Claas Abert
Optics
A High Responsivity Broadband Photodetector Based on a WSe2 NiO Nanowire Heterostructure with Engineered Nanophotonic Enhancement
Chandra Sekhar Reddy Kolli, Gowtham Polumati, Aleksandra A. Kutuzova et al. (+5 more)
Engineering nanoscale light matter interaction in mixed dimensional
semiconductor heterostructures offers a pathway to mitigate the intrinsic gain bandwidth trade off in photodetectors. Here, we report a broadband, high responsivity 2D and 1D photodetector formed by integrating monolayer p type WSe2 with electrospun p type NiO nanowires. The device photoresponse spans 350 to 780 nm and is governed by a nanophotonic field confinement mechanism rather than bulk optical absorption. The high index NiO nanowire acts as a dielectric Mie type nanoresonator that supports geometry defined optical modes and produces
antenna like near field concentration at the nanoscale WSe2 and NiO junction. This localized optical mode increases the local absorption cross section and enhances the photocarrier generation rate within the junction region, identified as the dominant active volume for photocurrent. A coupled optoelectronic model linking full wave electromagnetic simulations to carrier generation, recombination, and extraction accurately captures the measured responsivity spectrum and its power dependence using only two electronic fitting parameters. The device achieves responsivities of 627 A/W in the visible region, 227 A/W in the UV, and 167 A/W in the NIR, demonstrating broadband operation with ultrahigh gain. These results show that
geometric resonance in mixed dimensional junctions is a powerful design principle for next generation high gain optoelectronic detectors.
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All authors Chandra Sekhar Reddy Kolli, Gowtham Polumati, Aleksandra A. Kutuzova, Ekaterina E. Maslova, Andres De Luna Bugallo, Nitish Kumar Gupta, Mikhail V. Rybin, Parikshit Sahatiya
Computational Physics · Cross-listed from gr-qc
Addressing the gravitational collapse of a massless scalar field with Physics-Informed Neural Networks
Antonio Ferrer-Sánchez, Nino Villanueva-Espinosa, Carlos Hernani Morales et al. (+4 more)
The gravitational collapse of a massless scalar field remains a demanding
benchmark for numerical methods in numerical relativity, as it exhibits critical behavior at the boundary between dispersion and black hole formation. In this work we revisit this problem by relying on Physics-Informed Neural Networks (PINNs) as flexible solvers for partial differential equations, thereby providing a comparative assessment of several recent neural architectures. Building on the Einstein-massless-Klein-Gordon formulation in polar-areal coordinates, we consider four initial-value problems encompassing subcritical, critical, and supercritical regimes and use high-resolution finite-difference simulations as reference solutions. Our study is primarily comparative: we evaluate several state-of-the-art deep learning architectures, including vanilla and high-precision PINNs, sinusoidal-feature and quadratic-residual variants, and Kolmogorov-Arnold Networks, all trained under a common loss design that encodes the field equations, boundary conditions, and causal time-space enforcement, together with a novel adaptive spacetime sampling. Within this framework we also introduce ModPINN, a modest modification of standard PINNs that augments standard multilayer perceptrons with coordinate
embeddings, quadratic layers, and other common ingredients in recent literature. This study shows that deep-learning-based methods can reproduce finite-difference solutions for the scalar field and the spacetime metric with competitive accuracy using significantly fewer collocation points than more traditional methodologies. While no single architecture dominates in all regimes, ModPINN achieves particularly stable and accurate solutions near criticality, indicating that suitably designed
embeddings and adaptive sampling can enhance the robustness of PINNs for challenging gravitational-collapse scenarios.
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All authors Antonio Ferrer-Sánchez, Nino Villanueva-Espinosa, Carlos Hernani Morales, Roberto Ruiz de Austri-Bazan, José A. Font, José David Martín-Guerrero, Matthew W. Choptuik
Instrumentation and Detectors
Magnetic signal scan imaging system based on giant magnetoimpedance (GMI) differential sensor
Tao Yang, Zhoulu Yu, Xuekui Xi et al. (+2 more)
This paper presents the design and implementation of a
magnetic signal scanning and imaging system based on the
giant magnetoimpedance (GMI) effect. The system employs a pair of performance-matched GMI sensing elements configured as a differential probe structure. Through co-optimized low-noise electronic and probe design, the system effectively suppresses both intrinsic sensor common-mode drift and external environmental
magnetic noise, enabling high signal-to-noise ratio detection of nono-tesla to micro-tesla-level
magnetic signals without
magnetic shielding. Experimental results demonstrate that the differential system achieves significantly lower noise spectral density in unshielded environments compared to conventional GMI sensors (\SI{46}{pT}/$\sqrt{\text{Hz}}$ versus \SI{286}{pT}/$\sqrt{\text{Hz}}$ at \SI{1}{Hz}), with a sensitivity of 186,790 V/T and spatial resolution better than 200 micrometers. The system's excellent performance in weak
magnetic field detection and spatial resolution was verified through scanning experiments of
magnetic ink on US banknotes and
magnetic reference samples. Compared to SQUID scanning systems, which requiring
liquid helium cooling, this system based on the GMI effect offers advantages of room-temperature operation, compact structure, and low cost. Relative to conventional single-element GMI microscopes, it achieves significant improvements in signal-to-noise ratio and environmental adaptability. This research provides a practical solution for high-resolution
magnetic field imaging at room temperature with broad application potential in materials magnetism, biomagnetic imaging, and nanomagnetic detection.
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All authors Tao Yang, Zhoulu Yu, Xuekui Xi, Changjun Jiang, Guozhi Chai
Fluid Dynamics · Cross-listed from cs.GR
Fluid Control with Localized Spacetime Windows
Yixin Chen, David I.W. Levin and Timothy R. Langlois
We present a physics-based fluid control method utilizing localized spacetime windows, extending force-based fluid control to substantially larger simulation scales. In many practical editing scenarios, user-specified objectives affect only a small region of an otherwise satisfactory simulation, resulting in optimal control force distributions that are highly sparse in both space and time. However, existing optimization-based fluid control methods typically solve for control forces over the entire spacetime domain, leading to unnecessarily high computational cost and poor scalability. Motivated by this observation, we restrict optimization to localized spacetime regions surrounding the edit of interest, significantly reducing the dimensionality of the control problem. Within this framework, control forces are parameterized on a coarse "floating" background grid, decoupling control degrees of freedom from simulation resolution and promoting smooth, physically plausible forces. We further analyze spacetime-window selection as a joint spatial-temporal problem. While the full problem can be formulated as a 2D search over spatial and temporal window extents, practical workflows can often leverage user-specified spatial regions and lightweight temporal-window selection strategies to reduce search cost. Our method enables a range of intuitive editing tasks, where sparse user inputs can induce coherent motion in surrounding fluid structures. We demonstrate the effectiveness and efficiency of our method with various 2D and 3D particle-based free-surface simulation examples.
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Applied Physics
Probing Electro-Magnetic Field Enhancement in 3D Plasmonic Nanopores Using DNA-PAINT and Nanorulers
German Lanzavecchia, Anastasiia Sapunova, Alan Szalai et al. (+6 more)
Plasmonic nanopores combine nanofluidic confinement with electromagnetic field enhancement, enabling optical interrogation of single molecules in sub-wavelength volumes. Yet, direct optical readout within these metallic geometries has remained challenging due to fluorescence quenching near the surface. Here, we implement DNA-PAINT as a molecular reporter of local optical fields inside plasmonic nanopores. Transient hybridization of fluorescent imager strands at the nanopore tips yields
stochastic emission bursts that map active binding sites with nanometric precision. By varying the fluorophore-metal distance using DNA spacers of controlled length, we observe a non-monotonic intensity response consistent with near-field quenching and plasmonic enhancement, identifying an optimal separation of around 6 nm. Finally, we extend the concept to dual-material Au/Si nanopores, demonstrating lateral coupling between plasmonic and semiconducting regions. These results establish DNA-PAINT as a quantitative probe of nanoscale optical environments in hybrid nanopores.
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All authors German Lanzavecchia, Anastasiia Sapunova, Alan Szalai, Shukun Weng, Ali Douaki, Makusu Tsutsui, Roman Krahne, Guillermo Acuña, Denis Garoli
Optics
Intelligent Inverse Design of Multi-Layer Metasurface Cavities for Dual Resonance Enhancement of Nanodiamond Single Photon Emitters
Omar A. M. Abdelraouf
Single-
photon emitters (SPEs) based on nitrogen-vacancy centers in nanodiamonds (neutral NV0 (wavelength 575 nm) and negative NV- (wavelength 637 nm)) represent promising platforms for
quantum nanophotonics applications, yet their emission efficiencies remain constrained by weak light-matter interactions. Multi-layer metasurfaces (MLM) offer unprecedented degrees of freedom for efficient light manipulation beyond conventional single-material metasurfaces, enabling dual-resonance cavities that can simultaneously enhance pump excitation and SPE collection. However, traditional trial-and-error and forward optimization methods face significant challenges in designing these complex structures due to the vast parameter space and computational demands. Here, we present NanoPhotoNet-Inverse, an artificial intelligence-driven inverse design framework based on a hybrid deep neural network architecture. This model efficiently performs inverse design of two dual-resonance MLM cavities to amplify pump and SPE emissions of different vacancies in nanodiamond and improve SPE collection. Our approach achieves inverse design prediction efficiency exceeding 98.7%, demonstrating three orders of magnitude amplification in SPE count rate and 50 picosecond lifetime, significantly surpassing conventional cavity designs. These remarkable enhancements in emission rates and collection efficiency position our platform as a transformative technology for advancing
quantum communication networks,
quantum computing architectures,
quantum sensing applications, and
quantum cryptography systems. Therefore, it opens new pathways for intelligent photonic device engineering in
quantum technologies.
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Accelerator Physics
Drive beam depletion with multi-Joule energy transfer in a plasma wakefield accelerator
R. Ariniello, V. Lee, D. Storey et al. (+7 more)
A
collider based on beam-driven
plasma wakefield acceleration will require the drive beam to transfer 10-100s of Joules to the
plasma in each stage, with a drive-to-wake energy transfer efficiency exceeding 70%. Using an all-optical
plasma source, we demonstrate significant progress towards these parameters, transferring at least 5.6 J from a 1.52 nC, 10 GeV electron beam to a $4.5\times 10^{16}\,\mathrm{cm^{-3}}$ hydrogen
plasma while achieving at least $37\pm 3\%$ drive-to-wake energy transfer efficiency. We observe deceleration of some particles to less than 0.93 GeV with up to 90% of the charge participating in the interaction.
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All authors R. Ariniello, V. Lee, D. Storey, C. Emma, S. Gessner, M. J. Hogan, A. Knetsch, M. D. Litos, N. Majernik, B. O'Shea
Instrumentation and Detectors
A Novel Pixel-Chip-Based Region-of-Interest Readout Circuit Design
Shi-Qiang Zhou, Li-Rong Xie, Dong Wang et al. (+9 more)
This paper presents a novel pixel chip readout scheme: the Region-of-Interest Readout
Circuit (ROIRC), which is designed for large area, large array pixel chips and Gas Pixel Detector (GPD). This design employs a sentinel pixel detection strategy, enabling rapid identification and prioritized readout of the pixel regions containing signal events. During the scanning readout of these signal events, ROIRC employs a Block-based readout approach, effectively minimizing the readout of non-signal pixels. The functionality of ROIRC has been successfully implemented on both the ASIC and FPGA platforms. In the tests of the ROIRC, the pixel chip embedded in the GPD is capable of detecting low-energy X-rays in the range of 2-10 keV and supports multiple event readouts, and the pixel chip can read out photo-electron signal events with the count rate up to 15k / (cm2 x s).
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All authors Shi-Qiang Zhou, Li-Rong Xie, Dong Wang, Cheng Lian, Si-Ying Liu, Zi-Yi Zhang, Xiang-Ming Sun, Hong-Bang Liu, Chao-Song Gao, Jun Liu, Huan-Bo Feng, Di-Fan Yi
Optics
Thermalization of quantum light induced by classical nonlinear wave dynamics
Fouad Chahrour, Şahin K. Ozdemir, Kurt Busch et al. (+2 more)
Thermalization of isolated
quantum systems is an intriguing phenomenon at the forefront of contemporary physics. In this work, we demonstrate that nonlinear multimode optical platforms can be harnessed to induce effective
quantum interactions between
photons. Through numerical experiments where
quantum beams propagate alongside classical light within multimode nonlinear optical systems, we reveal the thermalization of fundamental
quantum light states–specifically single- and two-
photon states. This thermalization is clearly manifested by the emergence of Rayleigh-Jeans and Boltzmann statistical distributions. Beyond providing a deeper understanding of how classical nonlinearities can be used to investigate
quantum many-body dynamics, our findings will enable the exploration of a broader range of complex
quantum phenomena, including aspects of
quantum phase transitions, within readily accessible classical optical settings.
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All authors Fouad Chahrour, Şahin K. Ozdemir, Kurt Busch, Ramy El-Ganainy, Armando Perez-Leija
Physics and Society
The SolarEV City Paradox: A Critical Review of the Fragmented Integration of Rooftop Photovoltaics and Electric Vehicles for Urban Decarbonization
T. Kobashi, R. C. Mouli, J. Liu et al. (+13 more)
Urban decarbonization is central to meeting global
climate goals, yet progress toward integrated low-carbon energy systems remains slow. The SolarEV City Concept, linking rooftop photovoltaics with electric vehicles as mobile storage offers a technically robust pathway for deep CO2 reduction, potentially meeting 60-95 percent of municipal electricity demand when deployed synergistically. Despite rapid global growth of PVs and EVs, integration through bidirectional Vehicle-to-Home and Vehicle-to-Grid systems has lagged, revealing a persistent SolarEV paradox. This review examines that paradox through a socio-technical framework across four dimensions, technology, economics, policy, and society. Cross-national comparison shows that while technical feasibility is well established, large-scale implementation is limited by fragmented charging-protocol standards, immature and often non-profitable V2G business models, regulatory misalignments between energy and transport sectors, and social-equity barriers that restrict participation mainly to high-income homeowners. Emerging national archetypes from Japans resilience-driven model to Europes regulation-first trajectory highlight strong path dependence in current integration strategies. The analysis concludes that advancing SolarEV Cities requires a shift from parallel PV-EV promotion toward coordinated policy frameworks, interoperable digital infrastructure, and inclusive
market designs that distribute economic and resilience benefits more equitably. Achieving this integrated energy transition will require strategic collaboration among researchers, governments, industries, and communities to build adaptive, resilient, and socially just urban energy systems.
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All authors T. Kobashi, R. C. Mouli, J. Liu, S. Chang, C. D. Harper, R. Zhou, G. R. Dewi, U. W. R. Siagian, J. Kang, P. P. Patankar, Z. H. Rather, K. Say, T. Zhang, K. Tanaka, P. Ciais, D. M. Kammen
Chemical Physics
Chromatographic Peak Shape from Stochastic Model: Analytic Time-Domain Expression in Terms of Physical Parameters and Conditions under which Heterogeneity Reduces Tailing
Hernán R. Sánchez
A time-domain representation of chromatographic peak shapes is presented as an analytic expression designed for high computational efficiency, which can be used for direct time-domain peak fitting with parameters that represent physical quantities. The underlying model integrates the effects of axial
diffusion (molecular and multipath/eddy), finite initial spatial variance, and two distinct retention mechanisms: one characterized by a high rate of short-duration events (fast kinetics), and another by a low rate of long-duration events (slow kinetics). Fits to experimental chromatograms yield substantially smaller residual standard error (RSE) than the standard EMG and the lowest average normalised RSE among 12 established peak-shape functions in the examined cases. The
stochastic approach is reformulated using single-particle probability laws, providing a rigorous basis for future theoretical extensions. The validity of the foundational Poisson assumption is critically examined by deriving expressions for the excess variance caused by correlated microscopic retention rate fluctuations. A statistical interpretation of the HETP is presented and used to determine a lower bound on the number of microscopic retention events from chromatogram-derived macroscopic observables. This, in turn, justifies the applicability of the Gaussian limit for the mobile-plus-fast component, as established by analysis of the cumulant generating function of the closed-form
benchmark derived herein. The contribution from the slow-kinetic mechanism is incorporated via a decoupling approximation, whose validity is established through a cumulant-based analysis that explicitly bounds the decoupling-induced error. Finally, the notion that mechanistic heterogeneity necessarily exacerbates peak tailing is qualified, analytically delineating parameter regions in which it leads to a reduction in peak asymmetry.
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Atomic Physics · Cross-listed from quant-ph
Time series learning in a many-body Rydberg system with emergent collective amplification
Zongkai Liu, Qiming Ren, Chris Nill et al. (+12 more)
Interacting Rydberg atoms constitute a versatile platform for the realization of non-
equilibrium states of matter. Close to phase transitions, they respond collectively to external perturbations, which can be harnessed for technological applications in the domain of
quantum metrology and sensing. Owing to the controllable complexity and straightforward interpretability of Rydberg atoms, we can observe and tune the emergent collective amplification. Here, we investigate the application of an interacting Rydberg vapour for the purpose of time series prediction. The vapour is driven by a
laser field whose Rabi frequency is modulated in order to input the time series. We find that close to a non-
equilibrium phase transition, where collective effects are amplified, the capability of the system to learn the input becomes enhanced. This is reflected in an increase of the accuracy with which future values of the time series can be predicted. Using the Lorenz time series and temperature data as examples, our work demonstrates how emergent phenomena enhance the capability of noisy many-body systems for data processing and
forecasting.
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All authors Zongkai Liu, Qiming Ren, Chris Nill, Albert Cabot, Wei Xia, Yanjie Tong, Huizhen Wang, Wenguang Yang, Junyao Xie, Mingyong Jing, Hao Zhang, Liantuan Xiao, Suotang Jia, Igor Lesanovsky, Linjie Zhang
Physics and Society
Structural transitions induced by adaptive rewiring in networks with fixed states
R. Cárdenas-Sabando, M. G. Cosenza and J. C. González-Avella
We investigate structural transitions in adaptive networks where node states remain fixed and only the connections evolve via state-dependent rewiring. Using a general framework characterized by probabilistic rules for disconnection and reconnection based on node similarity, we systematically explore how homophilic and heterophilic interactions influence network
topology. A mean-field approximation for the stationary density of active links-those connecting nodes in different states-is developed to determine the conditions under which fragmentation occurs. Analytical results closely agree with numerical simulations. To distinguish community formation from fragmentation, we introduce order parameters that integrate modularity and connectivity. This enables the characterization of three distinct network phases on the rewiring parameter space: i) random connectivity, ii) community structure, and iii) fragmentation. Community structure emerges only under moderate homophily, while extreme homophily or heterophily lead to fragmentation or random networks, respectively. These findings demonstrate that adaptive rewiring alone, independent of node dynamics, can drive complex structural self-organization, with implications for social, technological, and ecological systems where node attributes are intrinsically stable.
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Applied Physics · Cross-listed from cond-mat.mtrl-sci
Pressure-Induced Reversal of Thermal Anisotropy in Bi2O2Se
Zunyi Deng, Wenwen Xuan, Bin Wei et al. (+1 more)
Bi2O2Se is an emerging
semiconductor with intrinsically low thermal conductivity, making it a promising material for thermoelectric applications. Hydrostatic pressure can effectively tunes the thermal conductivity, with various pressure-dependent trends reported. However, its impact on thermal anisotropy, particularly in the highly anisotropic Bi2O2Se, remains poorly understood. Here, we report a pressure-driven reversal of thermal anisotropy: k_z < k_x at 0 GPa transforms into k_z > k_x at 60 GPa without phase transition. This stems from distinct
phonon dispersions along the x- and z-directions under pressure, leading to a reshaped group velocity landscape. Below 10 meV, vz > vx at both pressures, with a much greater advantage at 60 GPa. Above 10 meV, vx > vz at 0 GPa; however, the difference nearly vanishes at 60 GPa. These changes result from anisotropic
lattice compression, with the z-axis shrinking more significantly than the x-axis and suppressing the lone pair activity of Bi atoms. This study calls for revisiting the pressure dependence of thermal conductivity anisotropy and provides insights for pressure-driven thermal switching applications.
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All authors Zunyi Deng, Wenwen Xuan, Bin Wei, Yongheng Li
Plasma Physics
Impact of edge turbulence spreading on broadening the heat flux width with plasma approaching the density limit
T. Wu, P.H. Diamond, L. Nie et al. (+8 more)
This paper investigates the impact of edge
turbulence spreading on broadening the heat flux width in Ohmic-
plasma approaching the density limit of the J-TEXT tokamak. At the
plasma edge, the EXB shear flow collapses while
turbulence transport and spreading enhances significantly when approaching the density limit. The heat flux width increases with normalized density. An energy production ratio model is used to quantify the contribution of edge
turbulence spreading to the origin of the SOL
turbulence. Experimental data show that the energy production ratio is much larger than 1, indicating that
turbulence spreading at separatrix is the origin of the SOL
turbulence. The heat flux widths increase with edge
turbulence spreading as well as the energy production ratio. The impact of blob-induced transport on the heat flux width is investigated in detail. Especially, the average blob-induced spreading is about 81% of the total edge spreading in the high-density scenario. Blobs with larger radial scales enhance edge spreading into the SOL, thus dominating the SOL
turbulence and consequently broadening the heat flux width. These results suggest that edge
turbulence spreading plays a crucial role in broadening the heat flux width as
plasma approaches the density limit.
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All authors T. Wu, P.H. Diamond, L. Nie, R. Ke, Z. P. Chen, Q. H. Yang, W. J. Tian, T. Long, Z. J. Yang, Z.Y. Chen, M. Xu
Atomic and Molecular Clusters
A note on the minimal pairwise distance in optimal Lennard-Jones $N$-body clusters
Michael K.-H. Kiessling and David J. Wales
Good a-priori bounds on the smallest pairwise distance $r_{\rm{{min}}}(\mbox{LJ}_N^{\rm{gmin}})$ for a three-dimensional (3D) Lennard-Jones $N$-body cluster of globally minimal energy can significantly reduce the computational search space in the NP-hard problem to find this configuration. In this contribution the virial
theorem is exploited for this purpose. We prove that if a configuration ${C}^{(N)}$ is a member of $\mbox{LJ}_N^{\rm{equ}}$ (the stationary points), then $r_{\rm{{min}}}({C}^{(N)}) \leq r_{\rm{{min}}}(\mbox{LJ}_2^{\rm{gmin}})$. It is also shown that if ${C}^{(N)}\in$ LJ$_N^{\rm{gmin}}\subset$ LJ$_N^{\rm{equ}}$, equality holds if and only if $N\in\{2,3,4\}$. We
conjecture that $r_{\rm{{min}}}(\mbox{LJ}_N^{\rm{gmin}}) >1$ in units for which $r_{\rm{{min}}}(\mbox{LJ}_2^{\rm{gmin}})= 2^\frac16 \approx 1.122462048$. This conjectured lower bound, if correct, would improve the best lower bound currently known, $r_{\rm{{min}}}(\mbox{LJ}_N^{\rm{gmin}})\geq 0.767764$, by about 25$\%$. In these units the smallest minimal pair distance found through numerical searches for LJ$_N^{\rm{gmin}}$ with $N\leq 1000$ is $r_{\rm{{min}}}(\mbox{LJ}_{923}^{\rm{gmin}}) \approx 1.01361$, so the conjectured lower bound would presumably be close to optimal. From the virial
theorem we obtain an identity for any ${C}^{(N)}\in \mbox{LJ}_N^{\rm{equ}}$, which expresses $r_{\rm{{min}}}({C}^{(N)})$ in terms of the distribution of relative distances in ${C}^{(N)}$. This result reveals interesting connections with the Erdős distance, and related problems.
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Accelerator Physics
Field Emission Analysis in SRF Cavities for PIP-II Using GEANT4
S. A. K. Wijethunga, A. Sukhanov, O. Napoly et al. (+1 more)
Field emission (FE) remains a significant hurdle for achieving optimal performance and reliability in super-conducting radiofrequency (SRF) cavities used in accelerator cryomodules. A thorough understanding of the generation and propagation of FE-induced radiation is therefore essential to mitigate this problem. The absence of standardized measurement protocols further complicates the comparison of radiation data across different testing phases and facilities. This highlights the need for a precise quantitative method to diagnose and analyze FE-induced radiation. Such efforts could prove beneficial for improving cavity preparation and cleanroom assembly techniques during the prototype and production stages of Fermilab's
Proton Improvement Plan-II (PIP-II) project. This study presents the initial steps of detailed Geant4 simulations aimed at analyzing FE-induced radiation in the low-beta 650 MHz 5-
cell elliptical (LB650) cavity. Our goal is to combine these results with radiation diagnostics to enhance diagnostic accuracy and optimize detector positioning. This integrated approach ultimately aims to improve the preparation, assembly, and testing procedures for PIP-II SRF cavities, ensuring the delivery of FE-free cryomodules.
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All authors S. A. K. Wijethunga, A. Sukhanov, O. Napoly, K. McGee