Optics
Near-Zero Crosstalk and Ultra-Low Loss Waveguide Crossings Enabled by three-dimensional Ta2O5-on-LNOI Integrated Photonic Platform
Boyang Nan, Yuan Ren, Rongbo Wu et al. (+5 more)
Waveguide crossings represent one of the most critical components in very-large-scale photonic integration (VLSPI). Three-dimensional waveguide crossings, which distribute optical pathways across multiple planes, can achieve near-zero crosstalk and extremely low crossing-induced loss. However, they face an intrinsic trade-off between interlayer crossing performance and coupling efficiency. To address this challenge, we developed a low-cost fabrication method for 3D waveguide crossings by exploiting the edge rounding effect inherent to chemical mechanical polishing (CMP). Using this method, we demonstrate waveguide crossings with average loss below 0.002 dB and crosstalk below -62 dB on Ta2O5-on-LNOI integrated photonic platform. Our method maintains full compatibility with conventional
semiconductor manufacturing technology and paves the way for realizing VLSPI on the thin-film lithium niobate platform.
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All authors Boyang Nan, Yuan Ren, Rongbo Wu, Lvbin Song, Ruixue Liu, Yong Zheng, Min Wang, Ya Cheng
Computational Physics
VNS Tokamak OpenMC-Serpent Validation for Medical Isotope Studies
Christopher Ehrich, Christian Bachmann, Pavel Pereslavtsev et al. (+1 more)
The Volumetric
Neutron Source (VNS) tokamak is a proposed fusion reactor for testing and qualification of reactor components for future use in a fusion power facility, and has potential use for radioisotope production. The VNS geometry is modeled in the Serpent and OpenMC neutronics codes. Analog
neutron-
photon coupled simulations are carried out to compare the model's
vacuum vessel and blanket components across codes. In the
vacuum vessel,
neutron and
photon flux maps are calculated, while in the blanket region,
neutron and
photon spectra, (n,T), and (n,2n) reaction rates are calculated and compared between models. The detector response comparisons found the following:
neutron flux and (n,T) reactions achieved excellent agreement, the (n,2n) detector response had good agreement, and
photon flux had regional discrepancies depending on Serpent tracking used. Hybrid tracking lead to a relative difference of about 20% in the outboard side blanket, where as employment of delta tracking resulted in less than 1% relative difference. On an HPC cluster, Serpent was found to have shorter computation time than OpenMC in
neutron photon coupled simulations using both hybrid tracking and delta tracking, but longer in
neutron only simulations. An exemplary radioisotope production case is presented for the demonstration of additional VNS capabilities.
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All authors Christopher Ehrich, Christian Bachmann, Pavel Pereslavtsev, Christian Reiter
Atomic Physics
The Single Differential Cross Sections (SDCS) for H(3s) Ionization in the First-Born Approximation by Electron and Positron Impact
Fahadul Islam and Sunil Dhar
A theoretical study was conducted on the impact of electron and positron impact ionization of excited hydrogen atoms that were in the 3s state; this study was conducted within the First-Born Approximation (FBA), which provides an analytical expression for the transition
matrix in terms of the Bethe-Lewis Integral Formalism. This formalism utilized both Coulomb continuum and confluent hypergeometric functions to describe the scattering states involved. Single Differential Cross Sections (SDCS) were calculated for incident energies of 100, 150, 200, and 250 eV. The data obtained indicated a peak in the ionization rates approximately at 200 eV, with the ionization rate decreasing as the incident energy increased further. The diffuse radial nature of the 3s wave function is shown to increase the sensitivity of the ionization dynamics to the incident particle energy. Asymmetries in charge were also detected; specifically, at low energy of the ejected electron, the SDCS values for positrons were greater than the corresponding values for electrons; however, as the energy of the incident particles was increased, these differences disappeared, thereby demonstrating the applicability of the FBA at high energy limits. The residual differences at low energy were due to the omission of exchange and post-collision interactions from the model. The results of this work can be used as benchmarking for the development of more complex distorted wave and multi-scattering theories in excited state ionization processes.
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Fluid Dynamics · Cross-listed from cond-mat.stat-mech
Degrees of universality in wave turbulence
Jiasheng Liu, Vladimir Rosenhaus and Gregory Falkovich
Turbulence of weakly interacting waves displays a great deal of universality: independence of the details of the interaction and of the pumping and dissipation scales. Here we study how inverse turbulent cascades (from small to large scales) transition from weak to strong. We find that while one-loop corrections can be dependent on excitation and dissipation scales, new types of universality appear in strong
turbulence. We contrast
turbulence of
spin waves in ferromagnets with turbulent cascades in the Nonlinear Schrödinger Equation (NSE) and in an MMT-like model in higher dimensions having a multiplicative interaction vertex: vertex renormalization gives rise to dependence on the pumping (UV scale) in the former but not in the latter. As a result of this spectral nonlocality,
spin-wave
turbulence stops being weak if one is sufficiently far from the pumping scale, even when the interaction of waves with comparable wavenumbers is weak. We paraphrase this as: nonlocality enhances nonlinearity. We then describe strong
turbulence in a multi-component version of these models with a large number of components. We argue that strong
spin-wave
turbulence is similar to
turbulence of the focusing NSE, as it realizes a critical-balance state. However, UV nonlocality causes the level of
spin-wave
turbulence at large scales to decrease with increasing pumping level, culminating in a state that is independent of the level of pumping.
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Computational Physics
PENCO: A Physics-Energy-Numerics-Consistent Operator for 3D Phase Field Modeling
Mostafa Bamdad, Mohammad Sadegh Eshaghi, Cosmin Anitescu et al. (+2 more)
Accurate and efficient solutions of spatiotemporal partial differential equations (PDEs), such as phase-field models, are fundamental for understanding interfacial dynamics and microstructural
evolution in materials science and fluid mechanics. Neural operators (NOs) have recently emerged as powerful data-driven alternatives to traditional solvers; however, existing architectures often accumulate temporal errors, struggle to generalize over long temporal horizons, and require large training
datasets. To overcome these limitations, we propose PENCO (Physics-Energy-Numerics-Consistent Operator), a hybrid operator-learning framework that integrates physical laws with data-driven neural operator methods, using either the
Fourier Neural Operator (FNO-4D) or the Multi-Head Neural Operator (MHNO) architecture as the backbone. The formulation introduces an enhanced L^2 Gauss-Lobatto collocation residual around the temporal midpoint that robustly enforces the governing dynamics and significantly improves accuracy, a
Fourier-space numerical consistency term that captures the balanced behavior of semi-implicit discretizations, and an energy-dissipation constraint that ensures thermodynamic consistency. Additional low-frequency spectral anchoring and teacher-consistency mechanisms further stabilize learning and suppress long-term error growth. This hybrid design enables PENCO to preserve governing physics while mitigating long-term error growth. Through extensive three-dimensional phase-field
benchmarks on periodic cubic domains, covering phase ordering, crystallization, epitaxial growth, and complex pattern formation, PENCO demonstrates superior accuracy, stability, and data efficiency compared to state-of-the-art neural operators, including FNO-4D and MHNO, while maintaining physically consistent
evolution. The associated
dataset and implementation are available at github.com/MBamdad/PENCO.
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All authors Mostafa Bamdad, Mohammad Sadegh Eshaghi, Cosmin Anitescu, Navid Valizadeh, Timon Rabczuk
Computational Physics
Stochastic Density Functional Theory Through the Lens of Multilevel Monte Carlo Method
Xue Quan and Huajie Chen
The
stochastic density functional theory (sDFT) has exhibited advantages over the standard Kohn-Sham DFT method and has become an attractive approach for large-scale electronic structure calculations. The sDFT method avoids the expensive
matrix diagonalization by introducing a set of random orbitals and approximating the density
matrix via Chebyshev expansion of a
matrix-valued function. In this work, we study the sDFT with a plane-wave discretization, and discuss variance reduction
algorithms in the framework of multilevel Monte Carlo (MLMC) methods. In particular, we show that the density
matrix evaluation in sDFT can be decomposed into many levels by increasing the plane-wave cutoffs or the Chebyshev
polynomial orders. This decomposition renders the computational cost independent of the discretization size or temperature. To demonstrate the efficiency of the
algorithm, we provide rigorous analysis of the statistical errors and present numerical experiments on some material systems.
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Biological Physics · Cross-listed from math.NA
A High-Order Discretization Scheme for Surface Integral Equations for Analyzing the Electroencephalography Forward Problem
Rui Chen, Viviana Giunzioni, Adrien Merlini et al. (+1 more)
A Nystrom-based high-order (HO) discretization scheme for surface integral equations (SIEs) for analyzing the electroencephalography (
EEG) forward problem is proposed in this work. We use HO surface elements and interpolation functions for the discretization of the interfaces of the head volume and the unknowns on the elements, respectively. The advantage of this work over existing isoparametric HO discretization schemes resides in the fact that the interpolation points are different from the mesh nodes, allowing for the flexible manipulation of the order of the basis functions without regenerating the mesh of the interfaces. Moreover, the interpolation points are chosen from the quadrature rules with the same number of points on the elements simplifying the numerical computation of the surface integrals for the far-interaction case. In this contribution, we extend the implementation of the HO discretization scheme to the double-layer and the adjoint double-layer formulations, as well as to the isolated-skull-approach for the double-layer formulation and to the indirect adjoint double-layer formulation, employed to improve the solution accuracy in case of high conductivity contrast models, which requires the development of different techniques for the singularity treatment. Numerical experiments are presented to demonstrate the accuracy, flexibility, and efficiency of the proposed scheme for the four SIEs for analyzing the
EEG forward problem.
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All authors Rui Chen, Viviana Giunzioni, Adrien Merlini, Francesco P. Andriulli
Instrumentation and Detectors
Performance Optimization and Characterization of 7-pad Resistive PICOSEC Micromegas Detectors
A. Kallitsopoulou, R. Aleksan, S. Aune et al. (+49 more)
We present a comprehensive characterization of resistive PICOSEC Micromegas detector prototypes, tested under identical conditions, constant drift gap, field configurations, and photocathode at the CERN SPS H4 beam line. This work provides a proof of concept for the use of resistive layer technology in gaseous timing detectors, demonstrating that robustness can be improved without compromising the excellent timing performance of PICOSEC Micromegas. Different resistive architectures and values were explored to optimize stability and ensure reliable long-term operation in challenging experimental environments. The prototype with a 10M{\Omega} resistive layer achieved the best overall performance, with a timing resolution of 22.900 {\pm} 0.002 ps and a spatial resolution of 1.190 {\pm} 0.003 mm, while charge sharing across multiple pads enabled combined timing resolutions below 28 ps. A lower-resistivity (200k{\Omega}) configuration exhibited enhanced charge spread, leading to minor systematic offsets in reconstructed pad centers, yet maintained robust timing and spatial performance. Capacitive charge-sharing architectures improved spatial resolution in some regions but suffered from signal attenuation and nonuniform charge distributions, resulting in slightly degraded timing (33.300 {\pm} 0.002 ps) and complex localization patterns. Mechanical precision, particularly readout planarity and photocathode
alignment, was identified as critical for uniform detector response. These studies
benchmark the potential of resistive layers for gaseous timing detectors and provide a foundation for scalable designs with optimized timing and spatial resolution across diverse experimental applications.
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All authors A. Kallitsopoulou, R. Aleksan, S. Aune, J. Bortfeldt, F. Brunbauer, M. Brunoldi, J.Datta, D. Desforge, G. Fanourakis, D. Fiorina, K. J. Floethner, M. Gallinaro, F.Garcia, I. Giomataris, K. Gnanvo, F.J. Iguaz, D. Janssens, F. Jeanneau, M. Kovacic, B. Kross, P. Legou, M. Lisowska, J. Liu, M. Lupberger, I. Maniatis, J. McKisson, Y. Meng, H. Muller, E. Oliveri, G. Orlandini, A. Pandey, T. Papaevangelou, M.Pomorski, E.Ferrer-Ribas, L. Ropelewski, D. Sampsonidis, L. Scharenberg, T. Schneider, E. Scorsone, L. Sohl, M. van Stenis, Y. Tsipolitis, S.E. Tzamarias, A. Utrobicic, I.Vai, R. Veenhof, P. Vitulo, X. Wang, S. White, W. Xi, Z. Zhang, Y. Zhou
Instrumentation and Detectors · Cross-listed from astro-ph.IM
Spaceflight KID Readout Electronics for PRIMA
Thomas Essinger-Hileman, C. Matt Bradford, Patrick Brown et al. (+23 more)
We present the design and testing of a prototype multiplexing kinetic inductance detector (KID) readout electronics for the PRobe far-Infrared Mission for Astrophysics (PRIMA) space mission. PRIMA is a Probe-class astrophysics mission concept that will answer fundamental questions about the formation of planetary systems, the co-
evolution of
stars and supermassive black holes in
galaxies, and the rise of heavy elements and
dust over
cosmic time. The readout electronics for PRIMA must be compatible with operation at Earth-Sun L2 and capable of multiplexing more than 1000 detectors over 2.5 GHz bandwidth while consuming around 30 W per readout chain. The electronics must also be capable of switching between the two instruments, which have different readout bands: the hyperspectral imager (PRIMAger, 2.6-4.9 GHz) and the spectrometer (FIRESS, 0.4-2.4 GHz). The PRIMA readout electronics use high-heritage SpaceCube digital electronics with a build-to-print SpaceCube Mini v3.0 board using a radiation-tolerant Kintex KU060 field programmable gate array (FPGA) and a custom high-speed digitizer board, along with RF electronics that provide filtering and power conditioning. We present the driving requirements for the system, as well as the hardware, firmware, software, and system-level design that meets those requirements.
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All authors Thomas Essinger-Hileman, C. Matt Bradford, Patrick Brown, Sean Bryan, Jesse Coldsmith, Jennifer Corekin, Sumit Dahal, Thomas Devlin, Marc Foote, Draisy Friedman, Alessandro Geist, Jason Glenn, Christopher Green, Tracee Jamison-Hooks, Kevin Horgan, Jared Lucey, Philip Mauskopf, Lynn Miles, Sanetra Bailey Newman, Gerard Quilligan, Cody Roberson, Adrian Sinclair, Salman Sheikh, Eric Weeks, Christopher Wilson, Travis Wise
Optics
Statistical Insight into the Correlation of Geometry and Spectral Emission in Network Lasers
Camillo Tassi, Riccardo Mannella, Andrea Tomadin et al. (+2 more)
Optically active networks show feature-rich emission that depends on the fine details of their geometry, and find diverse applications in random
lasers, sensing devices and photonics processors. In these and other systems, a thorough and predictive characterization of how the network geometry correlates with the resulting emission spectrum would be highly important, however such outright description is still lacking. In this work, we take a step toward filling this gap, by using the well-known Steady-State ab Initio
Laser Theory equations to carry out an extensive set of statistical analyses and establish connections between the random network geometry and their ultimate emission spectrum. Our results show that edge crowding (abundance of short edges in the network) is key to tune the uniformity of the modal intensity distribution of the emission spectrum. A statistical framework for the comprehensive understanding of the network statistical properties is highly significant to establish precise design rules for network-based photonic devices and intelligent systems.
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All authors Camillo Tassi, Riccardo Mannella, Andrea Tomadin, Andrea Camposeo, Dario Pisignano
Chemical Physics
Teaching a Transformer to Think Like a Chemist: Predicting Nanocluster Stability
João Marcos T. Palheta, Octavio Rodrigues Filho, Mohammad Soleymanibrojeni et al. (+6 more)
Atomically precise metal nanoclusters bridge the molecular and bulk regimes, but designing bimetallic motifs with targeted stability and reactivity remains challenging. Here we combine density functional theory (DFT) and physics-grounded predictive artificial intelligence to map the configurational landscape of 13-atom icosahedral nanoclusters X$_{12}$TM, with hosts X = (Ti, Zr, Hf), and Fe and a single transition–metal dopant spanning the 3$d$-5$d$ series.
Spin-polarized DFT calculations on 240 bimetallic clusters reveal systematic trends in binding and formation energies, distortion penalties, effective coordination number, d-band centre, and HOMO-LUMO gap that govern the competition between core-shell (in) and surface-segregated (out) arrangements. We then pretrain a
transformer architecture on a curated set of 2968 unary clusters from the
Quantum Cluster Database and fine-tune it on bimetallic data to predict formation energies and in/out preference, achieving mean absolute errors of about $0.6-0.7$eV and calibrated uncertainty intervals. The resulting model rapidly adapts to an unseen Fe-host domain with only a handful of labelled examples. At the same time,
attention patterns and Shapley attributions highlight size mismatch, $d$-electron count, and coordination environment as key descriptors. All data, code, and workflows follow FAIR/TRUE principles, enabling reproducible, interpretable screening of unexplored nanocluster chemistries for catalysis and energy conversion.
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All authors João Marcos T. Palheta, Octavio Rodrigues Filho, Mohammad Soleymanibrojeni, Alexandre Cavalheiro Dias, Diego Guedes-Sobrinho, Wolfgang Wenzel, Roland Aydin, Celso R. C. Rêgo, Maurício Jeomar Piotrowski
Accelerator Physics
High-repetition-rate, all-reflective optical guiding and electron acceleration in helium using an off-axis axicon
Jiří Šišma, Michal Nevrkla, Filip Vitha et al. (+17 more)
We present recent results on high-power guiding and
laser wakefield acceleration in the ELectron Beam Accelerator (ELBA) beamline at ELI Beamlines, using the L3-HAPLS
laser system (13 J, 30 fs, 0.2 Hz). By employing self-waveguiding in a 20 cm
plasma channel in helium, we achieved stable acceleration of electron beams to energies of approximately 5 GeV. A novel all-reflective optical setup, including an off-axis reflective axicon, enabled efficient acceleration at 0.2 Hz and guiding at repetition rates up to 3.3 Hz. This compact single
laser, single-compressor implementation of
plasma channels for electron acceleration stabilizes electron pointing and enhances energy gain without requiring modifications to the
laser system, paving the way for broader adoption of the technology across user facilities.
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All authors Jiří Šišma, Michal Nevrkla, Filip Vitha, Sebastian Lorenz, Illia Zymak, Alžběta Špádová, Andrea Kollárová, Matěj Jech, Alexandr Jančárek, Davorin Peceli, Carlo M. Lazzarini, Leonardo V. N. Goncalves, Gabriele M. Grittani, Sergei V. Bulanov, Jaron E. Shrock, Ela Rockafellow, Ari J. Sloss, Bo Miao, Scott W. Hancock, Howard M. Milchberg
Medical Physics
2bNIRS: a portable, multi-distance, broadband oximeter and cytochrome-c-oxidase monitoring system for in vivo applications
Luca Giannoni, Archie Barraclough, Chiara Carnati et al. (+2 more)
Conventional near-infrared spectroscopy (NIRS) instruments typically employ 2-3 wavelengths for monitoring tissue haemodynamics. However, the use of broadband illumination (hundreds of wavelengths) unlocks also the targeting of tissue metabolism by exploiting the wide differential-redox peak of absorption of cytochrome-c-oxidase (CCO). For this purpose, we present here a novel, broadband (780-900nm), multi-distance NIRS system, called 2bNIRS. Compact and portable (20 x 30 x 40 cm3), 2bNIRS was validated using a dynamic, optical phantom con-taining blood and yeast, and benchmarked against a multi-wavelength time-domain NIRS (TD-NIRS) system. Validation confirmed its accuracy in tracking haemody-namic and metabolic changes, with superior oximetry performance achieved via our BRUNO
algorithm, which integrates broadband spectral fitting with spatially-re-solved analysis. Preliminary in vivo, human applications demonstrated 2bNIRS ap-plicability to monitoring both muscle tissue, during arm cuff occlusions, and the
brain, during frontal cortex activation.
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All authors Luca Giannoni, Archie Barraclough, Chiara Carnati, Frederic Lange, Ilias Tachtsidis
Optics
Terahertz Fourier Ptychographic Imaging
Pitambar Mukherjee, Vivek Kumar, Frederic Fauquet et al. (+5 more)
High-resolution imaging in the terahertz (THz) spectral range remains fundamentally constrained by the limited numerical apertures of currently existing state-of-the-art imagers, which restricts its applicability across many fields, such as imaging in complex media or nondestructive testing. To address this challenge, we introduce a proof-of-concept implementation of THz
Fourier Ptychographic imaging to enhance spatial resolution without requiring extensive hardware modifications. Our method employs a motorized kinematic mirror to generate a sequence of controlled, multi-angle plane-wave illuminations, with each resulting oblique-illumination intensity image encoding a limited portion of the spatial-frequency content of the target imaging sample. These measurements are combined in the
Fourier domain using an aberration-corrected iterative phase-
retrieval algorithm integrated with an efficient illumination calibration scheme, which enables the reconstruction of resolution-enhanced amplitude and phase images through the synthetic expansion of the effective numerical aperture. Our work establishes a robust framework for high-resolution THz imaging and paves the way for a wide array of applications in materials characterization, spectroscopy, and non-destructive evaluation.
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All authors Pitambar Mukherjee, Vivek Kumar, Frederic Fauquet, Amaury Badon, Damien Bigourd, Kedar Khare, Sylvain Gigan, Patrick Mounaix
Optics
Demultiplexing through a multimode fiber using chip-scale diffractive neural networks
Qian Zhang, Haoyi Yu, Jie Zhang et al. (+7 more)
In today's information age, advanced fiber optic transmission technology is of paramount importance. Multimode fibers (MMFs) using space-division multiplexing (SDM) are promising for improved transmission capacity, connection flexibility, and security of data. However, the complex transmission characteristics of MMFs significantly hinder precise mode demultiplexing. Conventional approaches, including
holographic measurements, phase
retrieval algorithms, photonic lanterns, and multiplane light conversion, are limited by system complexity, size, and flexibility. In this paper, we demonstrate for the first time a purely optical, chip-scale AI solution for high-mode isolation, speed-of-light demultiplexing of MMF modes using a three-dimensional diffractive neural network (DNN). The DNN is trained with synthetic modal data and fabricated using two-
photon nanolithography. It features a compact size of $120{\mu}m \times 120{\mu}m \times 80{\mu}m$ and a diffractive structure size of $1{\mu}m^{2}$ for the
neurons at the hidden layers of the network. Experimentally, the DNN demultiplexer achieves a relative demultiplexing accuracy of over 80%. The AI approach of DNN allows for flexible design and overcomes the size and performance limitations of digital-optical demultiplexers. This work paves the way for compact, low-latency optical processors for high-performance demultiplexers and enables scalable, chip-integrated solutions for next-generation fiber optic networks.
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All authors Qian Zhang, Haoyi Yu, Jie Zhang, Yuedi Zhang, Chao Meng, Jiali Sun, Yu Miao, Qiming Zhang, Min Gu, Juergen W Czarske
Geophysics
UnwrapDiff: A Conditional Diffusion Model for InSAR Phase Unwrapping
Yijia Song, Juliet Biggs, Alin Achim et al. (+3 more)
Phase unwrapping is a fundamental problem in InSAR data processing, supporting geophysical applications such as deformation monitoring and hazard assessment. Its reliability is limited by noise and decorrelation in radar acquisitions, which makes accurate reconstruction of the deformation signal challenging. We propose a denoising
diffusion probabilistic model (DDPM)-based framework for InSAR phase unwrapping, UnwrapDiff, in which the output of the traditional minimum cost flow
algorithm (SNAPHU) is incorporated as conditional guidance. To evaluate robustness, we construct a synthetic
dataset that incorporates atmospheric effects and diverse noise patterns, representative of realistic InSAR observations. Experiments show that the proposed model leverages the conditional prior while reducing the effect of diverse noise patterns, achieving on average a 10.11% reduction in NRMSE compared to SNAPHU. It also achieves better reconstruction quality in difficult cases such as dyke intrusions.
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All authors Yijia Song, Juliet Biggs, Alin Achim, Robert Popescu, Simon Orrego, Nantheera Anantrasirichai
Space Physics · Cross-listed from astro-ph.SR
On the magnetic field evolution of interplanetary coronal mass ejections from 0.07 to 5.4 au
Christian Möstl, Emma E. Davies, Eva Weiler et al. (+8 more)
A central question for understanding interplanetary coronal mass ejection (ICME) physics and improving space weather
forecasting is how ICMEs evolve in interplanetary space. We have updated one of the most comprehensive in situ ICME catalogs to date, which now includes 1976 events from 11 space missions covering over 34 years, from December 1990 to August 2025. We have combined existing catalogs including
magnetic obstacles and identified and added boundaries of an additional 807 (40.8%) events ourselves. With this catalog, we demonstrate the most extensive analysis to date of total ICME
magnetic field values as a function of heliocentric distance. Parker
Solar Probe has observed 6 ICMEs at $< 0.23$ au (until April 2025), and
Solar Orbiter and BepiColombo have added more events near 0.3 au, bridging the major observational gap towards the
solar corona. Our main result is that a single power law can describe the
evolution of the mean total
magnetic field (exponent value of $k=-1.57$) and maximum field ($k=-1.53$) for ICMEs with
magnetic obstacles (MOs), from 0.07 to 5.4 au. Extending the power law to the
solar photosphere reveals a strong inconsistency with
magnetic field magnitudes observed in the quiet Sun and active regions by 2 and 4 orders of magnitude, respectively. We introduce a multipole-type power law with two exponents, $k_1=-1.57$, and $k_2=-6$, relating the ICME
magnetic field magnitude to an average
solar active region field strength. These results present important observational constraints for the
evolution of ICMEs from the Sun to the heliosphere.
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All authors Christian Möstl, Emma E. Davies, Eva Weiler, Ute V. Amerstorfer, Andreas J. Weiss, Hannah T. Rüdisser, Martin A. Reiss, Satabdwa Majumdar, Timothy S. Horbury, Stuart D. Bale, Daniel Heyner
Chemical Physics · Cross-listed from math-ph
A quantitative Hohenberg-Kohn theorem and the unexpected regularity of density functional theory in one spatial dimension
Thiago Carvalho Corso and Andre Laestadius
In this paper we investigate the (Kohn-Sham) density-to-potential map in the case of spinless
fermions in one spatial dimension, whose existence has been rigorously established by the first author in [Lett. Math. Phys. 116, (2026), no. 27. https://doi.org/10.1007/s11005-026-02051-1]. Here, we focus on the regularity of this map as a function of the density and the coupling constant in front of the interaction term. More precisely, we first prove a quantitative version of the Hohenberg-Kohn
theorem, thereby showing that this map is Lipschitz continuous with respect to the natural Sobolev norms in the space of densities and potentials. In particular, this implies that the inverse (Kohn-Sham) problem is not only well-posed but also Lipschitz stable. Using this result, we then show that the density-to-potential map is in fact real analytic with respect to both the density and the interaction strength. As a consequence, we obtain a holomorphic extension of the universal constrained-search functional to a suitable subset of complex-valued densities. This partially extends the DFT framework to non-self-adjoint Schrödinger operators. As further applications of these results, we also establish the existence of an exchange-only part of the exchange-correlation potential, and justify the Görling-Levy perturbation expansion for the correlation energy.
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Biological Physics · Cross-listed from cond-mat.soft
Why life is hot
Tanja Schilling, Patrick B. Warren and Wilson Poon
The process of
evolution by natural selection leads to phenotypes of increasing fitness. For cellular chemical reaction networks, this means optimising a variety of fitness functions such as robustness, precision, or sensitivity to external stimuli. We argue that these diverse goals can be achieved by a versatile, generic mechanism: coupling chemical reaction networks to reservoirs that are strongly out of
equilibrium. Using theory and numerics we show that this mechanism of optimisation comes at the price of significant heat dissipation. We compute the heat flux caused by kinetic proofreading in Escherichia coli and show that it constitutes a significant fraction of the total heat flux experimentally measured in this model organism. We then demonstrate that the degree of optimality achievable saturates, and that Nature appears to operate near saturation despite high energetic costs. We argue that `life is hot' largely because of the need for a versatile mechanism to optimise a variety of fitness functions.
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Plasma Physics
Optimization of laser illumination configuration for directly driven inertial confinement fusion
Masakatsu Murakami and Daiki Nishi
Optimum
laser configurations are presented to achieve high illumination uniformity with directly driven inertial confinement fusion targets. Assuming axisymmetric absorption pattern of individual
laser beams, theoretical models are reviewed in terms of the number of
laser beams, system imperfection, and
laser beam patterns. Utilizing a self-organizing system of charged particles on a sphere, a simple numerical model is provided to give an optimal configuration for an arbitrary number of
laser beams. As a result, such new configurations as M48 and M60 are found to show substantially higher illumination uniformity than any other existing direct drive systems. A new polar direct-drive scheme is proposed with the
laser axes keeping off the target center, which can be applied to
laser configurations designed for indirectly driven inertial fusion.
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Fluid Dynamics
Towards an AI Fluid Scientist: LLM-Powered Scientific Discovery in Experimental Fluid Mechanics
Haodong Feng, Lugang Ye and Dixia Fan
The integration of artificial intelligence into experimental fluid mechanics promises to accelerate discovery, yet most AI applications remain narrowly focused on numerical studies. This work proposes an AI Fluid Scientist framework that autonomously executes the complete experimental workflow: hypothesis generation, experimental design, robotic execution, data analysis, and manuscript preparation. We validate this through investigation of
vortex-induced vibration (VIV) and wake-induced vibration (WIV) in tandem cylinders. Our work has four key contributions: (1) A computer-controlled circulating water tunnel (CWT) with programmatic control of flow velocity, cylinder position, and forcing parameters (vibration frequency and amplitude) with data acquisition (displacement, force, and torque). (2) Automated experiments reproduce literature
benchmarks (Khalak and Williamson [1999] and Assi et al. [2013, 2010]) with frequency lock-in within 4% and matching critical spacing trends. (3) The framework with Human-in-the-Loop (HIL) discovers more WIV amplitude response phenomena, and uses a neural network to fit physical laws from data, which is 31% higher than that of
polynomial fitting. (4) The framework with multi-
agent with virtual-real interaction system executes hundreds of experiments end-to-end, which automatically completes the entire process of scientific research from hypothesis generation, experimental design, experimental execution, data analysis, and manuscript preparation. It greatly liberates human researchers and improves study efficiency, providing new paradigm for the development and research of experimental fluid mechanics.
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Plasma Physics
Generation of ultrahigh field by micro-bubble implosion
M. Murakami, A. Arefiev and M. A. Zosa
Breaking the 100-MeV barrier for
proton acceleration will help elucidate fundamental physics and advance practical applications from inertial confinement fusion to tumour therapy. Herein we propose a novel concept of bubble implosions. A bubble implosion combines micro-bubbles and ultraintense
laser pulses of 10^20-10^22W/cm^2 to generate ultrahigh fields and relativistic
protons. The bubble wall
protons undergo volumetric acceleration toward the centre due to the spherically symmetric Coulomb force and the innermost
protons accumulate at the centre with a density comparable to the interior of a white
dwarf. Then an unprecedentedly high electric field is formed, which produces an energetic
proton flash. Three-dimensional particle simulations confirm the robustness of Coulomb-imploded bubbles, which behave as nano-
pulsars with repeated implosions and explosions to emit
protons. Current technologies should be sufficient to experimentally verify concept of bubble implosions.
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Atmospheric and Oceanic Physics
Rotational and Irrotational Wind Forcing as dual drivers of El Nino Southern Oscillation variability
Gian Luca Eusebi Borzelli, Cosimo Enrico Carniel, Sandro Carniel et al. (+1 more)
El Niño Southern Oscillation (ENSO) is the Earth's strongest source of interannual
climate variability. Although its center of action is in the tropical Pacific, it has significant influences on the
climate at the planetary scale. ENSO is sustained by a feedback process between equatorial winds, vertical displacements of the thermocline, and sea surface temperature (SST) anomaly gradients. This produces an oscillation in the SST anomaly between a warm (El Niño) and a cold phase (La Niña). While the natural time-scale of ENSO variability is interannual, variations in its behavior and characteristics have been observed over longer time scales, including decadal and interdecadal. Here, we use the Helmholtz decomposition to break down the wind stress into two components: irrotational (curl free) and solenoidal (divergence free). We show that the irrotational component of the wind stress drives the dynamics of the thermocline on the interannual time-scale, while the solenoidal component, whose action is influenced by the stratification of the water column, affects the variability of the thermocline over decadal or interdecadal time-scales. Furthermore, we develop an integral relation that links the variability of the thermocline depth anomaly across the entire tropical Pacific to the variability of the average SST anomaly in the central tropical Pacific (known as the Niño-3.4 index) and conclude that the irrotational component of the wind stress determines the interannual variability of the Niño-3.4 index, while the solenoidal component determines its long-term variability.
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All authors Gian Luca Eusebi Borzelli, Cosimo Enrico Carniel, Sandro Carniel, Mauro Sclavo
Fluid Dynamics
Flux-controlled wall model for large eddy simulation integrating the compressible law of the wall
Youjie Xu, Steffen J. Schmidt and Nikolaus A. Adams
Recent advances in velocity and temperature transformations have enabled recovery of the law of the wall in compressible wall-bounded turbulent flows. Building on this foundation, a flux-controlled wall model (FCWM) for Large Eddy Simulation (LES) is proposed. Unlike conventional wall-stress models that solve the turbulent boundary layer equations, FCWM formulates the near-wall modeling as a control problem applied directly to the outer LES solution. It consists of three components: (1) the compressible law of the wall, (2) a feedback flux-control strategy, and (3) a shifted boundary condition. The model adjusts the wall shear stress and heat flux based on discrepancies between the computed and target transformed velocity and temperature, respectively, at the matching location. The proposed wall model is evaluated using LES of turbulent channel flows across a broad range of conditions, including quasi-incompressible cases with bulk Mach number \(M_b = 0.1\) and friction Reynolds number \(Re_\tau = 180 \sim 10{,}000\), and compressible cases with \(M_b = 0.74 \sim 4.0\) and bulk Reynolds number \(Re_b = 7667 \sim 34{,}000\). The wall-modelled LES reproduce mean velocity and temperature profiles in agreement with direct numerical simulation data. For all tested cases with \(M_b \leq 3\), the wall model achieves relative errors of \(|\epsilon_{C_f}| < 4.1\%\), \(|\epsilon_{B_q}| < 2.7\%\), and \(|\epsilon_{T_c}| < 2.7\%\) in friction coefficient, non-dimensional heat flux, and centerline temperature, respectively. In the quasi-incompressible regime, the wall model achieves \(|\epsilon_{C_f}| < 1\%\). Compared to the conventional
equilibrium wall model, the proposed FCWM achieves higher accuracy in compressible turbulent channel flows without solving the boundary layer equations, thereby reducing computational cost.
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Physics and Society
Evolutionary Dynamics Based on Reputation in Networked Populations with Game Transitions
Yuji Zhang, Minyu Feng, Jürgen Kurths et al. (+1 more)
The environment undergoes perpetual changes that are influenced by a combination of endogenous and exogenous factors. Consequently, it exerts a substantial influence on an individual's physical and psychological state, directly or indirectly affecting the evolutionary dynamics of a population described by a network, which in turn can also alter the environment. Furthermore, the
evolution of strategies, shaped by reputation, can diverge due to variations in multiple factors. To explore the potential consequences of the mentioned situations, this paper studies how game and reputation dynamics alter the
evolution of cooperation. Concretely, game transitions are determined by individuals' behaviors and external uncontrollable factors. The cooperation level of its neighbors reflects individuals' reputation, and further, a general fitness function regarding payoff and reputation is provided. Within the context of the donation game, we investigate the relevant outcomes associated with the aforementioned evolutionary process, considering various
topologies for distinct interactions. Additionally, a biased mutation is introduced to gain a deeper insight into the strategy
evolution. We detect a substantial increase in the cooperation level through intensive simulations, and some important phenomena are observed, e.g., the unilateral increase of the value of prosocial behavior limits promotion in cooperative behavior in square-
lattice networks.
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All authors Yuji Zhang, Minyu Feng, Jürgen Kurths, Attila Szolnoki
Instrumentation and Detectors · Cross-listed from astro-ph.IM
Progress towards a microchannel plate detector with AlGaN photocathode and cross-strip anode for ultraviolet astronomy
S. Diebold, J. Barnstedt, L. Conti et al. (+9 more)
Microchannel plates (MCPs) were the driving detector technology for ultraviolet (UV) astronomy over many years, and still today MCP-based detectors are the baseline for several planned UV instruments. The development of advanced MCP detectors is ongoing and pursues the major goals of maximizing sensitivity, resolution, and lifetime, while at the same time decreasing weight, volume, and power consumption. Development efforts for an MCP-based detector system for the UV are running at IAAT at the University of Tübingen. In this publication, we present our latest results towards coating aluminum gallium nitride (AlGaN) photocathodes directly on MCPs, to improve
quantum detection efficiency in the far- and extreme-UV. Furthermore, we report on the implementation of a non-iterative centroiding
algorithm for our coplanar cross-strip anode directly in an FPGA.
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All authors S. Diebold, J. Barnstedt, L. Conti, H.R. Elsener, L. Hanke, M. Höltzli, C. Kalkuhl, D. Rau, D. Schaadt, T. Schanz, B. Stelzer, K. Werner
Applied Physics · Cross-listed from quant-ph
Watt-level coherent microwave emission from dissipation engineered solid-state quantum batteries
Yuanjin Wang, Hao Wu, Mark Oxborrow et al. (+1 more)
Recently proposed metastability-induced
quantum batteries have shown particular promise for coherent microwave generation. However, achieving high-power coherent microwave generation in
quantum batteries remains fundamentally challenging due to
quantum correlations, aging, and self-discharging processes. For the cavity-
quantum-electrodynamics (CQED)-based
quantum batteries, a further trade-off arises between strong
spin-
photon coupling for energy storage and sufficient output coupling for power delivery. To overcome these constraints, we introduce dissipation engineering as a dynamic control strategy that temporally separates energy storage and release. By suppressing emission during charging and rapidly enhancing the output coupling during discharging, we realize nanosecond microwave bursts with watt-level peak power. By optimizing three dissipation schemes, we improve work extraction efficiency of the
quantum battery by over two orders of magnitude and achieve high power compression factors outperforming the state-of-the-art techniques, establishing dissipation engineering as a pathway toward room-temperature, high-power coherent microwave sources.
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All authors Yuanjin Wang, Hao Wu, Mark Oxborrow, Qing Zhao
Fluid Dynamics
Drift towards isotropization during the 3D hydrodynamic turbulence onset
D.S. Agafontsev, A.S. Il'yn and A.V. Kopyev
The incompressible three-dimensional Euler equations develop very thin pancake-like regions of exponentially increasing vorticity. The characteristic thickness of such regions decreases exponentially with time, while the other two dimensions do not change considerably, making the flow near each pancake strongly anisotropic. The pancakes emerge in increasing number with time, which may enhance the anisotropy of the flow, especially if they orient similarly in space. In the present paper, we study numerically the anisotropy by analyzing the
evolution of the so-called isotropy markers [Phys. Rev. Fluids 10, L022602 (2025)]. We show that these functions drift slowly towards unity, indicating the process of slow isotropization, which takes place without the viscous scales getting exited and despite the similar orientation of the emerging pancakes.
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Chemical Physics
Fate of amine-based selenenyl sulfides during interaction with glutathione reductase: a molecular dynamics perspective
Vishnu Rama Chari and Raghu Nath Behera
In the search for small organoselenium-based mimics of the glutathione peroxidase (GPx) enzyme, it has been observed that selenenyl sulfides (RSeSG) derived from amine-based GPx mimics have the potential to be reduced at the catalytic site of glutathione reductase (GR), thereby enhancing the catalytic efficiency of these mimics in biological systems. However, molecular insights into these interactions are lacking due to the absence of force field parameters for Se-S containing compounds. In this study, we present force field parameters for selenenyl sulfides with a phenyl selenide backbone developed using the General Amber Force Field (GAFF). Employing these parameters, a 200 ns molecular dynamics (MD) simulation of RSeSG was performed. The results indicate that both the amino nitrogen and its substituent significantly influence the interaction of RSeSG at the catalytic site of GR.
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Computational Physics · Cross-listed from quant-ph
Fermionic neural Gibbs states
Jannes Nys and Juan Carrasquilla
We introduce fermionic neural Gibbs states (fNGS), a variational framework for modeling finite-temperature properties of strongly interacting
fermions. fNGS starts from a reference mean-field thermofield-double state and uses neural-network transformations together with imaginary-time
evolution to systematically build strong correlations. Applied to the doped
Fermi-Hubbard model, a minimal
lattice model capturing essential features of strong electronic correlations, fNGS accurately reproduces thermal energies over a broad range of temperatures, interaction strengths, even at large dopings, for system sizes beyond the reach of exact methods. These results demonstrate a scalable route to studying finite-temperature properties of strongly correlated fermionic systems beyond one dimension with neural-network representations of
quantum states.
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