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2604.11800 2026-04-14 cond-mat.stat-mech

Diffusing diffusivity model with dichotomous noise

Dongho Lee, Jae-Hyung Jeon, Pascal Viot, Gleb Oshanin

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英文摘要

We study Langevin dynamics with stochastic diffusivity arising from fluctuations of the surrounding medium. The diffusivity is modeled as Ornstein-Uhlenbeck process driven by symmetric dichotomous noise, which confines it to a finite interval. We derive analytical expressions for the short-time probability density function (PDF) of the particle displacement and analyse its asymptotic behaviour. While the PDF retains the characteristic logarithmic divergence at the origin, its tails differ from the Gaussian white-noise case: exponential tails are replaced by Gaussian ones modulated by a power-law with a switching-rate-dependent exponent. At long times, the dynamics converges to ordinary Gaussian diffusion. We determine the variance and covariance of the time-averaged stochastic diffusivity and show that it is self-averaging. The model provides a minimal analytically tractable framework for stochastic transport in environments with bounded or switching fluctuations.

2604.11794 2026-04-14 astro-ph.HE

The nature of tilted supercritical accretion discs

P. Chris Fragile, Matthew J. Middleton, Brooks Brasseur, Deepika A. Bollimpalli, Zach Smith

Comments 10 pages, 11 figures, accepted for publication in MNRAS

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英文摘要

In this paper, we report on the first 3D general relativistic radiation magnetohydrodynamic simulations of large supercritical accretion discs that are tilted with respect to the black hole spin axis. We explore a range of black hole spin parameters (from $a_* = -0.9$ to 0.9), initial tilts (in the range from $β_0 = 0^\circ$ to $30^\circ$), and target mass accretion rates. We first confirm that, for all the untilted simulations, the Eddington accretion limit is obeyed ($\dot{M}_\mathrm{BH} \lesssim \dot{M}_\mathrm{Edd}$), consistent with our previous findings. However, for tilted discs we find that the mass accretion rate can be enhanced by up to a factor of ten and that factor depends linearly on tilt $\dot{M}_\mathrm{BH} \propto β_0 \ge \dot{M}_\mathrm{Edd}$. This could be an important aspect in solving the puzzle of the growth of the first supermassive black holes. We also find that for a given tilt, the mass accretion rate enhancement is proportional to the magnitude of the spin. Additionally, we find that tilted supercritical accretion discs are more advective than their untilted counterparts. We attribute all of these differences to the presence of standing shocks in the inner regions of the accretion flow, a feature unique to tilted discs.

2604.11785 2026-04-14 physics.atom-ph

Extraction of Effective Electromagnetic Material Properties for Rydberg Electrometer Vapor Cells from 10-300 MHz

D. Richardson, J. Dee, J. Yaeger, M. Viray, J. Marsh, B. Kayim, B. C. Sawyer, D. S. La Mantia, R. Wyllie, R. S. Westafer

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英文摘要

Quantum sensors often consist of packaging, such as dielectric-based vapor cells and metallic electrodes, that reduces and spatially alters the locally observed electromagnetic fields. These effects have been well studied in the optical regime, and even in the RF regime over a few GHz. However, there have been few studies in the electrically small regime below 1 GHz. In order to account for or remove the effects of the packaging, more studies are needed across a broad range of frequencies. This paper reports on the complex permittivity and conductivity of several commercially available vapor cells used for Rydberg electric field sensing from 10-300 MHz. A new method using a stripline transmission measurement was performed and full wave electromagnetics modeling was used to extract the effective dielectric constitutive parameters from the vapor cells. Additionally, the field reduction inside the vapor cell is reported, and published atomic measurements of the electric field are used to further validate the results presented here. Several observations were made from the measurements, such as the frequency dependencies of the RF dispersion and absorption. Applications of this technique include making precise numerical field corrections or physically designing a more optimal vapor cell via coatings, material changes, or geometric changes to improve field strength and uniformity.

2604.11783 2026-04-14 math.DG gr-qc math-ph math.MG math.MP

Hausdorff-type metric geometry of the space of Cauchy hypersurfaces

Christian Lange, Jonas W. Peteranderl

Comments 28 pages

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We equip the space of Cauchy hypersurfaces in a globally hyperbolic spacetime with a natural Hausdorff-type metric and study its properties, in particular completeness and local compactness, for Lorentzian manifolds and in more general synthetic Lorentzian settings. For this purpose, we also generalize results on completeness properties of spacetimes due to Beem and Takahashi.

2604.11781 2026-04-14 quant-ph

Measuring what matters: A scalable framework for application-level quantum benchmarking

Willie Aboumrad, Claudio Girotto, Joshua Goings, Luning Zhao, Miguel Angel Lopez-Ruiz, Daiwei Zhu, Ananth Kaushik, Sayonee Ray, Samwel Sekwao, Jason Iaconis, Andrew Arrasmith, Andrii Maksymov, Yvette de Sereville, Felix Tripier, Far McKon, Coleman Collins, Evgeny Epifanovsky, Masako Yamada, Martin Roetteler

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As quantum computing systems continue to mature, there is an increasing need for benchmarking methodologies that capture performance in terms of meaningful, application-level metrics. In this work, we present a scalable framework for application-level quantum benchmarking that is designed to support internal system evaluation and cross-platform comparison across technology providers. Our framework is guided by a set of core principles, including measurability, simplicity, scalability, and extensibility. We present 13 benchmark families that reflect realistic workloads across multiple domains. This enables the systematic evaluation of the quality of solutions, the total execution time, total used energy, as well as Time-to-Solution. The benchmarks are designed to be reproducible, interpretable across stakeholder groups, and adaptable to evolving system capabilities. The framework aims to bridge the gap between low-level performance metrics and real-world value, providing a unified approach to assessing quantum systems. The resulting benchmarks support development and validation and contribute to the foundation of industry-wide benchmarking standards.

2604.11780 2026-04-14 cond-mat.mtrl-sci physics.app-ph

Multiple spiking functionalities in annealing-optimized Ag/Hf$_{0.5}$Zr$_{0.5}$O$_2$-based memristive neurons

Nikita Zhidkov, Andrei Zenkevich, Anton Khanas

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英文摘要

Rapid progress of artificial neural network applications in recent years has led to the issue of an unprecedented energy consumption. It can be solved by the implementation of energy efficient hardware based on non-von-Neumann architectures, which requires the development of electronic components emulating the behavior of synapses and neurons. While research of synaptic elements is vast, the technology for fabrication of scalable and highly reproducible neuronal elements is far less developed. In this paper, we demonstrate an artificial neuron with multiple functionalities based on filamentary switching Ag/Hf$_{0.5}$Zr$_{0.5}$O$_2$ (HZO) memristors. To improve the parameters of memristors, we propose a two-step annealing method, which allows for better control of the crystallization of the functional dielectric layer (HZO) as well as of the diffusion of active electrode (Ag) atoms. Furthermore, we demonstrate the leaky integrate-and-fire (LIF) neuronal behavior in multiple spiking modes: time-to-first-spike (TTFS), number of spikes and firing rate coding. Moreover, the neuron operation does not require the additional electronic overhead and is supported solely by a Ag/HZO memristor with a current limiting resistor connected in series. The presented results pave the way for the creation of next generation energy efficient neuromorphic hardware operating on the principles of spiking neural networks.

2604.11779 2026-04-14 astro-ph.EP

Origin and characterization of super-Earths and sub-Neptunes

Léna Parc, Julia Venturini, François Bouchy, Ravit Helled, Caroline Dorn, Adrien Leleu, Yann Alibert, Simon Müller, Haiyang Wang

Comments Chapter accepted for publication in the NCCR PlanetS Legacy Book: Benz, W. et al. (Eds), The National Center for Competence in Research, PlanetS: A Swiss-wide network expanding planetary sciences. Springer (2026). 32 pages, 6 figures

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Super-Earths and sub-Neptunes represent the most common class of exoplanets discovered to date in our galaxy, yet they have no direct analogues in the Solar System. Since 2014, researchers within the NCCR PlanetS have made significant contributions to understanding the origin and nature of these small planets. This chapter provides an overview of the progress made in their detection, characterization, and theoretical interpretation during the 2014-2025 period. The combined data from space-based photometric missions such as Kepler and TESS, together with ground-based radial velocity campaigns using state-of-the-art spectrographs (e.g., HARPS, ESPRESSO, NIRPS), have enabled detailed demographic analyses of these planets. These observational efforts are complemented by theoretical work exploring their internal structures, bulk compositions, formation and evolution, shedding light on the physical processes responsible for the observed diversity. As high-precision observations from facilities like JWST begin to probe the atmospheric composition of individual planets, a more complete picture of super-Earth and sub-Neptune origins is emerging, one that continues to challenge and refine current planet formation theories.

2604.11776 2026-04-14 physics.flu-dyn physics.bio-ph physics.comp-ph physics.med-ph

Bicuspid Valve Closure and Backflow Prevention: Role of Leaflet Geometry

B. Kaoui, A. Bou Orm, P. Navet, J. Baish, L. L. Munn

Comments 13 pages, 9 figures

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Journal ref
Phys. Rev. Fluids 11, 033103 (2026)
英文摘要

Bicuspid valves with crescent-shaped leaflets are found in lymphatic vessels and veins, where their primary function is to prevent reflux and ensure unidirectional flow toward the heart. These valves are passive, and their functionality emerges spontaneously from a complex interplay between the properties of the valve leaflets and the flow patterns developing within the vessel sinus region surrounding the valve. The main function of the valves is to limit retrograde flow, or reflux, but the optimal valve structure has not been well-characterized. Here we investigate numerically how the length of the leaflets affects the valve efficiency in preventing reflux. The valves are subjected to backward flow, akin to that imposed by gravity. We report the flux through the valve orifice as a function of key parameters: valve length, leaflet length, and leaflet rigidity. We monitor the transition in the flow regime - from reflux to complete flow blockage - by varying only the leaflet length. The transition threshold is found to depend strongly on the valve shape and stiffness. We captured these control parameters numerically to evaluate the ability of the valve to close and prevent reflux. This study allowed us to explain reflux observed experimentally in certain incompetent abnormal and immature valves, particularly those with shorter leaflets.

2604.11774 2026-04-14 hep-ex physics.ins-det

Neutron Reconstruction via Blips in Liquid Argon Time Projection Chambers

Miguel Hernandez Morquecho, Bryce Littlejohn, Paola Sala, Linyan Wan

Comments 18 pages + 6 pages appendix

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Neutrons are important final-state particles in neutrino interactions, yet they are not considered or reconstructed in most current neutrino LArTPC physics analyses. In this paper, we present a simulation-based proof-of-concept study of neutron reconstruction in a generic LArTPC detector. Leveraging isolated, MeV-scale energy deposits, or blips, from neutron inelastic scattering, and using realistic blip response from published experimental results, we demonstrate the capability to identify neutrons and to reconstruct the direction and energy of the final-state neutron system in sub-GeV neutrino interactions. We then explore how neutron-related blip attributes can be used to improve physics studies of neutrino interactions, such as enhancing neutrino-antineutrino separation in atmospheric neutrinos and reverse-horn-current beam neutrinos. This simple study provides an initial quantification of LArTPC neutron reconstruction capabilities, which we expect to improve with future advancements in blip reconstruction, identification, and classification algorithms, as well as the modeling of neutrons.

2604.11773 2026-04-14 cs.LG cond-mat.mtrl-sci cs.CV

Autonomous Diffractometry Enabled by Visual Reinforcement Learning

J. Oppliger, M. Stifter, A. Rüegg, I. Biało, L. Martinelli, P. G. Freeman, D. Prabhakaran, J. Zhao, Q. Wang, J. Chang

Comments 20 pages, 16 figures

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Automation underpins progress across scientific and industrial disciplines. Yet, automating tasks requiring interpretation of abstract visual information remain challenging. For example, crystal alignment strongly relies on humans with the ability to comprehend diffraction patterns. Here we introduce an autonomous system that aligns single crystals without access to crystallography and diffraction theory. Using a model-free reinforcement learning framework, an agent learns to identify and navigate towards high-symmetry orientations directly from Laue diffraction patterns. Despite the absence of human supervision, the agent develops human-like strategies to achieve time-efficient alignment across different crystal symmetry classes. With this, we provide a computational framework for intelligent diffractometers. As such, our approach advances the development of automated experimental workflows in materials science.

2604.11771 2026-04-14 physics.flu-dyn physics.chem-ph

Shape-dependence of electrophoretic mobility

Arkava Ganguly, Ankur Gupta

Comments 29 pages, 7 figures, appendix includes representative prompts made to Claude, supplementary info includes codes generated by Claude

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The electrophoretic mobility of a spherical particle is well understood, yet how particle shape modifies this mobility at arbitrary Debye length remains an open question. Here, we compute the electrophoretic mobility of a nearly spherical particle whose surface is described by $r_s(θ) = a[1 + \varepsilon f(θ)]$, with $\varepsilon \ll 1$, at arbitrary ratio of particle size to Debye length $κa$. Using a volume-integral formulation combined with domain perturbation techniques, we derive a universal shape correction coefficient $σ_2(κa)$ such that the mobility takes the compact form $C_\parallel = f_H(κa)\,[1 + \varepsilon\,c_2\,σ_2(κa)]$, where $f_H$ is Henry's function. We show that $σ_2$ interpolates between $+1/5$ in the thick-double-layer (Hückel) limit, governed solely by the Stokes drag correction, and zero in the thin-double-layer (Smoluchowski) limit, recovering the classical shape-independence theorem. The perturbation theory agrees quantitatively with exact spheroid solutions for both prolate and oblate orientations. A key finding is that only the $P_2$ (quadrupolar) component of the particle shape affects the mobility at leading order; higher harmonics are electrophoretically silent due to angular selection rules governing the coupling between the dipolar applied field and the shape perturbation. The results in this paper were generated using Claude Code (Anthropic, Opus 4.6 model) with supervision from the authors. Our thoughts on the usage of AI for theoretical research, along with representative prompts from the development process, are provided in the manuscript and Appendix.

2604.11763 2026-04-14 physics.optics

Self-Configuring Universal Multichannel and Multidimensional Integrated Photonic Processing Engine

Zengqi Chen, Wu Zhou, Hao Chen, Kaihang Lu, Wenzhang Tian, Yiou Cui, Yuxiang Yin, Mingyuan Zhang, Xiaofu Pan, Jianqi Hu, Yeyu Tong

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Arbitrary manipulation of light across multiple physical dimensions is essential for harnessing its parallelism in fundamental research and advanced applications, such as optical interconnects, computing, imaging, sensing, and quantum networks. However, creating a universal device capable of arbitrary operations of multidimensional optical beams has been challenging, primarily due to their complex mutual interferences and dynamic transmission characteristics. In this study, we experimentally demonstrate a self-configuring integrated photonic processor designed for the arbitrary manipulations of multiple optical waves over their spatial and polarization dimensions. Despite the random nature of the input speckle, the photonic processor relies on an optical singular-value decomposition engine to sort all orthogonal input beams and implement arbitrary processing over both spatial and polarization dimensions precisely. Notably, the photonic processor can be self programmed in situ, enabling versatile functionalities such as beam shaping, optical switching, and reconfigurable optical add-drop multiplexing. Our findings advance the manipulation of multidimensional optical beams through a scalable, CMOS-compatible integration approach, paving the way for fully exploiting the parallelism of light in various applications.

2604.11762 2026-04-14 cs.CV cs.LG eess.SP physics.med-ph stat.ML

MosaicMRI: A Diverse Dataset and Benchmark for Raw Musculoskeletal MRI

Paula Arguello, Berk Tinaz, Mohammad Shahab Sepehri, Maryam Soltanolkotabi, Mahdi Soltanolkotabi

Comments 15 pages, 6 figures, preliminary version

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Deep learning underpins a wide range of applications in MRI, including reconstruction, artifact removal, and segmentation. However, progress has been driven largely by public datasets focused on brain and knee imaging, shaping how models are trained and evaluated. As a result, careful studies of the reliability of these models across diverse anatomical settings remain limited. In this work, we introduce MosaicMRI, a large and diverse collection of fully sampled raw musculoskeletal (MSK) MR measurements designed for training and evaluating machine-learning-based methods. MosaicMRI is the largest open-source raw MSK MRI dataset to date, comprising 2,671 volumes and 80,156 slices. The dataset offers substantial diversity in volume orientation (e.g., axial, sagittal), imaging contrasts (e.g., PD, T1, T2), anatomies (e.g., spine, knee, hip, ankle, and others), and numbers of acquisition coils. Using VarNet as a baseline for accelerated reconstruction task, we perform a comprehensive set of experiments to study scaling behavior with respect to both model capacity and dataset size. Interestingly, models trained on the combined anatomies significantly outperform anatomy-specific models in low-sample regimes, highlighting the benefits of anatomical diversity and the presence of exploitable cross-anatomical correlations. We further evaluate robustness and cross-anatomy generalization by training models on one anatomy (e.g., spine) and testing them on another (e.g., knee). Notably, we identify groups of body parts (e.g., foot and elbow) that generalize well with each other, and highlight that performance under domain shifts depends on both training set size, anatomy, and protocol-specific factors.

2604.11750 2026-04-14 physics.optics cond-mat.mes-hall

Magnetic switching of self-hybridized exciton-polaritons in CrSBr photonic crystal slabs

T. D. Gorelkina, I. E. Kalantaevskii, A. N. Abramov, K. A. Gasnikova, P. A. Alekseev, X. Zeng, D. Huang, T. Jiang, I. V. Iorsh, I. Y. Chestnov, V. Kravtsov

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Layered van der Waals antiferromagnet CrSBr supports strong light--matter coupling and formation of magnetically tunable exciton-polaritons, yet active magnetic control over polariton propagation direction has remained elusive. Here, we investigate self-hybridized exciton-polaritons in photonic crystal slabs fabricated from CrSBr flakes and their evolution across the antiferromagnetic-to-ferromagnetic spin-flip transition induced by moderate in-plane magnetic fields. Using angle-resolved reflectance and photoluminescence spectroscopy supported by modeling, we show that the polariton energy continuously tracks the layer-by-layer magnetization switching, revealing a gradual redistribution of oscillator strength from antiferromagnetic to ferromagnetic excitons near the critical field. Most notably, we demonstrate that the sign of the polariton group velocity can be reversed by a small change in the external magnetic field of only 40 mT, resulting in complete switching of the polariton propagation direction. Our results establish CrSBr photonic crystal slabs as a platform for magnetically controlled polariton transport, opening opportunities for active integrated photonic and polaritonic devices.

2604.11743 2026-04-14 quant-ph

Sub-nanosecond control for spin-defect quantum memories with a low-cost, compact FPGA platform

Victor Marcenac, Tommy Nguyen, Julie Chen, Weitao He, Enrique Garcia, Yuyang Han, Bethany E. Matthews, Tiamike Dudley, Andrew Mounce, Kai-Mei C. Fu, Maxwell F. Parsons

Comments 15 pages, 4 figures, submitted to QCE26

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Dynamical decoupling techniques are widely used to characterize and control the environments of solid-state quantum defects, enabling solid-state quantum memories and nanoscale quantum sensors. However, resolution is often limited by the timing granularity of control hardware, which can undersample narrow spectral features and distort extracted parameters. Here, we demonstrate sub-nanosecond timing control on an inexpensive FPGA-based platform by extending the open-source QICK (Quantum Instrumentation Control Kit) framework using a waveform-offset method. This approach achieves an effective timing resolution of 200~ps on an RF system-on-chip device without modification to the underlying hardware. We apply this capability to dynamical decoupling spectroscopy of nitrogen-vacancy centers in diamond, enabling precise extraction of hyperfine couplings of individual $^{13}\mathrm{C}$ nuclear spins and resolving spectral features that are otherwise undersampled. These results demonstrate that high-resolution, device-level characterization of spin-based quantum memories can be achieved using flexible, inexpensive control hardware, providing a scalable alternative to commercial arbitrary waveform generators.

2604.11740 2026-04-14 cond-mat.soft cond-mat.stat-mech physics.bio-ph

An active soft condensed matter approach to the Physics of living systems

Nitin Kumar

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Journal ref
Resonance Vol. 31, No. 3, 349-367 (2026)
英文摘要

This article aims to introduce the broad field of soft active matter physics and its relevance to the life sciences in simple, accessible language. Although this area of research is relatively new, it has already demonstrated significant potential in providing a physical understanding of many biological processes. While several review articles by leading researchers exist, they can be difficult to grasp for undergraduate students and even early-career researchers who wish to enter this field. In this article, I cover the basics, introduce the origins of soft active matter physics, and explain how it differs from traditional equilibrium condensed matter ideas at the fundamental level. For the most part, I will avoid mathematical equations and excessive technical precision in several statements. Instead, I will focus on communicating the core ideas and the overall spirit of the argument, using everyday examples to develop a physical intuition. The primary focus will be on the dynamical aspects of these systems. I will conclude by briefly discussing a published experimental study from our research group that examines universal features of the trajectories of homing and migrating organisms.

2604.11739 2026-04-14 cond-mat.str-el

Topological Kondo Insulator from Spin Loop Currents

Andreas Gleis, Kevin Lucht, Po-Jui Chen, Daniele Guerci, Andrew J Millis, J. H. Pixley

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We demonstrate that interacting electrons in AB-stacked $\mathrm{MoTe}_2/\mathrm{WSe}_2$ realize a topological Kondo insulator at hole filling $ν=2$ per moiré unit cell. In the presence of only local correlations, a symmetry of the moiré-scale bandstructure enforces a compensated topological semimetal by tying band inversion to band overlap. We show that non-local interactions change the physics qualitatively, since they allow intrinsic, quantum-geometry-induced spin loop currents to feed back on the effective bandstructure, which lift the remaining accidental degeneracies and open a full gap in the spectrum, leading to a fully gapped topological Kondo insulator. We establish this using real-frequency dynamical mean-field theory to capture Kondo physics alongside Hartree-Fock for non-local interactions. The topological Kondo insulator emerges at intermediate displacement fields, where strong correlations manifest through an enhanced spin susceptibility, a suppressed charge susceptibility, and a stronger thermal dependence of the resistivity. Our results are in good agreement with recent experiments on $\mathrm{MoTe}_2/\mathrm{WSe}_2$ bilayers demonstrating topological to trivial phase transitions controlled by the displacement field.

2604.11738 2026-04-14 cond-mat.supr-con

Reduced pair breaking from extended disorder in unconventional superconductors: implications to 4Hb-TaS$_2$

Yuval Tsur, Mark H. Fischer, Jonathan Ruhman

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Unconventional superconductivity is generally expected to be strongly suppressed by nonmagnetic disorder, as captured by Abrikosov--Gor'kov (AG) theory. However, several materials, including transition metal dichalcogenides, exhibit signatures of unconventional pairing despite relatively high resistivities, suggesting a breakdown of the conventional relation between momentum relaxation and pair breaking. Here, we study this problem in H-phase transition metal dichalcogenides by computing the disorder-dressed pairing susceptibility. We employ a multiband model with spin-orbit coupling and include an impurity potential that mimics a common lattice defect, namely a chalcogen vacancy or site ad-atom. This yields to an extended impurity potential, which we compare with the commonly considered on-site (point defect) potential. We evaluate the momentum-relaxation rate and the pair-breaking rate on equal footing. We find that extended impurity potentials lead to a parametrically reduced pair-breaking rate compared to the transport scattering rate, with $Γτ_D \sim 1/3$ over a wide parameter range. This reduction originates from the momentum structure of the disorder potential, which partially matches the internal structure of the superconducting gap and suppresses pair-breaking processes. As a result, unconventional pairing states are significantly more robust than predicted by standard AG theory. Our results provide a natural explanation for the persistence of unconventional superconductivity in systems with strong disorder and substantially alleviate the apparent conflict between high resistivity and unconventional pairing in materials such as 4Hb-TaS$_2$.

2604.11736 2026-04-14 hep-th

Poisson Gauge Theories in Three Dimensions: Exact Solutions and Conservation Laws

Alexey Sharapov, David Shcherbatov

Comments 22 pages, 2 figures

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We investigate Maxwell-Chern-Simons theory on a three-dimensional noncommutative spacetime endowed with a constant spacelike Poisson structure. By exploiting the residual rotational symmetry, we construct exact classical solutions corresponding to pointlike electric and magnetic charges. We demonstrate that noncommutativity acts as a natural regulator, ensuring a finite total electromagnetic energy and thereby resolving the classical self-energy divergence. Furthermore, some of these solutions exhibit a non-perturbative dependence on the noncommutativity parameter and allow for the generation of an arbitrary magnetic flux. We also present a noncommutative generalization of Gauss's law, providing a robust framework for the physical interpretation of these exact solutions.

2604.11728 2026-04-14 astro-ph.EP

The GAPS Programme at TNG. LXXIII. Confirmation of the hot sub-Neptune TOI-4602 b (HD 25295 b), a key target for future atmospheric characterization

C. Di Maio, S. Benatti, D. Locci, R. Spinelli, M. Baratella, K. Biazzo, J. Maldonado, A. F. Lanza, C. Dorn, P. E. Cubillos, A. Salmi, A. Maggio, L. Naponiello, F. Marzari, G. Micela, V. Fardella, L. Malavolta, M. Damasso, A. Sozzetti, G. Mantovan, D. Nardiello, I. Carleo, R. Claudi, R. Cosentino, M. Gonzalez, D. Muthukrishna, M. Pinamonti, T. Zingales

Comments 18 pages, 13 figures, accepted by A&A

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Precise mass and radius measurements of small, transitional exoplanets, such as super-Earths and sub-Neptunes, are essential to constrain their bulk density and formation history, serving as prerequisites for atmospheric characterization. The ArMS Large Programme, carried out within GAPS using the HARPS-N spectrograph at the Telescopio Nazionale Galileo, aims to confirm and characterize transitional planets in the radius valley through high-precision radial-velocity (RV) measurements. The ultimate goal is to identify ideal targets for atmospheric follow-up observations with next-generation facilities like the James Webb Space Telescope and the future ESA Ariel satellite. We present the first mass determination of a sub-Neptune planet using data entirely collected within the ArMS programme, focusing on the validated planet TOI-4602b. We monitored TOI-4602, which hosts a close-in validated sub-Neptune (P ~ 3.98 d) detected by the Transiting Exoplanet Survey Satellite (TESS), searching for planet-induced RV variations. We then performed a joint analysis of these RV measurements together with the TESS photometric data. We determined that TOI-4602b is a sub-Neptune with a radius of Rp = 2.5 Rearth and a mass of Mp = 5.5 Mearth. The resulting bulk density (rho_p = 2.1 ) and atmospheric evolution modelling suggest the planet is retaining a tenuous envelope while evolving toward a bare core, consistent with a position immediately above the radius valley. g cm^ -3 Given its bright (V = 8.4) and quiet host star and the high Transmission Spectroscopy Metric (TSM) value (140 +/- 54), TOI-4602,b is a prime target for atmospheric characterization. Simulated retrievals indicate that JWST and Ariel can effectively constrain its atmospheric composition, offering a unique window into the physical processes driving the sub-Neptune to super-Earth transition.

2604.11727 2026-04-14 physics.ins-det hep-ex

Characterization of the 20-inch Photomultiplier Tubes for RENE Detector

Junkyo Oh, Byeongsu Yang, Cheong Heo, Daeun Jung, Dong Ho Moon, Eungyu Yun, Hyun Woo Park, Jae Sik Lee, Jisu Park, Ji Young Choi, Kyung Kwang Joo, Ryeong Gyoon Park, Sang Yong Kim, Sunkyu Lee, Insung Yeo, Myoung Youl Pac, Jee-Seung Jang, Eun-Joo Kim, Hyunho Hwang, Junghwan Goh, Wonsang Hwang, Jiwon Ryu, Jungsic Park, Kyu Jung Bae, SeoBeom Hong, Hyunsoo Kim, Dojin Kim, Jonghee Yoo, Seunghwan Choi, Wonjun Lee, Jubin Park, Myung-Ki Cheoun, Intae Yu

Comments 22 pages, 20 figures

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To address the Reactor Antineutrino Anomaly (RAA) observed in neutrino experiments, the Reactor Experiment for Neutrino and Exotics (RENE) has been initiated using a liquid scintillation detector. In this study, we investigate the characteristics of two 20-inch Hamamatsu R12860 photomultiplier tubes (PMTs) intended for installation in the RENE detector. The charge and timing responses of the PMTs were evaluated at both the nominal and target gains expected during actual operation. In particular, gain non-uniformity arising from the large-diameter photocathode with a box-and-line type dynode structure was examined, and the maximum gain variation was measured. The occurrence rate, timing, and charge distributions of late pulses and afterpulses were also investigated to characterize the specific response features of the R12860 PMT. The results reported in this study will aid in the interpretation of signals from the RENE detector and serve as a reference for estimating potential systematic uncertainties in RENE data. Furthermore, these findings are expected to provide valuable information for other experiments employing the same type of PMTs.

2604.11722 2026-04-14 quant-ph cond-mat.mes-hall

First-principles study of dispersive readout in circuit QED

Angela Riva, Prakritish Gogoi, Nicolas Gheeraert, Serge Florens, Alex W. Chin, Alain Sarlette, Alexandru Petrescu

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The speed and fidelity of dispersive readout of superconducting qubits should improve by increasing the amplitude of the measurement drive. Experiments show, however, that beyond some drive amplitude there is always a saturation or drop in fidelity, often associated with a decrease in qubit energy relaxation time $T_1$. A simple Lindblad master equation does not capture the latter effect. More involved approaches based on effective master equations rely on strong assumptions about the spectra of the system and the bath and only partially agree with observations. Here, we perform a first-principles simulation of the full unitary dynamics of dispersive readout by considering the circuit QED Hamiltonian coupled to a microscopic model for the measurement transmission line, allowing for its arbitrary spectrum, including filters. Our access to the dynamics of the bath degrees of freedom allows us to investigate the emission spectrum of the system as a function of drive power. We show how the dependence of qubit $T_1$ on readout drive amplitude is sensitive to the details of the bath spectrum. In particular, we find that $T_1$ drops with increasing drive amplitude when a Purcell notch filter is placed at the qubit frequency, and that the Lindblad master equation shows general qualitative defects compared to the first-principles model.

2604.11713 2026-04-14 cond-mat.stat-mech cond-mat.soft

Thermodynamic fluctuations in freely jointed chains under force

Michael R. Buche, Alvin Chen

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英文摘要

It is common to study polymer physics through the use of idealized single-chain models, and the most popular of these is the freely jointed chain model. In certain thermodynamic ensembles, statistical mechanical treatment of this model is analytically tractable or sometimes exactly solvable. This enables useful relations to be ascertained, like the expected chain end-to-end length as a function of an applied force. However, most of these relations return ensemble averages, which are values with inherent uncertainty, as opposed to deterministic values with no variance. This is an important distinction to understand and quantify, because the majority of studies to date involving single-chain models effectively treat these values as deterministic rather than fluctuating. To address this issue, thermodynamic fluctuations are examined in the freely jointed chain model. Specifically, the probability densities and standard deviations of the longitudinal, lateral, transverse, and radial portions of the chain extension, as well as the extension and link angles, are examined for different numbers of links and applied forces. Fluctuations in these quantities are shown to be considerable until the applied force becomes large. Increasing the number of links in the chain gradually reduces fluctuations in all quantities except for the link angles, since they are independent for freely jointed chains in the isotensional ensemble. Quantities are obtained analytically whenever possible and numerically otherwise. Overall, these results provide intuitive admonitions to consider when modeling the stretching of single polymer chains or the deformation of entire polymer networks.

2604.11710 2026-04-14 astro-ph.HE

A bright flare in the obscured state of GRS 1915+105 as seen by NICER and Swift

Shuaitongze Zhao, Honghui Liu, Menglei Zhou, Swarnim Shashank, Cosimo Bambi, Andrea Santangelo

Comments 12 pages, 9 figures

详情
英文摘要

We report time-resolved NICER and Swift X-ray spectroscopy of a bright flare from the black hole X-ray binary GRS 1915+105 during its obscured state, which is characterized by heavy line-of-sight absorption by dense material with complex geometry. In April 2023, an unexpected flare was detected, with the observed X-ray flux increasing by nearly an order of magnitude relative to the typical obscured-state level. The spectra show pronounced variability, including significant evolution of the Fe K emission features. Time-resolved spectral modeling indicates that the main flare is associated with a combination of enhanced intrinsic emission and reduced obscuration. We further find that neutral and ionized reflection components are subject to distinct absorbers, whose evolving visibility implies a stratified absorber-reflector geometry. These properties are consistent with a re-illumination phase following a failed disk wind. A delayed radio flare detected about 2.5 days later suggests a coupling between accretion and jet activity.

2604.11706 2026-04-14 cond-mat.soft

Effect of Pre-Shear and Dispersity on Crystallization of a Model Polymer with Soft Pair Interactions using Molecular Dynamics Simulations

Tzortzis Koulaxizis, Antonia Statt

详情
英文摘要

Polymer crystallization is a process of great interest in both fundamental theory and industrial settings, particularly in polymer processing and applications involving semi-crystalline materials. The effect of processing on the initial stages of crystallization is not fully understood. Our study investigates the influence of pre-shear on monodisperse melts and bidisperse blends of a generic, segmentally coarse-grained polymer model. Through molecular dynamics simulations, we explore how polydispersity affects crystallization, where we found that the addition of short chains to a melt of longer chains increased the final crystallinity by about 10%, and increased the initial growth rate by roughly a factor of two. In contrast, however, pre-shearing the hot melt before quenching only showed a minor increase in both growth rates and final crystallinty, except in monodisperse melts of short chains. Crystal grain shapes were most influenced by pre-shearing monodisperse melts, where both asphericity and prolateness decreased. Additionally, we determined topological connectivity of crystal grains through tie- and loop-chain analysis. Again, only monodisperse melts showed a significant increase of tie chain fractions with pre-shear, while all other systems showed only modest increases. Our findings provide insight into the changes of crystallinity and cluster morphologies that emerge when pre-sheared, offering a deeper understanding of the initial crystallization processes in polymer melts when subjected to pre-shear.

2604.11702 2026-04-14 cond-mat.str-el

Strongly correlated model of acousticlike plasmons persisting across the phase diagram of cuprate superconductors

Luciano Zinni, Hiroyuki Yamase, Matthias Hepting, Matías Bejas, Andrés Greco

详情
英文摘要

Layered two-dimensional electron systems exhibit both optical and acousticlike plasmons around the Brillouin-zone center. In the layered cuprate La$_{2-x}$Sr$_x$CuO$_4$, resonant inelastic x-ray scattering (RIXS) has detected corresponding acousticlike plasmons in a low-energy regime comparable to that of other collective excitations associated with distinct regions of the cuprate phase diagram. This overlap in energy scale raises the question of whether the acousticlike plasmons are significantly influenced by phase-specific electronic phenomena, including the pseudogap, charge and spin order, superconductivity, and strange-metal behavior. Here we show that a single parameter set of the layered $t$-$J$-$V$ model, which incorporates strong correlations and the long-range Coulomb interaction $V$, consistently describes the acousticlike plasmon dispersion across all currently available RIXS data from the underdoped to the heavily overdoped regime. This transferability of a single parameter set exceeds that of earlier theoretical descriptions and supports a picture in which strong correlations persist into the heavily overdoped regime, while the collective plasmon mode exhibits only limited sensitivity to the phase-specific electronic phenomena that distinguish different regions of the phase diagram.

2604.11697 2026-04-14 hep-ph

Quantum entanglement in electron-nucleus collisions: Role of the linearly polarized gluon distribution

Michael Fucilla, Yoshitaka Hatta, Bo-Wen Xiao

Comments 21 pages, 7 figures

详情
英文摘要

We calculate the spin density matrix of a back-to-back quark-antiquark pair inclusively produced in electron-nucleus scattering, taking into account the gluon saturation effect and the linearly polarized gluon distribution. We then investigate concurrence and stabilizer Rényi entropy, quantifying entanglement, Bell-nonlocality, and magic. We find that the linearly polarized gluon distribution tends to enhance the entanglement of a heavy quark pair when the total and relative transverse momenta of the pair are orthogonal.

2604.11694 2026-04-14 astro-ph.CO

Cosmological inference with halo clustering reconstructed from the redshift-space galaxy distribution

Ryuichiro Hada, Teppei Okumura

Comments 16 pages, 6 figures, 1 table

详情
英文摘要

Accurate modeling of small-scale redshift-space clustering is crucial for full shape RSD analyses, where satellite galaxies contribute to 1-halo terms and Finger-of-God distortions. We investigate halo reconstruction based on the cylinder grouping (CG) method of Okumura et al. (2017), which selects an effective halo center tracer from the observed galaxy distribution, and how it impacts cosmological parameter inference. Using DESI-like luminous red galaxy mock catalogs from the AbacusSummit simulations at $z=1.1$, we perform effective field theory (EFT)-based full-shape modeling of the power spectrum of the reconstructed-halo sample. We show that the dominant reconstruction-induced systematics can be described and incorporated within the standard EFT framework. In particular, a simple multipole-dependent rescaling inferred directly from the data on large scales captures the dominant effect, while residual small-scale changes are absorbed by the standard counterterm and stochastic sector, without introducing additional reconstruction-specific parameters. The reconstructed-halo sample yields unbiased constraints on cosmological parameters, including the growth rate $fσ_8$ and Alcock-Paczynski parameters. Compared to the galaxy sample, it enables both improved robustness and increased statistical precision: the inferred $fσ_8$ remains stable when extending the fit beyond $k_{\max}\simeq 0.2\,h\,{\rm Mpc}^{-1}$, with its uncertainty reduced by more than $20\%$.

2604.11692 2026-04-14 cond-mat.supr-con

Statistical Signatures of Majorana Zero Modes in Disordered Topological Superconductor Antidot Vortices

Zhibo Ren, Jukka I. Väyrynen

Comments 9 pages, 4 figures

详情
英文摘要

An antidot-pinned vortex in a three-dimensional topological insulator-superconductor platform hosts a Majorana zero mode (MZM). However, numerous Caroli-de Gennes-Matricon (CdGM) states coexist with it. We develop a general theory to study the effects of disorder on the system, emphasizing the difference between Majorana zero mode and CdGM states. Using both an analytical random matrix theory approach and numerical simulations, we derive the statistical distributions of these states. Our results demonstrate that the variance of the MZM probability density is twice that of the CdGM states, a difference due to the former having a real wave function as opposed to a complex one. This distinction can be measured by using scanning tunneling microscopy in a disordered antidot vortex, providing a signature of MZM beyond the zero-bias conductance peak.

2604.11688 2026-04-14 quant-ph

Frustration-Induced Expressibility Limitations in Variational Quantum Algorithms

Sandip Maiti

Comments 12 pages, 15 figures, 1 table

详情
英文摘要

Geometric frustration, arising from competing interactions that prevent simultaneous energy minimization, presents a fundamental challenge for variational quantum algorithms applied to quantum many-body systems. We investigate the transverse-field Ising model on a square lattice with frustrated diagonal coupling and show that geometric frustration leads to strongly inhomogeneous correlations that are difficult to capture using standard Hamiltonian-inspired ansätze with global parameters. As a result, the required circuit depth increases significantly in the intermediate-field regime. We demonstrate that this limitation is not caused by optimization difficulties such as barren plateaus, but instead arises from insufficient expressibility of the ansatz. By introducing bond-resolved variational parameters, we recover accurate results at reduced circuit depth. We also study low-energy excitations and find that near-degenerate spectra in the frustrated regime further challenge variational methods. Our results provide a clear physical explanation for the limitations of variational quantum algorithms in frustrated systems and suggest improved ansatz design strategies for quantum simulation.