Peer Revenue Play credits. Real papers.

Papers

Fresh from arXiv, typeset properly. Highlighted words trade on the market.

Physics

Watch Physics

Monday 3 August

Materials Science

Physics-Informed and Knowledge-Driven Generative AI for Autonomous Discovery of Porous Oxide Energy Materials: Opportunities and Challenges

Dibakar Datta

The discovery of next-generation energy-storage materials is increasingly limited by the complexity of the underlying design problem rather than by computational capability alone. Porous transition-metal oxides represent a particularly challenging class of battery materials because their performance emerges from coupled interactions among crystal chemistry, pore architecture, ion transport, electrochemistry, electro-chemo-mechanics, synthesis, manufacturing, and battery-system operation. Recent advances in generative artificial intelligence (AI) have demonstrated remarkable capabilities for generating chemically plausible crystal structures. However, current approaches remain largely focused on crystallographic validity and thermodynamic stability. This perspective presents a roadmap for advancing generative AI beyond crystal generation toward physics-informed, application-aware, and synthesis-aware inverse design. Using porous oxide electrodes as a representative materials platform, we propose a seven-tier physics-informed inverse-design framework integrating chemistry, thermodynamics, transport, electrochemistry, durability, cell compatibility, and manufacturability. We further identify the "Missing Data Problem" as a fundamental bottleneck limiting application-aware AI and introduce an autonomous knowledge-generation framework supported by a Porous Oxide Energy Materials Ontology and a continuously evolving "Knowledge Base". Together, these concepts establish the foundation for Synthesis-Aware, Closed-Loop Autonomous Discovery, providing a general framework for AI-enabled autonomous materials discovery across energy-storage materials and other functional materials.
Read the full abstract

Chaotic Dynamics

Emergent Physical Intelligence in Biomimetic Scale Metabeams

Omid Bateniparvar and Ranajay Ghosh

Physical reservoir computing (PRC) leverages the intrinsic dynamics of physical systems to perform information processing while requiring training only in a linear readout layer. Here, we introduce a geometry-programmable metabeam inspired by the hierarchical overlapping architecture of biological scales as a physical reservoir. Contact-mediated interactions between embedded scales induce tunable nonlinear dynamics, enabling controlled transitions between periodic, multi-periodic, and chaotic responses under external excitation. The computational capability of the metabeam reservoir is evaluated using static nonlinear function approximation, Lorenz-63 prediction, and the NARMA-2, NARMA-5, and NARMA-10 benchmarks. Input signals are encoded through the excitation amplitude, whereas computation is realized through the vibrational amplitude of the metabeam followed by a trained linear readout. Across all benchmark tasks, the proposed metabeam consistently outperforms an equivalent linear beam reservoir, yielding lower normalized root-mean-square errors (NRMSEs) and improved computational performance. Different dynamical regimes of the metabeam exhibit distinct computational advantages, with the periodic regime providing the highest prediction accuracy for memory-intensive tasks and the multi-periodic regime achieving the best performance in static nonlinear function approximation. These findings demonstrate that simple interacting surface textures can simultaneously enrich reservoir dynamics and information processing capability, establishing scale-covered metabeams as tunable and mechanically programmable platforms for embodied physical intelligence and PRC.
Read the full abstract

Chaotic Dynamics

Thermal Control of Hysteresis and Deterministic Chaos in a Memristive MEMS Resonator

N.G. Koudafokê, Thierry Njougouo, Hilda A. Cerdeira et al. (+1 more)

We investigate the nonlinear dynamics of a thermo-electro-mechanically coupled memristive resonator comprising a doubly clamped Euler–Bernoulli microbeam, an RLC circuit, and a TiO$_2$ memristor with temperature-dependent ionic mobility governed by Mott and Efros–Shklovskii hopping conduction. The dynamics are analyzed using two-dimensional parameter-space maps, bifurcation diagrams, Lyapunov exponents, reconstructed attractors, Poincaré sections, Grassberger–Procaccia correlation-dimension analysis, empirical mode decomposition, the Hilbert–Huang spectrum, and electro-memristive hysteresis. Parameter-space maps reveal predominantly quasi-periodic and deterministic chaotic regimes without stable phase-locked periodic states. Bifurcation analyses show that the beam length and excitation frequency govern the dynamics through the frequency ratio $r_\omega=\omega_0/\omega_b$, whereas the excitation current mainly controls the oscillation amplitude and chaotic intensity. Under fixed operating conditions, the asymptotic regime depends on the initial conditions, and complementary diagnostics identify the thermo-memristive subsystem as the primary source of the nonlinear complexity, subsequently transmitted to the microbeam through electromechanical coupling. Temperature continuously reorganizes the electro-memristive hysteresis through the chain $T \to \sigma(T) \to M(w,T) \to i_m(t) \to w(t)$. The hysteresis area evolves non-monotonically with temperature, revealing a configuration-dependent optimal thermo-memristive operating point. These findings highlight temperature, beam length, and electrical excitation as complementary control parameters for tailoring thermo-memristive memory, deterministic chaos, and nonlinear dynamics in thermo-active MEMS, with potential applications in neuromorphic sensing and chaos-based secure communication.
Read the full abstract

All authors N.G. Koudafokê, Thierry Njougouo, Hilda A. Cerdeira, C.H. Miwadinou

Computational Physics

Computing with traceable tensor networks

Sarah Ellwein and Daniele Venturi

We introduce a new SVD-based tensor decomposition method for tensor networks with arbitrary graph topologies, extending classical hierarchical SVD-based techniques to networks with cycles and general connectivity. We also introduce addition and rounding procedures for traceable tensor graphs, enabling step-rounding time integration of high-dimensional PDEs directly in graph format, with rank truncation controlled to a prescribed tolerance at every time step. We demonstrate the new method on the decomposition of multivariate functions and on the numerical solution of the Fokker-Planck equation, and find that the graph-format representation attains comparable or better accuracy than the classical tensor train and hierarchical Tucker tensor formats, while using substantially fewer degrees of freedom at lower computational cost.
Read the full abstract

Quantum Physics

Heisenberg scaling under collective non-parallel directional noise via geometric state design

Francisco Riberi, Lorenza Viola and Milad Marvian

Spin-squeezed states enable entanglement-enhanced frequency estimation; however, the achievable performance is limited in practice by decoherence. We study the problem of parameter estimation under classical collective noise that acts along a fixed direction during signal encoding. While we restrict our analysis to Gaussian noise statistics, no assumption is made on the nature of the noise temporal correlations. Our approach captures both parallel (dephasing) and single-axis transverse noise as special cases, and covers both Markovian and non-Markovian metrological regimes. In the properly squeezed limit, where a Holstein-Primakoff description is accurate, we identify a geometric noise-immunity mechanism: for known non-parallel signal and noise axes, an appropriate one-axis-twisted input encodes the signal in a quadrature that is metric-orthogonal to the direction of noise-induced diffusion. Irrespective of the noise temporal correlations, the resulting estimation precision exhibits Heisenberg scaling in the probe number. Optimal performance is achievable by measuring a single collective spin component. Imperfect knowledge of the noise axis produces a crossover from Heisenberg scaling at moderate probe number back to the known collective-dephasing bounds asymptotically.
Read the full abstract

Solar and Stellar Astrophysics

New Spatially Resolved Observations of Betelgeuse from the VLA and ALMA: Evidence for Atmospheric Perturbations from a Close Companion

L. D. Matthews, A. K. Dupree, A. M. S. Richards et al. (+1 more)

We present new spatially resolved observations of the red supergiant Betelgeuse ($\alpha$ Orionis) at seven frequencies: 22 GHz ($\lambda$1.36cm); 44 GHz ($\lambda$6.8mm); 107 GHz ($\lambda$2.8mm); 136 GHz ($\lambda$2.2mm); 224 GHz ($\lambda$1.3mm); 338 GHz ($\lambda$0.89mm); and 485 GHz ($\lambda$0.62mm) using the Karl G. Jansky Very Large Array and the Atacama Large Millimeter/submillimeter Array. These observations (spanning 2021-2026) enable a characterization of the mean brightness temperature ($T_B$), shape, and symmetry of the star's extended atmosphere. At 22 GHz and 44 GHz $T_B$ has increased following the historic lows observed in 2019, just prior to the Great Dimming of late 2019/early 2020. We find that $T_B$ peaks at a larger projected radius ($r\sim2.7R_{\star}$) compared with measurements prior to 2016, consistent with a possible evolution in the atmospheric density profile. In addition we find a systematic decrease in $T_B$ from $\approx3500$K at $\sim2.7R_{\star}$ to $T_{B}\approx$2220K at $\sim1.2R_{\star}$, confirming a previously reported temperature minimum between the photosphere and chromosphere. At all observed frequencies $T_B$ is lower than temperatures inferred from ultraviolet measurements at comparable radii, indicating the continued presence of cooler plasma ($T\le T_{\rm eff}$) mixed with the warmer chromospheric material. The new measurements yield a global spectral index $\alpha=1.35\pm$0.03, with no evidence for a change in $\alpha$ over more than two decades in frequency. Recently, evidence of a close-in companion to Betelgeuse has been reported, with an orbital separation $r\sim2.3R_{\star}$. We have identified a correlation between the ellipticity of Betelgeuse, as obtained from radio measurements, and the companion's orbital phase. The results are consistent with periodic perturbations of the atmosphere by the companion.
Read the full abstract

All authors L. D. Matthews, A. K. Dupree, A. M. S. Richards, W. R. F. Dent

Quantum Physics

A First-principles Computational Framework for Quantum Decoherence in Complex Diamond Spin Environments

Huijin Park, Ha-young Jeong, Hyeonsu Kim et al. (+6 more)

Quantum decoherence induced by defects remains a major limitation for solid-state quantum technologies, yet predicting decoherence in realistic materials remains computationally challenging. Complex defect populations are often approximated as homogeneous spin baths, obscuring the role of defect-specific electronic structure and spin dynamics. Here, we develop a predictive framework for decoherence in diamond by combining first-principles electronic-structure calculations, quantum many-body spin-bath simulations, and experimental validation. The framework incorporates defect-resolved spin Hamiltonians and heterogeneous spin baths containing multiple paramagnetic defect species. Using diamond nitrogen-vacancy ensembles as a model platform, we investigate mixed nitrogen-, vacancy-, and hydrogen-related defect environments. We show that decoherence depends not only on defect density but also on defect identity and bath composition, whose distinct electronic structures, hyperfine interactions, and spin dynamics produce different coherence behavior. Heterogeneous defect populations can either suppress or enhance decoherence, producing trends unexplained by homogeneous-bath models. Magnetic-field-dependent Hahn-echo measurements on samples with different defect concentrations validate the framework. The calculations reproduce the observed coherence times and stretched-exponential decay behavior across a broad magnetic-field range and identify vacancy-related defects as critical contributors beyond the conventionally assumed P1 spin bath. By linking atomistic defect properties to quantum coherence, our framework provides a predictive route for identifying hidden defect environments and optimizing decoherence in defect-based quantum materials.
Read the full abstract

All authors Huijin Park, Ha-young Jeong, Hyeonsu Kim, Christoph Findler, Fedor Jelezko, Sangwon Oh, Junghyun Lee, Giulia Galli, Hosung Seo

Instrumentation and Methods for Astrophysics

Single-Photon Counting CMOS Detectors for the Habitable Worlds Observatory

Edwin Alexani, Justin P. Gallagher and Donald F. Figer

The Habitable Worlds Observatory (HWO) is NASA's current New Great Observatory concept. HWO will observe the universe to search for life beyond Earth. It will need unprecedented instrument stability and detector performance. However, no single detector technology currently satisfies HWO's demanding specifications. Complementary metal-oxide-semiconductor (CMOS) single-photon counting detectors (SPCDs) are excellent candidates for further development, as they already satisfy several specifications for HWO. We report the results of a characterization program for 9.4 Mpixel CMOS SPCDs. We measure a dark current of 0.0005 e-/s/pixel, a read noise of 0.19 e-/pixel, a peak quantum efficiency of 88% at 485 nm, negligible crosstalk and persistence, and we present conversion gain measurements. The detector satisfies several key HWO performance requirements, including deep sub-electron read noise and low dark current, while additional development is required in ultraviolet quantum efficiency and full mission qualification. We include a simulated low-flux observation using characterization results, along with a roadmap for developing CMOS SPCDs to satisfy HWO specifications, especially at UV wavelengths.
Read the full abstract

History and Philosophy of Physics

The orientation of historic churches in Las Palmas de Gran Canaria and its surroundings: preliminary results

Alejandro Gangui, Jose Ricra, Joaquin Pallares et al. (+1 more)

We present preliminary results of the analysis of the precise spatial orientation of colonial Christian churches located in the city of Las Palmas, capital of the island of Gran Canaria (Spain), and its surroundings. Our sample consists of 27 churches, 15 of which belong to the city proper while the rest are situated within roughly 12 km away inland. Most of these churches were constructed between the first decades after the Castilian conquest of the island, and the end of the 19th century. In our analysis we examine whether these orientations respond to calendrical coincidences, to the main features of the landscape, or whether the standard tradition was followed regarding the orientation of the churches' apses eastwards. We find that no church in the sample is oriented towards points of the horizon on which the Sun rises on the day of the patronal feasts. Furthermore, we find no correlation between the global orientation pattern and the orography of the island which, near the local prominent Guiniguada ravine, could have been an important factor at the time of the construction of the churches. What we do find is that most of the orientations fit within the solar range, mainly to the east but also with a few historic churches oriented towards the west, while less than 20% have astronomical declinations outside of this range. In the statistical analysis, the declination histogram for the sample shows a pattern where the apses of the churches point consistently to the north of due east. This might signal constructions that were oriented to the rising Sun on dates close to Easter. We briefly discuss the implications these findings may have for a future study of the rest of Gran Canaria, which includes several dozens of historic churches scattered throughout the valleys, slopes, and volcanic calderas of the island.
Read the full abstract

All authors Alejandro Gangui, Jose Ricra, Joaquin Pallares, Juan Antonio Belmonte

Lattice Field Theory

The Momentum Fraction, Helicity and Transversity Isovector Moments of Nucleons from \texorpdfstring{$2+1$}{2+1}-flavor Lattice QCD

Santanu Mondal, Rajan Gupta, Sungwoo Park et al. (+5 more)

Results for the isovector momentum fraction, $\langle x \rangle_{u-d}$, helicity moment, $\langle x \rangle_{\Delta u-\Delta d}$, and the transversity moment, $\langle x\rangle_{\delta u-\delta d}$, of the nucleon are presented using high-statistics data on thirteen NME ensembles of gauge configurations generated by the JLab/W&M/LANL/MIT/Marseille collaborations using $2+1$-flavors of dynamical Wilson-clover quarks. The much higher statistics facilitated better control over all systematics compared to our previous lattice calculation. The least controlled systematic—excited-state contamination—is quantified by studying the variation of the results as a function of three estimates of the mass gap of the first excited state, obtained from two- and three-point correlation functions. The final results are obtained using a simultaneous fit to extrapolate in the lattice spacing, $a$, pion and kaon masses, $M_\pi$ and $M_K$, and the finite volume parameter, $M_\pi L$. The data show no significant finite-volume correction, and some dependence on the lattice spacing and the renormalization factors. The largest systematic uncertainty is due to possible remaining excited states contributions. Our final results, in the $\overline{\rm MS}$ scheme at 2~GeV, are $\langle x \rangle_{u-d} = 0.154(10)(9)$, $\langle x \rangle_{\Delta u-\Delta d} = 0.177(10)(15)$ and $\langle x \rangle_{\delta u-\delta d} = 0.197(12)(18)$, where the first error is the overall statistical uncertainty and the second represents the various systematic uncertainties added in quadrature. Results for the momentum fraction and helicity moment are consistent with phenomenological global fit values, while the transversity moment is a prediction.
Read the full abstract

All authors Santanu Mondal, Rajan Gupta, Sungwoo Park, Jun-sik Yoo, Tanmoy Bhattacharya, Boram Yoon, Bálint Joó, Frank Winter

Strongly Correlated Electrons

Tunable Skyrmions in a Topological Wigner Crystal

David A. Dahlbom, Daniel Kaplan, Premala Chandra et al. (+1 more)

In low density systems with strong interactions electrons are expected to crystallize into a Wigner solid. Recently, advances in two-dimensional systems where electrons carry Berry curvature have added a topological dimension to Wigner crystallization. Using a model for pseudospin interactions in a topological Wigner crystal, here we show that the competition between ferromagnetic Heisenberg exchange $J$ and the chiral interaction $\gamma$ on the triangular lattice stabilizes a zero-field skyrmion crystal whose density is continuously tunable through the ratio $\gamma/J$. The chiral interaction originates from finite Berry curvature in an underlying time-reversal broken Wigner crystal. In the continuum limit, the chiral interaction acts as a chemical potential for skyrmions, while higher-order gradient terms beyond the nonlinear sigma model select the skyrmion density. At large chiral coupling, we uncover a 24-site tetra-skyrmion crystal carrying four units of topological charge per magnetic unit cell, which becomes degenerate with four-sublattice tetrahedral order as $J \to 0$. We characterize the magnon structure for these phases and discuss the transition between the tunable skyrmion crystal to these states at large $\gamma/J$. Our results establish the phase diagram of ferromagnetic topological Wigner crystals.
Read the full abstract

All authors David A. Dahlbom, Daniel Kaplan, Premala Chandra, Cristian D. Batista

Quantum Physics

Improved Quantum Algorithms for Reinforcement Learning Under a Generative Model

Joao F. Doriguello

Reinforcement learning is a subfield of machine learning that studies how an agent interacts with an environment in order to extract as large a reward as possible. A standard approach to study such interaction is through Markov Decision Processes (MDPs) and the task of choosing an optimal policy — a function that tells the agent which action to take. In this work, we study two types of MDPs — finite-horizon and infinite-horizon discounted — and propose new quantum algorithms for computing approximate optimal policies. Our quantum algorithms are based on a new combination of standard value iteration and quantum subroutines like quantum mean estimation and quantum maximum finding, overall enhanced with techniques from sample-optimal classical algorithms. Our resulting query complexities improve upon previous works, thus approaching already established quantum lower bounds.
Read the full abstract

High Energy Astrophysical Phenomena

Structural quasi-universality in highly magnetized differentially rotating neutron stars

Pratul Manna and Surajit Kalita

Universal relations among macroscopic properties of neutron stars provide a powerful framework to probe their internal structures while minimizing uncertainties associated with the equation of state (EoS). Although such relations have been extensively studied for uniformly rotating stars, their extension to differentially rotating and strongly magnetized configurations is relatively less explored. We systematically investigate equilibrium configurations for a wide range of EoSs, rotation profiles, and magnetic field strengths with XNS numerical simulation code. For sequences with fixed angular momentum, we analyze the dependence of normalized moment of inertia on compactness. We establish a generalized quasi-universal relation between the moment of inertia and compactness that remains remarkably insensitive to the underlying EoS across uniformly rotating, differentially rotating, and strongly magnetized toroidal configurations. For sequences with fixed angular momentum, the normalized moment of inertia exhibits a quasi-universal dependence on compactness, with deviations primarily due to magnetic field strength and degree of differential rotation. We derive analytic expressions for these dependencies, enabling a unified phenomenological model applicable over a wide range of stellar configurations. As astrophysical applications, we quantify the systematic bias in magnetar luminosity estimates and the rotational kinetic energy of post-merger remnant of GW170817. These results extend quasi-universal relations beyond the standard assumptions of uniform rotation and weak magnetization, providing a robust framework for interpreting observations of highly magnetized and differentially rotating neutron stars, and enabling more reliable constraints on their astrophysical properties.
Read the full abstract

General Relativity and Quantum Cosmology

Regular fluid of strings black hole with non trivial core and asymptotic structure by gravitational decoupling

Milko Estrada, Luis C. N. Santos and Leonardo G. Barbosa

Cloud-of-strings (CS) geometries provide an effective description of one-dimensional string distributions. However, their central singularity cannot be removed through the standard regular black holes (RBH) mechanism based on an effective mass function, since the string sector contributes independently to the ultraviolet structure of the spacetime. Motivated by this observation, we investigate whether string-supported black holes can be consistently regularized while preserving the CS asymptotics and admitting a physically meaningful string-fluid interpretation. Using the gravitational decoupling method, we construct a RBH supported by an effective anisotropic string fluid. We show that the string sector deforms the de Sitter core, modifies the local topology of the spacelike slices, and introduces a longer-range correction dominating the usual Hayward/LQG term. The geometry admits non-extremal and extremal RBH, as well as a regular horizonless compact object. Moreover, the string parameter qualitatively modifies the thermodynamic evolution by shifting the Davies phase transition and the size of the black-hole remnant. Finally, the scalar quasinormal-mode spectrum exhibits systematic changes in both the oscillation frequencies and damping rates. These results show that regularizing string supported black holes is a physically distinct problem, with the matter sector governing the ultraviolet structure, thermodynamics, and dynamical response of the spacetime.
Read the full abstract

Chemical Physics

The Existence Regions for Transcomplex Recombination of Heavy Ions. Two-Dimensional Recombination Regions and Surroundings Indices

V. M. Akimov, V. M. Azriel, E. V. Ermolova et al. (+4 more)

In this paper, we examine transcomplex recombination RCs$^+$ + Br$^-$ $\to$ CsBr + R (R = Kr, Xe, Hg) for collision energies from 0.1 to 2.5 eV. Within the framework of the quasiclassical trajectory method on semiempirical diabatic potential energy surfaces, we have considered the existence regions for recombination in the space of kinematic parameters. Two-dimensional "slices" of the existence regions for recombination (on the sphere where the coordinates are the orientation angles of the initial direction of the axis of the ionic complex RCs$^+$) sometimes exhibit a chaotic structure. We have proposed a quantitative measure of chaoticity of two-dimensional existence regions for recombination (on the basis of the combinatorics of matrices of zeros and ones) and have presented examples of chaotic regions. We have introduced the surroundings index of recombinative trajectories and have explored its connection with the integration time of the trajectory and with the total internal energy of the product molecule CsBr.
Read the full abstract

All authors V. M. Akimov, V. M. Azriel, E. V. Ermolova, D. B. Kabanov, L. I. Kolesnikova, L. Yu. Rusin, M. B. Sevryuk

Quantum Physics

PaQit: Energy-Runtime-Fidelity Co-Optimization for Neutral Atom Quantum Computers

Jason Ludmir and Tirthak Patel

Neutral-atom quantum computers provide a scalable platform for large-scale quantum computation due to their all-optical control, room-temperature operation, and flexible lattice geometry. Although the favorable energy characteristics of these systems are well recognized, the relationship between system-level energy consumption, runtime, and computational fidelity remains poorly understood, limiting practical scheduling decisions. In this work, we develop a hardware-grounded analytical model that captures how energy and runtime scale with qubit utilization in neutral-atom systems. We introduce PaQit, a fidelity-aware qubit packing framework that integrates device-level Rydberg interaction physics with system-level scheduling to jointly optimize energy, runtime, and fidelity. By translating fidelity targets into packing decisions, PaQit identifies operating regimes that maximize parallelism while respecting interaction-driven crosstalk constraints. We validate the analytical framework using simulations of QuEra's analog Aquila system and digital Gemini system, as well as real hardware executions, demonstrating close agreement between the predicted trends and observed system behavior.
Read the full abstract

Solar and Stellar Astrophysics

The Bimodal Mass Ratio Distribution of the Hyades

Henri M.J. Boffin

The distribution of stellar mass ratios, q, in binary systems provides critical insights into the dynamical history and star-formation processes of open clusters. Here, I re-evaluate the recently published mass ratio distribution (MRD) of a sample of spectroscopic binaries in the Hyades cluster, which was based on stellar positions in colour-magnitude diagrams. I demonstrate that the mass ratios derived in that work are statistically inconsistent with a random distribution of orbital inclinations. Furthermore, several systems yielded non-physical results. By applying a Richardson-Lucy deconvolution to the spectroscopic mass functions and assuming a random distribution of inclinations, I re-derive the MRD for this sample, showing that it is statistically different from a uniform distribution. I further find a significant dependence on the primary mass: systems with lower-mass primaries exhibit a peak near q~1, whereas more massive primaries show a distribution heavily skewed toward low mass ratios (q~0.15). These findings highlight the potential pitfalls of photometric mass ratio derivations and underscore the need for further verification with future data releases such as Gaia DR4.
Read the full abstract

Mesoscale and Nanoscale Physics

Magneto-oscillations, nonlinearity, and nonreciprocity of Coulomb drag in quantum circuits

Alex Levchenko, Mingyang Zheng and Dominique Laroche

We consider the problem of Coulomb drag in interactively coupled quantum circuits built of adiabatic constrictions: quantum point contacts and short quantum-wire channels. The interplay of spatial confinement and magnetic field leads to a rich oscillatory response of the drag current as a function of gate voltage and magnetic field: drag peaks track the depopulation of magnetoelectric subbands, are asymptotically periodic in inverse field, and their visibility is controlled by the competition of temperature with the field-sharpened tunneling width of the constriction. We derive a closed expression for the linear drag conductance whose interaction kernel simplifies dramatically in the experimentally relevant limit of a long thermal length compared with the range of the interwire coupling, investigate the drag in the nonlinear regime, where the drag current measures the transconductance of the drive channel at any field, and discuss physically motivated models of dissipation-induced nonreciprocity of the drag signal. Extensions accounting for Zeeman splitting, interaction renormalization of the barrier transmission, backscattering at high field, and the frequency structure of the circuit coupling delineate how each mechanism imprints itself on the temperature dependence and lineshapes of the drag oscillations.
Read the full abstract

High Energy Astrophysical Phenomena

The Indian Pulsar Timing Array Data Release 2: III. Search for a Stochastic Gravitational Wave Background

Hemanga Tahbildar, Kunjal Vara, Mayuresh Surnis et al. (+28 more)

We present the first independent search for an isotropic stochastic gravitational wave background in the second data release of the Indian Pulsar Timing Array, comprising of 27 millisecond pulsars monitored simultaneously in two frequency bands with the upgraded Giant Metrewave Radio Telescope over a maximum 7.2 year baseline. Building on a comprehensive single pulsar noise analysis, we search for a common uncorrelated red noise process within a Bayesian inference framework and with the noise-marginalized optimal statistics, and we test the robustness of the result through per-pulsar dropout analyses and solar-wind exclusion cuts. Leaving the spectral index free, we recover a broad amplitude posterior, $\log_{10} A_{\rm CURN} = -13.71^{+1.06}_{-3.28}$, with an unconstrained spectral index $\gamma_{\rm CURN} = 2.98^{+3.62}_{-2.70}$ and a Savage-Dickey Bayes factor of $2.5$ for a common red process over the no signal model. The optimal-statistic signal to noise ratios for the monopole, dipole, and Hellings-Downs correlations are all consistent with zero. Fixing the spectral index to $\gamma = 13/3$, the value predicted by an idealized toy model in which the background is sourced by a population of supermassive black hole binaries in circular orbits evolving purely under leading-order gravitational radiation reaction, we place a $95\%$ upper limit on the common-process amplitude of $A_{\rm GWB} < 3.4\times10^{-14}$, stable across solar elongation cuts of $10^\circ$, $20^\circ$, and $30^\circ$. This limit lies approximately an order of magnitude above the amplitudes reported by other, longer-running pulsar timing array experiments. We also demonstrate through simulated datasets with the addition of simple chromatic and achromatic noise components that it will take at least a 10 year baseline to start recovering the common red noise signal.
Read the full abstract

All authors Hemanga Tahbildar, Kunjal Vara, Mayuresh Surnis, Churchil Dwivedi, Bhal Chandra Joshi, Sharika Dhakappa, Aman Srivastava, Shantanu Desai, Abhimanyu Susobhanan, Adya Shukla, Himanshu Grover, P. Arumugam, Manjari Bagchi, Neelam Dhanda Batra, Manoneeta Chakraborty, Shaswata Chowdhury, Debabrata Deb, A. Gopakumar, Sushovan Mondal, Kuldeep Meena, K Nobleson, Avinash Kumar Paladi, Arul Pandian B, Kaustubh Rai, Prerna Rana, Shubhit Sardana, Vidit Singh, Jaikhomba Singha, Keitaro Takahashi, Pratik Tarafdar, Zenia Zuraiq

General Relativity and Quantum Cosmology

Integral Hilbert spaces and the dynamics of loop quantum cosmos

Janek Kozicki and Tomasz Pawłowski

Polymer quantization program applied in Loop Quantum Gravity/Cosmology leads to nonseparable Hilbert spaces. Commonly, one sidesteps this problem by singling out and working with a separable superselection sector. This is however often no longer accessible in more involved models beyond isotropic ones. In an alternative approach one builds a separable Hilbert space as an integral over all available sectors. Here we test the dynamics following from the latter on the example of a flat isotropic Universe admitting negative cosmological constant and a massless scalar field. There, numerical evolution of (initially) semiclassical states shows that there is no relevant difference in their long term semiclassicality properties in comparison to those in a single sector approach. Further, the older (problem-specific) numerical methods are compared against an application of more common and more efficient standard tools (eigen library).
Read the full abstract

Optics

Real-time quasi-distributed fiber optic sensor based on resonance frequency mapping

Gyeong Hun Kim, Sang Min Park, Chang Hyun Park et al. (+3 more)

Distributed optical fiber sensors (DOFS) based on Raman, Brillouin, and Rayleigh scattering have recently attracted considerable attention for various sensing applications, especially large-scale monitoring, owing to their capacity for measuring strain or temperature distributions. However, ultraweak backscatter signals within optical fibers constitute an inevitable problem for DOFS, thereby increasing the burden on the entire system in terms of limited spatial resolution, low measurement speed, high system complexity, or high cost. We propose a novel resonance frequency mapping for a real-time quasi-distributed fiber optic sensor based on identical weak fiber Bragg gratings (FBG), which has stronger reflection signals and high sensitivity to multiple sensing parameters. The resonance configuration, which amplifies optical signals during multiple round-trip propagations, can simply and efficiently address the intrinsic problems in conventional single round-trip measurements for identical weak FBG sensors, such as crosstalk and optical power depletion. Moreover, it is technically feasible to perform individual measurements for a large number of quasi-distributed identical weak FBGs with relatively high signal-to-noise ratio (SNR), low crosstalk, and low optical power depletion. By mapping the resonance frequency spectrum, the dynamic response of each identical weak FBG is rapidly acquired in the order of kilohertz, and direct interrogation in real time is possible without time-consuming computation, such as fast Fourier transformation (FFT). This resonance frequency spectrum is obtained on the basis of an all-fiber electro-optic configuration that allows simultaneous measurement of quasi-distributed strain responses with high speed (>5 kHz), high stability (approximately 2.4 microstrain), and high linearity (R^2 = 0.9999).
Read the full abstract

All authors Gyeong Hun Kim, Sang Min Park, Chang Hyun Park, Hansol Jang, Chang-Seok Kim, Hwi Don Lee

Mathematical Physics · Cross-listed from math.QA

Zesting and the relative complexity of Reshetikhin-Turaev invariants

Colleen Delaney and Calvin McPhail-Snyder

We show that the computational complexity of Reshetikhin-Turaev invariants of simply colored links is preserved when their underlying ribbon fusion categories are related by the zesting construction. Zesting modifies an $A$-graded ribbon fusion category $\mathcal{C}$ with additional algebraic data $\zeta$ to produce a new category $\mathcal{C}^{\zeta}$ whose link invariants are known to differ from those of $\mathcal{C}$ by an invariant of $A$-colored links $\mathcal{J}_{\zeta}$ depending only on $\zeta$. Building on this understanding and on earlier work on quantum braid group representations under zesting, our result suggests how zesting contributes to the organization of (2+1)D topological quantum field theories and topological phases into complexity-theoretic hierarchies. To prove our main result we develop a local formalism analogous to the Reshetikhin-Turaev construction to compute tangle invariants $\mathcal{J}_{\zeta}(T)$, which leads to a polynomial time algorithm to compute invariants of links $\mathcal{J}_{\zeta}(L)$. A byproduct of our construction is an identification (up to a sign) of the link invariants $\mathcal{J}_{\zeta}(L)$ as rack cocycle invariants, which may be of independent interest. Our formalism also extends to define invariants of closed $3$-manifolds with $A$-structure and we obtain similar complexity results for homotopy quantum field theories built from $A$-modular fusion categories.
Read the full abstract

High Energy Physics (Phenomenology)

Fermionic Dark Matter in a Scotogenic Model with a Complex Scalar Singlet

Gustavo Ardila-Tafurth, Andrés Flórez, Victor Martín-Lozano et al. (+1 more)

We study the phenomenology of the complex scoto-singlet model, an extension of the scotogenic framework that simultaneously accounts for radiative neutrino masses and fermionic dark matter. We perform a Markov Chain Monte Carlo scan of the parameter space, imposing theoretical consistency together with constraints from neutrino oscillation data, lepton-flavor violation, collider searches and the observed dark matter relic abundance. Viable dark matter solutions are found both near the Higgs resonance and in coannihilation regions, extending the allowed mass range with respect to the minimal scotogenic model. Direct- and indirect-detection signals are strongly suppressed, placing most of the viable parameter space beyond the reach of current experiments. At colliders, monojet searches offer the best prospects to probe our model in compressed-spectrum scenarios, while long-lived charged scalars may give rise to displaced or detector-stable signatures.
Read the full abstract

All authors Gustavo Ardila-Tafurth, Andrés Flórez, Victor Martín-Lozano, Avelino Vicente

Optics

Phase-Locked Time-Stretch Optical Coherence Tomography for Contrast-Enhanced Retinal Microangiography

Gyeong Hun Kim, Seongjin Bak, Hyung-Hoi Kim et al. (+4 more)

Optical coherence tomography angiography has transformed retinal vascular imaging by providing non-invasive, high-resolution visualization. However, achieving an optimal balance between field of view, resolution, and three-dimensional microvasculature contrast, particularly in deeper retinal layers, remains challenging. A phase-locked time-stretch optical coherence tomography microangiography system is developed to address these limitations with a 5-MHz A-line rate and sub-nm phase sensitivity. Utilizing a dual chirped fiber Bragg grating architecture, the swept-source laser achieves an extended coherence length of approximately 10 mm and a 102-nm bandwidth. A time-stretch analog-to-digital converter overcomes the limitations of conventional multi-MHz optical coherence tomography systems, ensuring a 2-mm imaging depth in the air with high spatial resolution. The proposed system enables high-contrast, depth-encoded mapping of key retinal structures, including the superficial and deep capillary plexuses and the choriocapillaris. Compared to a state-of-the-art system, the proposed approach demonstrates enhanced resolution, improved contrast, and faster imaging speeds, enhancing its potential for diagnosing and monitoring retinal and systemic diseases like age-related macular degeneration, diabetic retinopathy, and Alzheimer's disease.
Read the full abstract

All authors Gyeong Hun Kim, Seongjin Bak, Hyung-Hoi Kim, Jun Geun Shin, Tae Joong Eom, Chang-Seok Kim, Hwidon Lee

Quantum Physics

PACE-QAOA: Physics-Constrained Quantum Optimization for Qubit-Efficient Power System Islanding

Yuqi Jiang, Zhiding Liang, Qiang Guan et al. (+2 more)

Increasing renewable-energy penetration heightens power-system variability and complicates disturbance containment. Controlled islanding mitigates cascading failures by partitioning a stressed network to limit disrupted power transfer while preserving each island's operational integrity, but this constrained partitioning problem is NP-hard. Although QAOA offers a complementary search strategy, limited near-term qubit capacity restricts conventional formulations. This paper presents a qubit-efficient hybrid quantum framework combining a physics-informed compact encoding with Lagrangian constraint handling and classical feasibility refinement. The encoding exploits grid structure while formally preserving the original feasible solution space and objective. For a fixed island count on sparse working graphs, the formulation reduces phase-separator and per-layer gate complexity from quadratic to linear scaling with system size. Tests on eight IEEE systems ranging from 9 to 89 buses and multiple quantum-provider backends produce feasible, high-quality islanding solutions under practical circuit and sampling budgets. Factorial ablation attributes resource and runtime improvements to the complementary effects of compact encoding and qubit-efficient constraint handling. Noise analysis shows stable solution quality under tested device noise, while landscape diagnostics reveal smoother, more consistently scaled QAOA cost surfaces and improved parameter-optimization behavior. These results offer a transferable approach for scaling constrained quantum optimization toward larger real-world applications on near-term hardware.
Read the full abstract

All authors Yuqi Jiang, Zhiding Liang, Qiang Guan, Yan Li, Ganesh Kumar Venayagamoorthy

Quantum Physics

Energy levels of the second-harmonic Hamiltonian at large photon numbers

Boulat Nougmanov

We study the energy spectrum of the degenerate $\chi^{(2)}$ Hamiltonian describing second-harmonic generation and parametric down-conversion at large total excitation numbers. Owing to the conservation of the total excitation number, the spectral problem reduces to the diagonalization of finite-dimensional tridiagonal matrices. Following the approach of Alvarez and Alvarez-Estrada, we map this problem onto an effective one-dimensional Schrödinger equation with a double-well potential. We then derive an implicit quantization condition for the energy levels near the top of the potential barrier and obtain two explicit asymptotic formulas applicable in complementary spectral regions. The ranges of applicability of the resulting formulas are established, and their accuracy is compared with exact matrix diagonalization and with the conventional JWKB approximation. The proposed approach provides an accurate analytical description of the energy levels near the center of the spectrum, where the conventional approximation loses accuracy.
Read the full abstract

Nuclear Experiment

Elliptic flow of $\pi^0$ mesons in Cu$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV and U$+$U at $\sqrt{s_{_{NN}}}=193$ GeV

PHENIX Collaboration: N.J. Abdulameer, U. Acharya, C. Aidala et al. (+380 more)

The second-order azimuthal anisotropy coefficients ($v_2$) of neutral $\pi$ mesons ($\pi^0$) have been measured as a function of the transverse momentum ($p_T$) and centrality of Cu$+$Au collisions at $\sqrt{s_{_{NN}}}=200$~GeV and U$+$U at $\sqrt{s_{_{NN}}}=193$ GeV at the Relativistic Heavy Ion Collider. The analysis used experimental data collected by the PHENIX experiment at midrapidity $|\eta|<0.35$ over a broad $p_T$ range up to $\approx10$~GeV/$c$, and the obtained results are compared with previous PHENIX measurements in Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$~GeV. In all three collision systems, the $\pi^0$~$v_2$ values follow the scaling with the second-order participant eccentricity and the cube root of the number of participating nucleons ($\varepsilon_2 N_{\rm part}^{1/3}$) up to $\approx4$~GeV/$c$. Furthermore, the behavior of the azimuthal-dependent $\pi^0$ nuclear-modification factors and associated fractional parton-energy losses are evaluated from measured nonzero $v_2$ values of $\pi^0$ at $p_T>5$ GeV/$c$ and found to be approximately the same for similar values of $N_{\rm part}^{1/3}$ in these collision systems. These findings demonstrate that the mechanism of $\pi^0$ $v_2$ generation exhibits a high degree of universality across different initial geometries of heavy-ion collisions.
Read the full abstract

All authors PHENIX Collaboration: N.J. Abdulameer, U. Acharya, C. Aidala, N.N. Ajitanand, Y. Akiba, R. Akimoto, J. Alexander, D. Anderson, S. Antsupov, K. Aoki, N. Apadula, H. Asano, E.T. Atomssa, T.C. Awes, B. Azmoun, V. Babintsev, M. Bai, X. Bai, B. Bannier, E. Bannikov, K.N. Barish, S. Bathe, V. Baublis, C. Baumann, S. Baumgart, A. Bazilevsky, M. Beaumier, R. Belmont, A. Berdnikov, Y. Berdnikov, L. Bichon, D. Black, B. Blankenship, D.S. Blau, J.S. Bok, V. Borisov, K. Boyle, M.L. Brooks, J. Bryslawskyj, H. Buesching, V. Bumazhnov, S. Butsyk, S. Campbell, P. Chaitanya, C.-H. Chen, D. Chen, M. Chiu, C.Y. Chi, I.J. Choi, J.B. Choi, S. Choi, P. Christiansen, T. Chujo, V. Cianciolo, B.A. Cole, M. Connors, R. Corliss, N. Cronin, N. Crossette, M. Csanád, T. Csörgő, L. D'Orazio, A. Datta, M.S. Daugherity, G. David, K. Dehmelt, A. Denisov, A. Deshpande, E.J. Desmond, L. Ding, V. Doomra, J.H. Do, O. Drapier, A. Drees, K.A. Drees, J.M. Durham, A. Durum, T. Engelmore, A. Enokizono, R. Esha, K.O. Eyser, B. Fadem, D.E. Fields, M. Finger Jr., M. Finger, D. Firak, D. Fitzgerald, F. Fleuret, S.L. Fokin, J.E. Frantz, A. Franz, A.D. Frawley, Y. Fukao, T. Fusayasu, K. Gainey, C. Gal, P. Garg, A. Garishvili, I. Garishvili, F. Giordano, A. Glenn, X. Gong, M. Gonin, Y. Goto, R. Granier de Cassagnac, N. Grau, S.V. Greene, M. Grosse Perdekamp, T. Gunji, T. Guo, H. Guragain, Y. Gu, J.S. Haggerty, K.I. Hahn, H. Hamagaki, J. Hanks, K. Hashimoto, R. Hayano, T.K. Hemmick, T. Hester, X. He, J.C. Hill, A. Hodges, R.S. Hollis, K. Homma, B. Hong, T. Hoshino, J. Huang, T. Ichihara, Y. Ikeda, K. Imai, Y. Imazu, M. Inaba, A. Iordanova, D. Isenhower, A. Isinhue, D. Ivanishchev, B.V. Jacak, S.J. Jeon, M. Jezghani, X. Jiang, Z. Ji, B.M. Johnson, K.S. Joo, D. Jouan, D.S. Jumper, J. Kamin, S. Kanda, B.H. Kang, J.H. Kang, J.S. Kang, J. Kapustinsky, G. Kasza, D. Kawall, A.V. Kazantsev, J.A. Key, V. Khachatryan, P.K. Khandai, A. Khanzadeev, K.M. Kijima, C. Kim, D.J. Kim, E.-J. Kim, Y.-J. Kim, Y.K. Kim, E. Kistenev, J. Klatsky, D. Kleinjan, P. Kline, T. Koblesky, M. Kofarago, B. Komkov, J. Koster, D. Kotchetkov, D. Kotov, L. Kovacs, F. Krizek, K. Kurita, M. Kurosawa, Y. Kwon, Y.S. Lai, J.G. Lajoie, A. Lebedev, D.M. Lee, G.H. Lee, J. Lee, K.B. Lee, K.S. Lee, S.H. Lee, M.J. Leitch, M. Leitgab, B. Lewis, X. Li, X. Li, S.H. Lim, M.X. Liu, D.A. Loomis, D. Lynch, S. Lökös, C.F. Maguire, Y.I. Makdisi, M. Makek, A. Manion, V.I. Manko, E. Mannel, M. McCumber, P.L. McGaughey, D. McGlinchey, C. McKinney, A. Meles, M. Mendoza, B. Meredith, Y. Miake, T. Mibe, A.C. Mignerey, A. Milov, D.K. Mishra, J.T. Mitchell, M. Mitrankova, Iu. Mitrankov, S. Miyasaka, S. Mizuno, A.K. Mohanty, S. Mohapatra, D.P. Morrison, M. Moskowitz, T.V. Moukhanova, B. Mulilo, T. Murakami, J. Murata, A. Mwai, T. Nagae, S. Nagamiya, J.L. Nagle, M.I. Nagy, I. Nakagawa, Y. Nakamiya, K.R. Nakamura, T. Nakamura, K. Nakano, C. Nattrass, P.K. Netrakanti, M. Nihashi, T. Niida, R. Nouicer, N. Novitzky, T. Novák, G. Nukazuka, A.S. Nyanin, E. O'Brien, C.A. Ogilvie, H. Oide, K. Okada, M. Orosz, A. Oskarsson, K. Ozawa, R. Pak, V. Pantuev, V. Papavassiliou, I.H. Park, J.S. Park, S. Park, S.K. Park, L. Patel, S.F. Pate, J.-C. Peng, D.V. Perepelitsa, G.D.N. Perera, D.Yu. Peressounko, J. Perry, R. Petti, C. Pinkenburg, R.P. Pisani, M. Potekhin, M.L. Purschke, H. Qu, J. Rak, I. Ravinovich, K.F. Read, D. Reynolds, V. Riabov, Y. Riabov, E. Richardson, D. Richford, N. Riveli, D. Roach, S.D. Rolnick, M. Rosati, M.S. Ryu, B. Sahlmueller, N. Saito, T. Sakaguchi, H. Sako, V. Samsonov, M. Sarsour, S. Sato, S. Sawada, K. Sedgwick, J. Seele, R. Seidl, Y. Sekiguchi, A. Seleznev, A. Sen, R. Seto, P. Sett, D. Sharma, A. Shaver, I. Shein, T.-A. Shibata, K. Shigaki, M. Shimomura, K. Shoji, P. Shukla, A. Sickles, C.L. Silva, D. Silvermyr, B.K. Singh, C.P. Singh, V. Singh, M. Skolnik, M. Slunečka, K.L. Smith, S. Solano, R.A. Soltz, W.E. Sondheim, S.P. Sorensen, I.V. Sourikova, P.W. Stankus, P. Steinberg, E. Stenlund, M. Stepanov, A. Ster, S.P. Stoll, M.R. Stone, T. Sugitate, A. Sukhanov, J. Sun, Z. Sun, A. Takahara, A. Taketani, Y. Tanaka, K. Tanida, M.J. Tannenbaum, S. Tarafdar, A. Taranenko, E. Tennant, A. Timilsina, T. Todoroki, M. Tomášek, H. Torii, R.S. Towell, I. Tserruya, B. Ujvari, H.W. van Hecke, M. Vargyas, E. Vazquez-Zambrano, A. Veicht, J. Velkovska, M. Virius, V. Vrba, E. Vznuzdaev, R. Vértesi, X.R. Wang, D. Watanabe, K. Watanabe, Y. Watanabe, Y.S. Watanabe, F. Wei, S. Whitaker, S. Wolin, C.L. Woody, M. Wysocki, B. Xia, Y.L. Yamaguchi, A. Yanovich, S. Yokkaichi, I. Yoon, I. Younus, Z. You, I.E. Yushmanov, W.A. Zajc, A. Zelenski, S. Zhou

Pattern Formation and Solitons

Transition to spatiotemporal chaos with multiple colliding pulse sequences of the nonlinear Schrödinger equation

Avner Peleg and Debananda Chakraborty

We present the first demonstration of transition to spatiotemporal chaos with multiple colliding pulse sequences in systems described by perturbed cubic nonlinear Schrödinger (NLS) equations. For this purpose, we consider propagation of multiple sequences of optical pulses in two distinct types of nonlinear waveguide arrays with cubic gain and loss. By employing a perturbation theory for NLS solitons, we show that the dynamics of pulse energies in the waveguide array systems is described by generalized Lotka-Volterra (LV) models, which exhibit dissipative chaos in a wide region in parameter space. We test the LV models' predictions for chaotic dynamics of pulse energies by extensive numerical simulations with perturbed systems of coupled-NLS equations. We find excellent agreement between the results of the LV and coupled-NLS models for energy dynamics in both types of waveguide array systems, despite the strong pulse pattern distortions and the strongly nonlinear nature of the dynamics.
Read the full abstract

Quantum Physics

QuScope: An Open-Source Python Framework for Quantum-Circuit Simulation of Transmission Electron Microscopy

Sean D. Lam and Roberto dos Reis

Image formation in transmission electron microscopy (TEM) is governed by the coherent evolution of the electron wavefunction through the specimen and the objective lens. This physics maps naturally onto the gate model of quantum computation. We present QuScope, an open-source Python framework that expresses the complete TEM image-formation pipeline as quantum circuits. The $N\times N$ electron wavefunction is amplitude-encoded in $2\log_2 N$ qubits, and every optical element, including phase-grating transmission, Fresnel propagation between specimen slices, and the aberrated objective lens, is implemented as a diagonal unitary conjugated by quantum Fourier transforms. On this foundation, QuScope v0.2.0 implements validated imaging pipelines, covering conventional TEM under the phase-object approximation, full multislice CTEM and STEM for thick specimens. All quantum results reported here come from exact, noise-free statevector simulation of the circuits on classical hardware, and every result is validated against a classical twin implementation. Quantum and classical multislice exit waves agree to unit fidelity, and all physical constants are verified against standard references. We provide transpiled quantum-resource estimates for each algorithm, an analysis of the diagonal-synthesis bottleneck that governs near-term hardware execution, and a fully tested, documented, and pip-installable package. QuScope v0.2.0 is available at https://github.com/QuScope/QuScope.
Read the full abstract

Fluid Dynamics

Particle trapping in vortex crystals

Jean-Régis Angilella and S. Ravichandran

We study the motion of inertial particles in two-dimensional inviscid and viscous vortex crystals, where vortices are placed at the tips of a regular polygon, and determine the conditions under which long-term trapping of particles can occur. In crystals with a central vortex, we find that trapping points in addition to those found in a previous analysis may exist finding, furthermore, that particle trajectories may approach a limit-cycle which can be described by means of asymptotic methods. We show that these newly discovered fixed points persist temporarily in the presence of viscosity, and study the different transitions following viscous vortex mergers. We find that for moderate Reynolds numbers, the annular merger of the vortex crystal form an annular vortex layer that can keep particles trapped within a disk centered at the origin. For larger Reynolds numbers, pairwise vortex merger leads to crystals with a smaller number of vortices, with particles clustering at the fixed points of the newly formed vortex crystal.
Read the full abstract