Fluid Dynamics
Statistical equilibria of two-dimensional turbulent flows for generic initial vorticity fields on a sphere, calculated on the basis of the original Miller-Robert-Sommeria theory
Koki Ryono and Keiichi Ishioka
Based on the original Miller-Robert-Sommeria theory, we explicitly compute a statistical
equilibrium of two-dimensional turbulent flow on a sphere for a generic initial vorticity field introduced in a previous study. The macroscopic vorticity field corresponding to the obtained statistical
equilibrium has a quadrupole structure. The resulting quadrupole structure is topologically consistent with the final state of the long-term time integration of the vorticity equation. However, the statistical
equilibrium does not predict the formation of concentrated
vortices as seen in the time integration. We also calculate statistical
equilibria for the initial vorticity field with a planetary vorticity term, and find a change of statistical
equilibria from quadrupole states to zonally symmetric states as the angular velocity of the sphere increases. The quadrupole statistical
equilibria show nearly linear relations between the macroscopic vorticity and the macroscopic stream function, implying that higher-order Casimir invariants are virtually ineffective even when all Casimir invariants are considered. The discrepancy between the
equilibria and the time integration results emphasizes the importance of mixing barriers, which prevent the relaxation of the evolving vorticity field to the statistical
equilibria and allow the point-
vortex-like dynamics of coherent
vortices to persist.
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High Energy Physics (Phenomenology)
HydroGrav: Precise hydrodynamics and gravitational waves for cosmological phase transitions
Flynn Linton, William Searle, Xiao Wang et al. (+1 more)
We present HydroGrav, a C++ code used to construct self-similar fluid profiles, using the exact equation of state determined directly from the effective potential, for any particle physics model capable of producing a first-order electroweak phase transition. HydroGrav also supports the bag and $\mu\nu$ (or improved bag) equations of state and includes an implementation of the sound shell model for computing the corresponding gravitational wave spectra. Using this framework, we compare the fluid profiles and gravitational wave spectra for the simplified (bag and $\mu\nu$) and exact equations of state for a $\mathbb{Z}_2$-symmetric extension of the Standard Model. Furthermore, we perform a scan across the parameter space of this model to identify regions where the simplified and exact equations of state differ in peak amplitude and spectral shape. Finally, we estimate the effect of using the exact equation of state on the signal-to-noise ratio across the parameter space, as measured by LISA after a 4-year mission.
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All authors Flynn Linton, William Searle, Xiao Wang, Csaba Balázs
Mesoscale and Nanoscale Physics
Confined exciton polaron in MoS$_2$ on twisted-hBN
Garima Gupta, Mayank Chhaperwal, Pankaj Kumar et al. (+5 more)
The simple electrostatic picture of a trion is that of an excess charge inducing an
exciton polarization and binding closer (farther) to the hole (electron) side of it. Trion formation can be forbidden when such spontaneous rearrangement of charges is not allowed by the application of external perturbation, such as electric field. Here we test this hypothesis experimentally using a non-monotonic electric field. We realize this scenario by imprinting the ferroelectric domains at the AA-stacked twisted-hBN (t-hBN) interface onto a monolayer of MoS2 placed over it. The spatially varying in-plane electric field around the domain wall serves the dual purpose of (a) confining and polarizing the 2D
exciton in the domain wall, and (b) depleting the free charge carriers from the domain wall. We observe a large quantized
exciton splitting confirming strong
exciton confinement in the domain wall. Forced by the confining potential, the electron side of the polarized
exciton lies closer to the domain with accumulated free electrons, which should ideally prevent any trion formation. Contrary to the laid hypothesis, we observe signatures of quantized charged
exciton emission, with an inter-level splitting that mimics the level-splitting of the quantized
excitons. This paradox is explained using the many-body picture of
exciton polaron, where a conduction band hole attractively binds the polarized
exciton and the electron
Fermi sea. The results provide a definitive way to unambiguously discern
exciton polaron from trion.
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All authors Garima Gupta, Mayank Chhaperwal, Pankaj Kumar, Pushkar Dasika, Kenji Watanabe, Takashi Taniguchi, Archana Raja, Kausik Majumdar
Quantum Gases
Collision and coalescence dynamics of bosonic quantum Hall droplets
Xinyi Liu, Zhendong Li, Yuwen Zhou et al. (+5 more)
Recently bosonic
quantum Hall droplets have been observed in rapidly rotating two-dimensional Bose-Einstein condensates (BECs), which exhibit robust dynamical stability. Inspired by this, we systematically investigate the collision and coalescence dynamics of these droplets within the Gross-Pitaevskii framework. For two-droplet collisions, we find two distinct collision outcomes, namely merging and separation, that are controlled by the initial relative velocity. The critical velocity exhibits a universal scaling law with the interaction and the particle number as $v_c \propto (gN)^{1/4}$, which can be interpreted from a simplified analytical model, revealing the essential role of the collision time. It differs fundamentally from the mechanism governing the conventional Lee-Huang-Yang stabilized
quantum droplets. Furthermore, while the collision can change the shape of the droplet significantly, the center of mass trajectory remains nearly unaffected, owing to the conservation of angular momentum. For overlapping stationary droplets,
vortex arrays can emerge through Kelvin-Helmholtz instability driven by phase-induced shear flow. Although two droplets may merge into a larger one, extended states cannot be constructed from multiple overlapping droplets. Instead, the system dynamically reorganizes into new isolated droplets, revealing the localized property in the bulk region. Our results reveal the unique nonequilibrium dynamics of
quantum Hall droplets and suggest new pathways for manipulating strongly correlated rotating
quantum fluids.
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All authors Xinyi Liu, Zhendong Li, Yuwen Zhou, Siying Li, Haoran Xu, Zihe Liu, Rongzhen Jiao, Mingyuan Sun
General Relativity and Quantum Cosmology
A Lagrangian formulation for Rastall gravity and a covariant formulation for unimodular gravity
Juilson A. P. Paiva, Julio C. Fabris and Vilson T. Zanchin
We propose a Lagrangian formulation for a non-conservative
gravity model in which the divergence of the energy-momentum tensor in curved spacetime does not vanish. This is accomplished by introducing an arbitrary vector field that couples with the gradient of the
Ricci curvature scalar. We first derive the field equations using the Palatini variational approach. Because the connection and the metric tensor are independent in the Palatini framework, the auxiliary vector field dictates whether the
manifold geometry is Weyl or Riemannian. By assuming certain physically reasonable conditions on this vector field, the resulting field equations reduce to those of Rastall
gravity. Furthermore, slightly different conditions on the vector field furnish unimodular
gravity. For comparison, we also employ the standard metric variational approach to obtain the field equations, demonstrating that the same models can be recovered under appropriate conditions. Our key results are the derivation of a covariant Lagrangian formulation for Rastall
gravity and a new Lagrangian formulation for unimodular
gravity.
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Quantum Physics
No Cloning of Quantum Ensembles
Zhenyu Du, Siyuan Cheng, Qi Zhao et al. (+2 more)
Modern
quantum physics now enables control of
quantum systems at the level of individual trajectories, opening a new frontier that links
quantum information theory,
quantum many-body physics, and
quantum thermodynamics, and uncovers novel non-
equilibrium phenomena such as deep thermalization and measurement-induced
entanglement. However, a central challenge remains: their characterization relies on measuring nonlinear properties of individual
quantum states, a task tantamount to fine-grained cloning of a
quantum ensemble. Here, the fundamental laws governing the cloning of
quantum ensembles are investigated. First, a general no-cloning
theorem for arbitrary ensembles is established from an information-theoretic perspective, even assuming multiple copies of the ensemble's purification. It is then shown that this barrier can be unexpectedly circumvented for physical ensembles generated by finite-time evolutions. Nevertheless, these tasks are proven to remain computationally intractable, even when the full
circuit description of state preparation is known. This stands in sharp contrast to the conventional no-cloning
theorem, which relies on the state being unknown. Together, these results establish new fundamental principles of
quantum mechanics, reveal intrinsic trade-offs among sample complexity, computational complexity, and
quantum measurements, and highlight the necessity of problem-specific strategies for probing measurement-induced
quantum phenomena.
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All authors Zhenyu Du, Siyuan Cheng, Qi Zhao, Xiongfeng Ma, Xiao Yuan
Materials Science
Three-dimensional visualization of threading dislocation in GaN by polarized-light microscopy
Yukari Ishikawa, Kisara Matsumoto, Kazuki Ohnishi et al. (+1 more)
We demonstrate high-throughput three-dimensional imaging of threading dislocations in ammonothermal GaN wafers using polarized-light microscopy with collimated LED illumination. Threading dislocations exhibited focal-depth-dependent in-plane shifts, enabling visualization of their three-dimensional inclination behavior over large areas. Synchrotron radiation X-ray topography indicated that dislocations with identical in-plane Burgers vector components tended to exhibit similar trace geometries and inclination directions. The threading dislocations were found to be tilted by approximately 3.3{\deg} from the c-axis in directions perpendicular to their Burgers vectors, indicating climb-mediated motion associated with strain relaxation during
crystal growth. These results demonstrate a simple nondestructive approach for large-area three-dimensional characterization of dislocations in GaN wafers.
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All authors Yukari Ishikawa, Kisara Matsumoto, Kazuki Ohnishi, Yongzhao Yao
Mathematical Physics
Bottleneck Effects and Harmonic-Type Velocity Bounds for Periodic Quantum Walks
Houssam Abdul-Rahman, Thomas A. Jackson and Darren C. Ong
We prove explicit upper bounds on the propagation velocity of one-dimensional
quantum walks with periodic coins of arbitrary period. We treat two complementary settings. First, in a perturbative regime where one transmission parameter is small, we show that the corresponding almost reflecting coin acts as a bottleneck for transport: the velocity is bounded linearly in this parameter, with an explicit leading order estimate. Second, for arbitrary nonzero transmission parameters, we prove a general a priori bound in terms of their harmonic mean, together with a refined version that detects the spatial variation of neighboring coins. Moreover, we prove a general lower bound on the velocity. These bounds apply directly to the corresponding CMV setting.
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Fluid Dynamics
Optothermal Actuation of Unidirectional Thermo-osmotic Flows
Tetsuro Tsuji, Shota Suzuki, Satoshi Taguchi et al. (+2 more)
In this paper, we experimentally demonstrate the microscale direction control of thermoosmotic flows using a focused-
laser heating. The key is the off-center
laser irradiation on an immobilized light-absorbing microparticle, which generates a nonuniform, asymmetric heat source. The resulting thermo-osmotic flows are evaluated using the optically trapped particle tracking velocimetry (ot-PTV), presented in our preceding paper (T. Tsuji, et al., Physical Review Fluids 11, 034901 (2026)). It is shown that the flow characteristics can be modulated by the ionic strength of a sample solution and/or the surface molecular coating of the substrate. In particular, the significance of ionic strength on thermo-osmotic flows are discussed based on the surface potential of the substrate measured by frequency-modulated atomic force microscopy.
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All authors Tetsuro Tsuji, Shota Suzuki, Satoshi Taguchi, Haruya Ishida, Hideaki Teshima
Quantum Physics
Fault tolerant computation of the static structure factor and finite size effects
Rishabh Bhardwaj, Alexander Reed Muñoz, Travis E. Jones et al. (+1 more)
Fault-tolerant
quantum algorithms offer a promising pathway for estimating the ground-state energies of periodic materials that are beyond the practical reach of classical electronic-structure methods. A remaining challenge is finite-size mitigation:
quantum algorithms evaluate a finite supercell or finite Brillouin-zone mesh, while materials properties are defined in the thermodynamic limit. In this work we develop a
quantum post-processing strategy for the leading two-body finite-size correction. After one-body shell effects are reduced by twist averaging, the dominant residual error is controlled by long-wavelength density fluctuations, which are encoded in the small-momentum static structure factor $S(q)$. We formulate the corresponding operator in a Bloch-orbital basis, construct its block encoding through the density operator, and estimate its ground-state expectation value using an amplified Hadamard test. We also introduce adaptive global and local binary search procedures for identifying the infrared fitting window used to reconstruct the two-body finite size error correction. The resulting cost remains subleading relative to the main ground-state energy estimation routine: the structure-factor correction has leading $\tilde{O}(N_bN_k)^3$ dependence on the Bloch-orbital basis size, avoids the large plane-wave prefactor of full
Hamiltonian simulation, and requires only $\tilde{O}(N_bN_k)$ logical
qubits. This provides a fault-tolerant alternative to down-sampling, replacing repeated energy calculations on larger
cells with targeted measurements of the infrared density correlations that control the finite-size effects.
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All authors Rishabh Bhardwaj, Alexander Reed Muñoz, Travis E. Jones, John Golden
General Relativity and Quantum Cosmology
Can a regular black hole be observationally distinguished from singular black holes as spinning lens partner in PSR-BH binaries?
G. Y. Tuleganova, R. Kh. Karimov, R. N. Izmailov et al. (+1 more)
To answer the question posed in the title, we consider a novel diagnostic, viz., the difference in the times of arrival (TOA) at the observer of two light rays that simultaneously emanate from a source behind a spinning lens and pass by either side of the lens to reach the observer. This is completely different from the usual Shapiro gravitational time delay, where only one onward light ray is reflected back to the observer. The TOA essentially samples the frame dragging caused by the spinning lens, apart from other lens parameters. Assuming a charged regular Ayón-Beato and García black hole as the spinning lens partner in some typical astrophysical PSR-BH binaries, which provide the best laboratory for testing the TOA effect, we theoretically study how the prediction depends on the gyromagnetic ratio $\left(Q/M\right)$ and how it compares with those when the role of spinning lens partner is played by the centrally singular Kerr-Newman and Kerr black holes. The numerical estimates for two illustrative binary lens systems show $\mu$sec level delay at the zeroth order, which should be measurable. However, the TOA predictions under thin-lens approximation are shown to differ only at third or higher orders of smallness indicating that the regular and singular black holes cannot be observationally distinguished despite significant qualitative differences existing among them.
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All authors G. Y. Tuleganova, R. Kh. Karimov, R. N. Izmailov, K. K. Nandi
Computational Physics · Cross-listed from math.NA
Analysis, thermodynamics, and a numerical solver for a pressure-temperature equilibrium closure of the four-equation model
Bennett Clayton, Joshua McConnell and Clell Solomon
We analyze an often used closure model for multi-material hydrodynamics where pressure-temperature
equilibrium (PTE) is assumed for every state; emphasis is placed on tabular equations of state. This multi-material model is often referred to as the four-equation model. The identification of the admissible set is presented and is proven to be convex, setting the foundation for development of invariant-domain preserving methods for this model. A novel numerical method is presented for solving the highly nonlinear system for the equilibrated pressure and temperature with an arbitrary number of materials. This new method is compared with some traditional iterative solvers through a collection of different tests. Additionally, we provide a detailed analysis of the thermodynamics of the mixture model for general equations of state and prove existence and uniqueness of the pressure-temperature
equilibrium solution under some thermodynamic assumptions.
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Earth and Planetary Astrophysics
KMT-2025-BLG-2093: Free-Floating Planet Candidate Near the Shore of the Einstein Desert
Yoon-Hyun Ryu, Andrew Gould, Kyu-Ha Hwang et al. (+16 more)
We analyze KMT-2025-BLG-2093, with angular Einstein radius $\theta_{\rm E}=13.1\pm 2.8\,\mu{\rm as}$, which makes it the second isolated microlens that lies in the “Einstein Desert” ($9\,\mu{\rm as}<\theta_{\rm E}<25\,\mu{\rm as}$) between free-floating
planets (FFPs) on one side and brown
dwarfs and
stars on the other. We discuss how its characteristics may give clues to future exploration of FFPs, especially in the era of satellite missions that have a major FFP focus, including Earth 2.0 and Roman.
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All authors Yoon-Hyun Ryu, Andrew Gould, Kyu-Ha Hwang, Qiyue Qian, Michael D. Albrow, Sun-Ju Chung, Cheongho Han, Youn Kil Jung, Zhixing Li, Shude Mao, In-Gu Shin, Yossi Shvartzvald, Hongjing Yang, Jennifer C. Yee, Weicheng Zang, Dong-Jin Kim, Chung-Uk Lee, Byeong-Gon Park, Richard W. Pogge
Materials Science
Vacancy-mediated nitrogen diffusion and aggregation via high-fluence electron beam irradiation in HPHT synthesized diamond crystal
Chikara Shinei, Yuta Masuyama, Jun Chen et al. (+5 more)
The negatively charged nitrogen vacancy (NV-) center in diamond is a promising point defect for highly sensitive
quantum sensing. The formation of high-density NV- centers is essential for improving sensitivity. We performed room-temperature electron beam irradiation (EBI) and annealing on nitrogen-doped high-pressure high-temperature diamond
crystals, aiming to convert all substitutional nitrogen into NV structures by increasing EBI fluence. While the Ns0 to NV0 and NV- conversion process dominated at low EBI fluences, in a high-fluence region, NV0 and NV- center and Ns0 and Ns+ concentrations decreased with increasing EBI fluence, indicating the formation of unknown nitrogen-related defects such as the H3 center, which is a nitrogen and vacancy aggregation defect. Although H3 centers were observed at high EBI fluence, their annealing temperature of 1375 +- 25 {\deg}C was lower than the typically reported temperatures over 1600 {\deg}C. We attribute this low-temperature formation to vacancy-mediated nitrogen
diffusion and aggregation.
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All authors Chikara Shinei, Yuta Masuyama, Jun Chen, Hiroshi. Abe, Masashi Miyakawa, Takashi Taniguchi, Takeshi Ohshima, Tokuyuki Teraji
Materials Science
Amorphous Fe-Sn nanofilms for anomalous-Nernst heat-flux sensing
Kenji Tanabe, Ko Mibu, Atsushi Tsukazaki et al. (+1 more)
Amorphous
magnetic films are promising for anomalous-Nernst heat-flux sensing because their low thermal conductivity can enhance the temperature gradient generated by an applied heat flux. However, amorphization often degrades electronic transport and thermoelectric properties, making it challenging to obtain a large anomalous Nernst response in structurally disordered films. Here, we demonstrate nanometer-thick amorphous Fe-Sn films as high-sensitivity anomalous-Nernst heat-flux sensing materials. By systematically controlling composition and thickness, we find that amorphous Fe-Sn nanofilms combine a large anomalous Nernst response with low thermal conductivity, resulting in a heat-flux sensitivity of 0.37 um/A. This value exceeds the sensitivities reported for both amorphous
magnetic thin films and representative crystalline topological magnets. X-ray diffraction and Mossbauer spectroscopy show that the optimized films lack long-range crystallinity while retaining local Fe-Sn environments, suggesting that short-range atomic order contributes to the anomalous Nernst response in the amorphous
matrix. The sensitivity is also reproduced on flexible
polymer substrates, indicating compatibility with mechanically compliant device architectures. These results establish amorphous Fe-Sn nanofilms as a platform for anomalous-Nernst heat-flux sensing and provide a materials design route based on local-structure control and thermal-conductivity reduction.
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All authors Kenji Tanabe, Ko Mibu, Atsushi Tsukazaki, Kohei Fujiwara
Cosmology and Nongalactic Astrophysics
Fast Radio Bursts as Cosmological Probes
Manisha Caleb, Jéferson A. S. Fortunato, Steffen Hagstotz et al. (+14 more)
Fast
radio bursts (FRBs) are brief, coherent
radio pulses of extragalactic origin. They typically last from microseconds to milliseconds and have energies large enough to be visible over cosmological distances. Since FRBs interact with free electrons along their paths, the original burst is dispersed (Dispersion Measure, DM) and broadened (scattering). Furthermore, the burst's polarization is altered by Faraday rotation. Consequently, FRBs are excellent probes of the cosmological distribution of
baryons, the expansion of the Universe,
magnetic fields, and minuscule effects of fundamental physics that accumulate over vast distances. This chapter is the second of a trilogy of FRB chapters and discusses FRBs as a standalone probe. We first introduce the foundation of FRB observables related to those questions. Next, we lay the groundwork for
forecasting SKA's potential by describing the method to simulate the expected FRB population observable with the SKA. These synthetic FRB catalogues are then used to investigate the SKA's potential to probe the Universe's expansion rate and fundamental physics, such as the equivalence principle and the existence of massive
photons. Furthermore, we investigate the possibility of tracing
cosmic magnetic fields and investigating different dark matter candidates.
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All authors Manisha Caleb, Jéferson A. S. Fortunato, Steffen Hagstotz, Clancy W. James, Joscha N. Jahns-Schindler, Dylan Jow, Evan Keane, Koustav Konar, Yin-Zhe Ma, Daniele Michilli, Robert Reischke, Amit Seta, Priyanka Singh, Laura G. Spitler, Yidan Wang, Amanda Weltman, The SKA Transients SWG
Solar and Stellar Astrophysics
Laura N. Driessen, Alex Andersson, Joseph R. Callingham et al. (+6 more)
Stellar radio emission is highly variable with
stellar flares lasting from milliseconds to hours. For some
stars, their
flares or bursts can repeat once every couple of hours, while other
stars may
flare only once in hundreds of hours of observing. Some
stars and
stellar systems vary slowly over months to years. In this chapter we present the current methods for identifying
radio stars and the important role that variability plays in these detection methods. We highlight that
radio stars are the second most common
radio variable object in image-plane searches for
radio variable sources. We also present our predictions for the number of
stars both the SKA-mid and SKA-low AA$^{*}$ arrays could detect based on searches using SKA pathfinders and precursors.
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All authors Laura N. Driessen, Alex Andersson, Joseph R. Callingham, Barnali Das, Jakob van den Eijnden, Tara Murphy, Kovi Rose, Joshua Pritchard, Miguel Pérez-Torres
Quantum Physics
On the generic structures of the protocols for quantum auction and quantum summation and their relation
Kabir Sandhu, Sandeep Mishra and Anirban Pathak
Secure multi-party computation (SMC) addresses the problem of jointly computing global functions of private inputs while revealing minimal information about individual data. Two prominent examples of SMC tasks are sealed-bid auction and secure multi-party summation. Existing schemes for
quantum auction and
quantum summation have largely been developed independently, motivated by distinct applications and employing different computational primitives. In this work, mutual reductions between the two tasks are established for single-item sealed-bid auctions with first-price payment. In one direction, an auction used as a black box computes a secure sum: each party bids a private random key drawn from its input, so the clearing price depends on the inputs only through their sum $S$. The reduction is perfectly private against colluding semi-honest parties and uses $O(S^2\log(1/\delta))$ auction rounds, which is optimal, or $O(S\log(1/\delta))$ under coherent access. It can be instantiated with an existing auctioneer-free
quantum auction after a one-line change to its disjunction subroutine, which as published leaks occupancy counts. In the other direction, summation with randomized inputs yields threshold disjunctions, and a single search over composite keys locates the highest bid and a winner, revealing nothing else. Because each query consumes the bidders' encodings, a bidder can adapt its effective bid undetected, while a fixed query set restores sealed bidding. Combinatorial auctions and general payment rules lie outside this framework. On a superconducting processor, one instance of each direction is executed, recovering the winner for four-bidder instances with ties and the sum of private inputs from repeated auctions.
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Astrophysics of Galaxies
Mapping the Milky Way with Masers
Ye Xu, Kazi Rygl, Huib Jan van Langevelde et al. (+10 more)
SKA-VLBI is poised to revolutionize our understanding of the
Galactic structure through its unprecedented astrometric precision and sensitivity. As a next-generation facility, it will answer long-standing questions about the
Galactic structure by mapping its entire spiral structure in detail, spanning from the
solar neighborhood, through the
Galactic Center, to the far side of the Milky Way. Its access to the Southern sky will allow us to obtain more precise 3D parameters of the
Galactic bar, reveal the nature of the 3-kpc Arm, and clarify the dynamical coupling between the bar and the spiral arms. By leveraging high-precision astrometry of numerous celestial objects with SKA-VLBI, the
Galactic fundamental parameters such as the
Solar motion and the
Galactic rotation curve can be constrained more precisely. These advancements will not only elucidate the structure of our Milky Way, but also provide
benchmarks for understanding barred spiral
galaxies in general. Furthermore, they are important for advancing our knowledge of cosmological structure formation. The capabilities of SKA-VLBI will open a new era of high precision
Galactic astrometry.
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All authors Ye Xu, Kazi Rygl, Huib Jan van Langevelde, Dejian Liu, Jingjing Li, Yingjie Li, Simon P. Ellingsen, María J. Rioja, Richard Dodson, Zehao Lin, Chaojie Hao, Yiwei Dong, Jun Yang
High Energy Astrophysical Phenomena
A Model for Magnetic Reconnection as the Origin of TeV Outbursts from NGC 1275
Zhen-Jie Wang, Hong-Bin Tan and Ruo-Yu Liu
NGC 1275 showed two TeV $\gamma$-ray outbursts between November 2022 and January 2023, as detected by the Large High Altitude Air Shower Observatory (LHAASO). The source was also active in the X-ray and GeV bands during the TeV outburst period. Very-long-baseline
radio observations reported a sudden acceleration and deflection of a jet
knot in late 2022, before the main TeV activity. Motivated by this sequence, we examine whether
magnetic reconnection triggered by the interaction between the jet and the ambient medium can explain the TeV
flares. In this picture, reconnection produces many plasmoids, and a large “monster” plasmoid becomes the main
flare region. We model the low-state emission with a multi-zone
stochastic-dissipation component and add a compact reconnection-powered region for the flaring state. We then compare leptonic and hadronic interpretations. The leptonic model explains the enhanced X-ray emission as electron synchrotron radiation and the TeV emission mainly as inverse-Compton radiation. A pure
proton–
proton model can also produce TeV
photons if dense target gas is present, but it requires a compact cloud with a density above the values directly inferred from free–free absorption and a large
proton power. These requirements are demanding, but they do not by themselves exclude the hadronic interpretation, because the gas may be compressed by the jet or may contain denser cloud cores. Our results show that
magnetic reconnection in the parsec-scale jet is a viable origin of the 2022–2023 TeV activity of NGC 1275, while better constraints on the gas density and jet power are needed to distinguish between leptonic and hadronic radiation channels.
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Astrophysics of Galaxies
OzSSy1: The Australian Southern Seyfert-1 Spectroscopic Atlas and Catalogue at z < 0.1
Neelesh Amrutha, Christian Wolf, Christopher A. Onken et al. (+3 more)
We present a spectroscopic atlas of 887 broad-line active
galactic nuclei (AGNs) in the Southern sky, spanning
redshifts $z < 0.1$, declinations $\delta < 0$ deg and
Galactic latitudes $|b| > 10$ deg. The sample aims at being a largely complete census of nearby broad-line AGN. The atlas is constructed from observations with $R\sim3000$ using the integral-field Wide Field Spectrograph at the Australian National University 2.3 m
telescope. Spectra are extracted in a 6.7 arcsec aperture and have a median signal-to-noise ratio of 13 and 23 per Angstrom in the blue and red arms, respectively. Each spectrum is accompanied by a spectral decomposition that models the AGN continuum and host
galaxy, along with fits to the emission lines H$\gamma$, H$\beta$, H$\alpha$, He II, He I, [O III], [O I], [N II] and [S II], including broad Balmer and Helium components. The data products are publicly available and designed to support studies of population demographics and AGN variability in conjunction with future time-domain surveys.
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All authors Neelesh Amrutha, Christian Wolf, Christopher A. Onken, Wei Jeat Hon, Samuel Lai, Rachel Webster
Materials Science
Defying Diamagnetism: Anomalous Redshift and Robust Chiral Spin Mixing in 2D Perovskites under High Magnetic Fields up to 50 T
D. Y. Park, S. Park, Yongmin Kim et al. (+4 more)
We report circularly polarized magneto-photoluminescence (MPL) measurements on the enantiomeric pair of two-dimensional
chiral perovskites R- and S-(C4H9NH3)2PbI4 in pulsed
magnetic fields up to 50 T at 4.2 K. The R-form exhibits strong preferential emission into the RC channel (I_RC/I_LC = 10:1), with the S-form showing the opposite sense, robust against the applied field. Three key observations are reported: (i) an anomalous
redshift of all
exciton transition energies with increasing field-contrasting with the normal diamagnetic blueshift of achiral perovskites-with a non-monotonic initial blueshift to 7.6 T in the dominant RC channel of the R-form; (ii) complete invariance of PL peak positions upon reversal of the field direction, consistent with Rashba-induced mixing of the bright
exciton with a nearby m_x = 0 dark state; and (iii) field-induced increase in PL intensity and narrowing of the linewidth, attributed to suppression of disorder scattering as the cyclotron orbit contracts. These results are interpreted in the framework of Rashba
spin-splitting and polaron formation in the
chiral two-dimensional perovskite
lattice.
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All authors D. Y. Park, S. Park, Yongmin Kim, N. Myoung, Z. Yang, Y. Kohama, Y. H. Matsuda
Instrumentation and Methods for Astrophysics
A Dual-Burst Geometrical Prescription for Concurrent Signaling
Naoki Seto
We propose a dual-burst implementation of concurrent signaling for technosignature searches. Concurrent signaling is a Schelling-point prescription for implicit coordination between transmitters and receivers without prior communication, using salient astronomical phenomena as coordination anchors. It allows possible transmitters at different line-of-sight distances to be searched collectively through a time-dependent locus on the sky. In the dual-burst implementation, the coordination anchors are two cosmological transients. At a chosen observing time after the later burst, the leading geometrical prescription specifies a precisely defined sky ring from the two burst directions and their observed arrival times at the receiver. No distance to either burst, to a candidate transmitter, or to a
Galactic spatial anchor is required to construct this angular search locus. The finite width of the ring is therefore controlled primarily by burst localization rather than by an astrophysical distance scale, thereby reducing the set of sky directions to be searched.
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High Energy Astrophysical Phenomena
Extreme Mass Ratio Inspirals in Light of Quasi-periodic Eruptions: Milli-Hertz Gravitational Wave Background
Brennen Black, Xian Chen and Zhen Pan
Quasi-periodic eruptions (QPEs) are repeated X-ray bursts originating in
galactic nuclei. Of the many proposed models, the favored model is the disk-collision model in which a
stellar mass orbiter collides with a disk formed from a
tidal disruption event, generating
flares twice per orbit. In this model QPEs are tracers of circular extreme mass ratio inspirals (EMRIs) and can be used to infer the EMRI formation rate and estimate their contribution to the
stochastic gravitational wave background (SGWB) in the
Laser Interferometer Space
Antenna (LISA) band. Whether the secondary is a
stellar-mass black hole or a main sequence
star is still debated and leads to different results for the EMRI rate and SGWB. We obtain fiducial rates – subject to systematic uncertainties – of $R_{\rm SE} = 2.88\times10^{-6}$ per
galaxy per year for
stellar EMRIs and $R_{\rm BHE} = 6.07\times10^{-6}$ per
galaxy per year for black hole EMRIs, then estimate their contribution to the SGWB. We find that only black hole EMRIs contribute to the 1 - 10 milliHertz band resolvable by LISA, and depending on the secondary mass and formation radius can contribute from just below the LISA sensitivity curve to roughly two orders of magnitude above it.
Stellar EMRIs, being tidally disrupted before reaching the 1 - 10 milliHertz band, only contribute to sub-milliHertz frequencies and remain below the LISA sensitivity curve.
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General Relativity and Quantum Cosmology · Cross-listed from math.AP
Constraint damping on subextremal Kerr spacetimes
Peter Hintz
In the context of
hyperbolic formulations of Einstein's field equations obtained via gauge fixing, constraint damping is a desirable feature that ensures that violations of the gauge condition and thus of the constraint equations are suppressed in
evolution. Besides its utility in numerical relativity, it has played a key role in several (linear and nonlinear) stability proofs of spacetimes as solutions of the Einstein equation. In this paper, we show that an enhanced form of constraint damping can be implemented for the linearization of the Einstein equation around any subextremal Kerr black hole metric: the constraint propagation wave operator satisfies mode stability and has an arbitrarily large indicial gap at zero energy. The results proved here are a key ingredient in the author's proof of the nonlinear stability of the subextremal Kerr family.
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Quantum Physics
Memory and thermal amplification in spin–cavity squared commutators
Yong-Hong Ma, Hui-Hui Xu, Jian-Zhuang Wu et al. (+4 more)
Squared commutators in the Holstein–Primakoff limit of a
spin–cavity system provide a compact way to separate propagation from covariance growth in a finite-temperature reservoir with
memory. In the finite-temperature NMQSD construction, the linear quadrature commutator is fixed by the retarded
spin–cavity propagator, whereas a quadratic commutator carries the same retarded factor together with a covariance factor. For a zero-mean Gaussian state, \(C_{R_i^2,R_j}(t)=4|\kappa_{ij}(t)|^2V_{ii}(t)\); the symmetrized expression gives the
spin-side and mixed channels. Since \(\bar n\) enters the covariance sector but not the homogeneous retarded kernel, raising \(\bar n\) from 0 to 1 leaves the linear transfer unchanged while increasing the quadratic signal. Varying the bath-
memory rate and the counter-rotating coupling within the stable HP region then shows how stored cavity history changes both the transfer weight and its distribution in time. The calculation separates
memory-dependent propagation from thermal covariance growth in collective
spin–cavity dynamics.
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All authors Yong-Hong Ma, Hui-Hui Xu, Jian-Zhuang Wu, Quan-Zhen Ding, Wu-Ming Liu, Xin-Yu Zhao, E Wu
Optics · Cross-listed from cs.CV
VLM-Aware Meta-Optic Front-End Design for Frozen Vision-Language Models
Chanik Kang, Raphaël Pestourie and Haejun Chung
Conventional machine-
vision pipelines typically rely on high-quality optics that produce clean, human-interpretable images, and optical design has therefore been driven by image-level criteria such as resolution, aberration correction, and pixel fidelity. However, such optics are often impractical for size-, cost-, or form-factor-constrained applications, where compact meta-optics offer an attractive alternative but operate under strict physical efficiency limits. We propose CODA, a co-design framework that optimizes a continuous-density meta-optic front-end for frozen-model recognition using differentiable image formation and adjoint-gradient updates of Maxwell-based simulations. CODA directly optimizes the cross-
entropy loss of a fixed zero-shot CLIP classifier without learned reconstruction, image signal processing, or image-fidelity auxiliary objectives. In a two-dimensional simulated imaging
benchmark on ImageNet-100, CODA improves CLIP ViT-L/14 zero-shot accuracy from 53.75 $\pm$ 3.57$\%$ with a focal-concentration baseline to 65.41 $\pm$ 3.99$\%$. The optimized optics further transfer without re-optimization across CLIP, SigLIP, and DINOv2 on ImageNet-100, CIFAR-100, and Food-101. These results demonstrate that, under constrained meta-optic imaging, downstream recognition can be improved by aligning optical design with frozen
vision-model objectives rather than conventional image-formation criteria.
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General Relativity and Quantum Cosmology
First Demonstration of Optical Feedback Control to Parametric Instability at Advanced LIGO
Juntao Pan, Carl Blair, Vladimir Bossilkov et al. (+5 more)
Increasing the circulating power in gravitational-wave detectors to the megawatt level is essential for future sensitivity improvement, but this is critically limited by optomechanical parametric instabilities. Current mitigation strategies are projected to be inadequate against instabilities when circulating power reaches a megawatt. Optical feedback offers a novel independent paradigm to mitigate parametric instability. In this Letter, we report the first demonstration of optical feedback control in a full-scale gravitational wave detector. We successfully suppressed an unstable mode at 10.428 kHz, reducing the parametric gain from R = 2 to R < 0.02. This work validates optical feedback control as an effective mitigation scheme for kilometre-scale interferometric gravitational-wave detectors, providing an effective strategy to allow detectors to reach the megawatt level.
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All authors Juntao Pan, Carl Blair, Vladimir Bossilkov, Jian Liu, Alex Adam, Chunnong Zhao, Li Ju, Anamaria Effler
Solar and Stellar Astrophysics
Unprecedent fast winking of solar flares triggered by bursty magnetic reconnection
Ting Li, Xuchun Duan, Yijun Hou et al. (+13 more)
Flare ribbons form as a result of energy deposition associated with particles accelerated in low layers of the
solar atmosphere. The fine-scale structures of
flare ribbons, also called ribbon kernels, offer a potentially powerful diagnostic of the
flare reconnection process, however to date the dynamic
evolution of ribbon kernels has not been fully characterized in statistical studies. Here, we checked the state-of-the-art observations (cadence $\leq$ 2.5 seconds) of
solar flares in the ultraviolet from space by Interface Region Imaging Spectrograph (IRIS) over the past 12 years. Our results showed the first statistical study of multiple spatially-resolved
flare kernel quasi-periodic pulsation events for 31
flares, with the period of 6-24 seconds. The ribbon kernels have a spatial scale of 480$-$1200 km and some kernels exhibit unprecedent fast “winking" process, i.e., quasi-periodic pulsation-like flashing of individual kernels. The shortest heating time reaches about 2$-$3 s, implying that the energy is deposited only in a small localized region within
flare ribbons, persisting for only a few seconds. Meanwhile, some ribbon kernels were observed to slip along the ribbon at speeds of 20-1800 km s$^{-1}$. These observations strongly imply a joint picture for the dynamics and the bursty nature of ribbon kernels as being due to coupled effects of plasmoid formation and three-dimensional (3D)
magnetic reconnection in the overlaying coronal current sheet. We suggest that the observed
flare behaviors provide strong observational evidences of 3D bursty reconnection.
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All authors Ting Li, Xuchun Duan, Yijun Hou, Guillaume Aulanier, Ivan Zimovets, Jun Zhang, Juraj Lorincik, Larisa Kashapova, Zhentong Li, Yining Zhang, Yulei Wang, Leping Li, Suli Ma, Jing Huang, Shuhong Yang, Guiping Zhou
Superconductivity
Thickness dependence of diode efficiency in superconducting Fe(Se,Te)/FeTe thin-film heterostructure devices
Kaito Arizono, Kenshin Inamura, Kouta Kondou et al. (+4 more)
The superconducting diode effect (SDE) is a nonreciprocal transport phenomenon, in which the superconducting critical current density depends on the polarity of the current. It has attracted recent
attention because of its potential applications to a rectifier without energy dissipation. While SDE has been observed in a wide range of superconducting materials with broken inversion
symmetry as well as thin-film
heterostructures, the microscopic origin linking structural inversion asymmetry of electronic band,
spin-orbit interaction, and
vortex pinning remains to be clarified. In this study, we investigate SDE in Fe(Se,Te)/FeTe
heterostructure devices as a function of the superconducting Fe(Se,Te) layer thickness tFST to elucidate the role of structural inversion asymmetry on the
vortex-induced SDE. We find that the SDE efficiency monotonically increases with increasing tFST, which can be understood by considering that the band bending in the bulk Fe(Se,Te) layer induces the structural inversion asymmetry and thus, the Rashba
spin-orbit interaction. In addition, we demonstrate almost 100% rectification for the Fe(Se,Te)/FeTe
heterostructure devices in half- and full-wave oscillation configurations. Our findings point out the importance of structural architecture for realization of highly efficient SDE devices based on superconducting thin-film
heterostructures.
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All authors Kaito Arizono, Kenshin Inamura, Kouta Kondou, Yusuke Kobayashi, Tsutomu Nojima, Jobu Matsuno, Junichi Shiogai