Fluid Dynamics
Buoyancy-driven melt rate of a vertical ice surface in seawater
Ho Yin Ng and Emily S.C. Ching
Reliable estimates of the melt rate of tidewater glaciers require accurate knowledge of salt and heat fluxes at the near-vertical ice-ocean interface and such knowledge is currently lacking. In this paper, we present a theory for salt and heat fluxes in the idealized system of turbulent double-diffusive convection in an infinite vertical channel and show how this theory can be extended to give theoretical estimate of the buoyancy-driven melt rate of a vertical ice surface in seawater. Our theoretical results are shown to be in good agreement with direct numerical simulation data and measurements from laboratory experiments.
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Pattern Formation and Solitons
Shocks in a Lossy Nonlinear Transmission Line: The Inverse-Design Approach
Eugene Kogan
We formulate a traveling-wave equation describing traveling fronts in a lossy transmission line with a nonlinear voltage–charge relation. Within the inverse-design approach, we start from a prescribed front profile and determine exactly the voltage–charge relation supporting it, together with the associated squared local sound speed, whose finiteness and positivity determine whether the front is physically admissible. We specifically consider fronts whose profiles belong to the five-parameter asymmetric power-logistic family. For such fronts, the voltage–charge relation and the squared local sound speed can be expressed in terms of the lower incomplete beta function. All physically admissible fronts of this form are shocks rather than kinks. We formulate a variational method for solving the traveling-wave equation when the voltage–charge relation is prescribed. Finally, a local spectral analysis of the original partial differential equations shows that short-wavelength perturbations are damped when the squared front speed and the squared local sound speed are positive. A long-wavelength characteristic analysis independently reproduces the distinction between compressive shocks and noncompressive kinks obtained from the mechanical analogy.
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Astrophysics of Galaxies
Supernova feedback in porous photoionized Giant Molecular Clouds
Cheryl S. C. Lau, Ian A. Bonnell, Yueh-Ning Lee et al. (+1 more)
We present a new suite of numerical simulations of Type II
supernovae (SNe) detonating in
Giant Molecular Clouds with a variety of density structures shaped by photoionization feedback. Ionizing radiation sculpts cavities and channels that guide SN energy to emerge from the cloud as shock-driven blowouts, rather than as a coherent spherically expanding shell as assumed in most sub-grid SN models adopted in
galaxy or cosmological simulations. We investigate how such
outflows differ to the 1-D descriptions, and whether or not the perturbations induced by the blowouts are sensitive to the host cloud's structure. A channelling parameter $P_\mathrm{chnl}$ is introduced to characterise the cloud's porosity and boundness using the morphology of the ionized channels. Our results reveal that the
outflow velocities, whilst consistently higher than that of the spherical blasts, are in fact rather independent of the porosity of its local environment. The total kinetic energy and momentum deposited also appear similar across all runs. What is most sensitive to $P_\mathrm{chnl}$ is the mass of the materials carried in the
outflows and their migration distances. It implies that SNe exploding in compact clouds with distinctive channel structures may have more confined metal injection radii and shortened turbulent driving scales, which consequently lead to a clumpier interstellar medium with higher density and
metallicity fluctuations. We argue that molecular cloud structures play an equally important role to SN rates and energy budgets in
stellar feedback sub-grid modelling.
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All authors Cheryl S. C. Lau, Ian A. Bonnell, Yueh-Ning Lee, Ke-Jung Chen
Materials Science
Conditional grain-graph diffusion for property-guided inverse design of polycrystalline microstructures
Yuheng Zhou, Xiao Shang, Huicong Chen et al. (+1 more)
Graph representations compactly encode polycrystalline microstructures while retaining grain
topology and grain boundary information. We present a conditional graph
diffusion framework for property-guided inverse design of dual-phase Ti-6Al-4V microstructures. An enhanced grain graph neural network (GNN) with grain boundary edge features, learnable node and edge
embeddings, and multi-statistic pooling serves as a forward surrogate for stress prediction and candidate evaluation. The conditional
diffusion model generates candidates through reverse
diffusion under prescribed {\alpha}-phase volume fraction, elastic modulus, and yield-stress proxy targets. Across four target regimes and independently seeded starting sets, generated candidates consistently approach the prescribed properties, including a target outside the property envelope of the existing microstructures. Local crystallographic consistency is evaluated post-generation from deviations from the Burgers orientation relationship (BOR). BOR-aware ranking increases mean BOR consistency by up to 44.9% and 56.4% for the in- and out-of-envelope targets, respectively, while maintaining property
alignment. Finite element validation of the five best candidates in each primary design case yields a maximum absolute relative error of 1.0% in their mean properties. In a representative
benchmark,
diffusion requires 32 candidate evaluations per input graph, compared with approximately 40,000 for random search and evolutionary optimization, and reduces runtime by approximately two orders of magnitude in the tested implementations. These results establish conditional grain-graph
diffusion as an efficient framework for property-guided polycrystalline microstructure design.
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All authors Yuheng Zhou, Xiao Shang, Huicong Chen, Yu Zou
Quantum Physics
Non-Hermitian dynamics in a driven-dissipative and spatially correlated light-matter system
Ruiyang Huang, Eliott Beraud, Antoine Glicenstein et al. (+1 more)
Pure
quantum states, as described in
quantum mechanics textbooks, are ideal representations inevitably deteriorated in real systems by any dissipative connection to the environment. In this work we derive a unified theoretical frame to study the non-Hermitian dynamics of a driven-dissipative
quantum system and validate it by comparison to experimental data of matter-wave diffraction. To highlight the role of dissipation, we perform the comparison in a near-resonant regime of light-matter interaction, where perturbative approaches fail. Here, we show that the developed formalism enables both exact simulations and an intuitive interpretation based on modal analysis. The theoretical analysis is based on the general master equation description of driven-dissipative systems, from which we derive an effective complex potential $V_\mathrm{eff}(\Omega,\Delta)$ that depends on control parameters such as the amplitude and detuning of the light matter interaction. Experimentally, we drive a $^{87}$Rb BEC near resonance using periodic excited-state engineering, mapping the spatially modulated $V_{\rm eff}[\Omega,\Delta(x)]$ into momentum space for precise quantification. The experimental results agree with numerical simulations of the master equation and demonstrate the interplay between coherent drive and dissipation, with an exceptional signature: a reduced decay rate with increasing drive. Such dynamics is then interpreted by a modal analysis of the non-Hermitian
Hamiltonian $H_\mathrm{eff}=p^2/2m+V_\mathrm{eff}$ which provide an intuitive and qualitative explanation for such driven-dissipative system.
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All authors Ruiyang Huang, Eliott Beraud, Antoine Glicenstein, Simon Bernon
Materials Science
Reconstruction-Dependent Imaging, Reactivity and Local Reduction of the CeO$_2$(100) surface
Kyungmin Kim, Manuel González Lastre, Estefanía Fernández-Villanueva et al. (+7 more)
The possibility of mapping the local reactivity and reduction state to the atomic structure of chemically active
oxide surfaces opens new avenues for further understanding of catalysis. Here, we combine scanning tunnelling (STM) and atomic force microscopy (AFM) with first-principles modelling to explore this possibility on the CeO2(100) surface. While STM reveals the periodicity of cerium-terminated and oxygen-terminated CeO$_2$(100) reconstructions coexisting on the same surface, AFM imaging and force spectroscopy provide direct identification of the exposed atomic species and their reactivity as the chemical interaction with the probe. Density functional theory based STM and AFM simulations reproduce the main experimental observations and show that STM contrast cannot be in general assigned to the atomic positions of certain chemical species, as traditionally assumed from previous studies. Simulated STM contrast of the two reconstructions across different reduction states associated with the removal of oxygen atoms in deeper layers, evidence that STM alone does not offer a robust fingerprint of the local reduction state for the cerium-terminated reconstruction, but it is sensitive to the reduced state in the case of the oxygen-terminated one, being able to provide information on a mixed distribution of Ce$^{3+}$ and Ce$^{4+}$ ions on the first sub-surface Ce layer.
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All authors Kyungmin Kim, Manuel González Lastre, Estefanía Fernández-Villanueva, Pablo Pou, Hossein Sepehri-Amin, Masayuki Abe, Shigeki Kawai, M. Verónica Ganduglia-Pirovano, Ruben Perez, Oscar Custance
Materials Science
Ultrahigh Intrinsic Hole Mobilities in $M$N$_2$ ($M$= Mo and W) at Room Temperature
Zhongjuan Han, Rong-Tian Pang, Wu Xiong et al. (+3 more)
High-mobility $p$-type
semiconductors are essential for advanced electronic devices but remain scarce. Here, using a hierarchical screening framework that combines first-principles calculations with Boltzmann transport theory, we identify $M$N$_2$ ($M$= Mo and W) family as polar
semiconductors with exceptionally high intrinsic hole mobilities. In particular, 1H-WN$_2$ exhibits a room-temperature hole mobility exceeding $10^{4}$~$\mathrm{cm^2\,V^{-1}\,s^{-1}}$. This exceptional transport performance arises from the synergistic suppression of polar-optical-
phonon and acoustic-
phonon scattering, together with a reduced intervalley-scattering phase space induced by
spin–valley locking. These effects arise from anomalously small Born effective charges, strong covalent N–N bonds, and orbital hybridization between N-$2p_x$/$2p_y$ and W-$5d_{xy}$/$5d_{x^2-y^2}$ in the N$_2$-dimer-based structure. Our results establish MoN$_2$ and WN$_2$ as a promising class of high-mobility polar
semiconductors and introduce a
crystal-structure-based strategy for concurrently suppressing multiple electron–
phonon scattering channels, thereby revising design principles for high-mobility materials.
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All authors Zhongjuan Han, Rong-Tian Pang, Wu Xiong, Zhonghao Xia, Jin-Jian Zhou, Jiangang He
Optics
Solitons in optical couplers: introduction and perspectives
Boris A. Malomed
This minireview provides a brief summary and a discussion of directions for further development of theoretical and, chiefly, experimental studies of bright
solitons in optical couplers, i.e., dual-core waveguides which combine the linear inter-core coupling (tunneling of light between the parallel cores with the intra-core group-velocity dispersion and self-focusing Kerr (cubic) nonlinearity. Following a short introduction to the field, the article focuses on a brief review of relatively recent experimental results for the switching of
solitons in dual-core nonlinear optical fibers and the spontaneous emergence of stable asymmetric two-core
solitons in the couplers with the symmetric dual-core structure.
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Astrophysics of Galaxies
Spectral Microlensing of Extragalactic H II Regions by Stellar-Mass Black Holes
Dezi Liu
Most of the Milky Way's predicted
stellar-mass black holes remain hidden, especially at high
Galactic latitudes or in the
Galactic halo, where traditional dense-field
stellar microlensing is ineffective. We propose an alternative method to map this isolated population via the spectral microlensing of compact, extragalactic H II regions. Projected onto the source plane, the physical Einstein radius of a
Galactic black hole can match the typical core sizes of H II regions in distant
galaxies. Microlensing triggers an achromatic magnification, producing distinct narrow emission-line excesses in integrated
galaxy spectra. Because gravitational
lensing is wavelength-independent, intrinsic line ratios are preserved, offering a robust discriminant against false-positive astrophysical transients. Notably, the efficiency of this method depends critically on the size of the H II regions: while extended regions suffer from low optical depth, compact regions with a physical size $\lesssim 10$ pc offer significantly higher magnifications. These compact cores, however, are heavily
dust-obscured at optical wavelengths, making infrared and
radio observations the primary windows for this method. Even so, the spatial sparseness of background H II regions and the stringent
alignment requirement for high magnification limit the expected event rate to $\sim 10^{-6}$ per year. Nevertheless, this method offers a unique opportunity to detect
stellar-mass black holes and constrain their abundance in such low-density environments.
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Earth and Planetary Astrophysics
ESCAPE: a small explorer mission to study the stellar drivers of exoplanet evolution
Allison Youngblood, Kevin France, Brian Fleming et al. (+37 more)
The long-term stability of exoplanetary atmospheres depends critically on the extreme-ultraviolet (EUV)
photon and high-energy particle fluxes from the host
star, which are poorly constrained. To address this key gap in our understanding of atmospheric retention, we present the Extreme-ultraviolet
Stellar Characterization for Atmospheric Physics and
Evolution (ESCAPE) mission, a NASA Small Explorer concept proposed in 2026. ESCAPE employs extreme- and far-ultraviolet spectroscopy (80 - 1650 Ang) to provide the first comprehensive study of the
stellar EUV history and
stellar coronal mass ejection (CME) environments that control atmospheric mass-loss and determine the habitability of rocky
exoplanets. This paper outlines both the primary science goals of the mission, the breadth of future general observer investigations, and a detailed design study of the mission's instrumentation. The ESCAPE instrument comprises a grazing incidence
telescope that feeds multiple diffraction gratings and a
photon-counting detector. We describe a demonstration of the Hettrick-Bowyer
telescope, etched silicon diffraction gratings, the microchannel plate detector and housing, and gold and zirconium coatings. We present a STOP analysis that verifies ESCAPE's ability to meet its structural integrity, thermal stability, and optical performance requirements throughout the mission environment.
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All authors Allison Youngblood, Kevin France, Brian Fleming, Tim H. Hellickson, Alan C. Hoskins, James Paul Mason, Dolon Bhattacharyya, Hannah Diamond-Lowe, Girish M. Duvvuri, Cynthia S. Froning, Vinay L. Kashyap, Tommi T. Koskinen, Yuta Notsu, Seth Redfield, David J. Wilson, Ute V. Amerstorfer, Tracy M. Becker, Francesco Borsa, David A. Brain, Luca Fossati, Briana Indahl, Meng Jin, Graham S. Kerr, Adam F. Kowalski, Rachel A. Osten, Tom L. Patton, Steven V. Penton, Ignazio Francesco Pillitteri, Kurt D. Retherford, Astrid M. Veronig, Aline A. Vidotto, Jennifer G. Winters, Adina D. Feinstein, Guillaume P. Gronoff, Jeffrey L. Linsky, R. O. Parke Loyd, Susan E. Mullally, Jorge Sanz-Forcada, Peter J. Wheatley, Amber V. Young
Exactly Solvable and Integrable Systems
Ermakov-Painleve' II Symmetry Reduction of a Class of Moving Boundary Problems for a Reciprocal Extended mKdV Equation
Colin Rogers and Sandra Carillo
A reciprocal transformation is applied to link an integrable extension of the classical solitonic mKdV to a novel nonlinear
evolution equation incorporating a source term. Application of Ermakov-Painleve' II
symmetry reduction is made to determine the exact solution to a class of associated moving boundary problems of Stefan-type.
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Computational Physics · Cross-listed from stat.ML
Round-Trip Consistency: Bidirectional Diffusion Models Can Predict Their Own Rollout Errors
Alexander Scheinker
Autoregressive models accumulate error over long rollouts, yet at deployment there is no ground truth to measure it against. We train a single conditional latent
diffusion model that steps a dynamical system forward or backward in time via a direction flag, and show that this bidirectionality supplies a measurement-free test-time error signal: rolling forward $i$ steps and then backward $i$ steps must return the model to its start, so the round-trip discrepancy $\mathcal{C}_i$ is a self-supervised proxy for the unobservable rollout error: no ensembles, no held-out data, no governing equations, for one extra rollout. We validate on compressible magnetohydrodynamics (MHD), an astrophysical turbulent radiative mixing layer, and natural face
videos (CelebV-HQ). On held-out MHD trajectories, $\mathcal{C}_i$ ranks rollout error (Spearman $0.91$-$0.98$ at fixed depth; $0.69 \pm 0.16$ within trajectories), and a simple calibrator fit on training rollouts predicts its magnitude to within $1.14\times$ ($68\%$) and $1.29\times$ ($95\%$) with near-nominal coverage - one nat beyond a depth-only predictor, transferring to all six decoded physical fields. The same signal flags the out-of-distribution Orszag-Tang
vortex (AUROC $0.98$; $1.0$ by depth $10$) exactly where sampling-dispersion baselines invert, and it cuts incurred error by $15\%$ at $80\%$ coverage - three times the depth-only baseline. Bidirectional training comes at negative cost, beating direction specialists in both directions, and the backward direction doubles as a fast inverse solver. On LE-PDE-UQ's turbulent Navier-Stokes
benchmark, a single bidirectional model reaches accuracy within $1.3\times$ of their ten-model ensemble at a tenth of the training cost, with the best training-free pixel-level calibration. Round-trip consistency turns reversibility into a practical trust signal for generative models.
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Quantum Physics
Coordinate space representation for quantum simulation of scalar field theory
Gaetan Bardy, Matthieu Saubanere and Adrian Tanasa
Quantum computing provides a promising framework for the simulation of
quantum field theories, where the computational cost depends both on the
quantum algorithm employed and on the representation of the
Hamiltonian. We investigate a formulation of the $\phi^4$ model based on the harmonic-oscillator basis in coordinate space. We derive the
lattice $\phi^4$
Hamiltonian in this representation and analyze the structure of the resulting one-body
matrix and interaction tensor. We show that both exhibit an effective band-diagonal structure, allowing controlled truncations of the
Hamiltonian while preserving the low-energy spectrum. We validate this formulation by comparing low-energy observables obtained from numerical diagonalization with those computed in the standard harmonic-oscillator momentum-space representation. Finally, we estimate the resources required to encode the
Hamiltonian on a
quantum computer using both binary and unary
boson-to-
qubit mappings. By exploiting effective locality, the coordinate-space representation reduces the resources required for
quantum simulation over a broad range of parameters.
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High Energy Physics (Theory)
Spectral Functions of $J/\psi$ Meson in Rotating Thermal Background from Holography
Xin-Li Sheng, Jun-Xia Chen, Defu Hou et al. (+1 more)
We investigate the spectral functions of the $J/\psi$
meson in a rotating thermal background within the soft-wall
holographic model. The global rotation is implemented through a rotating AdS-like metric, while a local inertial frame is introduced in which the vector field can be decomposed into different
spin states. We solve the equations of motion of the vector field in the bulk with incoming wave condition near the horizon and compute the retarded Green function, from which we extract the invariant-mass spectral functions for $J/\psi$. When the momentum is parallel to the rotation axis, the peak energies shift by $-\Omega J_z$, as expected by a coupling between rotation and angular momentum, while the widths are nearly independent to $\Omega$. When the momentum is in perpendicular direction, the spectral functions for
spin-$\pm1$ states deviate significantly from the single-peak behavior and the energy shifts depart from $-\Omega J_z$. The resulting triplet splittings of the spectral functions provides a
holographic perspective on
spin-dependent vector
meson properties in rotating systems.
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All authors Xin-Li Sheng, Jun-Xia Chen, Defu Hou, Hai-Cang Ren
High Energy Astrophysical Phenomena
Morphology-aware periodicity searches in Fermi-LAT blazars
Aaron A. Maldonado, Alberto Domínguez, Adithiya Dinesh et al. (+4 more)
Standard periodicity searches in active
galactic nuclei assume sinusoidal modulation, whereas gamma-ray blazar emission often features asymmetric
flares and localized bursts. We investigate how periodicity significance in
Fermi-LAT light curves depends on intra-cycle morphology and data-quality cuts. We analyze 101 seven-day binned light curves from the
Fermi-LAT Light Curve Repository (LCR) using the Fast Template Periodogram with sinusoidal, Gaussian burst, and empirical asymmetric templates. Significances are calibrated with red-noise simulations including a Poisson noise floor. A Random Forest classifier scores sources using periodogram, phase-coherence, and period-stability features. Unconstrained likelihood fits in a few bins flatten the periodogram and make the simulated null effectively white. After quality cuts, three sources exceed a per-source significance of 3 sigma, versus 0.14 expected by chance. One is the established candidate PG 1553+113, but none reaches 3 sigma after correcting for the 101 light curves searched. Template choice substantially affects significance: for 4FGL J0102.8+5824, it is 0.24 sigma with a sinusoid and 3.85 sigma with a Gaussian burst. Such a gain is expected for about one source in simulated noise, while about 40 percent of sources favor a sinusoid. The significance distribution has a heavier upper tail than the Gaussian null predicts, consistent with
flares. We report no new periodicity detection. Non-sinusoidal templates complement sinusoidal searches, but a large significance gain alone does not establish periodicity. The classifier also responds to isolated
flares, indicating that the null does not fully capture
flare behavior. Our results agree with recent systematic searches. Applying the LCR convergence criterion, supplemented by a consistency check, is important for periodicity searches, especially with seven-day bins.
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All authors Aaron A. Maldonado, Alberto Domínguez, Adithiya Dinesh, Alba Rico, Pablo Peñil, Sara Buson, Marco Ajello
Biological Physics
No persistent circadian oscillator at genome resolution: pseudo-coherence in gut microbiome dynamics
V. Troude, L. Takayasu, R. Maskawa et al. (+4 more)
Diurnal rhythms in the gut microbiome are commonly read as evidence of host-driven entrainment or of microbial oscillators that synchronise to a common clock. We reanalyse hourly genome-resolved (MAG-level) mouse-gut time series with diagnostics tailored to test that interpretation. At this resolution and for both animals in the
dataset, the time-frequency representation carries no persistent ridge; the time-averaged spectrum is enhanced at low frequencies and depleted at intermediate frequencies; the lagged covariance is markedly time-asymmetric, with a global imbalance peak near tens of hours; and an amplitude-adjusted
Fourier surrogate test identifies a weak time-averaged construction in the candidate circadian band, never as a fixed time-frequency ridge. The two functional guilds that carry the inferred non-normal amplification are identified independently by the rankings of two inferred dynamical modes (the reaction mode, into which fluctuations are transiently amplified, and the non-normal mode, which injects them), and recover the primary polysaccharide degraders of Bacteroidota and the secondary butyrate and propionate fermenters of Bacillota A without invoking any phase information. The conjunction of these signatures matches a stable but strongly non-normal
stochastic regime, that is, pseudo-coherence:
geometric amplification reshapes
stochastic fluctuations onto a low-dimensional reaction subspace, producing intermittent synchronisation-like episodes, broken time-reversal
symmetry, and emergent time-averaged characteristic scales without an underlying oscillator. We propose a falsifiable test via high-resolution clock-gene-knockout cohorts.
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All authors V. Troude, L. Takayasu, R. Maskawa, W. Suda, D. Sornette, H. Takayasu, M. Takayasu
Biological Physics
Is K+ current in Action Potential real?
János Végh
The correct description of ion traffic during an Action Potential in
neurons has fundamental importance from its theoretical description to practical clinical applications. The classical Hodgkin-Huxley theory hypothesized that a delayed K+ current causes the hyperpolarization of the Action Potential. The paper shows that the membrane's capacitive current was misinterpreted as K+ current, and that the direct evidence for that current is an experimental artifact, both arising from an incomplete understanding of the electrical model. After introducing the Axon Initial Segment (discovered decades after constructing the classical model) and using the correct cross-disciplinary physical laws for living nature (instead of using laws valid for inanimate nature), one can construct the correct model for neuronal operation, which provides the perfect description of neuronal operation, including the Action Potential, in full accordance with the laws of science.
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Quantum Physics
Work Statistics of Autonomous Quantum Energy Pumps
Yang Peng
We develop a terminal-resolved theory of work statistics for autonomous
quantum energy pumps. By modeling the systems that supply and receive energy as explicit
quantum terminals, the energy exchanged with each terminal is defined directly from its
Hamiltonian change. When the terminals are modeled by ideal clocks, these full-space observables admit exact representations on the pump
Hilbert space and recover the conventional phase-derivative currents of periodically and quasiperiodically driven systems. The framework resolves transported work from energy accumulated in the pump. It also incorporates arbitrary initial pump–terminal correlations and identifies when correlations can enhance directional energy transfer under uncertain driving phases. For periodic pumps, we derive finite-cycle work statistics in Floquet eigenstates, relate their fluctuations to Floquet
quantum geometry, and show that the long-time terminal currents become mutually compatible. An exactly solvable two-terminal
qubit exhibits noise matching, in which transport becomes sharp through cancellation of common-mode terminal fluctuations even though the individual terminal energies remain noisy. Finally, for physical terminals beyond the ideal-clock limit, we introduce a positive work-variance gap that quantifies the fluctuations missed by a pump-only description. A coherent-cavity
benchmark shows systematic convergence toward the ideal-clock regime with increasing occupation while demonstrating that agreement of the mean current alone does not guarantee accurate work statistics.
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Mathematical Physics
Remarks on Regular Approximations to the Robin Aharonov-Bohm Hamiltonian
Cesar R. de Oliveira
In the space $\mathbb R^3$, for Robin parameter $L>0$, it is shown that there is a family of Schrödinger operators with penetrable toroidal solenoid and variable conductivity that approximates the
magnetic Aharonov-Bohm operator with a Robin boundary condition at the solenoid (border). It is also shown that approximations via smooth potentials and then a barrier in the solenoid interior give Dirichlet boundary conditions. The approximations are in the strong resolvent sense and obtained through the $\Gamma$-convergence technique, and they hold for the more general setting of smooth, closed and compact surfaces and continuous and bounded
magnetic potentials.
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Astrophysics of Galaxies
Formation of extragalactic Star Clusters
Gerhard Hensler, Yannick Hein, Alessandro Boselli et al. (+1 more)
The outskirts of
galaxies show their beauty by an assembly of Globular Clusters and satellite
galaxies, but also by interactions with their environment.
Galaxies in clusters experience dynamical effects by mutual encounters and by the intra-cluster gas. This latter exerts a drag to remove gas from the outskirts. These stripped clouds are capable to form
stars and open fundamental questions on astrophysical processes, as e.g. the survival of intergalactic clouds, the
star-formation process, the
evolution of isolated
star clusters, etc. Our studies target at
star clusters around the Virgo cluster spiral
galaxy NGC 4254, observed within the VESTIGE survey. 60 young clusters are identified in the GALEX/FUV with different masses, ages, and separations from the mature
galactic disk. Only half of them are also emitting H-alpha as long as the clusters are still encompassed by gas until ram pressure strips it off leading to
star-formation quenching and LyC escape.
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All authors Gerhard Hensler, Yannick Hein, Alessandro Boselli, the VESTIGE consortium
High Energy Astrophysical Phenomena
Metal sign of a large-scale AGN feedback in cool-core cluster MACS J1931.8-2634
Qinnan Zhu, Junjie Mao, Ping Zhou et al. (+2 more)
The spatial distribution of metals in the intracluster medium (ICM) is a sensitive tracer of the chemical and dynamical history of
galaxy clusters. While most cool-core (CC) clusters exhibit a centrally peaked Fe abundance profile, several outliers show an anomalous central Fe drop, potentially associated with the AGN activities. We revisit the reported large-scale (sim 100 kpc) central Fe drop in the massive CC cluster MACS J1931.8-2634 using new XMM-Newton observations. We aim to verify this feature and search for imprints of AGN feedback on the ICM
metallicity distribution. We analyzed sim 170 ks of new XMM-Newton observations and re-analyzed sim 100 ks archived Chandra observations. We derived radial and two-dimensional (2D) Fe abundance maps from CCD spectra. High-resolution RGS spectra were used to constrain the Ne/Fe abundance ratio to test the
dust depletion scenario. Spectral fitting was performed in SPEX using an updated atomic database and both single- and multi-temperature collisional ionization
equilibrium models. The previously reported central Fe drop is not confirmed in the radial profile from XMM-Newton. However, the 2D Fe distribution is clearly asymmetric: Fe-rich regions are elongated along the axis of the AGN cavities, extending beyond their immediate scale. The Ne/Fe ratio in the core is consistent with
solar (${\rm Ne/Fe} = 1.03^{+0.25}_{-0.23}$), arguing against the
dust depletion scenario.
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All authors Qinnan Zhu, Junjie Mao, Ping Zhou, Yuanyuan Su, Dan Hu
Solar and Stellar Astrophysics
Three-dimensional Magnetic Structures of Ellerman Bombs revealed by SUNRISE III/SCIP
Yusuke Kawabata, Yukio Katsukawa, Masahito Kubo et al. (+37 more)
Ellerman bombs (EBs) are widely recognized as photospheric and chromospheric signatures of
magnetic reconnection. However, the three-dimensional (3D)
magnetic topology has remained elusive due to the lack of seamless height coverage in observations. Here, we present initial results from the SUNRISE III/SCIP (Sunrise Chromospheric Infrared spectroPolarimeter) observations of an emerging flux region. Exploiting the seeing-free, high-spatial-resolution observations provided by the 1-meter balloon-borne
telescope, SCIP achieved seamless multi-line spectropolarimetry from the photosphere to the lower chromosphere. We analyzed the multi-line Stokes profiles of the photospheric Fe I and K I lines and the chromospheric Ca II lines, and applied the Weak Field Approximation to the K I and Ca II lines to reconstruct the 3D
magnetic field structure. The blue- and red-wing brightenings of the Ca II 8542 Å line appear at spatially offset locations, indicating bi-directional reconnection flows. The reconstructed 3D
magnetic field reveals that the opposite-polarity field structure reaches different heights in the two events analyzed. In one event, it is confined to the lower layers and is absent at the formation height of Ca II 8542 Å core, which shows no intensity enhancement, whereas in the other event it extends up to the Ca II 8542 Å core formation height, where enhanced line-core intensity is also observed. We interpret this as the reconnection current sheet reaching different altitudes. These results demonstrate that SCIP has successfully resolved the 3D structure of EBs, distinguishing
magnetic reconnection events occurring at different atmospheric heights.
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All authors Yusuke Kawabata, Yukio Katsukawa, Masahito Kubo, Takayoshi Oba, Takuma Matsumoto, Ryohtaroh T. Ishikawa, Yoshihiro Naito, Hirohisa Hara, Toshifumi Shimizu, Fumihiro Uraguchi, Toshihiro Tsuzuki, Kazuya Shinoda, Tomonori Tamura, Yoshinori Suematsu, Carlos Quintero Noda, Jose Carlos del Toro Iniesta, David Orozco Suárez, María Balaguer Jimenez, Sami K. Solanki, Andreas Lagg, Achim Gandorfer, Pietro Bernasconi, Thomas Berkefeld, Alex Feller, Tino L. Riethmüller, Alberto Álvarez-Herrero, H. N. Smitha, Bianca Grauf, Michael Carpenter, Alexander Bell, Valentín Martínez Pillet, Francisco Javier Bailén, Julian Blanco Rodríguez, Juan Sebastián Castellanos Durán, Edvarda Harnes, Johannes Hoelken, Francisco A. Iglesias, Azaymi L. Siu-Tapia, Hanna Strecker, Dušan Vukadinović
Optics
Generation and manipulation of multipole and vortex events in (1+1)-dimensional spacetime
Yiming Pan and Guowei Chen
An event is usually regarded as a zero-dimensional coordinate label in spacetime, rather than as an object with spatial extent, internal structure or
topology. Here we show that in nonlinear photonic spacetime
crystals, a complete energy-momentum gap ($\omega k$-gap) suppresses extended radiation channels, while Kerr self-trapping localizes an optical occurrence in the physical $(x,t)$ plane. Imposing and relaxing
symmetry constraints then yields multipole and
vortex events with distinct internal structure. Their spacetime action of these states establishes a hierarchy of structural cost, Bogoliubov-de Gennes spectra distinguish phase-winding
vortices from real-valued multipoles, and initial-value reconstructions provide an independent robustness check together with a finite preparation window. Using representative optical parameters, we predict that these structured events span transverse scales of 30-60 $\mu$m and temporal duration of 85-170 fs. These results suggest that an event can be treated not only as a point label, but also as a localized wave object with controllable internal degrees of freedom, offering a route to wave control in time-varying nonlinear media.
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High Energy Physics (Phenomenology)
Complex chromoelectric polarizability of a heavy-quarkonium resonance: pole response and channel-resolved effective-theory representation
Arkadiy I. Syamtomov
For a stable compact quarkonium state in the pNRQCD multipole regime, chromoelectric polarizability arises at leading order from two E1 transitions through virtual color-octet states. For an unstable state, we define the corresponding response through the quadratic displacement of its complex resonance pole in a weak chromoelectric background, so that its real and imaginary parts describe field-induced shifts of the pole mass and width. Starting from a renormalized background-field correlator, we show that the resonance polarizability is given by the complete two-field kernel normalized by the energy derivative of the full inverse propagator at the pole. In an effective theory with explicitly separated intermediate sectors, the kernel contains the standard E1-octet-E1 contribution, the complete source response of decay channels already coupled at zero field, and local contributions. This distinction becomes essential above open-
flavor threshold and reduces to the standard pNRQCD polarizability in the stable, energy-independent limit. A simple $D\bar D$ realization for the $\psi(3770)$ gives the complex pole-residue factor $1/[1-\sigma'(z_\psi)]=0.800-0.336$, illustrating that threshold dressing can substantially modify both the magnitude and phase of the response. The resulting pole-based relation identifies the quantity required for a source-dependent coupled-channel determination of the chromoelectric polarizability of a heavy-quarkonium resonance.
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Atomic Physics
Spectroscopy of the Hyperfine Structure of HD$^+$ in Rotationally Excited States with 10-ppb Uncertainty
D. Kliukin, V. Barbé, T. Klijn Velderman et al. (+5 more)
We report the first measurement of the total hyperfine interval in the
manifold of the ($v=0,L=3$) rovibrational state of HD$^+$ using microwave spectroscopy of HD$^+$ ions in a linear Paul trap. To overcome the low (0.2%) occupancy of the
quantum states involved, we employ a novel technique that combines intermittent Majorana depolarization of the HD$^+$ ensemble with redistribution of rotational-state population by blackbody radiation to effectively amplify the occupancy by a factor of 25. This enables the observation of a single field-insensitive
magnetic subcomponent of the hyperfine transition, leading to a measured total hyperfine interval of ${1\,050\,804.511}\pm 0.011\,$kHz with an unprecedented relative uncertainty of 10 parts per billion. This differs from the theoretically predicted value ${1\,050\,802.78}\pm 0.89\,$kHz by 1.9$\sigma$. We show that our experimental value is consistent with the recently measured hyperfine structure of the ($v=0,L=0$) rovibrational state of HD$^+$ [C.M. König et al., High-precision Penning trap spectroscopy of the ground state
spin structure of HD$^+$, Phys. Rev. Lett. $\mathbf{136}$,143002 (2026)], for which a similar deviation from theory was found. Our work may help resolve puzzling discrepancies between the theoretical and experimental hyperfine structure observed previously in optical rovibrational spectra of HD$^+$.
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All authors D. Kliukin, V. Barbé, T. Klijn Velderman, J.B.E. Schokking, J. John, K.S.E. Eikema, J.C.J. Koelemeij, J.-Ph. Karr
Optics
Electro-Optic Active Metasurfaces for High-Speed Photonic Applications
Mingwei Tang, Ruochong Chen, Yue Cao et al. (+6 more)
Metasurfaces are artificially engineered ultrathin nanostructured surfaces, capable of flexibly manipulating light-matter interactions on compact platforms, and thereby of great significance for a wide range of applications within modern optics and photonics, including communications, computing, sensing, and
quantum technologies. However, the inherently static nature of conventional metasurfaces severely limits their functionalities and thus range of possible applications. Benefiting from integration of the metasurface platform for shaping optical wavefronts with ultrafast electro-optic (EO) materials, active EO metasurfaces have emerged as a frontier research direction targeting advanced photonic devices. This paper systematically reviews the latest progress in this field, featuring a comprehensive comparison of performances and application scenarios of mainstream EO materials such as lithium niobate, barium titanate and organic EO
polymers. Modulation mechanisms based on the Pockels and Kerr effects along with the corresponding active metasurface implementations are summarized. Furthermore, improvements in modulation efficiency enabled by advantageously exploiting resonant structural designs and associated phenomena, including Fabry-Perot resonances, Mie resonances, surface plasmon polaritons, quasi-bound states in the continuum, surface
lattice resonances, and guided-mode resonances, are presented and summerized in detail. Current challenges related to metasurface design, nanofabrication, performance and heterogeneous integration are also discussed. Finally, future research directions are outlined, highlighting interdisciplinary developments, novel material engineering, and AI-assisted design as key pathways to enable practical use of active EO metasurfaces in modern optics and photonics, including
quantum information technologies.
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All authors Mingwei Tang, Ruochong Chen, Yue Cao, Chao Meng, Fei Ding, Yadong Deng, Yubing Han, Kai Wei, Sergey I. Bozhevolnyi
Physics and Society
Beyond Lanes: Traffic Flow Dynamics in Disordered Conditions Based on High-Resolution Trajectory Data
Shrey Agrawal, Gowri Asaithambi, Venkatesan Kanagaraj et al. (+3 more)
Disordered traffic flow is characterized by weak or non-existent lane discipline in the presence of strong vehicle heterogeneity and continuous lateral interactions, challenging traditional lane-based modeling assumptions. This study presents an empirical study of macroscopic and microscopic aspects of disordered traffic using high-resolution
UAV trajectory data collected on an urban arterial. A two-dimensional extension of Edie's framework is applied to quantify aggregate traffic variables and produce a two-dimensional fundamental diagram, revealing that traffic states cannot be adequately represented using one-dimensional formulations and highlighting the persistent role of lateral redistribution. The propagation of congestion is estimated directly from the spatiotemporal speed fields, demonstrating the emergence of coherent stop-and-go waves and showing a similar dynamics as conventional lane-based flow, in spite of the heterogeneous vehicle interactions. At the microscopic level, steady-state follower-leader identification is used to examine desired time gaps and minimum lateral spacing, vehicle dimension distributions, and kinematic characteristics, revealing pronounced inter-class heterogeneity that explains disordered traffic behavior. The study provides an empirical framework linking vehicle-level interactions and aggregate traffic dynamics and establishes a data-driven basis for the calibration and validation of traffic models for disordered mixed traffic systems.
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All authors Shrey Agrawal, Gowri Asaithambi, Venkatesan Kanagaraj, Martin Treiber, Ostap Okhrin, Harish Babu Kumara
Quantum Physics · Cross-listed from cs.IT
Symplectic Barnes-Wall GKP Codes: Deterministic $O(N \log^2 N)$ Decoding and Logarithmic Rate Scaling
Shanxiang Lyu
We construct an explicit
symplectic realization of the Barnes-Wall
lattice that yields a family of multimode Gottesman-Kitaev-Preskill (GKP) codes with encoding rate $R = \frac{1}{2}\log_2 N$ and a deterministic $O(N\log^2 N)$ bounded-distance decoder. The recursive generator $G_{m+1} = \bigl(\begin{smallmatrix} G_m & 0 \\ G_m & R_m G_m \end{smallmatrix}\bigr)$ with $R_m = I + \Omega$ simultaneously guarantees
symplectic integrality for valid
quantum stabilizers and preserves the exact Barnes-Wall decoding structure through a chain of isometric isomorphisms. The code distance is constant at $\Delta^2 = 1$ (in units of $2\pi$), representing an explicit distance–rate tradeoff in which logarithmic encoding efficiency is achieved at the cost of non-scaling protection. This construction provides a deterministic, space-efficient paradigm for GKP error correction in platforms supporting non-local modular connectivity.
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Mesoscale and Nanoscale Physics
Spin selectivity induced by non-collinear spins in Rashba wires
Luciano Jacopo D'Onofrio, Maria Teresa Mercaldo, Mario Cuoco et al. (+1 more)
We report a previously overlooked general mechanism to obtain highly efficient
spin selectivity in conventional time-reversal symmetric one-dimensional systems without invoking phase decoherence. We reveal that Rashba
quantum wires featuring non-collinear
spin states at the
Fermi level inherently possess
spin-selective transport properties. We show that this
spin noncollinearity can be systematically designed and engineered by introducing an additional pseudospin degree of freedom - such as valley, sublattice, or orbital angular momentum - into
spin-orbit coupled systems. By applying this framework to multi-subband semiconducting
quantum wires and
oxide nanowires, we establish a generalized route toward
quantum-coherent
spin selectivity up to 10 %. Our findings offer practical design principles for
spin-selective transport devices.
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All authors Luciano Jacopo D'Onofrio, Maria Teresa Mercaldo, Mario Cuoco, Carmine Ortix
Soft Condensed Matter
Confinement-Induced Optimization of Fluctuation-Induced Forces in Active Fluids
Reza Shaebani, Hashem Fatemi, Hamidreza Khalilian et al. (+1 more)
Active matter generates nonequilibrium fluctuations that mediate effective interactions between immersed objects. While fluctuation-induced (FI) forces in active fluids depend on activity, density, and geometry, their dependence on confinement remains poorly understood. We study FI forces between fixed intruders in two-dimensional active fluids composed of self-propelled circular or rodlike particles using Langevin dynamics simulations. We find that the FI force exhibits a pronounced nonmonotonic dependence on intruder separation, reaching a maximum at an optimal gap size well beyond the depletion regime, in contrast to the commonly assumed monotonic decay. This optimal confinement is robust across parameters and is more pronounced for elongated particles. The effect arises from a confinement-controlled balance between particle transport and crowding: narrow gaps hinder exchange between inner and outer regions, whereas large separations effectively decouple the intruders. At intermediate distances, enhanced crowding around the intruders generates maximal collision-rate asymmetries, leading to the strongest effective interactions. These results identify confinement geometry as a key control parameter for FI forces in active matter.
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All authors Reza Shaebani, Hashem Fatemi, Hamidreza Khalilian, Jalal Sarabadani