Mesoscale and Nanoscale Physics
Enhanced localization length in a disordered one-dimensional band via cavity coupling to delocalized states
Francesco Mattiotti, Guido Pupillo, Jérôme Dubail et al. (+1 more)
We investigate the localization properties of cavity-coupled electronic states in disordered systems, motivated by recent proposals of cavity-mediated hopping in
quantum Hall systems. We first introduce a minimal two-band model in which localized states in a disordered one-dimensional band are coupled, through a homogeneous cavity mode, to an excited band of delocalized states. Combining perturbation theory with a transfer-
matrix approach, we show that cavity-assisted hopping between localized states decays exponentially with distance, implying that the eigenstates remain localized even beyond the perturbative regime. Nevertheless, the corresponding localization length increases with the light-matter coupling strength and can extend over several
lattice sites in the single-electron ultrastrong-coupling regime. We then study a disordered Landau band coupled to a cavity mode within the framework developed in Refs.[1,2]. We find that the effective cavity-mediated coupling between edge states also decays exponentially with distance, but with a localization length that can reach micrometer scales for experimentally realistic parameters. By analyzing the inverse participation ratio, we show that this enhanced coupling is predominantly mediated by the most extended states of the upper Landau band. Our results demonstrate that, while cavity-induced hopping in disordered
quantum Hall systems remains exponentially localized, the associated localization length can become sufficiently large for the corresponding states to exhibit effectively delocalized behavior on mesoscopic length scales.
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All authors Francesco Mattiotti, Guido Pupillo, Jérôme Dubail, David Hagenmüller
Strongly Correlated Electrons
Structural responses incipient to pressure-driven antiferromagnetic quantum critical point of van der Waals heavy-fermion metal CeSiI
Hanming Ma, Tong Shi, Wenhao Li et al. (+12 more)
CeSiI is a van der Waals heavy-
fermion metal recently found to exhibit unconventional superconductivity near a pressure-induced
antiferromagnetic quantum critical point (QCP) at Pc =6 GPa. Here, we report a comprehensive single-
crystal X-ray diffraction study of CeSiI under high pressures up to 8.3 GPa at room temperature, revealing subtle structural responses that precede pressure-driven QCP. We find that the unit-
cell volume decreases smoothly upon compression without showing any structural phase transition in the investigated pressure range. Intriguingly, we observe abrupt and concurrent anisotropic responses of the
lattice parameters around Pc =6 GPa, i.e., the a-axis contracts while the c-axis enlongated suddenly, with the unit-
cell volume smoothily varies with pressure. Structural refinements further show that these
lattice anomalies primarily originate from changes of Ce-Ce and Ce-Si bond lengths, as well as a flattening of the inner honeycomb Si layer within the CeSiI monolayer around Pc. Our findings establish an interesting case linking pressure-driven electronic transition of QCP at low temperatures to incipient structural responses at room temperature, thereby providing fresh insight into the pressure-temperature phase diagram of CeSiI.
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All authors Hanming Ma, Tong Shi, Wenhao Li, Qingxin Dong, Xiaoli Ma, Shaoheng Ruan, Zhongjin Wu, Pengtao Yang, Zhaoming Tian, Jianping Sun, Yoshiya Uwatoko, Xiaohui Yu, Hechang Lei, Bosen Wang, Jinguang Cheng
Materials Science
Quantum dynamic simulation of triplet formation in an effective model of Y6 (BTP-4F)
Isabel Creed, Lucy J. F. Hart, Pranay Venkatesh et al. (+2 more)
We construct a five-state model for photoexcitation in Y6 (BTP-4F) dimers, and then solve the non-adiabtic dynamics using the Hierarchical Equations of Motion (HEOM) method. We find that triplets are populated mainly via a transiently excited intermolecular charge-transfer singlet to triplet Frenkel
exciton route; this route is not available to the monomer. Analysis of one-particle transition density
matrices suggests that the charge-transfer states are spatially distinct to the Frenkel
exciton states, indicating that the large
spin-orbit-coupling for this transition is due to it being permitted by an associated change in orbital character. Aggregation in Y6 therefore directly enables fast and high-yield intersystem crossing. We selenise our model dimers, significantly enhancing
spin-orbit-coupling, which then accelerates this charge-transfer mediated route. Looking forwards to simulations on larger aggregates, we show that, though Marcus theory gives qualitatively correct dynamics, the long-time yields are incorrect due to it missing
quantum recurrences. Instead, we show that the recently developed
memory-kernel projector\cite{Gestsson2025-ez} method can produce semi-classical rates directly from the HEOM equations which lead to quantitatively correct dynamics and yields.
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All authors Isabel Creed, Lucy J. F. Hart, Pranay Venkatesh, Tom Ward, Jarvist Moore Frost
Quantum Physics
Time-Frequency Grid States for Reconstruction and Correction of Channel-Induced Distortion in Entangled Photons
Siang-Yun Liu, Bo-Ren Huang, Zhi-Xuan Zen et al. (+2 more)
Characterization of time-frequency (TF)
quantum states requires reliable reconstruction of their TF distributions. However, imperfect transmission or measurement channels can distort reconstructed joint spectral intensities (JSIs), especially when the underlying perturbation mechanism is unknown. Here, we experimentally demonstrate a reconstruction and correction framework that uses a TF grid state as an intrinsic frequency-domain reference. By analyzing the displacement of the grid points, a Gaussian process regression model is employed to reconstruct a correction mapping for the nonlinear coordinate deformation without assuming a prior physical model of the distortion. The learned mapping reduces the residual coordinate deviation of the TF grid state by approximately a factor of 11 and, when applied to an independent frequency-entangled test state, improves the Gaussian-shape fidelity from 76.2% to 90.0%. These results establish TF grid states as practical metrological resources for diagnosing and correcting distortions in TF
quantum systems, providing a pathway toward distortion-resilient
quantum communication and high-dimensional
quantum information processing.
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All authors Siang-Yun Liu, Bo-Ren Huang, Zhi-Xuan Zen, Yen-Hung Chen, Pin-Ju Tsai
Quantum Physics
Quantum Occam Learning: Sample-Supported Expressibility for Circuit-Based Quantum Learning
Jeongho Bang, Kyoungho Cho and Jeongwoo Jae
A central principle in
quantum machine learning is that an ansatz should be expressive enough to represent the
quantum data of interest. Yet, the expressibility is statistically meaningful only insofar as it can be learned from finitely many copies of an unknown
quantum state. In this work, we develop an information-theoretic Occam theory for
quantum data generated by finite-size
quantum circuits. For the class $S_{n,G}$ of $n$-
qubit pure states preparable with at most $G$ two-
qubit gates, a metric-
entropy argument gives the realizable sample law $\widetilde{\Theta}(G/\epsilon^2)$ in the
circuit-limited regime. For an arbitrary source $\hat{\rho}$, we introduce the best $G$-gate approximation error $d_G(\hat{\rho})$ and the approximate
circuit complexity $C_\eta(\hat{\rho})$. We prove an agnostic
quantum Occam
theorem: with $M$ copies, one can learn up to the best $G$-gate approximation error plus a statistical penalty $\widetilde{O}(\sqrt{G/M})$. We then remove the need to know $G$ in advance through an adaptive model-selection
theorem whose oracle inequality selects the
circuit complexity justified by the data. Matching lower bounds yield a sample-supported expressibility law: at trace-distance accuracy $\epsilon$, $M$ samples can support only $G_{\rm supported} \simeq M\epsilon^2$ gates, up to logarithmic factors and
tomography saturation at $2^n$. Thus, the
circuit complexity becomes an adaptive statistical resource rather than a static promise. Our framework turns bounded
circuit complexity into a model-selection principle for
quantum machine learning.
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Quantum Gases
Weakly interacting Bose gases in the canonical ensemble
Jonata S. Soares, Axel Pelster and Arnaldo Gammal
Based on the canonical description of a non-interacting Bose gas, we work out how both thermodynamic and statistical properties change perturbatively with respect to weak two-particle interactions. Up to first order, we obtain a recursion formula for the canonical partition function, which consists of the same Feynman diagrams as the grand-canonical description but with different Feynman rules. Resumming this recursion formula for the canonical partition function allows one to characterize the statistics of the ground-state occupancy by its respective cumulants. We demonstrate the applicability of this approach by analyzing a dilute Bose gas with contact interaction in a box trap. To this end, we used Dirichlet boundary conditions in view of their relevance for current experiments with atomic gases, where the box trap is implemented, for instance, with digital mirror devices.
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High Energy Astrophysical Phenomena
Evidence for additional structure in the effective spin distribution hints at multiple formation pathways in GWTC-5.0
Sofia Alvarez-Lopez, Jack Heinzel and Salvatore Vitale
The distribution of the effective inspiral
spin ($\chi_\mathrm{eff}$) of the binary black holes detected by LIGO-Virgo-KAGRA can shed light on their formation pathways. We analyze the GWTC-5.0
dataset with two models-one flexible, one fully parametric-that jointly describe $\chi_\mathrm{eff}$ and primary mass. We clarify that the previously-reported skewness in the $\chi_\mathrm{eff}$ distribution is better understood as additional structure beyond a non-skewed Gaussian bulk centered at small $\chi_\mathrm{eff}$. This additional structure extends to larger $|\chi_\mathrm{eff}|$, a result previously reported using GWTC-4.0 data. We measure the asymmetry of the distribution of $\chi_\mathrm{eff}$ outside the Gaussian bulk from the data. With both the parametric and the flexible analyses, we find suggestive evidence for a mass-dependent excess of positive $\chi_\mathrm{eff}$ over negative ones outside the Gaussian bulk. We find only a mild statistical preference for a negative $\chi_\mathrm{eff}$ component outside the Gaussian bulk. This preference is highest at $m_1 \in [47,65]\,M_\odot$, with $13\text{:}1$ odds. Excluding the event GW191109, whose data have known data-quality issues, reduces these odds to $5\text{:}1$. If $\chi_\mathrm{eff}$ outside the Gaussian bulk are produced by hierarchical mergers-as has been suggested-then a fraction of those mergers may be produced in environments that can generate a surplus of binaries with positive $\chi_\mathrm{eff}$, such as the disks of active
galactic nuclei.
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Strongly Correlated Electrons
Kinetic kagome magnetism: from self-trapping RVB polarons to semiclassical correlations
Yufei Pei, Shuai A. Chen, Claudio Castelnovo et al. (+1 more)
To gain deeper insight into the role of hole kinetics in determining magnetism in highly frustrated doped Mott
insulators, we consider the single-hole counter-Nagaoka problem on the kagome
lattice, using magnetization as a tuning parameter. Near full polarization, a doped hole delocalizes upon binding reversed
spins in a pattern of singlet bonds which we term resonating-valence-bond (RVB) polaron. These RVB polarons can have extremely small effective bandwidths, and hence exhibit self-trapping. By tuning the
spin polarization, we track the
evolution of these states toward the unpolarized sector, where we observe the emergence of $\sqrt{3}\times\sqrt{3}$
antiferromagnetic correlation reminiscent of the classical Potts and Heisenberg models on the kagome
lattice. These results provide a framework to understand how RVB physics at short scales evolves into conventional
magnetic correlations at long scales.
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All authors Yufei Pei, Shuai A. Chen, Claudio Castelnovo, Roderich Moessner
Disordered Systems and Neural Networks
Roughening of active nonlinear interfaces with broken tilt symmetry
Ailén M. Cámara, Alejandro B. Kolton and José Luis Iguaín
We study the roughening of an interface with nonlinear elasticity driven by temporally correlated noise, which breaks statistical tilt
symmetry. Using scaling arguments and a self-consistent Hartree approximation, we derive the crossover diagram and the steady-state structure factor. We identify three scaling regimes associated with the Larkin, anharmonic Larkin, and Edwards–Wilkinson universality classes, and obtain the crossover lengths separating them. Numerical simulations of large systems confirm the analytical predictions over the full parameter range. Our results provide a unified description of finite-size and crossover effects in a minimal nonlinear-elastic Ornstein–Uhlenbeck active interface.
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Mesoscale and Nanoscale Physics
Experimental straintronics in nanotube quantum dots
L. Huang, I. G. Rebollo and A. R. Champagne
Single-wall carbon nanotubes (SWCNTs) are narrow ribbons of
graphene with atomically precise edges and a single
quantum transport channel, at experimentally-relevant dopings. This makes them ideal systems to harness
quantum transport straintronics (QTS), i.e. using mechanical strain to control accurately
quantum transport. We present QTS data from three single-wall carbon nanotube
quantum dot (SWCNT-QD) transistors over a broad range of in-situ tunable and reversible uniaxial strain ($\Delta\varepsilon_\text{mech}\approx$ 0 to 3 %). We first present the nanofabrication of the suspended SWCNT transistors whose channel lengths are $\approx$ 30 nm. The channels are strained by moving gold clamps holding firmly the nanotubes. We present detailed charge transport data, $dI/dV_{\text{B}} - V_{\text{B}} - V_{\text{G}}$ and $dI/dV_{\text{B}} - V_{\text{B}} - \Delta\varepsilon_\text{mech}$, showing a large mechanical-gating effect of the SWCNT-QDs. The precise reversibility of the data, and their agreement with QTS theory, confirms that the tubes are strained elastically. We demonstrate that the mechanical control of the QD doping is not due to capacitive-gating effects, but to quantitatively predictable bandstructure changes including a strain-tunable bandgap. This precise mechanical control of the doping and bandgap of SWCNT-QDs could find applications in
qubits, condensed matter physics, and homojunction molecular transistors.
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High Energy Physics (Phenomenology)
Factorizing quarkonium LDMEs and TMDSTFs using effective field theory
Marston Copeland
We use effective field theory to factorize production
matrix elements that appear in the NRQCD framework for quarkonium cross sections. By applying a Hubbard-Stratonovich transformation and appropriate field redefinitions, we show that the soft and ultrasoft sectors of NRQCD can be decoupled from the heavy
quark and antiquark fields in a hybrid vNRQCD/pNRQCD Lagrangian at leading order in the velocity power-counting. This enables us to re-factorize quarkonium production
matrix elements in terms of
matrix elements of color-singlet composite fields, which we can write as the wave-function at the origin, and state independent
vacuum correlators of chromo-electric and chromo-
magnetic gluon fields. This approach verifies powerful relationships between the LDMEs of different S-wave quarkonia originally derived using pNRQCD. Additionally, it allows us to derive new relationships for the production
matrix elements used in the transverse momentum dependent factorization (TMD) framework, known as TMD soft transition functions, providing a much stronger set of constraints on these nonperturbative operators. This work significantly advances our understanding of quarkonium production, particularly in the TMD framework.
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Quantum Physics
On-Chip Quantum Randomness Amplification
Lang Li, Yutian Wu, Giulio Chiribella et al. (+1 more)
Randomness amplification, the task of extracting uniform private bits from biased seeds that may be partly known by a malicious third party, is of central importance in cryptography. The highest security in this task is provided by a class of
quantum protocols known as device-independent, which however are challenging to integrate into scalable devices. Semi-device-independent (SDI) protocols are a promising alternative that guarantees security under few natural assumptions, such as bounds on the amount of energy used by the devices. Here, we provide the first demonstration of SDI randomness amplification on an integrated silicon photonic chip, achieving a throughput rate of 20 Mbps suitable for practical applications. This rate is achieved through a novel technique for SDI
entropy certification, which delivers strictly tighter von Neumann
entropy bounds compared to existing methods and remains valid even if the preparation and measurement devices share
quantum correlations. Overall, the methods developed in this work enable the integration of SDI technology into portable telecom devices, opening up a new generation of
quantum cryptographic hardware.
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All authors Lang Li, Yutian Wu, Giulio Chiribella, Ravishankar Ramanathan
High Energy Physics (Theory)
$T\overline{T}$ correlators from tensionless strings
Andrea Dei and Kiarash Naderi
Motivated by earlier approaches, we develop a worldsheet framework for computing correlation functions in the single trace $T \overline{T}$-deformed tensionless AdS$_3$/CFT$_2$ duality. By describing the deformed bulk theory as a Berkovits-Vafa $\mathcal{N}=4$ topological string, we obtain a consistent definition of physical states and correlation functions, yielding a tractable setup for testing aspects of holography beyond AdS/CFT. We construct deformed physical vertex operators and compute their tree-level two-point functions exactly. We discuss the relation of our results to previous proposals for $T \overline{T}$-deformed two-point functions obtained from alternative worldsheet approaches, JT
gravity, and perturbative field theory computations.
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Cosmology and Nongalactic Astrophysics
A Stochastic Framework for the Spherical Jeans Equation Motivated by Scalar-Tensor Gravity
Velasquez-toribio and A. M
We develop a
stochastic framework for the stationary spherical Jeans equation, motivated by the field-dependent nature of the gravitational coupling in scalar–tensor theories. We model unresolved spatial fluctuations of the scalar sector as an effective
stochastic contribution to the gravitational coupling, $\Geff(r,\omega)=\Gbar(r)+\Gamma_G(r)\xi(r,\omega)$. This approach induces a linear Itô
stochastic differential equation for the radial velocity dispersion $y(r)=\sigma_r^2(r)$, defining a nonautonomous radial random flow rather than a time-
evolution problem. We derive the associated Fokker–Planck equation and obtain integral expressions for the mean, variance, and covariance of the radial velocity dispersion. Because the noise is additive, the deterministic Jeans solution is recovered as the mean profile, while the
stochastic sector produces a probability band around it. We specialize the construction to Navarro–Frenk–White, Hernquist, and Einasto
halo models and propagate the radial covariance to the projected line-of-sight velocity dispersion. This provides a semi-analytical framework for assessing how effective gravitational fluctuations can affect
halo kinematic observables in the stationary Jeans regime.
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Optics
Fabricating fiber cavity mirror substrates compatible with high coupling efficiency
Michael Caouette-Mansour, Thomas J. Clark, Valeria Mosso Tsedilkina et al. (+1 more)
Fiber optical cavities offer small mode volumes and correspondingly strong light-matter interactions in an open Fabry-Perot geometry. However, existing fabrication techniques do not reliably produce substrates with surface profiles amenable to high mode matching between the cavity mode and fiber core, thereby limiting the achievable collection efficiency. Here we present a technique to fabricate fiber mirror substrates while using $\textit{in situ}$ reflectometry to constrain the achievable mode matching prior to coating. By measuring the back-reflection from freshly cleaved fiber tips, we pre-select 138 fibers compatible with 96.5-99.5% mode matching, and after a single CO$_2$
laser ablation pulse, these fibers remained compatible with 95.3-99.2%. This simple technique provides rapid feedback during each stage of substrate fabrication, greatly enhancing the yield of viable fiber mirror substrates prior to (expensive) coating runs.
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All authors Michael Caouette-Mansour, Thomas J. Clark, Valeria Mosso Tsedilkina, Jack C. Sankey
Nuclear Theory
Maxwell Rothman, Gaute Hagen, Matthias Heinz et al. (+1 more)
There is a conundrum regarding the binding of $\alpha$ particles in
nuclei. On one hand, auxiliary-field Monte Carlo simulations of
Hamiltonians on discrete spatial
lattices proposed that attractive two-nucleon potentials, alone or together with attractive three-nucleon potentials, yield accurate
nuclear binding. On the other hand, such
Hamiltonians typically overbind all but the lightest
nuclei in continuum-space approaches. We address this puzzle by performing Hartree-Fock computations of the light
nuclei $^4$He, $^8$Be, $^{12}$C, and $^{16}$O, and of
nuclear and
neutron matter using established
lattice Hamiltonians. These variational upper bounds for the ground-state energies show that the
Hamiltonians with only two-nucleon potentials do not yield accurate binding, in contrast to the results from auxiliary-field Monte Carlo simulations. The case is different for
Hamiltonians with three-nucleon potentials although it is the dense packing on the
lattice – and not repulsive potentials – that yield a constant binding energy per nucleon.
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All authors Maxwell Rothman, Gaute Hagen, Matthias Heinz, Thomas Papenbrock
Fluid Dynamics
Adaptive, efficient, and scalable water wave modeling with dispersive hyperbolic systems
Carlos Muñoz-Moncayo and David I. Ketcheson
Accurate modeling of tsunamis (such as those generated by landslides) requires capturing both wave dispersion in the deep ocean and wave breaking near the shore. The shallow water equations are often preferred for working with tsunamis, but neglect dispersion and may be inaccurate in scenarios where dispersive effects are significant. In this work, we develop an approach that seeks to incorporate the best aspects of both
hyperbolic and dispersive models by combining either of two
hyperbolic reformulations of the Serre-Green-Naghdi equations away from the shore with the non-dispersive shallow water equations near the shore. The model is discretized and implemented within the GeoClaw software, and incorporates adaptive mesh refinement as well as shared-
memory parallelism. We validate it through comparison with
benchmarks and real tsunami data. The results and performance compare favorably with the existing dispersive water wave solvers, including a speedup of about 2x relative to GeoClaw's existing dispersive solver for a large-scale tsunami simulation.
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Statistical Mechanics
Path convergence in diffusion models
Roi Holtzman, Roman Beauvallet and Werner Krauth
We discuss
diffusion-model paths interpolating between a target distribution known only through p patterns and a reference distribution that can be sampled. These interpolating paths can be constructed symmetrically or else in forward direction (often referred to as a "noising") from the target patterns to the reference distribution or in backward direction (as a "denoising") from the reference distribution to the patterns. For backward paths with identical
diffusion noise, we consider the path convergence in number of patterns p towards the path for infinitely many patterns. In a one-dimensional test case, we show that this convergence is on a scale 1/sqrt(p), but with infinite mean square deviation. We demonstrate that the path convergence allows for extrapolation towards the p=infinity path which samples the target distribution. We provide a proof-of-concept extrapolation
algorithm and propose the convergence and extrapolation of paths as a possible strategy for density estimation and generalization. We illustrate all our
algorithms through pseudo-codes and provide Python implementations.
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Quantum Gases
Grand-canonical phase diagram and chiral-current suppression at $\pi$ flux in a bosonic two-leg ladder
Meng Zhang, Qingyun Xu and Zhi Lin
We investigate the ground-state phase diagram of repulsively interacting
bosons on a two-leg ladder threaded by a uniform artificial
magnetic flux, using the cluster Gutzwiller mean-field method. In the strong-rung-coupling regime, self-consistent calculations are performed on a $2\times4$ cluster. By analyzing the superfluid order parameter, leg-resolved currents,
chiral current, the current ratio on adjacent legs, and the density imbalance between the two legs, we distinguish Mott-insulating from superfluid regimes and characterize the observed states as Meissner-like,
vortex-like (superfluid or Mott insulating), or biased-ladder. In regions overlapping with previous DMRG studies, our results qualitatively agree with the established phase structure, demonstrating that the cluster Gutzwiller approach balances computational efficiency and physical accuracy. We then construct the first grand-canonical $t$–$\mu$ phase diagrams for this system, revealing how the
magnetic flux modifies the shape, tilt, and extent of the Mott lobes. We further explore previously inaccessible regimes, including higher fillings $\rho\gtrsim1$ and the intermediate interaction window $U/t\in[7.69,9.09]$. Special
attention is paid to $\varphi=\pi$, where the effective triangular-ladder mapping becomes singular. Owing to the equivalence of $\varphi=\pi$ and $-\pi$ modulo $2\pi$, a combined
symmetry forbids net
chiral currents, leading to a nonchiral Mott-insulating state, in contrast to the
chiral-superfluid tendency expected away from $\varphi=\pi$. Our results offer a computationally efficient route for mapping the global phase structure of bosonic flux ladders and provide guidance for future ultracold-atom experiments in artificial gauge fields.
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High Energy Physics (Experiment)
Hidden-sectors search and probe of discrete symmetries at the REDTOP experiment
The REDTOP COllaboration
The $\eta$ and $\eta^{\prime}$
mesons are nearly unique in the particle universe since they are nearly Goldstone
bosons, and their decay dynamics are strongly constrained. While earlier experiments collected samples of order $\sim 10^{9}$ $\eta$, the proposed REDTOP (Rare Eta Decays To Observe Physics Beyond the Standard Model) facility targets $\mathcal{O}(10^{14})$ $\eta$ and $\mathcal{O}(10^{12})$ $\eta'$, enabling broad searches for physics beyond the Standard Model. In this work, we present studies evaluating REDTOP sensitivity to processes that couple the Standard Model to New Physics through four portals: the Vector (dark
photon), the Scalar (
Higgs-mixing), the
Axion-like, and the Heavy
Lepton. In parallel, the proposed statistics allow precise tests of $CP$ and $T$ invariance and
lepton universality and improve determinations of the $\eta/\eta'$ transition form factors, which are crucial inputs to the hadronic light-by-light contribution to the
muon anomalous
magnetic moment $(g-2)_\mu$.
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Computational Physics
fitPALSpectra: Python fitting of positron annihilation lifetime spectra
Georgios E. Pavlou
Positron annihilation lifetime spectroscopy (PALS) spectra are commonly analyzed by fitting multi-exponential lifetime models convoluted with the detector resolution function. In practice, this inverse problem is sensitive to initial parameter choices, parameter bounds, source corrections, and correlations between lifetime and intensity parameters. This paper presents fitPALSpectra, an open-source Python workflow for configurable PALS spectrum simulation, fitting, visualization, and reporting. The implementation uses an analytically integrated exponential–Gaussian response model, configurable source and sample components, constrained optimization, optional least-squares refinement, and machine-readable output of fit results, correlation
matrices, and fitted curves. Validation on fully synthetic spectra with known ground-truth parameters shows accurate recovery of the simulated lifetimes, intensities, detector full width at half maximum,
prompt shift, and background.
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Astrophysics of Galaxies
Quenching of Star Formation in Massive Galaxies
Katherine E. Whitaker and Rachel Bezanson
The shutdown of
star formation - quenching - marks a pivotal transition in the lives of massive
galaxies, which dominate the present-day
stellar mass density. This review synthesizes our current understanding of the mechanisms that trigger and maintain quiescence. We discuss the nuances of how quiescent systems are identified across
cosmic time and summarize the evolving physical properties of the growing massive population, including their
stellar populations, chemical enrichment histories, and gas and
dust reservoirs, highlighting several key results: (1) Quiescent
galaxies can be identified with empirical color selections, but evolving specific
star formation rate thresholds offer a more robust physical distinction from
star-forming systems. (2) The earliest massive quiescent
stellar populations show rapid formation histories and high
metallicities, with enhanced $\alpha$-elemental abundances often distinct from local analogs. (3) Nascent studies of gas and
dust in quiescent
galaxies reveal diverse multiphase reservoirs and
outflows, pointing to fast ejective and slow regulatory modes of
galaxy quenching. (4) In situ processes establish
galaxy central density, while assembly continues via (minor) mergers post-quenching, reshaping all massive
galaxies and disrupting rotation in most cases. We distill observations into two broad modes by which massive
galaxies form and quench: one involves a rapid, early shutdown driven by supermassive black hole
outflows on short timescales; the other proceeds gradually through gas exhaustion, virial heating, or preventative feedback, each leaving distinct observational signatures. Together, these pathways offer a testable framework for modeling the formation and
evolution of massive
galaxies, which will be informed by future studies of their
stars, gas,
dust, and dynamics.
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High Energy Physics (Phenomenology)
Neutron Capture Information in Improving IBD Angular Resolution
Qishan Liu and Kenny C. Y. Ng
One of the most important
neutrino interactions is the Inverse Beta Decay (IBD). However, the IBD events typically carry no directional information in water Cherenkov detectors as the positron directions are mostly isotropic at low energies, such as those in
supernova studies. As gadolinium is being added to Super-Kamiokande, the improved
neutron tagging efficiency not only allows better background rejection, but the
neutron capture information could potentially provide additional information that allows better event reconstruction. Due to
neutron diffusion in water, event-by-event reconstruction is difficult. However, if the final
neutron capture position is correlated with the initial
neutrino momentum, it may be possible that
neutrino directionality could be reconstructed statistically, with or without using the positron information. In this work, we use Geant4 to simulate
neutron propagation in water. We show that in a wide range of
neutrino energies from about 10 MeV to several hundred MeV,
neutron capture information could statistically enhance the
neutrino directionality, compared to positron-only inference, even with
neutron diffusion considered. However, practical application of this technique depends crucially on detection effects, especially the vertex reconstruction resolutions. Our work therefore motivates developments of better reconstruction
algorithms and techniques, as well as detector upgrades.
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Atmospheric and Oceanic Physics
The TEAMx Observational Campaign
Manuela Lehner, Claudia Acquistapace, Marco Arpagaus et al. (+44 more)
As part of the international research programme TEAMx (multi-scale transport and exchange processes in the atmosphere over mountains - programme and experiment) a one-year long measurement campaign, the TEAMx Observational Campaign (TOC), was conducted between 2024 and 2025 in a north-south transect through the Alps. Building on the dense operational measurement network in the Alps, the TOC was designed to collect long-term atmospheric observations over the highly complex Alpine terrain. During two six-week long Extended Observational Periods, more than 40 research institutions came together to instrument about 30 sites in the four target areas of the TEAMx domain and study different transport processes, from
gravity waves to orographic convection, thermally driven flows, and turbulent exchange. In addition to a suite of ground-based in-situ and remote-sensing instruments, observational activities included airborne measurements with up to three research aircraft and multiple UAS. This paper gives an overview of the science goals and the TOC design, together with preliminary analyses that highlight the potential of the collected
dataset.
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All authors Manuela Lehner, Claudia Acquistapace, Marco Arpagaus, Timothy P. Banyard, Francesco Barbano, Kathrin Baumann-Stanzer, Christophe Brun, Warren R. L. Cairns, Charles Chemel, Helen E. Dacre, Paolo di Girolamo, Luca di Liberto, Giorgio Doglioni, Philipp Gasch, Giacomo Gerosa, Lorenzo Giovannini, Sonja Gisinger, Alexander Gohm, Jan Handwerker, Neil P. Hindley, Stefan Kneifel, Peter Knippertz, Martin Kohler, Meinolf Kossmann, Stephen Mobbs, Andrew Orr, Andreas Platis, Ian Renfrew, Didier Ricard, Andrew Ross, Harald Saathoff, Leopold M. Schlagbauer, Stefano Serafin, Peter Sheridan, Ivana Stiperski, Nadia Vendrame, Hannes Vogelmann, Jutta Vüllers, Helen C. Ward, Clemens Wastl, Stephanie Westerhuis, Andreas Wieser, Norman Wildmann, Günther Zängl, Dino Zardi, TOC team, Mathias W. Rotach
Materials Science
Tracking atomic-scale interdiffusion in immiscible bimetallic nanoparticles via four-dimensional electron tomography
Jisheng Xie, Dijin Jiang, Zhen Sun et al. (+4 more)
The interdiffusion of immiscible elements is generally considered both thermodynamically unfavorable and kinetically hindered. At the nanoscale, however, the mixing behavior of multielements materials often diverges from bulk
equilibrium, yet a quantitative, atomically resolved description of this transformation has remained challenging. Using ex situ four dimensional atomic resolution electron
tomography combined with in situ scanning transmission electron microscopy, here we reveal the atomic scale miscible transition driven by interdiffusion in immiscible PdIr nanoparticles at temperatures far below the melting point. The pathway involves surface reconstruction atom hopping at 200oC and surface flattening at 300oC, followed by a critical transition at 400oC where Ir interfacial
diffusion and discrete Ir intermediates drive miscible intermixing. Upon reaching the nanoscale melting point 900oC, collective inward Ir
diffusion yields the thermodynamically stable IrPd configuration. Our findings provide quantitative atomic scale insights into how metastable nanostructures evolve through distinct intermediates, offering a design framework for advanced multielement materials.
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All authors Jisheng Xie, Dijin Jiang, Zhen Sun, Yiheng Dai, Zezhou Li, Yao Zhang, Jihan Zhou
Solar and Stellar Astrophysics
Near-core magnetic field strengths inferred from gravity modes in intermediate-mass stars
Oliver Durfeldt-Pedros, Victoria Antoci, Daniel Lecoanet et al. (+2 more)
In this work, we derive upper limits for the strength of the near-core
magnetic field in intermediate-mass
stars, since high-order g-modes can be fully suppressed by a critical
magnetic field. Both poloidal and toroidal components of the
magnetic field are included. We examine how the upper limits on
magnetic field strengths are affected by the degree and azimuthal order of the oscillations, as well as the
magnetic field configuration. We consider two gamma-Doradus
stars hosting high-order g-modes and an evolved delta-Scuti
star with mixed modes, all with prior mode identification from observations. We determine the best structural model from their
stellar parameters through grid-based modeling with MESA. Frequencies for the best models are extracted using GYRE and matched to the observed modes. The critical
magnetic fields for all calculated frequencies in our models are obtained from the Dedalus code, from which we can infer an upper limit on the near-core field strength. We find an upper limit on the near-core radial field strength of Br ~ 130 kG and Br ~ 13 kG, assuming a dipole field configuration, for the two gamma-Doradus
stars KIC 3127996 and KIC 5876187, respectively. For 44 Tau, analysis of mixed modes yields a field strength of Br ~ 1771 kG. Different
magnetic field configurations and mode degrees lead to different estimates. The results for the radial component of the
magnetic field in the main sequence gamma-Doradus
stars are consistent with estimates of
magnetic field strengths in red
giant stars that assume an internal field generated by a core dynamo, although the stronger of the two inferred
magnetic fields may require some enhancement by a fossil field. The toroidal component does not affect g-modes significantly and is required to be more than 200 times stronger than the radial component to suppress g-modes. (abridged for arXiv)
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All authors Oliver Durfeldt-Pedros, Victoria Antoci, Daniel Lecoanet, Zhao Guo, Jonathan Labadie-Bartz
Superconductivity
Structural Changes and Transport Properties of $\mathrm{YBa_2Cu_3O_7}$ Locally Modified by a He$^+$ Focused Ion Beam
Ross Carter, Robin Hutt, Paul Zimmermann et al. (+9 more)
Irradiation of a material with ions can cause various defects that can lead to structural phase transitions and the modification of the material's properties. Here we study the irradiation of the epitaxyally grown thin films of the high-temperature
superconductor $\mathrm{YBa_2Cu_3O_7}$ with $30\,\mathrm{keV}$ He$^{+}$ ions which leads to the expansion of the
crystal lattice, decrease of the critical temperature $T_c$ and eventually transition to an
insulator. Fabrication of such insulating regions with a focused He-Ion beam with a spot size of $\sim 10\,\mathrm{nm}$ is a powerful technique for fabrication of superconducting nano-devices. Using low-temperature resistivity measurements, diffraction with a nanofocused X-ray beam and atomic force microscopy, we investigated how the structure and the electric transport properties of $\mathrm{YBa_2Cu_3O_7}$ depend on the irradiation dose in a range $10$–$100\,\mathrm{ions/nm^2}$ and on the lateral size of the irradiated area in a range $30$–$5000\,\mathrm{nm}$.
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All authors Ross Carter, Robin Hutt, Paul Zimmermann, Ainur Abukaev, Jan Ullmann, Simon Koch, Christoph Schmid, Manfred Burghammer, Reinhold Kleiner, Dieter Koelle, Edward Goldobin, Ivan A. Zaluzhnyy
Cosmology and Nongalactic Astrophysics
A Unified Halo Mass Function Across Dark Matter Models from High-Resolution Multi-Scale Simulations
Andrew J. Benson, Ethan O. Nadler, Xiaolong Du et al. (+1 more)
We measure the dark matter
halo mass function, with backsplash
halos removed, from a wide range of cosmological-box and zoom-in simulations. These include the MultiDark Planck boxes, along with a suite of zoom-in simulations of Group, Milky Way, and LMC-mass
halos. The Milky Way simulations include both CDM and non-CDM initial conditions. Using these measurements, we calibrate the parameters of flexible fitting functions for the
halo mass function and the window function, along with parameterized models for various systematics, including finite box size effects,
halo isolation criteria,
halo detection efficiency, and contamination by artificial
halos (objects forming from particle noise in the initial conditions). We show that this model shows remarkable consistency with N-body simulations over a broad range of
redshifts, and ten orders of magnitude in
halo mass ($10^6\mathrm{M}_\odot$ to $10^{16}\mathrm{M}_\odot$). Our model typically maintains a high precision of 12% and captures complex behaviors, including small-scale cut-offs, oscillations, and enhancements. In specific mass intervals for certain power spectra, we see larger deviations of 40-50%. Furthermore, when integrated with a simple model for environmental dependence, this fitting function provides a robust description of how environmental density influences the
halo mass function. This precision model captures a wide variety of dark matter paradigms (including thermal relics,
axions, and models with dark-sector interactions), is accurate for
halo masses down to $10^7\mathrm{M}_\odot$, and is a critical ingredient for model-independent dark-matter inference from forthcoming data.
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All authors Andrew J. Benson, Ethan O. Nadler, Xiaolong Du, Vera Gluscevic
Strongly Correlated Electrons
From Topological Order to Mixed-State Phases: A Ground-State Probe of Fractionalized Excitations
Yunlong Zang, Yu-Bin Li and Shenghan Jiang
How do we detect topological phases from a single ground state?
Entanglement entropy and spectrum have long been the standard tools – but the reduced density
matrix (RDM) itself contains far more information. We show that the RDM of a 2D topologically ordered system, expressed at the
entanglement cut, realizes a 1D mixed-state phase. For the $\mathbb{Z}_2$ toric code phase, it is a 1D $\mathbb{Z}_2$ strong-to-weak spontaneous
symmetry breaking (SW-SSB) phase, where deconfinement of anyons manifests as the short-range correlation of both $\mathbb{Z}_2$ charge and $\mathbb{Z}_2$ domain-wall in the RDM. The bulk $e$-$m$ duality translates into a Kramers–Wannier self-duality of the SW-SSB phase. Extending the framework to gapped $\mathbb{Z}_2$
spin liquids, the global
spin-rotation
symmetry manifests as an additional weak
symmetry for the 1D RDM.
Spin-$\frac{1}{2}$ spinons result in a cusp on the disorder parameter of
spin-rotation at $\theta=\pi$, providing a direct, ground-state signature of
symmetry fractionalization. We verify this prediction analytically using the
matrix product density operator formalism and numerically for the kagome-
lattice resonating valence bond state. The proposed observable requires only a single ground-state wavefunction, making it amenable to
quantum simulation platforms.
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Plasma Physics
Ionization-Induced Electrostatic Hose Instability in Electron-Beam-Sustained Plasmas
Jia-Hong Chen, Yi Yu, Jian Chen et al. (+1 more)
We report the discovery of a previously unrecognized electrostatic hose instability in electron-beam-sustained
plasmas, driven by the coupling between the electron beam centroid and the
plasma generated via the beam-impact ionization. Unlike the conventional hose instability of relativistic beams propagating in underdense
plasmas, this instability requires only ionization-capable electron beams readily produced by common emission processes and sheath acceleration, indicating broad relevance across various discharges. A linear theory is developed to predict the hosing frequency and growth rate, and particle-in-
cell/Monte Carlo simulations confirm both the onset of instability and the theoretical predictions.
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All authors Jia-Hong Chen, Yi Yu, Jian Chen, Zhi-Bin Wang