Materials Science
A Differentiable DFT-Based Framework for Inverse Materials Design
Kohei Ishii, Hisazumi Akai, Tetsuya Fukushima et al. (+4 more)
Discovering solid-state materials with target properties remains a central challenge in computational materials science. Existing data-driven approaches rely on training data and may generalize poorly outside the training distribution. Here we develop a first-principles inverse-design framework that requires no training data. It integrates reverse-mode automatic differentiation (AD) into the Korringa–Kohn–Rostoker method combined with the coherent potential approximation (KKR-CPA), in which elemental concentrations serve as continuous optimization variables. Reverse-mode AD computes all concentration gradients in one backward pass, enabling optimization over dozens of candidate elements. Any differentiable quantity computable within KKR-CPA can serve as an optimization objective. We demonstrate this generality in permanent-magnet and half-metal design, identifying candidates such as (Nd$_{0.983}$Pr$_{0.017}$)(Co$_{0.72}$Fe$_{0.28}$)$_2$Fe$_3$ and FeMn(As$_{0.83}$P$_{0.17}$), respectively. We also synthesized materials with five SmCo$_5$-based compositions selected during optimization for higher magnetization. Their measured magnetization agreed closely with calculated values. Our framework offers a first-principles route to designing materials with target properties.
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All authors Kohei Ishii, Hisazumi Akai, Tetsuya Fukushima, Hikari Shinya, Hyuga Hosoi, Noritsugu Sakuma, Koji Inui
Astrophysics of Galaxies
Probing the ubiquity of complex ices in protostars with JWST: the first systematic quantification of weak ice bands between 6.8 and 7.9 micron
Yuan Chen, Ewine F. van Dishoeck, Katerina Slavicinska et al. (+18 more)
Complex organic molecules (COMs) are the key to understanding the chemical
evolution from simple interstellar molecules to potential prebiotic material. Although COMs have been extensively studied in the gas phase toward protostars, their counterparts in ices, where they are thought to form at earlier stages, remain far less constrained. A number of diagnostic features of complex ices lie between 6.8 and 8.8 um, a region known as the "COM ice fingerprint range," but previous infrared facilities lacked the sensitivity and spectral resolution required to quantify the weak bands therein. With the unprecedented sensitivity and resolving power of JWST, these limitations can now be overcome. Here, we present the first large-sample quantitative study of the absorption features at 7.02, 7.24, 7.40, and 7.67 um, using MIRI-MRS spectra of 21 protostars. The CH4 band at 7.67 um is the strongest band and shows remarkably uniform peak positions (7.67-7.68 um) and FWHMs (0.06-0.08 um), suggesting CH4 ice as its dominant carrier. The 7.24 and 7.40 um bands exhibit larger source-to-source variations in peak positions and FWHMs, but their occurrence and intensities are strongly correlated with each other. Comparisons with existing and new laboratory spectra suggest HCOO- as the most likely carrier of these two bands, yet HCOO- cannot fully reproduce their intensity ratios, implying additional contributions from other species such as C2H5OH, CH3CHO, and CH3COCH3. Our results reveal, for the first time, the potential ubiquity of weak features of complex ices in protostars, which have remained largely undetected due to observational limitations.
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All authors Yuan Chen, Ewine F. van Dishoeck, Katerina Slavicinska, Lukasz Tychoniec, Martijn L. van Gelder, Logan Francis, Adwin C. A. Boogert, Mayank Narang, Charlotte A. F. Schravendijk, Henrik Beuther, Alessio Caratti o Garatti, Eyze K. H. Eenhorst, Caroline Gieser, Thomas Henning, Manuel Gudel, Valentin J. M. Le Gouellec, Melissa K. McClure, Pooneh Nazari, Simon D. Reyes, Mees Tolman, Yao-Lun Yang
High Energy Physics (Theory)
Holonomies and Boundary Symmetries in the Discrete BF Formulation of Carroll Dilaton Gravity
H.T.Özer and Aytül Filiz
We construct a discrete realization of two-dimensional Carroll dilaton
gravity based on a BF-type gauge structure with holonomy variables on
lattice links. The bulk theory remains topological, while the physical dynamics is encoded in boundary degrees of freedom. Imposing admissible boundary conditions, we derive the asymptotic
symmetry structure directly at the
lattice level. The least restrictive conditions yield an affine extension of the Carroll
algebra, while additional constraints reduce the
symmetry to a conformal sector governed by a discrete Virasoro-type
algebra. In the continuum limit, the
lattice symmetry structure reproduces the expected affine Carroll
algebra together with its conformal reduction. The construction therefore provides the ultra-relativistic counterpart of discrete Jackiw-Teitelboim(JT)
gravity.
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High Energy Physics (Phenomenology)
Implementation of DIS at N$^3$LO for PDF determination
Andrea Barontini, Marco Bonvini and Niccolò Laurenti
In this work we construct an accurate description of Deep-Inelastic Scattering (DIS) at third order in perturbative QCD that is valid at all energy scales. We do so by assembling massless and massive results in a variable flavour number scheme, performing a careful power counting of the various contributions. We also propose an improved approximation for the massive neutral-current DIS coefficient function at order $\alpha_s^3$, whose construction is validated against lower order results. These results are instrumental for state-of-the-art next-to-next-to-next-to-leading order fits of parton distribution functions.
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Nuclear Theory
The renormalization of the shell-model neutrinoless double-beta decay operator starting from effective field theory at leading order
L. Coraggio, G. De Gregorio, S. L. Lyu et al. (+1 more)
In this work, we approach for the first time the task to perform a shell-model calculation of the
matrix element for the neutrinoless double-beta decay, within a fully-consistent framework where the expressions of the
nuclear Hamiltonian and of the decay operators have been derived through
chiral perturbation theory. More precisely, the effective shell-model
Hamiltonian and all transition operators have been constructed by way of the many-body perturbation theory, and then employed to calculate both spectroscopic properties of the
nuclei involved in the decays under our consideration - namely 48Ca, 76Ge, and 82Se -, as well as the
nuclear matrix elements of the electromagnetic and neutrinoless double-beta decays. We also present a study of the convergence properties of the calculated
matrix elements in order to provide the elements for an estimate of the theoretical uncertainty.
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All authors L. Coraggio, G. De Gregorio, S. L. Lyu, N. Itaco
Atomic Physics
Statistical Characteristics of Tunneling States in Strong-Field Atomic Ionization
M. W. Cao, Z. Y. Chen, J. N. Wu et al. (+5 more)
The state of the tunneling electron under the potential barrier is important in strong
laser-atom interaction but is difficult to identify. Recent experiments showed that the tunneling electron may be located in a bound state with high
symmetry [Phys. Rev. Lett. 134, 213201 (2025)]. However, the quantitative characteristic of the tunneling state in a tunneling event remains unclear. Here, we study tunneling ionization of atoms in strong circular
laser fields. The calculated photoelectron momentum distribution (PMD) through numerical solution of time-dependent Schrödinger equation (TDSE) presents an isotropic ring-shaped distribution and the most probable momentum (MPM) along the ring can be easily identified. The kinetic energy related to MPM is remarkably smaller than that predicted by the strong-field approximation (SFA) that ignores Coulomb potential. Surprisingly, for different target atoms and
laser parameters, the kinetic energy difference of MPM between TDSE and SFA is always close to half of the corresponding Coulomb potential at the tunnel exit. This phenomenon can be well described by a proposed model, which indicates that the tunneling electron is in an exit-position-dependent quasibound state agreeing with the virial
theorem. These results quantitatively reveal the characteristics of tunneling states from a statistical perspective.
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All authors M. W. Cao, Z. Y. Chen, J. N. Wu, S. Q. Shen, S. Wang, W. Y. Li, J. Y. Che, Y. J. Chen
Strongly Correlated Electrons
Automatic-differentiation-enabled dynamic parameter retrieval with sub-pulse-width resolution
Huaiyue Peng, Yuchen Lin, Fu Deng et al. (+2 more)
Time-resolved terahertz time-domain spectroscopy (THz-TDS) is a phase-sensitive tool in condensed matter physics for tracking photoinduced non-
equilibrium dynamics of low-energy elementary excitations. However, the measured response function, optical conductivity $\sigma(\omega,t_{pp})$, becomes unreliable in reporting the state of matter when material properties drastically change on a timescale comparable to or less than the probe pulse duration, obscuring the sub-pulse-width dynamics. To resolve this issue, we present a full-waveform inversion framework inspired by the multi-dimensional
retrieval philosophy of frequency-resolved optical gating (FROG). By leveraging the automatic differentiation (AD) technique and the two-dimensional time-domain signal $E(t_{g},t_{pp})$, we show one can uniquely solve the inverse problem, at the sub-pulse-width resolution, of retrieving physical observables that are still well-defined, i.e., time-dependent scattering rate $\gamma(t)$,
plasma frequency $\omega_\mathrm{p}(t)$ and resonance frequency $\omega_0(t)$, while the response functions are not. Further optimization by gradient-based routines (Adam + L-BFGS) via JAX makes the method exceptionally robust against experimental noise and probe pulse distortions. The validity of the AD-enabled methodology is benchmarked both by a self-consistent numerical approach and by experimental data from real ultrafast THz spectroscopy measurements.
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All authors Huaiyue Peng, Yuchen Lin, Fu Deng, Xiaoyue Zhou, Jingdi Zhang
Fluid Dynamics
From Propulsion to Suction: Unraveling Thrust Reversal in Propellers at Intermediate Reynolds Numbers
Rong Fu, Siyu Li and Yang Ding
This study investigates propeller hydrodynamics at intermediate Reynolds numbers (Re), crucial for small-scale robotic systems but still uncharted. Experiments on a propeller-driven
underwater vehicle and numerical simulations reveal thrust reversal–a phenomenon where clockwise propeller rotation leads to backward motion–in the approximate range 1.3 < Re < 150 under specific conditions. Notably, counterclockwise rotation consistently results in backward motion. Simulations reveal that this behavior arises when centrifugal suction, an inward force along the axis caused by radial outward flow from the propeller's rotation, dominates over fluid backward acceleration, the primary thrust mechanism at high Re. These findings provide critical insights into the unique dynamics of the intermediate Re regime and inform the design of efficient propulsion systems for miniature aquatic
robots.
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Quantum Physics
A phase-space approach for performing continuous-variable quantum teleportation with a non-Gaussian resource
Ankita and Arpita Chatterjee
We present a detailed phase-space analysis of continuous-variable
quantum teleportation using a
photon-subtracted two-mode squeezed Fock state (PS-TMSFS) as an entangled resource. We investigate the performance of PS-TMSFS within the Braunstein-Kimble teleportation protocol. The resource-state preparation is described and the success probability related to the
photon-subtraction process is derived analytically. The Wigner characteristic function of PS-TMSFS is calculated and then employed to determine the fidelity for input Gaussian and non-Gaussian states. The dependence of the success probability and the teleportation fidelity on the squeezing parameter and the beam-splitter transmissivity is analyzed for both symmetric and asymmetric
photon-subtraction scenarios. This results that the symmetric
photon subtraction consistently outperforms the corresponding asymmetric configurations with the $(2,2)$ configuration providing the highest teleportation fidelity among the considered PS-TMSFS resources. A significant improvement over the Gaussian two-mode squeezed
vacuum (TMSV) resource is observed for teleporting Gaussian input states, particularly in the low-squeezing regime, whereas the relative advantage for non-Gaussian input states depends on the functioning resource parameters and gradually diminishes as squeezing increases.
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Materials Science
Spin-flip optical excitations in van der Waals antiferromagnet CrPS$_4$
Dipankar Jana, Aljoscha Soll, Zdenek Sofer et al. (+4 more)
We investigate the near-infrared optical response of the semiconducting van der Waals antiferromagnet CrPS$_4$ and identify previously unreported
spin-entangled optical resonances. The strong and anisotropic
magnetic-field dependence of these resonances reflects the underlying
magnetic order and confirms the biaxial
antiferromagnetic nature of CrPS$_4$. From the
magnetic field
evolution of the optical transition, we extract key
magnetic parameters, including the
spin-flop ($\approx0.9$~T) and
spin-saturation ($\approx8$~T) fields. These results demonstrate a potential pathway for all-optical probing of
spin states in van der Waals antiferromagnets, with relevance for
spin-sensitive optoelectronic and magneto-optical devices.
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All authors Dipankar Jana, Aljoscha Soll, Zdenek Sofer, Milan Orlita, Clement Faugeras, Maciej Koperski, Marek Potemski
Solar and Stellar Astrophysics
Solar Radio Burst Fine Structures
Eduard Kontar, Daniel Clarkson, Hamish Reid et al. (+5 more)
Solar radio bursts exhibit intricate variability in time, space, and frequency, often displaying a rich variety of fine frequency-time structures such as spikes, drift pairs, striae in Type III bursts, and herringbone patterns in Type II bursts, etc. Historically, limited spatial, spectral, and temporal resolution has hindered detailed investigation of these narrow-band, rapidly evolving features, restricting progress in identifying their physical origins and underlying processes at these scales. Advances in high-time-frequency-resolution
solar imaging now offer transformative opportunities. Recent sub-second imaging spectroscopy has revealed that many fine structures challenge existing theoretical models, pointing to the need for new frameworks and a reassessment of current interpretations. The Square Kilometre Array (SKA), with its full-Stokes imaging spectroscopy at sub-second cadences, will provide unprecedented data essential for resolving these long-standing questions. These capabilities promise to significantly deepen our understanding of electron acceleration and transport,
magnetic reconnection, and coronal
plasma turbulence, thereby advancing our knowledge of
solar energetic processes and improving assessments of their space-weather impacts.
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All authors Eduard Kontar, Daniel Clarkson, Hamish Reid, Yingjie Luo, Nicolina Chrysaphi, Alexey Kuznetsov, Galina Motorina, Carine Briand
High Energy Astrophysical Phenomena
Amortized Simulation-Based Inference of Relativistic Mean-Field Couplings for Neutron-Star Equations of State
Prashant Thakur and Tuhin Malik
We present a simulation-based inference framework for constraining microscopic relativistic mean-field parameters of
neutron-
star equations of state. Neural posterior estimation is applied to two representative RMF families, a density-dependent DDB model and a nonlinear RMF-NL model, using
nuclear saturation properties,
chiral effective-field-theory pure-
neutron-matter pressures, and the maximum-mass constraint as conditioning observables. The inferred posteriors are validated against the conventional nested sampler (PyMultiNest) calculations and tested with the TARP coverage diagnostic. For both RMF parametrizations, the neural posterior reproduces the nested-sampling constraints on model couplings,
nuclear-matter properties, and
neutron-
star observables with no significant bias. The amortized
estimator generates $3\times 10^{4}$ posterior samples in about $2.5\,\mathrm{s}$ on a CPU, enabling a rapid inference workflow without the need for retraining for updated data. This constitutes a proof of concept that NPE-emulated RMF models, once validated, can be safely used for superfast exploratory inference. As an additional mock-observation test, imposing $R_{1.4}=12\,{\rm km}$ and $M_{\rm max}>1.97\,M_\odot$ leads to consistent predictions for the maximum-mass configuration, with DDB giving $M_{\rm max}=2.10^{+0.09}_{-0.07}\,M_\odot$, $R_{\rm max}=10.71^{+0.14}_{-0.21}\,{\rm km}$ and RMF-NL giving $M_{\rm max}=2.05^{+0.10}_{-0.06}\,M_\odot$, $R_{\rm max}=10.69^{+0.18}_{-0.19}\,{\rm km}$; although fixing $R_{1.4}$ confines both families to a narrow EOS region, RMF-NL remains marginally softer than DDB at high density, consistent with its slightly lower maximum mass.
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Solar and Stellar Astrophysics
Exploring Activity Across the Stellar Main Sequence with the Sun as a Benchmark
Atul Mohan, Stephen M. White, Sven Wedemeyer et al. (+1 more)
The active atmospheres of cool main-sequence
stars (F-M type) often release a fraction of their stored
magnetic energy, producing enhanced emissions (
flares) across
radio to X-ray wavelengths and associated space weather events like coronal mass ejections (CMEs) and energetic particle events (EPEs). Detailed imaging of active regions and CMEs, and in-situ EPE measurements are possible only in our Sun, making it a
benchmark for
stellar activity research. Multiwaveband
solar imaging
datasets let us define robust disk-integrated Sun-as-a-
star diagnostics of active region and space weather, extendable to
stellar datasets.
Radio waveband provide diagnostics of particle acceleration, CMEs and EPEs, essential to model
flare events and their space weather impacts. The Square Kilometre Array (SKA)
telescopes will facilitate sub-second scale spectropolarimetric imaging of the
solar corona across 0.05 - 15GHz, enabling detailed vertical tomographic studies of the active region across a range of coronal heights. Coupled with high energy instruments, the SKA
telescopes will allow well-constrained modeling of large samples of diverse active phenomena and the defintion of robust Sun-as-a-
star diagnostics of active region and space weather. Besides, the supreme sensitivity and angular resolution of the SKA
telescopes will help detect quiescent and active emissions from several nearby
stars. This chapter discusses the importance of comparative
solar-
stellar studies using Sun-as-a-
star diagnostics in understanding activity and associated space weather conditions in
stars across the cool main-sequence, and presents some research avenues that will benefit
solar and
stellar astrophysics.
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All authors Atul Mohan, Stephen M. White, Sven Wedemeyer, Vladimir Airapetian
Fluid Dynamics · Cross-listed from math.AP
Three-Dimensional Positive-Cone Oldroyd-B Flows:Geometric Continuation and Residual-Work Criteria
Sai Peng
We prove a three-dimensional positive-cone continuation criterion for the stress-
diffusion-free Oldroyd-B system on the periodic
torus. Writing the positive conformation tensor as A = exp(B), we show that finite-time breakdown of a strong H^s solution, s > 5/2, can occur only through loss of the logarithmic spectral envelope of A or divergence of the endpoint vorticity clock given by the time integral of the B^0_{infty,1} norm of curl u. The proof combines compact positive-cone envelopes, endpoint Biot-Savart estimates, and high-order logarithmic conformation estimates, without using stress
diffusion. We also derive a positive-cone Reynolds admissibility criterion with an exact residual-work cost. The least L^2 conformation residual needed to pay positive pressure-free residual work is determined by the
entropy-dual lever G = I - A^{-1}, and this cost degenerates quantitatively near the
equilibrium A = I. Together, the two criteria identify the same positive-cone obstruction in the strong and relaxed regimes: before breakdown one must control the endpoint flow clock on a compact logarithmic cone, while after passage to a relaxed description positive residual work must be paid for by an exact
entropy-dual conformation defect.
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High Energy Physics (Phenomenology)
Weak decay of the positronium ion
Nishat Ul Sani, M. Jamil Aslam and Ishtiaq Ahmed
The positronium ion ($\mathrm{Ps}^-$), a coulombic three-body bound state of two electrons and a positron, predominantly decays via electron-positron annihilation into electromagnetic final states. While its radiative decay channels have been extensively studied, much less
attention has been given to weak processes in this system. In this work, we investigate the rare decay $\mathrm{Ps}^- \to e^- \nu_\mu \bar{\nu}_\mu$, obtained by replacing the
photon in $\mathrm{Ps}^- \to e^- \gamma$ with a virtual $Z$
boson. Treating the three-body process as an effective two-body transition, $\mathrm{Ps}^- \to e^- Z^*\left(\to \nu_\mu\bar{\nu}_\mu\right)$, we compute the decay rate by explicitly evaluating all
spin configurations of the initial bound state and final particles. The result agrees with that obtained using the standard
spin-summation formalism of
quantum field theory. We find that the branching ratio is comparable to that of the weak decay of ortho-positronium, $\mathrm{o\text{-}Ps} \to \gamma \nu \bar{\nu}$.
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Soft Condensed Matter
Suppression of Active Super-Diffusion: Impact of String Defects and Canted Multi-Domains
Ritik Rajak, Manish Agarwal, Sanjay Puri et al. (+1 more)
We investigate the transport dynamics of an active Brownian particle (ABP) traversing a complex, non-Newtonian
liquid crystal (LC)
matrix. Employing the Generalized Lebwohl-Lasher (GLL) model, we systematically vary higher-order orientational interactions to stabilize three distinct host environments: isotropic, uniform nematic, and structurally frustrated canted phases. Modeling the coupled system via off-
lattice over-damped Langevin dynamics, the resulting trajectories are characterized by evaluating their step-size distributions (SSDs), mean-square displacements (MSDs), and Hurst exponents. In the uniform nematic phase, the anisotropic
matrix elastically channels the ABP, producing a left-skewed exponential SSD and persistent ballistic motion parallel to the director $\hat{\mathbf{n}}$. Similarly, transverse transport obeys a Rayleigh distribution and acquires a prominent $t \ln t$ super-diffusive correction-an explicit signature of the particle coupling to the host's gapless transverse Goldstone modes, as predicted by Toner et al. [Phys. Rev. E 93, 062610 (2016)]. Crucially, we reveal that this active super-
diffusion is systematically suppressed when the long-range Goldstone fluctuations are disrupted by topological defects. This breakdown manifests both macroscopically within the fractured, multi-domain canted phase due to a structural mass gap, and locally in the unfrustrated nematic phase through scattering by
vortex disclination lines. Consequently, while the local SSDs qualitatively mirror the ideal nematic state, the transverse $t \ln t$ scaling vanishes in the presence of these structural constraints. Our findings demonstrate that tuning the background defect architecture of a complex fluid can fundamentally alter the transport universality class of active matter, offering a novel paradigm for controlling microscopic mobility.
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All authors Ritik Rajak, Manish Agarwal, Sanjay Puri, Varsha Banerjee
General Relativity and Quantum Cosmology
Accretion of a Plasma Vlasov Gas onto a Reissner-Nordström Black Hole
Yongqiang Liu and Hongsheng Zhang
We develop a steady-state, spherically symmetric
accretion model for a two-component
plasma Vlasov gas in the background of a Reissner–Nordström black hole. Analytical expressions in parametric form for the critical angular momentum and impact parameter are derived for each species, leading to a rigorous partition of the absorption and scattering domains in phase space. For both monoenergetic and Jüttner distributions, electromagnetic attraction enhances, while repulsion suppresses, the particle number density, energy density, pressure and
accretion rates of individual charged components relative to the neutral case. After proper normalization, the total physical quantities of the
plasma (under non-extreme conditions) can be expressed exactly, or to high accuracy, as weighted averages of the two species. When the two components share identical distribution functions,
accretion drives the Reissner–Nordström black hole naturally toward the Schwarzschild limit—a charge
evolution that is absent in neutral-gas models. Numerical results further reveal that near the horizon the radial pressure is significantly smaller than the tangential pressure, sharply distinguishing the Vlasov gas from a perfect fluid.
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Atmospheric and Oceanic Physics
Evaluation of medium range machine learning models for sub-seasonal prediction
Catherine de Burgh-Day, Chen Li, Debra Hudson et al. (+4 more)
The performance of two machine learning (ML) atmosphere models - GraphCast and FourCastNetV2 - is evaluated in the context of sub-seasonal prediction, including their ability to represent key
climate drivers of variability, namely the Madden-Julian Oscillation and the Southern Annular Mode. Model skill is assessed over both a 38-year hindcast period and a 2.5-year hindcast period. The longer period overlaps with the training windows of the ML models but provides a larger sample for robust evaluation, while the shorter period is independent of the ML model training period. This dual evaluation illustrates a compromise approach to the problem of insufficient independent data for evaluation of the models for sub-seasonal prediction. The ML models are compared against the Bureau of Meteorology's physics-based seasonal prediction system, ACCESS-S2, for the 38-year period, and a more recent physics-based coupled model for the shorter hindcast period. Across the two evaluation periods, both ML models have surprisingly good skill for sub-seasonal timescales, given they were designed for
forecasting on medium range timescales. In general, the ML models are as skilful as the physical model ensemble mean at shorter lead times and comparable to the physical model ensemble members at longer lead times.
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All authors Catherine de Burgh-Day, Chen Li, Debra Hudson, Li Shi, Harrison Cook, Robin Wedd, Griffith Young
Superconductivity
Emergence of Quasi-two-dimensional Superconductivity in W-doped Bulk Noncentrosymmetric 3$R$-TaSe$_2$
P. Manna and R. P. Singh
Noncentrosymmetric transition-metal dichalcogenides offer a rich environment for the study of unconventional superconducting phenomena. Here, we present a comprehensive analysis of single-crystalline W-doped 3$R$-TaSe$_2$, revealing weakly coupled anisotropic unconventional superconductivity at $T_c$ = 2.82(2) K, with an in-plane upper critical field exceeding the Pauli limit by 1.7 times. The angular dependence of the upper critical field, along with the observation of a Berezinskii-Kosterlitz-Thouless transition, reveals quasi-two-dimensional superconductivity. Crucially, magnetotransport reveals a distinct two-fold rotational
symmetry within the superconducting state under in-plane fields, breaking the underlying three-fold
lattice symmetry. These findings establish W-doped $3R\text{-TaSe}_2$ as a bulk model system for exploring intrinsic low-dimensional superconductivity and broken rotational
symmetry, thus opening new directions for future
quantum technologies.
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Instrumentation and Detectors
NeuXtalViz: Interactive Three-Dimensional Visualization and Analysis for Single-Crystal Neutron Diffraction
Zachary Morgan, Zhongcan Xiao, Sylwia Pawledzio et al. (+7 more)
NeuXtalViz (
Neutron Single-
Crystal Visualization) is a Python-based software package developed at Oak Ridge National Laboratory to provide interactive three-dimensional visualization and analysis tools for single-
crystal neutron diffraction experiments. Built on the Mantid framework for data reduction, and leveraging PyVista and Matplotlib within a Python Qt environment, NeuXtalViz adopts a model-view-presenter architecture that separates the user interface from the core processing components. The software provides a unified interface for tasks central to single-
crystal diffraction, including UB-
matrix determination, experiment planning, visualization of normalized reciprocal-space volumes, and real-space
crystal-structure calculations. It also integrates with widely used community tools and has been deployed on instrument and analysis servers, where it is now being adopted by instrument teams and users. By
embedding advanced three-dimensional visualization directly into the experimental workflow, NeuXtalViz enhances the planning, execution, and analysis cycle for single-
crystal neutron diffraction experiments, while providing a flexible framework for future development.
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All authors Zachary Morgan, Zhongcan Xiao, Sylwia Pawledzio, Iris Ye, Kathleen Loughlin, Shiyun Jin, Vickie Lynch, Thomas Proffen, Christina Hoffmann, Xiaoping Wang
Earth and Planetary Astrophysics
Resonant Super-Earths Dancing With EKL Oscillations: TTV Phase Excitation and Resonance Disruption by EKL Interactions between a Cold Jupiter and Stellar Companion
Pin-Gao Gu and Gongjie Li
Near-resonant Kepler
planets are dynamically hot, as evidenced by nonzero transit timing variation (TTV) phases, indicating that free eccentricities are not damped. Recent observations suggest that circulating near-resonant
planets tend to be dynamically unstable, and hence dynamically hot, likely representing an intermediate stage in the close-in super-Earth population at young ages. We investigate whether a cold Jupiter interacting with a
stellar companion through the eccentric Kozai-Lidov mechanism (EKL) can excite TTV phases and increase the libration amplitude of resonant angles in close-in resonant pairs. We find that the EKL model that drives the observed eccentricity of cold Jupiters can also excite TTV phases, increase the libration amplitude of resonant angles away from ideal
geometric alignment, and even disrupt them in a significant fraction of planetary systems in our simulated samples over 16 Myr. We also find that the TTV phases of the resonant pairs tend to be small (< 90 degrees), while the resonant angles are more easily elevated to become circulating during EKL excitation.
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Strongly Correlated Electrons
Jie Liu, Xiaofan Zhou and Suotang Jia
We investigate the
magnetic order of a one-dimensional
spin-1/2
fermion dynamical
lattice, where itinerant
fermions are coupled to bond-centered localized
spins via an Ising-like
spin dependent hopping. The model provides an anisotropic dynamical extension of conventional
spin-1/2
fermion systems, in which the motion of itinerant
fermions is directly modulated by the configuration of localized
spins. Using density
matrix renormalization group simulations, we map out the ground state phase diagram in various parameter spaces. Depending on the interplay among the hopping dependent on localized
spins, the longitudinal field, and the external Zeeman field, two distinct phases are obtained: a paramagnetic phase and a
spin-density-wave phase. Most notably, in the partially
spin-polarized
fermion phase, the
spin-density wave ordering wave vector exhibits two distinct phenomena, corresponding respectively to the nesting vectors $2k_{F\uparrow}$ and $2k_{F\downarrow}$ of the
spin-resolved
Fermi surfaces. We further demonstrate that the two
spin-density wave phases are robust against the repulsive Hubbard interaction between itinerant
fermions. Our results reveal a novel route for tuning
magnetic modulations in one-dimensional correlated systems and enrich the microscopic understanding of dynamical
lattice magnetism.
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Materials Science
Intrinsic Defect Energetics and Fluorine Doping Effects in Li2CO3 and Li2O2: A First-Principles Study
Youjeong Choi, Tasuku Sugiura, Keisuke Mukai et al. (+3 more)
Lithium carbonate, Li2CO3, is a thermodynamically stable carbonate phase whose defect energetics are closely related to its stability and decomposition behavior in various lithium-based electrochemical systems. These properties of Li2CO3 are particularly important in lithium-oxygen battery environments. In these systems, Li2CO3 can form as a parasitic discharge product alongside Li2O2, the primary discharge product, leading to performance degradation. However, compared with Li2O2, the intrinsic defect thermodynamics of Li2CO3 and how chemical doping modifies its defect energetics remain insufficiently understood. In this study, first-principles calculations were performed to systematically analyze the intrinsic point-defect energetics of Li2CO3 and to evaluate the effects of fluorine doping on vacancy formation energies in Li2CO3 and Li2O2. Intrinsic defect analysis reveals that defect behavior is predominantly governed by lithium-related defects. Upon fluorine doping, lithium and carbon vacancy formation energies decrease selectively in Li2CO3, partially destabilizing the carbonate framework, while a reduction in lithium vacancy formation energy is also observed in Li2O2. These results suggest that fluorine doping modulates the defect energetics of both discharge products, potentially providing a thermodynamic basis for controlling the stability of Li2CO3 and Li2O2 under thermodynamic conditions representative of lithium-oxygen batteries.
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All authors Youjeong Choi, Tasuku Sugiura, Keisuke Mukai, Nanako Ishihara, Shuji Nakanishi, Teruyasu Mizoguchi
Fluid Dynamics
Mitigating adjoint chaos in wall turbulence
Qi Wang and Tamer A. Zaki
Estimating past events in wall
turbulence based solely on surface measurements and first principles is an ill-posed problem that is complicated by chaos. The sensitivity of a measurement to the earlier flow state is described by the adjoint Navier-Stokes equations, which are solved in reverse time starting from the measurement kernel at the sensing position and time. The resulting adjoint field is the spatio-temporal domain of dependence (DOD) of the sensor, which is a dual to the concept of the domain of influence (DOI) of an actuator in the linearized forward equations. In channel
turbulence, the energy of each adjoint realization grows exponentially in backward time according to the Lyapunov exponent, even though the energy of the ensemble average should decay. We introduce a linear eddy-viscosity closure model in the ensemble-averaged adjoint equations, and directly compute the mean DOD and compare our prediction to the ensemble average. Furthermore, we demonstrate that the DOD of a wall-stress measurement and the DOI resulting from a wall-stress perturbation exhibit respective universal behaviors across Reynolds numbers. However, their spatio-temporal structures differ qualitatively, due to the time-asymmetry of the governing equations. The DOD field has a two-part structure: one component is associated with the Orr mechanism, characterized by rapid reorientation under mean shear, and the other is related to self-similar expanding streaky structures. These two components jointly define the sensitivity of the wall-stress measurement to past flow events.
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Quantum Physics
Y. Fang, J. Kuttruff, Z. Zhao et al. (+3 more)
Determining the
quantum state of a given
quantum-mechanical system is a fundamental task in physics.
Quantum-state
tomography has been pivotal for establishing
quantum optics [1-4] and for revealing the properties of bound charges in materials [5-7]. An emerging other object for studying and utilizing
quantum effects are free electrons, elementary particles that are central to high-resolution microscopy [8,9], electron-based
quantum optics [10-17], ul-trafast electron microscopy [18-24] and particle accelerators [25-27]. However, free electrons are intrinsically incoherent, and we lack a broadly applicable method to measure and control their
quantum state beyond special cases with discrete energy sidebands [28,29]. Here, we report a universal approach to measure arbitrary free-electron
quantum states in continuous variables. Two monochromatic but spectrally shifted
laser waves produce interfering quan-tum paths that directly reveal the density
matrix and thus all essential properties of the pure wavepackets, the ensemble, and their interlinks. As a first application, we show how the
quantum state of a single electron is modified by many-body Coulomb interactions of a sur-rounding electron gas. The reported concepts and results provide insight into otherwise hid-den correlations in electron beams and enable the controlled optimization of exceptional
quantum states for free-electron
quantum optics or
quantum electron microscopy.
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All authors Y. Fang, J. Kuttruff, Z. Zhao, L. Moehrle, P. Hommelhoff, P. Baum
Solar and Stellar Astrophysics
Ruijie Li, Chengyuan Wu, Zhibin Dai et al. (+1 more)
Accreting white
dwarfs (WDs) are considered one of the most promising progenitor candidates for Type Ia
supernovae (SNe Ia).
Dwarf novae (DNe), a subclass of cataclysmic variables (CVs), consist of a carbon–oxygen (CO) WD accretor and a low-mass donor
star, which may be either a main-sequence (MS)
star or a slightly evolved subgiant. Previous studies have suggested that, under the thermal–viscous disk instability mechanism, the time-averaged
accretion rate in long-period DNe may approach the regime of stable hydrogen burning, potentially allowing the WD to grow toward the Chandrasekhar mass, (M_Ch). However, whether such periodic
accretion can sustain stable hydrogen burning and lead to WD mass growth remains uncertain. In this work, we explore whether high
accretion rates on short periodic timescales can maintain stable hydrogen burning on the WD surface and drive the WD toward (M_Ch). Using Modules for Experiments in
Stellar Astrophysics (MESA), we investigate the mass-retention efficiency of WDs undergoing intermittent DN-like
accretion and examine its dependence on duty cycle,
accretion rate, and initial WD properties. We find that periodic
accretion fails to maintain stable hydrogen burning. During quiescent phases, the WD cools and becomes increasingly degenerate, leading to nova outbursts with progressively decreasing mass-retention efficiency and ultimately preventing further WD mass growth. We therefore suggest that DNe are unlikely to be progenitors of SNe Ia.
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All authors Ruijie Li, Chengyuan Wu, Zhibin Dai, Bo Wang
Applied Physics
Direct stress imaging from shear wave propagation
Yiwei Duan, Michel Destrade, Wenchang Tan et al. (+1 more)
Quantitative imaging of stress fields in heterogeneous solids remains challenging because stress is not directly measurable and is typically inferred from deformation using constitutive models. Here we present Acoustoelastic Imaging (AEI), a non-destructive framework for reconstructing stress fields from shear wave propagation. AEI exploits the acoustoelastic effect, whereby pre-existing stress modifies local wave dynamics, and formulates stress recovery as an inverse problem of the governing wave equations. Using full shear waveform inversion with physics-informed learning, AEI reconstructs wave-equation coefficients from full-field wave measurements, enabling estimation of stress magnitude and principal directions without explicit constitutive model specification or material-parameter calibration. We demonstrate sub-wavelength spatial resolution (< 0.28 {\lambda}) and accurate reconstruction of nonuniform stress fields in heterogeneous materials through numerical simulations and ultrasound shear wave elastography experiments. These results establish a general framework for high-resolution stress imaging and provide a route toward non-invasive mapping of internal mechanical states in complex materials and biological tissues.
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All authors Yiwei Duan, Michel Destrade, Wenchang Tan, Guo-Yang Li
Solar and Stellar Astrophysics
Data-inspired simulation of AR 11158
Matthias Rempel and Georgios Chintzoglou
We present a data-inspired simulation of NOAA active region AR 11158. We simulate the formation of a collisional polarity inversion line (cPIL) by moving sunspots in a quadrupolar configuration along the centroid positions extracted from AR 11158. This process builds up free energy in the corona exceeding $4\cdot 10^{32}$ erg, out of which about $2\cdot 10^{32}$ erg are released in a X-
flare followed by a series of smaller
flares in the B to M range. The 4 strongest
flares are associated with coronal mass ejections. About 1-2 hours prior to the X-
flare a
magnetic flux rope (MFR) is forming above the cPIL. About 5 minutes before the
flare an upflow at chromospheric heights indicates a rise of the MFR. The eruption starts when parts of the MFR enter regions with a decay index larger than 1.5, indicating that the
flare initiation is consistent with the
torus instability. Comparing the series of
flares in this simulation to properties of observed
flares, we find a comparable trend between
flare energy and GOES X-ray flux, but
flare duration falls into the short end of the observed
solar distribution. As a consequence, energy fluxes into the
flare ribbons can be substantial, reaching $10^{13}$ erg cm$^{-2}$ s$^{-1}$ for the simulated X-
flare. The X-
flare causes step-function like changes of the horizontal
magnetic field in the photosphere, a propagation of a momentum pulse into the convection zone and quasi-periodic pulsations in the volume of the corona with periods from sub-seconds to multiple 10 seconds.
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Strongly Correlated Electrons
Spectroscopic signatures of Kohn anomaly in a topological crystalline insulator
Jingwen Li, Arpita Dutta, Kush Saha et al. (+4 more)
Topological crystalline
insulators extend the concept of topological
insulators by hosting surface states protected by crystallographic
symmetry. Their topological phase transitions arise from
spin-orbit-driven band inversion in the bulk electronic structure, reshaping the low-energy electronic environment and its coupling to
lattice excitations. While the electronic aspects of band
topology are well established, the corresponding dynamics of
lattice and electron-
phonon interactions remain largely unexplored. Here, we report a pronounced softening of a low-energy surface
phonon mode across the topological phase transition in Pb$_{0.77}$Sn$_{0.23}$Se, revealed by temperature-dependent time-domain terahertz spectroscopy. Unlike the well-known
phonon softening in ferroelectrics, this effect does not signal a structural instability but instead reflects electronic reconstruction. We attribute the softening to the spectroscopic manifestations of a Kohn anomaly, indicating a strong coupling between
lattice vibrations and Dirac-like surface electrons in the topological phase. Consistently, the
phonon linewidth deviates from the standard anharmonic temperature dependence, further evidencing enhanced electron-
phonon coupling. The observed changes in
phonon frequency and linewidth at around 120 K are consistent with the reported topological phase transition temperature in this material. Our results thus provide a spectroscopic route for the distinct identification of the onset of a topological phase.
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All authors Jingwen Li, Arpita Dutta, Kush Saha, Andrzej Szczerbakow, Tomasz Story, Manfred Fiebig, Shovon Pal
Applied Physics
Wide-field NV magnetometry under simultaneous high-pressure and high-temperature conditions
Masahiro Ohkuma, Eikichi Kimura, Shumpei Ohyama et al. (+7 more)
We demonstrate wide-field optically detected
magnetic resonance (ODMR) under simultaneous high-pressure and high-temperature conditions using nitrogen-vacancy (NV) centers. Although NV-center magnetometry has been widely used for spatially resolved
magnetic-field imaging, its application to extreme environments combining pressure and temperature remains challenging. In this work, we show that ODMR can be observed at 5 GPa and 500 K, demonstrating the feasibility of NV
spin readout under such combined extreme conditions. We further perform wide-field ODMR of iron at 7 GPa and 500 K, where the stray
magnetic field from the sample is spatially visualized through the pressure
cell. These results establish NV-center magnetometry as a promising platform for imaging
magnetic phenomena in materials under high-pressure and high-temperature environments.
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All authors Masahiro Ohkuma, Eikichi Kimura, Shumpei Ohyama, Miu Tezuka, Ryo Matsumoto, Shinobu Onoda, Yoshihiko Takano, Shintaro Azuma, Kenji Ohta, Keigo Arai