Materials Science
Thermal stability and structural ordering of thick Co$_2$MnAl films grown on MgO and Si substrates
David Robles-Cuenca, Juan Antonio González, Juan Pedro Andrés et al. (+3 more)
While most studies on Co$2$MnAl (CMA) focus on the ultrathin regime for spintronic junctions, applications scaling with
magnetic volume–such as Anomalous Nernst Effect (ANE) energy harvesters, integrated power inductors, and
magnetic MEMS–require significantly thicker films. In this work, 750 nm thick CMA films were grown on MgO (001) and Si substrates to establish a roadmap for their thermal integration. Structural analysis reveals that B2 ordering is optimized on MgO at 600 $^\circ$C, which is important for functional devices. In contrast, samples on Si substrates exhibit a disorder transition toward the A2 phase, closely linked to
diffusion-driven degradation processes. Above 500 $^\circ$C, Si interdiffusion into the Heusler layer triggers the formation of interfacial silicides and Kirkendall voids, leading to microcracking, electrical resistivity jumps, and a final fully disordered A2 phase. Despite the Mn-poor stoichiometry (Co$2.25$Mn$0.7$Al$1.05$), the films maintain a robust saturation magnetization of ~600 emu/cm$^3$, consistent with recent theoretical models for off-stoichiometric Heusler
alloys. These results define the processing windows for integrating thick CMA layers into multifunctional CMOS-compatible platforms.
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All authors David Robles-Cuenca, Juan Antonio González, Juan Pedro Andrés, Miguel Ángel Arranz, Mohamed Salaheldeen, Ricardo López Antón
Optics
Recovery-Oriented Optical System Design Based on Fisher Information
Zhuang Qian, Yan Mo, Hao Tan et al. (+5 more)
Traditional optical system design for imaging applications has long been guided by image quality metrics such as geometrical RMS spot size, wavefront error, and modulation transfer function (MTF). Although these metrics effectively characterize direct imaging performance, they do not necessarily indicate optimal behavior when image restoration is subsequently applied. In modern imaging pipelines, however, optical systems are increasingly combined with physics-based or learning-based restoration methods, making the information transfer properties of the optical system critically important. In this work, we propose a recovery-oriented optical design approach that explicitly links optical system optimization with image restoration performance through an estimation-theoretic framework based on Fisher information. A new design criterion is adopted to ensure that the information encoded by the optical system can be reliably recovered during image restoration. To validate the proposed approach, two dual separated aspheric lenses are designed under identical configurations using conventional RMS-based optimization and the proposed recovery-oriented optimization, respectively. Although the RMS-optimized lens exhibits superior direct imaging quality, it underperforms after image restoration compared to the recovery-oriented design. These results demonstrate that recovery-oriented optical design provides a physically interpretable and effective extension of traditional optical design criteria for imaging systems operating within modern computational imaging pipelines.
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All authors Zhuang Qian, Yan Mo, Hao Tan, Yu Chen, Haibo Wang, Weining Guo, Yijie Ni, Donglin Ma
Instrumentation and Detectors
Performance and Radiation Damage of the Heavy-Ion Silicon Beam Tracker in the BM@N Experiment
D. Chemezov, S. Khabarov, Yu. Kopylov et al. (+6 more)
The Silicon Beam Tracker (SiBT) of the BM@N experiment at the NICA complex (JINR, Dubna) is designed to reconstruct trajectories of beam ions upstream of the target. It consists of three stations based on double-sided silicon strip detectors (DSSDs) installed directly in the relativistic heavy-ion beam. The SiBT performance and radiation damage were studied using data from the 2026 experimental run with $^{124}$Xe beams at~$1.6$,~$2.2$, and~$3.0$~AGeV. During the run, the leakage current of the DSSD of the third station of SiBT increased by $28.95~\mu\mathrm{A}$, while the charge collection efficiency in the beam center decreased to approximately $68\%$ at the nominal bias voltage of 30~V. Increasing the bias voltage to 90~V restored the charge collection efficiency to approximately $95\%$. Despite the radiation-induced signal degradation, the tracking efficiency remained close to $99\%$. The accumulated radiation damage was also used to reconstruct the spatial distribution of the integrated beam fluence from strip-by-strip leakage-current measurements, yielding an average fluence of approximately $1.3\times10^{12}~\mathrm{n_{eq}/cm^2}$.
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All authors D. Chemezov, S. Khabarov, Yu. Kopylov, I. Osokin, A. Sheremeteva, E. Streletskaya, O. Tarasov, E. Zubarev, N. Zamiatin
Mesoscale and Nanoscale Physics
WannierSTM: Efficient superconducting scanning-probe spectroscopy from maximally localized Wannier functions
Oscar Moreno Segura, Dorye L. Esteras, Andrei Shumilin et al. (+3 more)
We present a Python-based program that combines maximally localized Wannier functions-based first-principles electronic structure with the nonequilibrium Green's function formalism to enable efficient simulations of scanning tunneling microscopy (STM). The workflow builds upon standard density functional theory packages to construct compact transport
Hamiltonians that preserve the properties of realistic materials. Superconductivity is incorporated via an effective pairing potential within the Nambu-spinor formalism, while coupling to the STM tip and substrate electrodes is treated using the wide-band limit approximation. Within this formulation, transport quantities such as current-voltage characteristics and differential conductance are evaluated in a closed analytical form. This avoids explicit numerical energy integrations and enables rapid spectroscopic calculations over broad parameter spaces. The framework provides a unified and computationally efficient approach for modeling superconducting hybrid nanostructures with
spin-orbit coupling,
magnetic textures, and
spin polarization. Representative applications in
spin chains, two-dimensional and molecular magnets on a
superconductor demonstrate its robust capabilities for both simple model systems and realistic ab initio molecular structures relevant to modern STM experiments.
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All authors Oscar Moreno Segura, Dorye L. Esteras, Andrei Shumilin, Gonzalo Rivero-Carracedo, Riku Tuovinen, José J. Baldoví
Fluid Dynamics · Cross-listed from math.NA
Space-Time Parallel Direct Numerical Simulation of Rayleigh-Bénard Convection
Thomas Saupe, Thibaut Lunet, Mathis Bode et al. (+3 more)
Rayleigh-Bénard convection (RBC) is a model for turbulent flow and challenging to simulate by direct numerical simulation (DNS). Adequate resolution of all relevant length scales requires very fine grids in space and stability restrictions can dictate small step sizes. In this paper, we investigate the use of parallel spectral deferred correction (SDC) as a high-order time-stepping method to reduce wall-clock times of direct numerical simulation of RBC. Performance results on JUSUF (CPUs) and JUPITER (GPUs) with two different codes show parallel SDC can offer some concurrency along the temporal axis plus larger maximum stable time steps. Taken together, this allows for a reduction of wall-clock time required for simulations over one free-fall time by having to compute fewer steps and being able to mitigate the higher cost per time step through temporal parallelization.
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All authors Thomas Saupe, Thibaut Lunet, Mathis Bode, Robert Speck, Sebastian Götschel, Daniel Ruprecht
Mathematical Physics · Cross-listed from math.AP
Cubic Nonlinear Schrödinger Systems and Orthonormal Fermionic Ground States in $\mathbb R$
Bin Chen, Yujin Guo, Yong Luo et al. (+1 more)
We study the one-dimensional nonlinear Schrödinger system \[ -u_i''-2\Big(\sum_{k=1}^N u_k^2\Big)^{p-1}u_i=\mu_i u_i \quad \mbox{in } \ \mathbb R,\ \ i=1,2,\cdots,N, \tag{S} \] where $u=(u_1,\cdots,u_N)\in H^1(\mathbb{R})^N$, $\mu_1\leq\mu_2\leq\cdots\leq\mu_N<0$, $1<p<3$ and $N\geq 2$ are arbitrary. For the cubic case where $p=2$ and $N\ge 2$, we establish the following structural results of the system $(S)$: (i) all nontrivial solutions can be classified completely; (ii) the linearized operator at any nontrivial solution is non-degenerate; (iii) exact $L^2$-mass formulas of all nontrivial solutions are derived in terms of distinct Lagrange multipliers $\mu_i$. As the applications of the above structural results, we first show that the system $(S)$ with $p=2$ does not have any orthonormal solution for any $N\ge2$. We then investigate a fermionic variational problem $J_N(p)$ with $N\ge2$, whose minimizers correspond to ground states of the system $(S)$ under orthonormal constraints. More precisely, we prove that there exists a sufficiently small $\delta_N>0$ such that $J_N(p)$ is attained for any $p\in(2-\delta_N,2)$, whereas $J_N(p)$ is not attained for any $p\in[2,2+\delta_N)$. These settle some
conjectures of [Gontier–Lewin–Nazar, ARMA, 2021] and [Frank–Gontier–Lewin, CMP, 2021].
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All authors Bin Chen, Yujin Guo, Yong Luo, Juncheng Wei
High Energy Physics (Experiment)
Real-time monitoring of LHCb beam spot properties based on FPGA hit reconstruction
Giulio Cordova, Elena Graverini, Daniele Passaro et al. (+3 more)
We present a real-time trackless method to monitor the centre of the LHCb luminous region and the relative
alignment of the two halves of the LHCb Vertex Locator, using cluster counts accumulated in selected regions of the detector and processed in firmware. A Principal Component Analysis performed on simulated data yields a set of weight vectors that reduce the position
estimators to scalar products of the counter rates, executable with negligible computational overhead. With pp collision data from 2024, the transverse position of the luminous region is reconstructed with a statistical precision of approximately 4 micrometre per coordinate in a 90 millisecond accumulation window. A measurement of the longitudinal centre is demonstrated with a statistical precision of a few millimetres in simulated studies. The introduction of run-time configurable firmware counters has been studied in simulation to improve the transverse and longitudinal resolutions by a factor of three with respect to the fixed-geometry baseline.
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All authors Giulio Cordova, Elena Graverini, Daniele Passaro, Federico Lazzari, Michael J. Morello, Giovanni Punzi
Earth and Planetary Astrophysics
Radiation limits on amino acid preservation and chiral measurement at Oxia Planum
Dimitra Atri
Amino acid enantiomeric excess (EE) is a potential biosignature, but its measurement requires sufficient surviving material as well as preserved chirality. We derive a criterion that separates abundance-limited from racemization-limited preservation and apply it to the Mars Organic Molecule Analyzer (MOMA) on the ExoMars Rosalind Franklin rover. The model combines
cosmic-ray and radiogenic doses with laboratory destruction kinetics and assumed ratios of interconversion to destruction rates. For an initially homochiral population of 1000~ppmw, the surviving EE is 58% or 25% when the total abundance reaches 1~ppmw for rate ratios of 0.04 or 0.10, respectively. This abundance criterion does not ensure that both enantiomers can be quantified. Applying provisional estimates of 1~ppmw per enantiomer and 10% EE, serine at 2~m requires initial concentrations of 340 and 960~ppmw after
cosmic-ray exposures of $10^{7}$ and $10^{8}$~yr, respectively, under transferred fused-silica–perchlorate kinetics and a 1.57-MGy radiogenic dose. These concentrations exceed measured meteoritic serine abundances, but do not predict the initial Oxia inventory. For organics retained in a closed host since deposition 3.9~Ga ago, the modeled radiogenic dose is 1.6–5.6~MGy across the adopted compositions. In the lower-dose case, drilling to 2~m reduces the total dose by only a factor of 1.5 after $10^{7}$~yr. The boundaries depend on mineral kinetics and organic residence time; they distinguish preserved chirality from a measurable excess.
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Mathematical Physics
Dynamical BEC formation and vanishing entropy for trapped bosons in non-relativistic QED via nonlinear resonance cascades
Thomas Chen and Ali Mezher
The dynamical formation of a complete Bose-Einstein condensate and the asymptotic purification of trapped
bosons coupled to a quantized radiation field are rigorously established. By tracking the macroscopic one-particle density
matrix $\kappa_T$ through a nonlinear resonance cascade, it is demonstrated that radiative relaxation irreversibly depletes all excited trap modes, even when the initial macroscopic state $\kappa_0$ is genuinely mixed. Here $\kappa_T$ is an average, with respect to a de Finetti measure $\mu_0$, over mean-field particle-field orbits, so that the mixedness of $\kappa_0$ reflects a statistical ensemble of orbits. Under the assumptions of a non-vanishing initial ground state component and strictly positive downward Fermi-Golden-Rule rates, strong trace-norm convergence to a pure condensate is proven, $$ \lim_{T\to\infty} \| \kappa_T-|\chi_0\rangle\langle\chi_0| \|_{\mathfrak{S}_1(\mathfrak{h})} = 0 \, . $$ Furthermore, the von Neumann
entropy of the macroscopic one-particle density
matrix is shown to vanish asymptotically, $$ \lim_{T\to\infty}S[\kappa_T]=0 \, , $$ without any claim of monotonicity in $T$. Thus, any initially mixed, positive-
entropy state ($0<S[\kappa_0]<\infty$) is purified to the ground state $|\chi_0\rangle\langle\chi_0|$. For the proof, we derive the Hartree hierarchy of the coupled system of
bosons and
photons from the finite-$N$ BBGKY hierarchy of the microscopic
quantum many-body system, establishing trace-norm convergence in the mean-field limit as $N\to\infty$. The limits are taken successively; first $N\to\infty$, then the weak-coupling limit, and finally $T\to\infty$. Although the global particle-field
evolution remains
unitary, the macroscopic one-particle state converges to a pure state as energy and correlations are continuously radiated into the dispersive field.
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Solar and Stellar Astrophysics
A breath of fresh air: Oxygen enhancement from silicate sublimation during early protostellar evolution
F.J. Ballieux, M.K. McClure, Ł. Tychoniec et al. (+5 more)
Recently, an analog to the t = 0 moment of our Solar System's meteoritic record was identified for the first time around the Class I protostar HOPS-315. Crystalline silicates were found to recondense from SiO gas that cools as it advects upward from a hot thermostat region in the inner midplane. This t=0 moment may be associated with the formation of the first planetesimals in this disk. We explore whether HOPS-68, a Class I protostar with similar properties and system geometries, is engaged in such refractory recondensation as well. A detection of cooler gas-phase SiO in absorption above a hot disk midplane would allow us to achieve this goal, thanks to a previous detection of crystalline silicates. HOPS-68 was observed with the JWST MIRI and NIRSpec, showing multiple bands of molecular absorption. We use local thermal
equilibrium slab models to measure the temperature, column density, velocity, and radial location of these bands. The molecular absorption bands of gaseous SiO, H2O, CO2, and 13CO trace a warm molecular inversion layer (300-500 K) at mid-altitudes above the hot disk midplane from 0.3-16 AU, which is consistently blue-shifted with respect to the system velocity by 33-53 km/s. Atacama Large Millimeter/submillimeter Array (ALMA) observations of HOPS-68 kinematically resolve an SiO-rich jet and wind. We confirm that HOPS-68, like HOPS-315, is undergoing an epoch analogous to the t=0 moment in the Solar System's
planet formation timeline. The detected warm molecular layer traces the base of a disk wind, which carries sublimated material from the thermostat region near 2 AU up into the outer disk. As for HOPS-315, the molecular layer in the inner few AU of HOPS-68 is enhanced in bulk oxygen as a result of this sublimation. Since HOPS-68 is less evolved than HOPS-315, this may indicate a prolonged epoch in protostellar
evolution in which such oxygen enhancement occurs.
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All authors F.J. Ballieux, M.K. McClure, Ł. Tychoniec, L. Francis, A. Egliene, E.A. Bergin, M.R. Van 't Hoff, E.F. Van Dishoeck
Strongly Correlated Electrons
Conformal soft modes at elastic instabilities
Lars Franke, Nick Sander and Markus Garst
In case a
crystal is close to a continuous elastic phase transition, pronounced critical fluctuations emerge. We show that on the level of linear elasticity theory the displacement vector for these critical modes obeys a condition reminiscent of the conformal Killing equation. For an isostructural instability, four critical modes arise corresponding to one dilation and three special conformal transformations. At
crystal symmetry-breaking instabilities, the critical fluctuations include a continuum of modes even for
crystals with finite size. For certain cases, these comprise the conformal transformations associated with two-dimensional Minkowski space. These results have implications for critical elastic phenomena as well as for extremal mechanical metamaterials.
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Earth and Planetary Astrophysics
Rattling Resonant Chains with Dynamical Tides and Parametric Resonance Passage
Mohammad Farhat and Eugene Chiang
Close-in sub-Neptunes are born in mean-motion resonant chains that break apart on a timescale of $\sim$100 Myr. If the chains are first ”rattled” — have their free eccentricities excited to a few percent — then breaking occurs on the required timescale. We propose that chains are rattled by internal oscillations tidally driven by the
star in the innermost
planet. Unlike other proposals, there is no need to invoke any reservoir of planetesimals or external perturbers — the chain unravels from within. We develop a
Hamiltonian theory (and an accompanying toy model) which predicts a parametric instability whereby chain librations exponentially amplify when the tidal forcing frequency equals the sum of the internal mode frequency and the chain libration frequency. We also introduce a new eigenmode solver for rotating
planets, $\texttt{MAQAM}$, that in combination with the evolutionary code $\texttt{ORCHARD}$ enables us to track the frequency
evolution of pressure,
gravity, and inertial modes in cooling sub-Neptunes. Inertial modes in the gas envelope and fluid mantle can evolve to become momentarily parametrically resonant. Passage through a single parametric resonance can raise the free eccentricities in the chain to a few percent within a few tens of Myrs.
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Optics
A Photonic Integrated Light Generation, Control, and Delivery Engine for Creating Cold Atoms
Andrei Isichenko, Calisto Ruiz, Chuan Zhong et al. (+7 more)
The creation of cold atoms underpins
quantum sensing and precision metrology, computing, timekeeping, and fundamental science experiments. Miniaturizing the
lasers and optical infrastructure, which occupy over 80% of the volume of these experiments, through photonic integration could improve robustness, reliability, and manufacturability while reducing cost and enabling portable space-based precision measurements and
quantum tools for non-experts. Yet, there has been limited progress towards integration of the
laser and optical infrastructure required to generate cold atoms onto a single chip. We demonstrate a photonic engine that generates, controls, and delivers precision light to create cold atoms in a rubidium 3-dimensional magneto-optical trap (3D-MOT). We integrate on a single chip two frequency-agile self-injection-locked
lasers,
laser frequency and intensity control, passive beam combining and splitting, signal monitoring, and high-efficiency beam delivery to a rubidium vapor
cell. The integrated engine is shown to support multiple functions required for generating cold atoms including stable generation of low-noise cooling and repump light, frequency control for atom spectroscopy and stabilization, real-time
laser monitoring, routing for
laser offset locking, optical power modulation, and large-area three-beam delivery of 3 mW to the physics package. Fully electrically controlled, the engine enables sustained 3D-MOT operation, trapping more than 1 million atoms at an average temperature of 350 uK and supporting atom-number and temperature measurements. These results demonstrate the first single-chip integration of light generation, control, and delivery for cold-atom generation, offering a path toward smaller, more robust, and manufacturable cold-atom systems for applications including cold-atom clocks and sensors.
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All authors Andrei Isichenko, Calisto Ruiz, Chuan Zhong, Nick Montifiore, Sam J. Harding, Meiting Song, Chenghang Liu, Nitin Indukuri, Karl D. Nelson, Daniel J. Blumenthal
Atmospheric and Oceanic Physics
Cumulus parameterization controls simulated rainfall more than microphysics, but not at heavy thresholds: a 3 * 2 factorial WRF study over the Western Himalaya
Satyam Kumar, Akshay Sunil and Devesh Sheoran
Rainfall forecasts over the Western Himalaya remain poor, and the relative contributions of the cumulus and microphysics parameterizations to that error are not well constrained.
Mathematical Physics · Cross-listed from math.SG
Metaplectic-c prequantizations and the Einstein–Brillouin–Keller quantizability condition
Hyunmoon Kim
We show that every symplectic
manifold admits a symplectic form whose metaplectic-c prequantizations give quantizability conditions on all its Lagrangian submanifolds. Metaplectic-c prequantizations descend to prequantizations over the Lagrangian Grassmannian bundle that are fibrewise flat with holonomies primitive fourth roots of unity on the generators of the fundamental groups. This fibrewise holonomy is consistently interpreted as that of both Leray two-orientations and normalized Blattner–Kostant–Sternberg half-forms. The prequantizations pull back to flat circle bundles on each Lagrangian submanifold whose holonomy character defines a quantizability condition. The first and second Stiefel–Whitney classes are identified as splitting obstructions to the Lagrangianwise holonomies. These holonomies split into a product of holonomies on any orientable Lagrangian submanifold, and split consistently for all Lagrangian submanifolds of a
manifold with metaplectic structure. When the first Chern class vanishes, the holonomy splits into the Bohr–Sommerfeld factor and a quarter phase Maslov correction, recovering the classical Einstein–Brillouin–Keller condition. We develop the underlying obstruction theory for circle extensions associated to general Lie group double coverings with first hypercohomology groupoids.
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Earth and Planetary Astrophysics
Size, atmospheric, and ring constraints on the large Kuiper belt object (55565) Aya from a stellar occultation
Ko Arimatsu, Hidekazu Hanayama, Satoshi Takita et al. (+3 more)
We aim to constrain the projected size,
geometric albedo, possible atmosphere, and possible ring material of the mid-sized trans-Neptunian object (55565) Aya from the stellar occultation of 2024 May 10 (UT). We observed the event from three Japanese sites with high-cadence optical imaging. We combined one positive occultation chord with an informative prior on the shadow centre derived from orbital and astrometric uncertainties, and inferred the body radius with
Bayesian Markov chain Monte Carlo modelling. We constrained a possible atmosphere by fitting refraction models for pure CH$_4$, N$_2$, and CO atmospheres to multi-band light curves, and searched for ring-like extinction signatures in unbinned and binned high-time-resolution photometry. We derive an equivalent radius, i.e., the radius of the circle fitted to the projected shadow, of $r=401^{+28}_{-40}$ km for Aya, corresponding to a
geometric albedo of $p_V=0.101^{+0.023}_{-0.013}$. This estimate is insensitive to the adopted ephemeris solution and is consistent with an ephemeris-independent analysis that makes no assumption about the position of the shadow centre. We obtain 3$\sigma$ upper limits on the atmospheric surface pressure of $p_0=60$, 90, and 80 nbar for pure CH$_4$, N$_2$, and CO compositions, respectively. No significant ring-like extinction is detected over projected distances of about 430-8060 km sampled by the three stations, and our most sensitive data exclude dense narrow features with apparent opacity $p'\gtrsim0.1$ and radial widths of a few kilometres or larger over $\sim3r$-$14r$. This is the first stellar occultation by Aya ever observed. In addition to constraining Aya's size and albedo and finding no ring-like extinction, we place a stringent atmospheric upper limit that supports diversity in atmospheric states among similarly sized trans-Neptunian objects.
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All authors Ko Arimatsu, Hidekazu Hanayama, Satoshi Takita, Fumi Yoshida, Tsutomu Hayamizu, Jun-ichi Watanabe
Statistical Mechanics · Cross-listed from cs.LG
Deep Mesoscopic Dynamics
Yue Zhao, Shiqi Wu, Yihang Ouyang et al. (+6 more)
Microscopic simulations resolve spatial patterns but are feasible only over small domains and short timescales, whereas bulk descriptions erase those patterns through spatial averaging. Mesoscopic fields preserve this spatial organisation, but their effective equations are known only for selected microscopic systems and scaling limits. We introduce Deep Mesoscopic Dynamics (DeepMesoD), which uses neural networks to learn an effective mesoscopic field equation from microscopic trajectories at a prescribed coarse-graining scale. For the nonconserved dissipative dynamics studied here, DeepMesoD learns the free-energy functional with a spatial interaction kernel and a state-dependent dissipation operator constrained by the fluctuation-dissipation relation. We first validate the construction in the Ising-Kac model, where the learned mesoscopic equation recovers the known hydrodynamic limit and rollouts remain stable far beyond the training horizon. We then treat two systems without closed-form mesoscopic descriptions. For a two-dimensional Heisenberg ferromagnet governed by atomistic
spin dynamics, DeepMesoD learns a mesoscopic model whose predictions match atomistic references up to 1 ns, and a rollout with an unseen initial condition remains bounded up to 25 ns. For layered CrBr$_3$, the learned kernel captures the suppression and sign reversal of interlayer coupling at a stacking fault whose location and strength are not supplied as inputs. Controlled changes to the learned interaction show how fault number and placement shape multistep
magnetic responses, complementing our magneto-photoluminescence measurements. Across the two atomistic systems, DeepMesoD achieves a three-to-four-order-of-magnitude reduction in wall-clock time compared with atomistic
spin dynamics.
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All authors Yue Zhao, Shiqi Wu, Yihang Ouyang, Sergey Grebenchuk, Magdalena Grzeszczyk, Xiaoxu Zhao, Kostya S. Novoselov, Maciej Koperski, Qianxiao Li
Mathematical Physics
Dynamics of low energy wave packets in the one-dimensional quantum Heisenberg ferromagnet
Mateusz Kwaśnicki, Marcin Napiórkowski, Sören Petrat et al. (+1 more)
Spin wave theory plays a central role in the analysis of low-energy properties of the
quantum ferromagnetic Heisenberg model. In this work, we present a first step towards a rigorous justification of this approximation in the context of
quantum dynamics in one dimension. According to
spin wave theory, the
evolution of a
spin wave state should be well approximated by its free
evolution with the appropriate energy of free quasiparticles called
magnons. Our main result establishes this idea rigorously for a class of
spin wave packets. We focus on
spin-$\frac{1}{2}$ systems, and consider wave packets composed of two
magnons. We argue our result is optimal with respect to the timescales.
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All authors Mateusz Kwaśnicki, Marcin Napiórkowski, Sören Petrat, Michał Pietruszka
Superconductivity
Imaging atomic-scale surface structure and superconducting gap of the misfit layered compound (SnS)1.17NbS2
Dongming Zhao, Shamarita Deb, Lichen Ji et al. (+8 more)
Superlattices of van der Waals-coupled two-dimensional materials offer a platform for engineering electronic band structure and fostering emergent
quantum states. Misfit layered compounds provide naturally assembled superlattices, in which crystallographically distinct two-dimensional subsystems coexist within a single bulk
crystal. Therein, the presence of both commensurate and incommensurate
lattice directions introduces structural modulation, which might alter real-space electronic orders such as superconductivity. Here, we investigate the atomic-scale surface structure and local superconductivity of the misfit layered compound (SnS)1.17NbS2 using structural characterization, electrical transport, and low-temperature scanning tunnelling microscopy (STM). While X-ray diffraction and cross-sectional scanning transmission electron microscopy confirm the bulk misfit structure, STM resolves large SnS- and NbS2-terminated terraces, where the surface atomic registry differs from the bulk misfit structure. Furthermore, tunnelling spectroscopy at 2 K reveals nearly identical superconducting gaps on both terminations, and the spatial variation of the gap shows no visible modulation that corresponds to the misfit
lattice. These results establish an atomic-scale picture of the surface structure and superconducting states of this naturally assembled misfit
heterostructure.
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All authors Dongming Zhao, Shamarita Deb, Lichen Ji, Souvik Das, Paul Simon, Raúl Cardoso-Gil, Steffen Wirth, Walter Schnelle, Sushmita Chandra, Jian-Feng Ge, Claudia Felser
Optics
On-chip optical isolators
Abanoub Mikhail, Nikolay Solodovchenko, Sen Xu et al. (+5 more)
Optical isolation suppresses back-reflections that destabilize
lasers, produce parasitic interference, and increase crosstalk in photonic systems. Although free-space and fibre-optic isolators are mature, no broadly adopted on-chip technology yet combines strong isolation, low insertion loss, broad bandwidth, compact footprint, and scalable fabrication. The difficulty is twofold: Lorentz reciprocity must be broken, and every relevant backward spatial, spectral, and polarization channel must be suppressed. This Review develops a common framework for assessing proposed solutions. We first distinguish pairwise nonreciprocity from intensity-asymmetric transmission and from true isolation using the constitutive relations and scattering
matrix. We then compare three physical routes to an integrated nonreciprocal response: magneto-optical bias, externally driven space-time modulation, and nonlinear optical processes. Topological and non-Hermitian systems are treated as cross-cutting design frameworks that can route, protect, or enhance an underlying nonreciprocal response, but do not by themselves break reciprocity. Finally, we examine fundamental constraints and practical trade-offs among isolation, insertion loss, bandwidth, footprint, modal coverage, drive requirements, and fabrication compatibility. The resulting mechanism-based perspective connects reciprocity-breaking physics to the requirements of scalable photonic integrated
circuits.
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All authors Abanoub Mikhail, Nikolay Solodovchenko, Sen Xu, Fan Zhang, Maksim Tumashov, Mingzhao Song, Sergei Makarov, Andrey Bogdanov
Cosmology and Nongalactic Astrophysics
Mapping Dark Matter in Merging Clusters with Weak Lensing for CSST: Morphology and Filament Recovery
Xinyue Chen, Ran Li, Qiao Wang et al. (+6 more)
Weak gravitational
lensing offers a direct probe of the projected dark matter distribution in cluster-scale structures and the surrounding
cosmic web. We investigate the capability of the China Space Station
Telescope (CSST) to recover non-spherical dark matter morphologies using mock reduced-shear maps generated from cosmological N-body simulations. We apply the deep-learning-based MIU2Net mass-reconstruction framework to CSST-like wide- and deep-field source densities, focusing on two representative systems: filament-connected
halo pairs and elongated
halos. MIU2Net accurately recovers
halo centers, elongated mass distributions, and the filamentary structures connecting
halo pairs in both survey configurations.
Halo centers are localized within about 0.1 h^(-1) Mpc, and elongated-
halo shapes and orientations are reliably recovered. Filament paths are stable against shape noise, with mean normalized instability parameters I_F, defined as the mean deviation from the true filament locus in units of R_200, decreasing from 0.041 to 0.037 in the low-
redshift bin and from 0.051 to 0.045 in the high-
redshift bin from the wide to deep field. The recovered filament shapes remain consistent with the true maps at the percent level. Compared with conventional Kaiser-Squires reconstruction, MIU2Net better preserves low-contrast anisotropic structures while suppressing small-scale noise. These results demonstrate that CSST weak-
lensing data, combined with machine-learning-based mass reconstruction, will enable statistical studies of cluster assembly, anisotropic matter
accretion, and the connection between massive
halos and the filamentary
cosmic web.
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All authors Xinyue Chen, Ran Li, Qiao Wang, Hengjie Lin, Liang Gao, Xiangkun Liu, Huanyuan Shan, Ji Yao, Ming Li
Quantum Physics
Emergent Non-Biorthogonal Born Rule at Dynamical Quantum Phase Transitions
Wei-Wei Yang, Henning Schomerus, Jiangping Hu et al. (+1 more)
Non-Hermitian dynamics possesses distinct left and right eigenstates, but their normalization freedom obscures a direct probabilistic interpretation. Starting from a globally Hermitian system governed by the standard Born rule, we generalize dynamical
quantum phase transitions (DQPTs) from a reference state to a physical subspace. This generalization provides a clear probabilistic interpretation of left and right states: when each state is normalized to itself, their mutual overlap determines a directly accessible dynamical transition rate. We discuss the new phenomena governed by this emergent non-biorthogonal Born rule and further identify a class of exceptional-point DQPTs (EP-DQPTs), at which the eigenstates of the critical propagator coalesce. Our theory places the probabilistic interpretation of non-Hermitian
quantum mechanics on the firm footing of Hermitian
quantum mechanics.
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All authors Wei-Wei Yang, Henning Schomerus, Jiangping Hu, Zhesen Yang
Materials Science
ARES: a plane-wave density-functional-theory code in Rust
Zehan Liu, Qian Wang, Xiangyu Zheng et al. (+7 more)
ARES (Ab initio atomic mateRial modEling Software at JLU) is a plane-wave density-functional-theory (DFT) code written entirely in Rust as a layered 22-crate workspace. It supports norm-conserving pseudopotentials and the projector augmented-wave (PAW) method with the local-density approximation (LDA) and Perdew-Burke-Ernzerhof (PBE) functionals, {\Gamma}-only and explicit k-point sampling, smearing and mixing, forces, stress, relaxation, band structures, densities of states (DOS) and dispersion corrections; execution is serial or MPI-distributed over k-point pools, band groups and plane-wave rows. The code's distinguishing engineering choice is its validation apparatus. Every numerical component is checked against
Quantum ESPRESSO driven from the same physical and numerical inputs, and the comparison is organized as numbered fixtures kept in the repository whose reference data is regenerated by a script instead of being captured once. On six materials spanning a
semiconductor, three metals and two two-dimensional systems, band energies within one electronvolt of the Fermi level agree with the reference to a median below 0.4 meV. The pseudopotentials the code reads are validated against all-electron reference data as well: the median delta factor is 0.696 meV/atom over all 65 paired elements. Restrictions are stated with the capabilities: two functionals, no
spin-polarized or
spin-orbit path, a stress implementation with an explicit scope, and no accelerator execution.
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All authors Zehan Liu, Qian Wang, Xiangyu Zheng, Jiaxiang Li, Chuntian Wu, Yongshuo Chen, Xuecheng Shao, Qiang Xu, Yu Xie, Yanming Ma
Nuclear Theory
Contribution of incomplete fusion to the evaporation residue cross sections in the $^{30}$Si$+^{186}$W reaction
Bakhodir Kayumov and Avazbek Nasirov
The formation of the evaporation residues in the $^{30}$Si$+^{186}$W reaction leading to the compound
nucleus $^{216}$Ra$^*$ has been studied in the framework of the dinuclear system (DNS) model. The capture, complete fusion, quasifission, and incomplete fusion cross sections have been calculated at the collision energies $E_{c.m.}=107.6-172.2$MeV by averaging over the orientation angles of the axial
symmetry axes of the deformed $^{30}$Si and $^{186}$W
nuclei. The incomplete fusion is considered as the breakup of the DNS with the emission of the $\alpha$ particle from its very mass-asymmetric configuration, which is populated by the nucleon transfer in collisions with large orbital angular momentum. The survival probabilities of the excited $^{216}$Ra and of the conjugate
nucleus $^{212}$Rn formed after the $\alpha$-particle emission have been calculated using the statistical model. It is shown that the complete fusion is the main source of the evaporation residues at the lower collision energies, while above $E_{c.m.}=128$MeV the Rn isotopes formed in the incomplete fusion give more than half of the calculated evaporation residue cross section. The sum of both contributions describes the slow decrease of the measured total evaporation residue cross section at these energies, where the yield of the Ra isotopes decreases by an order of magnitude. The calculation of the de-excitation of $^{216}$Ra$^*$ with the emission of
protons and $\alpha$ particles shows that the contribution of the complete fusion to the cross sections of the isotopes $^{212}$Rn and $^{211}$Rn is negligible, and these isotopes are formed in the incomplete fusion. The fusion probability calculated for the partial waves $\ell\leq30\hbar$ is about 0.75 in comparison with the value $0.57\pm0.08$ extracted from the experimental data at the same collision energies.
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Materials Science
Colossal Spin–Lattice–Charge Coupling in Noncollinear Ferrimagnetic NbMnX$_2$ ($X$ = S, Se, Te) Monolayers
Peng Wang, Nanshu Liu, Hongkuan Yuan et al. (+2 more)
Noncollinear ferrimagnets combine a net
magnetic moment with internal
spin degrees of freedom, creating opportunities to couple
magnetic, mechanical, thermal, and electronic responses. Using first-principles calculations,
symmetry analysis, atomistic
spin simulations, and transport modeling, we identify stable NbMnX$_2$ ($X$ = S, Se, Te) monolayers with noncollinear ferrimagnetic ground states and Curie temperatures up to 313 K. Competing exchange, Dzyaloshinskii–Moriya interactions, and
magnetic anisotropy produce field-responsive canted states that couple strongly to the
lattice and charge carriers. Magnetization rotation changes the elastic modulus of NbMnTe$_2$ by up to 36%, while
lattice entropy substantially enhances the near-room-temperature magnetocaloric response of NbMnS$_2$ and NbMnSe$_2$. In NbMnSe$_2$, rotation restores a mirror-protected crossing, continuously closes an approximately 0.13 eV gap, and produces a conductivity-based anisotropic magnetoresistance ratio up to 10,000% at 100 K. The combined results establish noncollinear NbMnX$_2$ monolayers as a multifunctional platform for two-dimensional spintronics, nanomechanics, and thermal control.
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All authors Peng Wang, Nanshu Liu, Hongkuan Yuan, Xue Jiang, Jijun Zhao
Optics
Theory of deeply subwavelength electromagnetic structuring of semiconductors due to thermal-ionization instability
I. V. Oladyshkin, D. I. Kulshin and E. O. Smolina
We develop a theory of ionization-assisted instability that governs the reflection of intense electromagnetic pulses from a
semiconductor surface. Local overheating of the material increases the free-carrier density and conductivity, which in turn enhances the absorption of the incident radiation and further amplifies local heating and avalanche ionization. At high pump repetition rates, the overheating accumulates from pulse to pulse, leading to a gradual rise of the local material temperature and free carrier density - a positive feedback loop that drives thermal runaway. However, this effect competes with diffraction of the pump field on the emerging perturbation of the dielectric permittivity or on the surface relief, which reduces the local electric field amplitude in the overheated regions, thus providing negative feedback. We show that the competition between heat
diffusion and diffraction near-field weakening creates conditions for the exponential growth of temperature perturbations with a certain wavenumber determined by the pulse repetition rate, pump field, thermal conductivity and other material parameters. The derived analytical expressions accurately describe the spatial period of deeply subwavelength structures observed in recent experiments on silicon structuring by intense terahertz radiation, and reproduce qualitatively dependencies of their period on the pump intensity, the incident wavelength and the number of pump pulses.
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Quantum Physics
A Tutorial on Quantum Amplitude Embedding with Data Re-Uploading
Hyojun Ahn and Joongheon Kim
Amplitude
embedding lets a variational
quantum model read many classical features with few
qubits, but the model output is then only a quadratic form in the normalized input. Data re-uploading, which encodes the input repeatedly between trainable blocks, can be used to enrich such a model. Because every additional upload of an amplitude
embedding repeats a costly state preparation, the gain that an upload buys has to be known before the gates are spent. This tutorial thus addresses the problem of explaining what data re-uploading adds to an amplitude-embedded model and how large the gain is. We express sequential re-uploading and parallel re-uploading with two copies in one notation and show that each upload raises the reachable
polynomial order by two. Under one trainable
circuit family and one budget of trainable parameters, simulation results show that re-uploading raises the test coefficient of determination from 0.689 to between 0.883 and 0.975 on targets of order four and from 0.337 to between 0.642 and 0.783 on targets of order six, on all ten seeds. On a quadratic target and on handwritten digits, one upload remains the best choice, and every additional upload lowers the gate error that the classifier tolerates. These results help designers match the number of uploads to the
polynomial order of the task at hand.
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Quantum Physics
Broadening the reflection band of atomic mirrors by engineering the emitter-waveguide coupling
C.-Y. Lee, G.-D. Lin, H. H. Jen et al. (+1 more)
We theoretically investigate single-
photon coherent transport through a finite waveguide
quantum electrodynamics (QED) array with spatially modulated emitter-waveguide couplings. By combining exact scattering calculations with spectral factorization and a semiclassical WKB analysis, we identify how the coupling profile controls the reflection bandwidth and its finite-size dependence. A Gaussian transverse displacement produces an exponential-of-Gaussian decay-rate profile that broadens the high-reflectivity window and suppresses the boundary-induced Fabry-Perot oscillations compared with a uniform array. The transmission zeros remain exactly degenerate at the atomic resonance for arbitrary positive coupling profiles at non-Bragg spacings. In contrast, the collective poles reorganize under the spatial modulation, redistributing their radiative widths and preventing individual subradiant resonances from terminating the reflection window. We further derive an algebraic 1/N scaling law for the contraction of the bandwidth toward its bulk value. The bulk bandwidth is determined by the largest local decay rate, whereas the finite-size correction increases as the profile becomes sharper, leading to an optimal profile width. These results establish spatial coupling engineering as a practical tool for designing broadband atomic mirrors in atom-nanofiber and
circuit-QED platforms.
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All authors C.-Y. Lee, G.-D. Lin, H. H. Jen, K.-T. Lin
Mathematical Physics
How many switches does two-Hamiltonian universality require?
Matas Garbaravičius and Michael M. Wolf
Any pair of sufficiently generic
Hamiltonians on $\mathbb{C}^d$ generates the full
unitary group, i.e., any $W\in U(d)$ can be synthesized to arbitrary precision by alternating between the two evolutions for suitably chosen durations. For any given pair of
Hamiltonians, the minimal number of switches required to cover the entire group is at least $d$ and unbounded in general. Despite this, we show that it scales linearly in $d$ in expectation. Assuming that the two spectra are sufficiently generic, we derive constructive upper bounds on the minimal switching number as a function of the change-of-basis
matrix between the two eigenbases. In particular, if this
matrix has a column whose entries all have equal moduli, as for a complex Hadamard
matrix, then $9d$ switches suffice to reach every
unitary. To obtain these results, we construct a short exact representation of any
unitary as a product of
unitaries that are alternately diagonal in two given bases. All bounds are extended to non-generic spectra and bounded
evolution times.
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Optics
Practical Mid-infrared Dual-comb Spectroscopy with Absolute Frequency Referencing Based on a Single-cavity Dual-comb Fiber Laser
Akifumi Asahara and Kaoru Minoshima
We demonstrate a practical mid-infrared (MIR) dual-comb spectroscopy (DCS) method based on a bidirectional dual-comb fiber
laser. By exploiting the inherently high relative stability and mutual coherence of the dual-comb
laser, we stabilize the MIR dual-comb modes with sufficient precision using only piezoelectric control of the repetition frequencies. This simple configuration enables correction of residual timing jitter and phase noise in interferograms while preserving the absolute optical frequency scale defined by the experimentally obtained comb parameters, without requiring an external continuous-wave
laser reference or tight phase-locking. Importantly, the proposed method does not merely produce apparently clean interferograms through signal processing, but enables coherent averaging while retaining both the physically meaningful interferometric waveforms and well-defined absolute frequency information. The proposed system is experimentally validated through MIR spectroscopy of N$_2$O around 3.9 $\mu$m, achieving a signal-to-noise ratio of approximately 690 through coherent averaging of 10,000 interferograms over 65 s, along with the acquisition of an absorption spectrum consistent with the reference data. These results demonstrate a simple and practical approach to absolute-frequency-referenced MIR-DCS.
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