Optics
Resonant subspace approximation for photonic crystal slabs
Nikolay A. Gippius, Ilia M. Fradkin, Natalia S. Salakhova et al. (+1 more)
Resonant approximations are indispensable for the interpretation and efficient modeling of photonic
crystal slabs, yet most of them describe an eigenmode as a pole in the complex energy plane at a fixed set of the remaining parameters. Tracking such poles and their hybridization across the Brillouin zone or upon variation of structural parameters is labor-intensive and severely limits the use of resonant approximations in band-structure calculations and structural optimization. Here we introduce a resonant subspace approximation that treats the
photon energy and all other parameters on an equal footing. Considering a wide class of photonic
crystal slabs that can be split into two non-resonant parts, we show that their resonances arise solely from the round-trip propagation of coupled
Fourier harmonics between these parts, in direct analogy with Fabry–Pérot and waveguide modes. We generalize the scalar round-trip phase to round-trip and phase
matrices, whose smooth dependence on all parameters allows us to project the problem onto a small resonant subspace defined at a single anchor point and to extrapolate it throughout a local region of parameter space of arbitrary dimensionality. As a result, rigorous computations at only a few points suffice to reconstruct the band structure, modal linewidths, complex hybridization, and optical spectra as functions of energy, wavevector,
geometric dimensions, or permittivity within seconds. We demonstrate the accuracy and versatility of the approach on a strong hexagonal silicon grating, resolving intricate mode hybridization,
symmetry-protected features, and subtle geometry-controlled effects that are hardly accessible to straightforward computations. The method is fast, accurate, and readily extensible, offering a practical route to the exploration, design, and optimization of resonant photonic
crystal slabs.
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All authors Nikolay A. Gippius, Ilia M. Fradkin, Natalia S. Salakhova, Sergey A. Dyakov
Quantum Physics
Dynamic Observable Subspaces: Fast Simulation of Observable Quantum Dynamics
Hannes Leipold
By decomposing
quantum dynamics across the Lie orbits of a list of observables, we find
polynomial bounded classical simulations for the dynamics of the
quantum system given a
polynomial sized dynamic Lie
algebra (DLA) for the generators of the
quantum system. To do so, we describe how to construct the Dynamic Observable Subspace (DOS) that captures all the relevant dynamics for calculating expectation values for a specific observable for Pauli strings, diffusor mixers, and general local generators. Efficient sparse
matrix representation, decoupling nonlinearity from such representation and basis construction with permissible
pruning allows us to simulate the closed dynamics of such systems with hundreds of
qubits. Moreover, we find that while restricted DOS
circuits may not express the space of an associated
Hamiltonian, they can dramatically outperform a fully expressive
circuit due to the absence of the Barren Plateau. While classically simulatable, such
circuits can still exhibit a form of
quantum advantage through inference, act as warm starting for more expressive
circuits, and find high quality trial states for
Quantum Amplitude Amplification or
Quantum Phase Estimation. In the simulation of
quantum dynamics, we find that our restricted
circuit can be simulated in
polynomial time while producing high quality guiding state for downstream tasks like
Quantum Phase Estimation with significantly lower energy than
circuits with full expressivity.
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Quantum Physics
Electrically tunable, two-photon interference from remote silicon-vacancy centers in industrial silicon carbide
Fedor Dzmitryevich Hrunski, Daniel Scheller, Maximilian Hollendonner et al. (+8 more)
Distributed
quantum networks rely on spatially separated, independently operated
quantum systems as network nodes, whose emitted
photons must be interfered with high visibility to establish end-to-end
entanglement. Crucially, for network-relevant applications, high visibilities must be achieved over prolonged timescales to reduce overheads for error correction, and to increase network rates. Here, we demonstrate experimentally that silicon vacancy $\mathrm{V_{Si}}$ color centers in silicon carbide (SiC) achieve these requirements, notably in a mass-deployable fashion. We integrate $\mathrm{V_{Si}}$ centers in different industrial-grade SiC p-i-n diodes, which are controlled via voltage biassing. This way, we demonstrate both, spectral overlapping of 19 randomly selected $\mathrm{V_{Si}}$ centers in different diodes, as well as spectral narrowing close to the lifetime limit, i.e., typically below 60 MHz. Notably, these performance parameters are long-term stable, e.g., readjusting the p-i-n diode bias is required only every 8.4 hours, which reduces significantly the overall experimental overhead. We then use these assets to demonstrate high-quality two-
photon interference between $\mathrm{V_{Si}}$ centers located in two different cryostat setups, which are spatially separated by two meters. Notably, we perform a 26-days long measurement campaign, demonstrating two-
photon interference with state-of-the-art raw interference visibilities of 82%, which aligns with the current state-of-the-art. These results establish $\mathrm{V_{Si}}$ centers in industry-grade SiC devices as a scalable, spectrally stable building block for distributed
quantum networks.
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All authors Fedor Dzmitryevich Hrunski, Daniel Scheller, Maximilian Hollendonner, Kim Ullerich, Shravan Kumar Parthasarathy, Chiun Fu, Andre Pointner, Wolfgang Knolle, Florian Kaiser, Durga Bhaktavatsala Rao Dasari, Roland Nagy
Quantum Physics
Small-Bias Quantum Approximate Counting via the Multiplicative Adversary Method
Albert Lin and Han-Hsuan Lin
We study the two-weight decision version of
quantum approximate counting: given oracle access to $x\in\{0,1\}^N$, distinguish $|x|=M$ from $|x|=M+\Delta$ with success probability $1/2+\zeta$. Using the multiplicative adversary method, we prove $\Omega\left(\max\left\{\zeta\sqrt{(N-M)(M+\Delta)}/\Delta,\sqrt{\zeta N/\Delta}\right\}\right)$. The same parameter dependence follows from the
polynomial-method characterization of the two-layer symmetric function by Podder, Yao, and Ye. Our contribution is a multiplicative-adversary derivation that tracks the progress produced by individual oracle queries. For the first term, after complementing the input if necessary, we assume $M+\Delta\le N-M$. We use the Hamming-layer subspaces from the eigenspace method of Ambainis, Spalek, and de Wolf and compose their adjacent-layer
unitary maps to relate the two nonadjacent promise layers. After fixing the queried coordinate, the analysis block-diagonalizes into four-dimensional subspaces. An exact calculation of the one-query progress ratio gives the first lower bound. The same estimate also implies $\left\|(I-\widehat{\Pi}_{\mathrm{bad}})\lvert\Psi^T\rangle\right\|^2=O\left(T^2\Delta^2/((N-M)(M+\Delta))\right)$ for the coherent input superposition used in the adversary argument. For the second term, we prove directly using a three-
eigenvalue multiplicative adversary that unique OR on $n$ bits with success probability $1/2+\zeta$ requires $\Omega(\sqrt{\zeta n})$ queries, and then reduce unique OR to the two-weight counting problem.
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Earth and Planetary Astrophysics
Hybrid Spin-Orbit Tomography for Earth-like Planets: Simultaneous Mapping of Static Surfaces and Dynamic Clouds from Multicolor Light Curves
Atsuki Kuwata and Hajime Kawahara
Photometric variability of directly imaged
exoplanets encodes information on both persistent surface features and time-variable phenomena such as clouds. We present Hybrid
Spin-Orbit
Tomography, a method that simultaneously retrieves multiple static components and a single dynamic component, together with their reflection spectra, from multiband photometric variability. The method integrates spectral unmixing and dynamic
spin-orbit
tomography by introducing a time-dependent component into the forward model. We employ sparse regularization for static surface distributions, volume regularization for reflection spectra, and a Kronecker-sum kernel regularization for the dynamic component. Applying the method to a toy Earth model, we successfully recover static surface distributions together with a single time-dependent cloud component. Furthermore, we apply the method to DSCOVR/EPIC observations of Earth and retrieve a dynamic component consistent with real cloud distributions, together with components broadly interpretable as oceans, vegetation, and land surfaces. Relative to static
spin-orbit unmixing, the hybrid model substantially reduces the residual scatter of the multiband light curves, demonstrating that explicit treatment of dynamic components improves global mapping from color variability. These results provide a step toward the simultaneous
retrieval of static and dynamic planetary components, while highlighting the need for more physical cloud-surface masking models and uncertainty quantification.
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High Energy Physics (Phenomenology)
Charmed baryon semileptonic decays in a relativistic three-quark model
Ru-Hui Ni, Zhen-Yang Wang, Jia-Jun Wu et al. (+1 more)
We study the
spin-$1/2\to1/2$ semileptonic decays of singly charmed
baryons ($\Lambda_c^+$, $\Xi_c^{0,+}$, and $\Omega_c^0$) into the light
baryon octet within a relativistic three-
quark model. The constituent
quark masses and spatial wave functions are determined by the
baryon mass spectrum. For the physical $\Xi_c$ states, the light
flavor $\mathrm{SU}(3)$ breaking ($m_s > m_{u,d}$) naturally induces a coherent mixing between the
flavor antitriplet and
flavor sextet configurations, which is completely fixed by the mass eigenstates. Consequently, no adjustable parameters are introduced in calculating the weak transition amplitudes. Using these wave functions, we calculate the $c\to s,d$ helicity amplitudes with the Bakamjian–Thomas boost, including the spatial Jacobian and the Wigner rotations of the constituent
spins. The branching fractions, $q^2$ distributions, longitudinal polarizations, and form factors are then obtained from these amplitudes. For the $\Lambda_c^+\to\Lambda\ell^+\nu_\ell$ and $\Lambda_c^+\to n\ell^+\nu_\ell$ modes, our branching fractions and form factors are in good agreement with the experimental data and
Lattice QCD results. For $\Xi_c^0\to\Xi^-e^+\nu_e$, we obtain branch ratio $\mathcal B_{\ell} \simeq 4.0~\%$, which is consistent with recent
Lattice QCD calculations but lies well above the current experimental average. Clarifying the origin of this discrepancy calls for further dedicated efforts from both experimental and theoretical sides. For the $\Omega_c^0\to\Xi^-\ell^+\nu_\ell$ decay, the
spin-$1$ $ss$ spectator yields a positive longitudinal polarization of the final $\Xi^-$, in contrast to the negative polarizations in the predominantly antitriplet decay modes. Our predictions for the $q^2$ spectra, angular asymmetries, and final
baryon polarizations may provide useful references for future measurements of singly charmed
baryon semileptonic decays.
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All authors Ru-Hui Ni, Zhen-Yang Wang, Jia-Jun Wu, Bing-Song Zou
Materials Science
uFlowCSP: Crystal Structure Prediction using Mean flow generative models
Sourin Dey, Dipannoy Das Gupta, Lai Wei et al. (+2 more)
Crystal structure prediction (CSP) is fundamental to computational materials discovery. Generative models including CDVAE, DiffCSP, FlowMM, and CrystalFlow learn stable-
crystal distributions directly, but
diffusion and flow-matching inference requires tens to thousands of sequential network evaluations per candidate. We introduce uFlowCSP, a MeanFlow-based CSP model that learns the average, rather than instantaneous, probability-flow velocity. It generates a complete structure in one to five evaluations, delivering 5x-58x faster inference with equal or better performance. A chemistry- and
symmetry-aware
Transformer uses canonical atom ordering, global composition, and per-
token chemistry
embeddings. A coarse
crystal-system
token is used only during training; it provides additive gains, particularly improving space-group agreement despite being absent at inference, which remains formula-only. On MP-20 with 20 candidates per target, one step matches CrystalFlow (78.38% vs. 78.34%) with 100x fewer evaluations and about 10x lower wall-clock time. Five steps reach 83.64%, exceeding CrystalFlow (78.34% at 2,000 evaluations) and DiffCSP (77.93% at about 20,000), while using 20x fewer evaluations. uFlowCSP generates 10,000 structures in 0.39-1.31 minutes, versus 6.5 for CrystalFlow and 76.1 for DiffCSP. Under CSPBench's energy-ranked top-five structure-and-space-group criterion, five-step uFlowCSP reaches 72%/72%/65% structure, space-group, and consensus match rates. CrystalFlow reaches 78%/73%/68% at 100 steps but falls to 49%/32%/31% at five. Thus, uFlowCSP improves accuracy per network evaluation, not merely peak accuracy.
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All authors Sourin Dey, Dipannoy Das Gupta, Lai Wei, Sadman Sadeed Omee, Jianjun Hu
Mathematical Physics · Cross-listed from math.DG
On the Asymptotics of the Volume of Hitchin Moduli Spaces
Shiyu Cao
Let $X$ be a compact Riemann surface of genus $g\geq2$, and let $\M$ be the
moduli space of rank-two trace-free
Higgs bundles with fixed determinant of odd degree. For the normalization of the Hitchin metric used in this paper, we prove that the volume of geodesic ball in the Hitchin
moduli space is given by $$ \Vol_{g_{L^2}}B_{L^2}(p,R) =\frac{2^{4g-3}\pi^{9g-9}}{(3g-3)!}\,R^{6g-6}+o(R^{6g-6}) $$ for every $p\in\M$. We also determine the leading asymptotics of
Hamiltonian sublevel volumes and exponentially weighted volumes. The proof combines homogeneity of the hyperkähler volume form with metric asymptotics on the regular Hitchin locus.
Symplectic reduction and the Prym polarization evaluate the coefficient, which is independently recovered by equivariant localization.
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High Energy Physics (Phenomenology)
More QCD Masterclass Lectures on Jet Physics and Machine Learning
Andrew J. Larkoski
These lectures were presented at the 2026 QCD Masterclass in Saint-Jacut-de-la-mer, France. They supplement the published notes from the 2024 school with presentation of a few new topics that have become popular in recent years. These include event metrics, anomaly detection, scaling laws, the limits of classification performance, and regression that respects spacetime
symmetries. Many of the presented results are known, but some new results are derived, especially related to anomaly detection. As was the case in those original notes, while all these problems are motivated from machine learning applied to QCD, no discussion of details of machine learning is presented in these notes. All results follow from application of fundamental principles of QCD. I begin these notes with an apology for humanist physics.
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Strongly Correlated Electrons
Semi-Dirac States and Quantum Linear Magnetoresistance in Helimagnetic Pnictide MnP
Prasanta Chowdhury, Jyotirmoy Sau, Sanat Kumar Adhikari et al. (+7 more)
Large linear positive magnetoresistance (LPMR) in topological and
magnetic materials remains a subject of intense debate, particularly in noncollinear
spin systems where
spin-dependent scattering complicates charge transport. Manganese phosphide (MnP), a helimagnetic binary pnictide with multiple field-induced
magnetic transitions, provides a useful platform to investigate the interplay between complex magnetism and electronic
topology. Here, we present a comprehensive experimental and theoretical investigation of phase-dependent magnetotransport in high-quality MnP single
crystals.
Hall measurements reveal an anomalous
Hall effect dominated by skew scattering at high temperatures and a finite topological
Hall effect in the noncollinear fan (FAN) and low-temperature screw (SCR) phases. At low temperatures, we observe a large, non-saturating LPMR reaching nearly 800 percent at 4 K and 15 T, with a pronounced linear field dependence in the field-polarized
ferromagnetic (FM2) state. First-principles calculations reveal a strongly anisotropic semi-Dirac-like band at the Y point that progressively approaches the
Fermi level from the SCR to FAN and FM2 states. Our analysis indicates that the resulting small
Fermi pocket can access the extreme
quantum-limit regime at experimentally accessible fields, providing a microscopic framework for the observed LPMR within Abrikosov's
quantum magnetoresistance theory.
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All authors Prasanta Chowdhury, Jyotirmoy Sau, Sanat Kumar Adhikari, Sourav Chowdhury, Peter Bencok, Matthias Gutmann, Souvik Chatterjee, Saurav Giri, Manoranjan Kumar, Subham Majumdar
Solar and Stellar Astrophysics
The changing optical and X-ray emission of the dormant $\gamma$ Cas star HD 45314
G. Rauw, Y. Nazé, E. Bryssinck et al. (+25 more)
$\gamma$ Cas
stars are Oe/Be
stars that exhibit bright and hard X-ray emission. HD45314 belonged to this category, but lost its $\gamma$ Cas characteristics as its circumstellar disc started to fade away. The
star was monitored in optical spectroscopy, optical photometry, and X-ray spectroscopy to follow its variability on timescales of hours to years. Time series of magnitudes, colours, line equivalent widths and violet over red peak intensity ratios were analysed with
Fourier methods to uncover possible periodicities. For five years, HD45314 exhibited oscillations of its magnitude and line strengths on a timescale of 230 d. It then declined towards a nearly disc-free stage and is now slowly rebuilding its disc. During these phases, the violet over red peak intensity ratio exhibited a modulation on a timescale of about 1190 d. Over the whole campaign, prominent short-term photometric variations, notably at a frequency of 3.369 d$^{-1}$, were probably due to $\beta$ Cep-type pulsations. The amplitude of these pulsations was stronger during phases of overall brightness changes. In parallel, the X-ray spectrum switched to a low state at the onset of the oscillation phase and has remained in this low state since then. Some residual hard emission is nonetheless observed. HD45314's long-term optical variations bear resemblance with the predictions of smooth particle hydrodynamics calculations, although a close look does reveal some inconsistencies. Unlike some other $\gamma$ Cas
stars, where the X-ray emission remained nearly constant despite major changes of the circumstellar disc, HD45314's X-ray properties changed dramatically as the disc begun to dissipate. These differences might arise from a wider orbital separation between the Oe
star and its putative white
dwarf companion or from the ablation of the disc by the radiation field of the Oe
star.
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All authors G. Rauw, Y. Nazé, E. Bryssinck, W. Vollmann, J. Guarro Fló, X. Dupont, M.A. Smith, C. Motch, G.W. Henry, J. Robrade, A. de Bruin, S. Charbonnel, A. Favaro, P. Fricker, O. Garde, O. Gayrard, S. Güssregen, F. Houpert, M. Larsson, R. Leadbeater, V. Lecocq, P. Le Dû, T. Lester, L. Mulato, T. Petit, R. Pomillo, O. Thizy, F. Weil
Quantum Physics
Split-Step Dirac Cellular Automata for Continuous-Time Dirac Dynamics on Finite Spatial Lattices
Wei-Ting Wang, Pei-Ming Ho and Ching-Ray Chang
Dirac Cellular Automata (DCA) provide a framework for simulating Dirac dynamics, yet the rigid coupling between spatial and temporal resolutions can introduce artificial phase-matching
symmetries on finite grids that suppress interference phenomena such as Zitterbewegung. In this work, we propose a Split-Step Dirac Cellular Automaton (SDCA) that enables continuous-time Dirac
evolution at fixed spatial discretization. By employing a Trotterized fractional-step scheme in the momentum representation, SDCA breaks the phase-matching cancellation present in the standard DCA and recovers the interference dynamics of the continuous-time limit. We
benchmark the SDCA through analytical and numerical studies and demonstrate its implementation on IBM
Quantum processors. Despite the increased
circuit depth required for finer temporal resolution, the NISQ implementation reproduces the characteristic velocity oscillations and
entanglement-
entropy dynamics of the continuous-time model. We further investigate hardware-
topology trade-offs and dynamic
circuit implementations of the
Quantum Fourier Transform (QFT), highlighting the competing effects of gate errors, measurement, and feed-forward latency. These results demonstrate that SDCA provides a practical framework for improving temporal resolution while maintaining a fixed spatial
quantum register, enabling the exploration of relativistic
quantum dynamics on near-term
quantum devices.
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Computational Physics
Nonlinear flame describing function and mean shift kinematics of slit flames under combined axial-transverse forcing
Juhoon Son, Yong Jea Kim, Jungho Sohn et al. (+1 more)
This study investigates the nonlinear kinematics of a premixed slit flame using a two-dimensional $G$-equation level-set framework. Results show that combined forcing induces nonlinear saturation in the FDF, characterized by early gain flattening and premature phase drops, which intensify with the transverse forcing amplitude. Kinematic analysis reveals that this
geometric nonlinearity manifests as a reduction in the time-averaged flame height, defined as the mean shift. In the quasi-steady limit, this mean shift is analytically quantified via a multivariate asymptotic expansion, where fourth-order terms successfully capture the saturation mechanism at elevated amplitudes. By introducing a scaling parameter to account for transverse dominance, the frequency-dependent decay of the mean shift in the compact limit collapses onto a single master curve, enabling the derivation of a unified theoretical model that integrates this asymptotic response with a second-order low-pass filter. Furthermore, because the mean shift reduces the physical extent of the flame, it alters the wrinkle propagation time. Correcting the Strouhal number using the measured mean shift collapses the dispersed nonlinear FDF curves onto the linear theory prediction. The analysis is further extended to disturbances convected at a finite speed, for which the linear transfer function is derived analytically and the correction with the measured mean shift continues to collapse the nonlinear FDF. These findings establish that the nonlinear FDF behavior under multidimensional forcing is fundamentally governed by the kinematic mean shift, providing a theoretical baseline for decoupling
geometric nonlinearities from other thermo-diffusive or hydrodynamic instabilities in turbulent flames.
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All authors Juhoon Son, Yong Jea Kim, Jungho Sohn, Dong-hyuk Shin
Materials Science
Facile hBN-hBN Interfacial Overlap Engineering for Enhanced Quantum Emitter Formation
Nhat Minh Nguyen, Trung Vuong Doan, Md Shakhawath Hossain et al. (+12 more)
Quantum emitters in two-dimensional materials, particularly hBN, are promising platforms for
quantum technologies. However, achieving high-density emitters at predetermined locations while preserving optical quality remains challenging. Here, we introduce a facile, cost-effective double-layer all-dry transfer approach to deterministically create overlap regions between hBN flakes. These pre-defined capped regions exhibit a significantly enhanced emitter density, with up to a 15-fold increase compared to uncapped areas. Importantly, this method does not compromise emitter quality: emitters within overlap regions demonstrate excellent optical performance, including high signal-to-background and signal-to-noise ratios, large Debye-Waller factors, high brightness, and strong spectral stability. Possible defect configurations are also discussed to contextualize the observed emission characteristics. This scalable strategy enables preferential formation of
quantum emitters in targeted regions, achieving higher densities than simple treatments such as
plasma irradiation while avoiding the complexity of advanced fabrication techniques. The approach provides a practical pathway for integrating high-quality
quantum emitters into scalable
quantum photonic platforms.
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All authors Nhat Minh Nguyen, Trung Vuong Doan, Md Shakhawath Hossain, Akila Elangasinghe, Duc Anh Ngo, Ha Ngoc Duy Huynh, Thi Ngoc Anh Mai, Yongliang Chen, Kenji Watanabe, Takashi Taniguchi, Michael G. Ruppert, Chaohao Chen, Xiaoxue Xu, Toan Dinh, Toan Trong Tran
Solar and Stellar Astrophysics
Connecting Dynamo Theory with DNS Data: A Computational Analysis of $\alpha$ and $\beta$ effects
Kiwan Park
We investigate the influence of current helicity on the turbulent
magnetic diffusivity $\beta$ using three complementary derivations of the $\alpha$ and $\beta$ coefficients, based on the large-scale
magnetic field $\overline{\mathbf{B}}$, the turbulent velocity $\mathbf{u}$, and the turbulent
magnetic field $\mathbf{b}$. Applying these coefficients to raw DNS data, we reconstruct $\overline{\mathbf{B}}$ and compare the results with the original simulations. In the kinematic regime all models agree well with the DNS data. In the nonlinear regime, however, $\beta_{\mathrm{vv-vw}}$ alone produces unbounded growth of $\overline{\mathbf{B}}$. Including the contribution from turbulent
magnetic fields ($\beta_{\mathrm{bb+jb}}$) suppresses this unphysical growth and restores agreement with the DNS results. We find that kinetic helicity drives $\beta$ more negative, while current helicity shifts it back toward zero. Weighted combinations of the coefficients further show that the $\beta$ effect dominates the
evolution of $\overline{\mathbf{B}}$ throughout, whereas the $\alpha$ effect becomes important mainly for sustaining the field in the nonlinear regime. The corresponding IDL analysis scripts are provided to facilitate practical implementation of the theoretical models.
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Astrophysics of Galaxies
Tracing M22's origins: Spatial and chemical constraints on its formation history
Emanuele Dondoglio, Antonino P. Milone, Randa Asa'd et al. (+9 more)
Globular clusters (GCs) are well known to host
stellar populations characterized by light-element variations. A subset of
Galactic GCs, beyond such 'canonical' populations, contains an additional group enriched in iron, s-process elements, and total C+N+O abundance (i.e., the anomalous
stars). We combine multi-facility photometry with APOGEE spectroscopy to investigate the spatial distribution, chemical properties, and formation history of the
stellar populations in M22, with particular focus on its anomalous component. We trace the canonical and anomalous populations, together with their subpopulations, from the cluster center out to eight half-mass radii. The anomalous population becomes increasingly dominant in the outermost regions, whereas no significant radial gradients are detected among its subpopulations. Our chemical analysis reveals light-element anticorrelations within both the canonical and anomalous components, although the latter are shifted toward higher C, N, and Al abundances. For the first time, we show that the Fe, s-process, and C+N+O enhancements among anomalous
stars are not uniform but correlate with their light-element composition: the most chemically extreme anomalous
stars are also the most Fe-, Ce-rich, and C+N+O-poor. We identify a distinct red overdensity on the horizontal branch, likely populated by the most He-poor
stars, and tentatively associate the extreme horizontal branch with the most chemically enriched anomalous population. These observations are difficult to reconcile with M22 being a merger between two GCs. Instead, they qualitatively favor a self-enrichment scenario regulated by dilution, similar to that recently proposed for $\omega$Centauri, with their close chemical correspondence suggesting that they experienced analogous formation histories.
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All authors Emanuele Dondoglio, Antonino P. Milone, Randa Asa'd, Anna F. Marino, Alessandra Mastrobuono-Battisti, Fabrizio Muratore, Tuila Ziliotto, Emanuele Bortolan, Giacomo Cordoni, Maria Vittoria Legnardi, Edoardo P. Lagioia, Marco Tailo
High Energy Astrophysical Phenomena
1LHAASO J1852+0050u: GeV-100TeV Gamma-ray emission Powered by Star-forming Region?
The LHAASO Collaboration
Star-forming regions (SFRs), including HII regions, have recently attracted significant
attention as potential sites of particle acceleration capable of producing PeV
cosmic rays, i.e. as potential
Galactic PeVatrons. Yet, SFRs known as candidate PeVatrons are still very rare. Here we report a highly likely physical association between the UHE gamma-ray source 1LHAASO J1852+0050u and coincident
star-forming regions. Using $\sim$4 years of LHAASO data, the extended source 1LHAASO J1852+0050u (called J1852 in this study) was reanalyzed with a significance of $\sim$13$\sigma$ and 39%-containment radius of 0.35$\deg$. This extended source projectively covers dozens of HII regions and an energetic
pulsar PSR J1853+0056. We reanalyzed $\sim$16 years of
Fermi-LAT data and found a GeV source (named SrcAG) coincident with the LHAASO source J1852. The CO-line observation shows a molecular clump which coincides with the gamma-ray sources and is related with the ultra-compact HII region G34.26+0.15 at the distance of $\sim$3.3 kpc. Fitting to the spectral energy distribution indicates that PSR J1853+0056 cannot afford the observed gamma-ray flux either for J1852 or SrcAG. Although the contribution from hidden
pulsars to the gamma-ray emission could not be excluded, it is most likely that the GeV-100TeV gamma-ray emission is dominantly powered by SFR through p-p hadronic interaction between the
protons accelerated in the SFR and MCs: the GeV emission is ascribed to the
protons accelerated by protostars' activities, while the TeV emission ascribed to the
protons accelerated by massive
stars in the SFR.
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Materials Science
Morphology and depletion force-based large-scale self-assembly of nanocubes on surface
Yeonhee Lee, Seungsang Cha, Yuna Kwak et al. (+3 more)
Self-assembling nanoparticles is a highly efficient and facile way to form functional nano-, micro- and macrostructures. However, currently available methods lack precision and controllability in size, shape and composition, suffer from poor reproducibility and scalability, and require complex steps and expensive materials. Here, we present the uniform morphology-induced and depletion force-directed nanoparticle assembly on surface (MIDAS) method with gold nanocubes (AuNCs). Using this approach, morphology-sensitive depletion forces trigger shape-selective flocculation and assembly of the AuNCs with uniform size and shape. Importantly, the surface roughness-controlled substrate drives the large-scale formation of AuNC-assembled monolayers (2D AuNAMs) or three-dimensional AuNC-assembled multilayers (3D AuNAMs) in a highly specific manner without any complex ligand modification or preparation steps.
Lattice-gas modeling and kinetic Monte Carlo simulations show the depletion force is the key parameter determining supercrystal morphology and corroborate the experimental findings. This work establishes a generalizable nanoparticle assembly mechanism and demonstrates the broad applicability of the MIDAS strategy for scalable fabrication and patterning of 2D and 3D nanoparticle architectures.
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All authors Yeonhee Lee, Seungsang Cha, Yuna Kwak, Nicholas Juntunen, Grant M. Rotskoff, Jwa-Min Nam
Applied Physics
Through-thickness coupling of diffusion and viscoelastic relaxation in the transient bending of bilayer microcantilevers
YingCheng Zhou, Kosuke Minami and Genki Yoshikawa
Static-mode microcantilever sensors detect chemical analytes through the bending of a
bilayer beam whose
polymer coating swells upon absorption. The transient bending is usually modeled as if the coating absorbed analyte uniformly, which is adequate for thin coatings but breaks down as the coating thickens and a moving
diffusion front couples to depth-dependent viscoelastic relaxation. We resolve this coupling with a purpose-built finite-element solver requiring only one linear solve per time step, and show that the through-thickness structure controls the transient response in ways uniform-uptake models cannot capture. Verified against a published analytical solution, the solver reproduces the full transition from a pronounced
curvature overshoot (up to nearly twice the steady-state value) when
diffusion is fast relative to relaxation to a monotonic rise when it is slow. In the intermediate-thickness regime the analytical solution cannot reach, the thickness maximizing the steady-state signal and the thickness preserving the transient overshoot are governed by different physics, one
geometric and one dynamic, so one coating cannot be optimized for both. The overshoot further survives realistic surface mass-transfer resistance, justifying the idealized surface boundary condition used throughout.
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General Relativity and Quantum Cosmology
Analytic motions of spinning particles in Schwarzschild-(anti-)de Sitter spacetime
Rui-Hui Li, Xing-You Zhou and Chao-Jun Feng
The motion of a spinning test particle in a static, spherically symmetric spacetime with a cosmological constant is studied within the Mathisson-Papapetrou-Dixon formalism, working to linear order in the particle's
spin. By exploiting the
symmetries of the background, the radial and latitudinal dynamics are reduced to first-order equations governed by a
spin-deformed quintic
polynomial. A complete classification of the real root structure of this quintic is carried out, from which the allowed orbital types for spinning particles in the Schwarzschild-anti-de Sitter and Schwarzschild-de Sitter geometries follow directly. The parameter dependence of the root structure and of the stable circular orbit interval is analyzed. In particular, for values of the cosmological constant beyond the Stuchlík limit, where spinless particles admit no bound orbits, spinning particles can still remain bound. The radial motion is expressed piecewise in terms of Lauricella hypergeometric functions, with the simple positive real roots of the quintic acting as branch cuts. The latitudinal motion consists of small oscillations about an equatorial plane, and its phase, governed by the same quintic, admits an analogous analytic representation.
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Quantum Physics
Generalized Fidelity, the Data Processing Inequality, and Convexity
Haobo Ma, Reza Rajaei and Wenlin Zhang
In this paper, we show that the generalized Bures–Wasserstein distance induced by the generalized fidelity fails the data processing inequality (DPI) in every dimension $n\geq2$. In dimension two, we derive three sufficient conditions guaranteeing the DPI by using an explicit formula for the real part of the generalized fidelity. Furthermore, we find a necessary and sufficient condition under which the generalized fidelity reduces to the Uhlmann fidelity. We also show that neither the generalized Bures–Wasserstein distance nor its square is convex in one state, even with the other state and the reference fixed, in every dimension $n\geq2$.
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Mathematical Physics
Euler-Poincare Reduction: A Geometric Treatment of the Relativistic Spinning Particle
Burak Gul and O. Teoman Turgut
The heavy top is a classic example of Euler-Poincare reduction on a semidirect product group, demonstrating how an advected quantity-the direction of
gravity-couples to rotational motion. While the description of relativistic spinning particles via Lie group configurations is well established in
Hamiltonian (
symplectic) mechanics, we demonstrate that an explicit Lagrangian Euler-Poincare reduction provides a direct, transparent parallel to the heavy top. Specifically, we show that the free relativistic spinning particle on the Poincare group is the precise Lorentzian analog of this system, with spacetime position being the advected quantity. This
geometric unification not only illuminates the underlying
symmetry of both systems but also clarifies why the introduction of external electromagnetic fields leads to a partial reduction. Finally, we establish that the transition to left-trivialized coordinates acts as a
geometric selection mechanism, naturally favoring a class of interaction Lagrangians where
spin-field coupling manifests as a dynamical redefinition of the particle's mass.
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Applied Physics
Maximum signal-to-noise ratio enhancement by averaging under a limited measurement time
YingCheng Zhou, Kosuke Minami, Genki Yoshikawa et al. (+1 more)
Averaging through repetitive measurement is a ubiquitous strategy for improving signal-to-noise ratio (SNR) and is commonly assumed to yield a $\sqrt{N}$ enhancement with the number of repetitions $N$. This assumption, however, implicitly requires the signal amplitude to be independent of measurement duration. This condition does not generally hold in dynamical sensing systems with finite response time and a fixed measurement time. We derive a closed-form expression for the SNR enhancement factor by analytically accounting for the competition between statistical noise reduction and dynamical signal attenuation, and demonstrate the existence of a strict upper bound on the SNR enhancement. The enhancement factor is a non-monotonic function of $N$ with a well-defined maximum at an optimal repetition number, beyond which further averaging degrades the SNR. Moreover, below a threshold set by the ratio of measurement time to response time, averaging yields no enhancement at all. These two regimes delimit where the conventional $\sqrt{N}$ law breaks down. Experimental validation using nanomechanical gas sensing, with two receptor-analyte systems deliberately chosen to bracket this enhancement transition, confirms the theoretical predictions. Our results show that measurement time is a finite resource to be optimally partitioned between signal accumulation and averaging, and provide a quantitative guideline for selecting the repetition number in time-constrained sensing such as real-time and repetitive gas or odor detection.
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All authors YingCheng Zhou, Kosuke Minami, Genki Yoshikawa, Gaku Imamura
Strongly Correlated Electrons
Orbital-selective electronic modes induced by doping and originating from distinct spin excitations: an essential feature of orbital-selective Mott transition
Masanori Kohno
The nature of the orbital-selective Mott transition (OSMT) remains elusive. This study shows that, by doping an orbitally degenerate
spin-1
antiferromagnetic insulator in the Kanamori-Hubbard model, electronic modes emerge in the band gap in an orbital-selective manner, exhibiting momentum-shifted
spin-mode dispersion relations. Electronic modes originating from conventional
spin excitations, including the low-energy one, appear in the doped orbital, while those from inter-orbital
spin excitations appear in the undoped orbital. These emergent modes constitute an essential feature of the OSMT.
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Chaotic Dynamics
Dynamics Creation through Neural Dynamical Transfer Learning
He Ma, Qiyang Ge, Yu Meng et al. (+2 more)
Data-driven machine learning has established a robust foundation for reconstructing nonlinear dynamical systems from observations, primarily for the purposes of
forecasting and control. However, most existing efforts focus on recovering specific observed dynamics rather than the generative synthesis of new ones. Inspired by image fusion and style transfer, we introduce a neural network framework termed Neural Dynamical Transfer Learning (NDTL) to create new systems with prescribed dynamics from pairs of parent nonlinear dynamical systems. By computing fundamental dynamical signatures, including the intrinsic dimension, the Kaplan-Yorke dimension, the invariant measure statistics, and the Lyapunov spectrum, we demonstrate that NDTL preserves key features inherited from the parent models while simultaneously generating novel dynamics. Beyond these validation examples, NDTL induces a criterion for dynamics classification, creates stable oscillatory coexistence in the Hastings-Powell food chain model, produces interpretable epidemiological models, and provides a chaotic source for image encryption.
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All authors He Ma, Qiyang Ge, Yu Meng, Celso Grebogi, Wei Lin
Statistical Mechanics
Intermittent continuous-time random walks under renewal reset mechanism
Guohua Li, Hong Zhang and Yuexiong Liu
Stochastic resetting as a practical and efficient search strategy in complex and disordered environments has long been a topic of interest to researchers. Based on the competition between jumping and resetting, this article proposes and investigates intermittent continuous-time random walks (CTRWs) under
stochastic resetting, using the smaller waiting time for jump and reset as the renewal time, where the waiting times for both jump and reset can have arbitrary distributions. After each renewal event, the system will proceed with new waiting times for jump and reset regardless of their previous histories. We study the governing equation and Montroll-Weiss equation with renewal resetting, as well as the Markovian resetting for intermittent CTRWs. We prove the existence of non-
equilibrium stationary states within the renewal reset mechanism when the jump and reset waiting times follow any exponential and power law distributions. For exponential and Gaussian distributed jump lengths, we examine the mean square displacements (MSDs) of particles to determine their monotonicity and asymptotic stability. Moreover, we calculate the first-arrival time to quantify search efficiency, and validate the intermittent CTRWs under renewal resetting lead to a finite mean first-arrival time (MFAT) to any fixed position for exponential jump and reset waiting time distributions (WTDs), power-law jump and exponential reset WTDs, as well as exponential jump and power-law reset WTDs. However, the MFAT diverges for power-law jump and reset WTDs. The intermittent CTRW model, which is based on the competition mechanism, can be applied to many physical scenarios, such as the foraging strategy of animals that return to their nests after an unsuccessful foraging attempt, or the work planning of intelligent
robots that return to energy replenishment points after prolonged operation.
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Solar and Stellar Astrophysics
Automated Detection of Double-Lined Spectroscopic Binaries in High-Resolution Spectra and a Probabilistic Analysis of Stellar Multiplicity
William B. Salazar, Steven Giacalone and Andrew W. Howard
The characterization of Sun-like
stars, including determining whether those
stars are single or have
stellar companions, has become increasingly important for missions seeking
planets beyond the
Solar System. With upcoming missions like the Habitable Worlds Observatory (HWO) on the horizon, vetting
stars for binarity and confirming potential targets as viable is essential precursor science. In this paper, we present an automated
algorithm that searches for double-lined spectroscopic binaries (SB2s) in high-resolution spectra. Using MOLUSC, we simulate realistic
stellar populations to quantify the capability of
algorithm for detecting
stellar companions around nearby
stars, with potential applications to HWO target
stars and
Gaia DR4
planet-host candidates. In addition, we explore how the detection rate is influenced by complementary observations like high-resolution adaptive optics imaging and time-series radial velocities. We find that our SB2 detection
algorithm alone can rule out 46.1% of
stellar-mass companions. High-resolution adaptive optics alone rules out 79.6% of
stellar companions. Radial velocity surveys alone ruled out 98.4% and 98.7% for 5-year and 10-year surveys, respectively. When all three methods are combined, the probability of a typical nearby
star having a
stellar companion is <1%. The combination of the methods allows us to better understand and resolve target lists for future surveys.
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Quantum Gases
Yan-Bin Yang, Jiong-Hao Wang, Shicheng Ma et al. (+1 more)
Twisted
bilayer materials provide a versatile platform for realizing correlated topological states. Motivated by the recent experimental realization of atomic Bose-Einstein condensates in twisted
bilayer optical
lattices, we investigate the emergence of fractional topological phases in such systems. For experimentally realistic parameters, the single-particle spectrum hosts a pair of quasi-degenerate nearly flat moiré bands. We show using self-consistent Hartree-Fock calculations that atomic interactions spontaneously break time-reversal
symmetry, lift the quasi-degeneracy, and generate an isolated nearly flat band with a nonzero Chern number. At fractional filling, exact diagonalization of the
Hamiltonian projected to this band reveals a threefold degenerate ground-state
manifold and a characteristic particle
entanglement spectrum, providing strong evidence for a fractional Chern
insulator. The resulting many-body gap is of order \(10^{-3}E_R\), corresponding to a nanokelvin energy scale accessible to state-of-the-art cold-atom experiments. Our scheme requires neither
spin-orbit coupling, as in transition metal dichalcogenides, nor a finite
magnetic field, as in existing twisted-
bilayer-
graphene experiments, providing a highly tunable route to strongly correlated topological phases in twisted
bilayer optical
lattices.
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All authors Yan-Bin Yang, Jiong-Hao Wang, Shicheng Ma, Yong Xu
Quantum Physics · Cross-listed from cs.IT
Conditions for Global Optimality in Quantum Arimoto-Blahut Algorithms
Geng Liu and Masahito Hayashi
Generalized Arimoto–Blahut (AB)
algorithms are widely used in information theory and
quantum optimization, but monotonic objective decrease and numerical stabilization do not guarantee global optimality. We establish necessary and sufficient conditions for the global optimality of full-rank AB fixed points for convex differentiable objectives under linear constraints. An AB fixed point is globally optimal if and only if the AB update direction and the objective gradient differ by an element of the constraint normal space at that point. The same compatibility condition characterizes agreement between individual AB and mirror-descent (MD) updates, whereas pathwise equivalence requires it along the entire common trajectory. Thus, an AB
algorithm may follow a trajectory different from MD and still reach the global optimum. We also develop a posteriori optimality certificates based on feasible directional derivatives, including finite-difference upper bounds on the objective gap that require only objective evaluations. For channel relative
entropy between dephasing and depolarizing channels, we analytically identify the global minimizer as the unique full-rank AB fixed point, although pathwise equivalence fails. Numerical experiments illustrate convergence of AB and MD along different trajectories and validate the certificates. By contrast, an amplitude-damping example shows that a monotone AB iteration can stabilize at a suboptimal fixed point, whose nonoptimality is detected by the finite-difference certificate. These results provide structural and computable criteria for assessing global optimality in
quantum AB
algorithms.
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Superconductivity
Record-Breaking Elemental Superconductivity in Tetralayer Kagome Borophene
Yingnan Liu, Yan Liu, Renyu Duan et al. (+4 more)
Superconductivity above the
liquid-nitrogen temperature remains rare in two-dimensional elemental
crystals, where strong covalent bonding often yields high
phonon frequencies but insufficient electron-
phonon coupling. Here, using first-principles calculations and fully anisotropic Migdal-Eliashberg theory, we predict tetralayer kagome borophene (TKB) stabilized by ABAB covalent stacking, as a
liquid-nitrogen-temperature elemental
superconductor. With a predicted critical temperature of 102 K, TKB sets a record-high value among previously reported elemental
superconductors. Unlike known high-Tc boron-based
superconductors dominated by in-plane sigma-bonding states and high-frequency in-plane B-B stretching modes, TKB realizes an out-of-plane s-pz-bonding-mediated pairing mechanism, in which interlayer s-pz bonding states at the
Fermi level are strongly coupled to low-frequency out-of-plane vibrations of boron atoms. These results reveal a distinct out-of-plane pairing channel in multilayer borophene and establish covalent stacking engineering as a potential route for high-Tc superconductivity in two-dimensional materials.
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All authors Yingnan Liu, Yan Liu, Renyu Duan, Menghui Wang, Meiling Xu, Hanyu Liu, Shoutao Zhang