Mesoscale and Nanoscale Physics
Quaternion-Kähler geometry of time reversal symmetric crystals
Hyeongmuk Lim, Junseo Jung, Yuting Qian et al. (+1 more)
Quantum geometry reveals how the shape of Bloch wave functions governs correlated
quantum phenomena. Its standard formulation describes isolated complex bands, where Berry
curvature is Abelian and ideal geometry is Kähler. However, time reversal symmetric
crystals with
spin require a different
language since Kramers degeneracy pairs Bloch states and turns Berry
curvature into a non-Abelian SU(2) field. Here we show that Kramers pair band geometry is quaternionic. A minimal Kramers pair defines a map into quaternion projective space, and its quaternionic
quantum geometric tensor unifies the
quantum metric with the three SU(2) Berry
curvature components. The non-negativity of this tensor imposes local metric-
curvature inequalities, whose saturation defines the non-Abelian counterpart of ideal Chern bands. In four dimensions, the ideal limit further yields an algebraic structure related to the four-dimensional
quantum Hall effect. Our results promote ideal
quantum geometry from the Abelian geometry of Chern bands to the quaternionic, non-Abelian geometry of time reversal symmetric
quantum matter.
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All authors Hyeongmuk Lim, Junseo Jung, Yuting Qian, Bohm-Jung Yang
High Energy Physics (Phenomenology)
Faddeev equations for the $J/\psi\,NN$ and $\phi\,NN$ three-body systems in momentum space
Xu Zhang
We construct Faddeev equations for the $J/\psi\,NN$ and $\phi\,NN$ three-body systems in momentum space. The two-body subsystem $t$-
matrix is obtained by solving the Lippmann-Schwinger equations. The $NN$ interactions are constructed using the Malfliet-Tjon potential. The $J/\psi\,N$ interaction potentials in the ${}^4S_{3/2}$ and ${}^2S_{1/2}$ channels are taken from HAL QCD. The $\phi\,N$ interaction potential in the ${}^4S_{3/2}$ channel is also taken from HAL QCD. The ${}^2S_{1/2}$ $\phi N$ interaction is obtained from the combination of the $\phi p$ correlation function analysis and the HAL QCD results, as well as from the assumption that the
spin-
spin parts of the $\phi N$ and $J/\psi N$ interactions are inversely proportional to the respective
hadron masses. The Faddeev equations are solved to find bound states in the $J/\psi\,NN$ and $\phi\,NN$ three-body systems. The numerical results suggest that there exist bound states in the $\phi\,NN$ three-body system, while there is no bound state in the $J/\psi\,NN$ system.
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Optics
Zero-change foundry compatible silicon photonics MEMS optical switch
Arkadev Roy, Daniel Klawson, Jianheng Luo et al. (+3 more)
Large-scale photonic switches are emerging as essential devices for energy-efficient optical interconnect in data centers and AI/ML clusters as a key enabler for high-bandwidth and low-latency connectivity. Combining micro-electro-mechanical (MEMS) based mechanical reconfigurability with silicon photonic integrated
circuits can enable a large-scale, low-loss, programmable platform required for large-scale optical
circuit switches. We demonstrate a broadband silicon photonics MEMS switch with more than 30 dB extinction ratio operating in C-band using a zero-change foundry-compatible process and Back-end-of-Line (BEOL) post-processing. The optical switch element exhibits an insertion loss of less than 1.5 dB with a low static power consumption of approx 20 nW at maximum actuation voltage. Our results illustrate that MEMS-based silicon photonics modulators and phase shifters can be used alongside standard silicon photonics components seamlessly in scenarios where performance in terms of footprint, extinction ratio, broad bandwidth, and low-loss operation is of paramount importance.
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All authors Arkadev Roy, Daniel Klawson, Jianheng Luo, Yiyang Zhi, Sirui Tang, Ming Wu
Astrophysics of Galaxies
PDRs4All XXII. Near-Infrared continuum in the Orion Bar
Takashi Onaka, Emmanuel Dartois, Els Peeters et al. (+13 more)
Conspicuous excess emission is present in the near-infrared (NIR) region in various objects, including reflection nebulae, planetary nebulae, and nearby
galaxies. However, the spatial distribution and spectral shape of the excess emission remain poorly understood. We studied the NIR continuum emission spectroscopically and obtained its spatial distribution relative to the aromatic infrared band (AIB) at 3.3um in the Orion Bar prototypical photodissociation region (PDR). We aim to characterize its spectral shape and discuss its origin. We employed 3D spectroscopic data of the Orion Bar taken with the integrated field unit of NIRSpec on JWST from the Early Release Science program "PDRs4All." Contribution from the foreground ionized gas was estimated using the Cloudy code and subtracted. The observed regions were divided into nine physically distinct regions and an average spectrum was derived for each region. The nine regions, including the ionized gas, atomic PDR, and molecular PDR, clearly show remaining continuum in the region 1–4.5um. The continuum at wavelengths longer than 2.7um shows good correlations with the 3.3um AIB, while the correlation of the continuum at 1.2um is not significant. We further find that the NIR continuum in the Orion Bar can be approximated by a summation of two blackbodies. The low-temperature component correlates with the AIB well, while the high-temperature component does not. The average spectra also show absorption features at 3.0 and 4.27um, which are attributed to the presence in the spectra of water ice and CO2 ice. We discuss possible origins of the NIR continuum, among which recurrent fluorescence from carbon clusters better explains the observed low-temperature component. The presence of ice species suggests a contribution from a deeper layer of the PDR along the line of sight producing characteristic ice absorption features.
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All authors Takashi Onaka, Emmanuel Dartois, Els Peeters, Olivier Berne, Emilie Habart, Christiaan Boersma, Jan Cami, Asuncion Fuente, Javier R. Goicoechea, Ozan Lacinbala, Yoko Okada, Alexander G. G. M. Tielens, Dries Van De Putte, Francois Boulanger, Thomas Pino, Yong Zhang
Mathematical Physics
The co-directional overtaking collision problem between a dispersive shock wave and a rarefaction wave for the Hirota equation
Yuan Xiang and Rui Guo
In this paper, we mainly investigate the overtaking collision problem between a dispersive shock wave (DSW) and a rarefaction wave (RW) propagating in the same direction in the defocusing Hirota equation framework. Based on the Whitham theory, the zero-phase and single-phase modulation systems corresponding to the defocusing Hirota equation are given, along with explicit expressions of Riemann invariants. For step-type initial conditions with left-side DSW and right-side RW propagating identically, the global initial configuration is constructed.~The modulation solution within the nonlinear collision domain is obtained via the generalized hodograph transformation and solutions of the Euler-Poisson-Darboux equation. Thus, by matching the Riemann invariants at the boundaries of DSW and RW, we can provide a detailed analytical description for the dynamical behaviors of the collision across all evolutionary stages. The accuracy of theoretical predictions is verified by comparison with direct numerical simulations.
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High Energy Physics (Phenomenology)
Spin correlation of hyperon-antihyperon systems in $e^+e^-$ annihilation
Wenyu Zhang, Yang Li, Xiaorong Zhou et al. (+1 more)
Quantum correlations in high-energy collisions provide a novel perspective on both fundamental physics and
hadron structure. We calculate the
quantum information observable in
spin-1/2 particle-antiparticle systems produced in $e^+e^-$ annihilation. Starting from the two-
qubit density operator, we calculate the Bell variable, concurrence and negativity as functions of the scattering angle and collision energy for the $\Lambda\bar{\Lambda}$, $\Sigma^+\bar{\Sigma}^-$, and $\Lambda^+_c\bar{\Lambda}^-_c$ systems in the process $e^+e^-\rightarrow B\bar{B}$ at BESIII experiments. Unlike elementary particle-antiparticle systems, the hyperon-antihyperon system exhibits non-vanishing transverse polarization for $B$ and $\bar{B}$ with respect to the production plane, which significantly restrict the kinematic region where the CHSH inequality is violated while leaving the
entanglement largely unaffected. We also extend our analysis to the general case of
spin-1/2 particle-antiparticle production, and explore the potential of using
quantum correlations as probes to
hadron structure, particularly to the parton-level
entanglement inside heavy-flavored
mesons.
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All authors Wenyu Zhang, Yang Li, Xiaorong Zhou, Qun Wang
Materials Science
Apparent Dresselhaus coefficient in (001) GaAs quantum wells: Correlation-time renormalization in D'yakonov-Perel' spin relaxation
Yuzo Ohno, Jun Ishihara and Satoshi Iba
We study the Dresselhaus coefficient inferred from D'yakonov-Perel'
spin relaxation in bulk GaAs and (001) GaAs
quantum wells using nonballistic Monte Carlo simulations. In bulk GaAs, inelastic LO-
phonon simulations reproduce the
spin relaxation with a cubic Dresselhaus coefficient \gamma_{3D}\simeq12.4 eVÅ^3 and a cubic-field correlation time \tau_3^{3D}\simeq150 fs. In a projected two-dimensional
quantum-well model, however, k_z^2 is replaced by the static expectation value \langle k_z^2 \rangle, converting the dominant Dresselhaus field into a term linear in the in-plane wave vector. We show that this projection changes the D'yakonov-Perel' correlation kernel from K_3^{2D} to a first- and third-order hybridized kernel K_{1+3}^{2D}, for which the correlation time \tau_{1+3}^{2D} approaches 235 fs in the strict two-dimensional limit, in contrast to the third-order correlation time \tau_3^{2D} of 130 fs. Consequently, the coefficient entering the projected two-dimensional model is not the intrinsic cubic coefficient itself but an apparent coefficient, \gamma_{2D}^{app}=\gamma_{3D} \sqrt{\tau_3^{2D}/\tau_{1+3}^{2D}}. Since \tau_{1+3}^{2D}\simeq1.8\tau_3^{2D} under LO-
phonon-dominated scattering, \gamma_{2D}^{app}\simeq9.2 eVÅ^3, consistent with
spin relaxation in (001) GaAs
quantum wells. This correlation-time renormalization clarifies why Dresselhaus coefficients extracted from two-dimensional
spin relaxation can differ from the cubic bulk coefficient and provides a useful framework for interpreting linear and cubic Dresselhaus parameters in
quantum wells.
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Physics and Society
Performance appraisal promotes cooperation in spatial public goods games
Tianjiao Li, Qin Li, Kangxi Zhu et al. (+2 more)
In real organizations, performance appraisal serves as an important means of evaluating employees' work outcomes and behaviors, while performance pay directly links compensation to the evaluation results. However, in traditional spatial public goods games, the total payoff of a group is equally distributed among all participants without considering individual differences in contributions, an approach that ignores the heterogeneity of individual efforts. To overcome this limitation, we propose a spatial public goods game model based on performance appraisal, in which individual payoffs are divided into two parts: an equally distributed component and a performance-weighted component. Specifically, each individual receives scores from its neighboring groups, and the individual's reputation is dynamically updated by accumulating these scores, which further modulates the fitness function during strategy imitation. Extensive numerical simulation results demonstrate that the performance appraisal mechanism significantly promotes the emergence of cooperative behavior. The reputation reinforcement mechanism amplifies this positive effect by creating fitness advantages for high-reputation individuals. These findings suggest that incorporating performance appraisal into payoff allocation helps mitigate social dilemmas and promote collective cooperation.
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All authors Tianjiao Li, Qin Li, Kangxi Zhu, Minyu Feng, Manuel Chica
Plasma Physics
Quasi-single-stage optimization for advanced stellarators
Guodong Yu, Yidong Xie, Hengqian Liu et al. (+1 more)
Advanced stellarator design requires a balance between
plasma performance and the manufacturability of three-dimensional modular coils. In conventional two-stage optimization, the coils required to realize an optimized
equilibrium can be limited by engineering feasibility. Here, we develop a quasi-single-stage (QSS) framework that incorporates coil feasibility directly into
plasma-boundary optimization. QSS uses the maximum normalized normal-field error, evaluated rapidly from surface currents on a uniformly offset winding surface, as a coil-feasibility surrogate. We apply this method to optimize configurations targeting quasi-axisymmetry, quasi-helical
symmetry, quasi-isodynamicity, and a combination of omnigenity with piecewise omnigenity. The QSS-optimized configurations exhibit smoother
plasma boundaries and winding surfaces, lower normal-field reconstruction errors, and reduced coil complexity, while preserving favourable
magnetic-
symmetry and transport properties. QSS provides a practical proof-of-principle strategy for co-optimizing
plasma physics and coil engineering in stellarator design.
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All authors Guodong Yu, Yidong Xie, Hengqian Liu, Caoxiang Zhu
Mathematical Physics
From Convex to Non-convex: Evolution of Rarefaction-dispersive shock interactions and the Influence of Non-convexity
Jia-Xue Niu, Rui Guo, Hua-Ying Ren et al. (+1 more)
In this paper, we focus on the analytical description of the interaction between a rarefaction and dispersive shock wave across both convex and non-convex cases, with particular
attention to the effect of the non-convexity, within the framework of the Gardner equation. For convex structures, internal oscillations degenerate into small amplitude harmonic waves or a modulated
soliton train as t tends to infinity, accompanied by either a retained rarefaction part, or a new dispersive shock wave emanating from it. Taking into account the non-convexity, when alpha>0, we find that kinks either remain non-participating in the interaction at all, or only act to switch polarities of convex structures. As for alpha<0, we solve the Gardner-Whitham equations with three varying Riemann invariants, to analyze the rarefaction-contact dispersive shock interaction where the only possible configuration is that the rarefaction wave is on the left. It is demonstrated that the rarefaction wave will be completely drawn into the interaction region, with a changed contact dispersive shock wave escaping from the left. And internal oscillations eventually degenerate into an asymptotic algebraic
soliton train as t tends to infinity. In addition, we study the interaction between a rarefaction wave and composite structure consisting of the contact and classical dispersive shock parts under two distinct situations: (i) For the composite structure-rarefaction interaction, the contact part remains inactive in the interaction, and internal oscillations ultimately degenerate into a contact dispersive shock wave. (ii) For the rarefaction-composite structure case, the entire composite structure participates in the interaction, during
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All authors Jia-Xue Niu, Rui Guo, Hua-Ying Ren, Ya-Hui Huang
High Energy Physics (Phenomenology)
Possible Bound States in the $D^\ast\bar D^\ast$/$B^\ast\bar B^\ast$ and $D^\ast D^\ast$/$\bar B^\ast\bar B^\ast$ Systems within the Bethe-Salpeter Formalism
Ce Li, Jing-Juan Qi, Zhu-Feng Zhang et al. (+2 more)
We investigate possible $S$-wave bound states in the $D^\ast\bar D^\ast$, $B^\ast\bar B^\ast$, $D^\ast D^\ast$, and $\bar B^\ast\bar B^\ast$ systems within the Bethe-Salpeter formalism using one-
boson-exchange interactions. Bound state solutions are obtained in the isoscalar hidden-heavy systems with $J^{PC}=0^{++}$, $1^{+-}$, and $2^{++}$, whereas no isovector solutions are found within the parameter range considered. For the doubly heavy systems, solutions are obtained in the allowed $I(J^P)=0(1^+)$, $1(0^+)$, and $1(2^+)$ systems, although the $1(0^+)$ solution requires a comparatively large cutoff parameter. The bottom systems are bounded more favorably than their charmed counterparts because of their larger reduced masses.
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All authors Ce Li, Jing-Juan Qi, Zhu-Feng Zhang, Zhen-Yang Wang, Xin-Heng Guo
Quantum Physics
Typical Output States of Monitored Random Clifford Circuits: A Graph-Theoretic Approach
Yu-Xuan Zhang and Yu-Xiang Zhang
In many-body physics, an explicit wavefunction often provides the most thorough understanding, yet for monitored random Clifford
circuit it has remained missing. Here we develop a framework that grants direct access to the typical output states. As every stabilizer state is local-Clifford-equivalent to a graph state, the graph adjacency
matrix, a classical bit
matrix, provides a complete description of the
quantum state. In the large-$N$ limit, we show that these graphs converge to the Erdős–Rényi random graph $G(N,1/2)$, which allows us to resolve the open problem of Greenberger–Horne–Zeilinger (GHZ)
entanglement generated by deep random Clifford
circuits. We obtain analytically the mean GHZ content $\langle g_3\rangle=1.204$ for even $N$ and $1.325$ for odd $N$. For monitored Clifford
circuits with a 1D layout, we uncover an emergent Erdős–Rényi subgraph $G(N_{\mathrm{sub}},1/2)$ in the output states of the volume-law phase, where $N_{\mathrm{sub}}/N\approx \sqrt{1-p/p_c}$ with $p$ the measurement rate and $p_c$ the critical point of the measurement-induced phase transition (MIPT). The output state is thus equivalent to the output of an unmonitored random Clifford
circuit on $N_{\mathrm{sub}}$
qubits, weakly perturbed by the remaining $N-N_{\mathrm{sub}}$
qubits carrying little
entanglement. This result directly accounts for the
quantum error-correcting capability of the volume-law phase, and implies the same GHZ statistics for the whole volume-law phase. We further identify a clustering effect for
qubits in the dense subgraph, which we reproduce with an infection-recovery toy model that exhibits a measurement-induced absorbing-state phase transition. Finally, a mean-field argument on the graph locates the MIPT critical point at $p_c = 0.1608$, in excellent agreement with the numerical value $p_c\approx 0.16$.
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Solar and Stellar Astrophysics
Lithium as a Signpost for Compact Object Binary Candidates in the LAMOST Medium Resolution Survey
Yang Shen, Joshua D. Simon, Kareem El-Badry et al. (+1 more)
Binary systems with black hole or
neutron star companions are often associated with lithium enhancement.
Gaia NS1, a recently discovered
neutron-
star binary with a lithium-enhanced main-sequence companion, demonstrates the potential of lithium as a signpost for identifying compact object binaries in existing spectroscopic surveys. In particular, we aim to use lithium as a signpost to find compact object binaries similar to
Gaia NS1 in the Large Sky Area Multi-Object Fibre Spectroscopic
Telescope (LAMOST) Medium Resolution Survey (MRS). From LAMOST MRS, we selected 4441 metal-poor main-sequence
stars like
Gaia NS1, measured the Li 6707 Å equivalent width, and then identified a sample of 33
stars with strong Li absorption. We used radial velocity variation and astrometric binarity signatures from
Gaia, narrowing the sample to 3 candidates. We identified one of these candidates as an eclipsing binary and demonstrated that massive companions for the other two are unlikely via follow-up spectroscopy.
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All authors Yang Shen, Joshua D. Simon, Kareem El-Badry, Casey Y. Lam
Earth and Planetary Astrophysics
HIP 61637 b: a TESS Brown Dwarf in a Near-circular Orbit around a Massive A-type Star
Nino Ephremidze, David W. Latham, Perry Berlind et al. (+8 more)
We present the characterization of HIP 61637 b (TOI-5401 b), a brown
dwarf discovered by TESS to transit an A-type
star. HIP 61637 is the most massive and the brightest
star known to host a transiting brown
dwarf to date. The companion lies in the middle of the "brown
dwarf desert". We perform a joint analysis of light curves from NASA's TESS mission and our high-resolution spectroscopy from the Tillinghast Reflector Echelle Spectrograph. We determine that HIP 61637 b has a radius of $R_{BD} = 1.149^{+0.049}_{-0.038}$ $R_J$, a mass of $M_{BD} = 47.8^{+1.5}_{-1.4}$ $M_J$, and transits its host
star every $6.829104 \pm 0.000011$ days in a near-circular orbit ($e = 0.054 \pm 0.013$). The host
star has a mass of $2.86\pm 0.12\,M_\odot$, a radius of $4.33 \pm 0.17\, R_\odot$, and an effective temperature of $T_{\text{eff}} = 9180^{+240}_{-230}$ K. We find that the host is nearing the end of its time on the main sequence and has begun to evolve, allowing for a precise age estimation of $396 \pm 46$ Myr for the system using
stellar evolution models. This adds an important data point to the handful of well-characterized transiting brown
dwarfs with reliable age estimates, allowing us to test the latest substellar
evolution models. Theory of
tidal evolution predicts that
tidal dissipation mechanisms have circularized the orbit, consistent with the observed near-zero eccentricity.
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All authors Nino Ephremidze, David W. Latham, Perry Berlind, Allyson Bieryla, Michael L. Calkins, Gilbert A. Esquerdo, Samuel N. Quinn, Joseph E. Rodriguez, Noah Vowell, Jack Schulte, Hugh P. Osborn
Quantum Physics
Correlating spin and optical properties of quantum emitters in hBN
Nika Teran, Benjamin Whitefield, Nicholas Sloane et al. (+3 more)
Optically addressable
spin defects in hexagonal boron nitride (hBN) are well suited for near-surface
quantum sensing. They offer bright, wavelength-tunable single-
photon emission with high optically detected
magnetic resonance (ODMR) contrast at room temperature. Here we controllably synthesise a high density of
spin-complex defects in carbon-doped hBN flakes. We find that the zero-field splitting parameter D is directly correlated with the zero-
phonon line of an emitter, while the ODMR contrast shows no such correlation. We further analyse an individual narrowband defect showing 68% ODMR contrast and enhance its
photon collection by ~40% using a solid immersion lens. By advancing both the practical synthesis of the
spin complexes and the understanding of their microscopic origin, our results move us toward the deterministic creation of ODMR-active
quantum emitters
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All authors Nika Teran, Benjamin Whitefield, Nicholas Sloane, Kenji Watanabe, Takashi Taniguchi, Igor Aharonovichand Mehran Kianinia
Fluid Dynamics
Construction of flexible wing models by combined manufacturing of additive and subtractive processes for transonic wind tunnel testing
Natsuki Tsushima, Kensuke Soneda, Kenichi Saitoh et al. (+1 more)
This study presents a systematic manufacturing approach that combines metal additive manufacturing and subtractive machining to construct flexible wing models for transonic wind tunnel testing. Two wing designs were fabricated and evaluated in terms of
geometric accuracy, structural characteristics, and aeroelastic behavior. Three-dimensional scanning, static load tests, ground vibration tests, finite element analyses, and transonic wind tunnel tests were conducted. The fabricated models reproduced the designed geometries and structural properties with good accuracy. The average surface roughness was below 1.0 micrometer, and the average surface deviation was below 0.3 mm, improving
geometric precision over previous skill-dependent polishing methods. Independently manufactured models also exhibited highly consistent flutter behavior, with measured flutter frequencies of 157.0 and 158.0 Hz. The results demonstrate that the combined additive and subtractive manufacturing approach enables efficient and reproducible production of flexible wing models for reliable aeroelastic wind tunnel experiments.
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All authors Natsuki Tsushima, Kensuke Soneda, Kenichi Saitoh, Kazuyuki Nakakita
Superconductivity
Pressure induced magnetic-field-free superconducting diode effect in NbSe2 flake
Shihao Zhu, Tian Le, Cuiying Pei et al. (+17 more)
The superconducting diode effect (SDE) is a fascinating nonreciprocal phenomenon where the critical current is different for opposite current directions. It is widely believed that realizing SDE requires breaking both inversion
symmetry (IS) and time-reversal
symmetry (TRS), which are usually achieved via
heterostructure engineering and applying external
magnetic fields. Here, we report a pressure-induced
magnetic-field-free SDE in NbSe2 flakes without any
heterostructures. We show that pressure alone breaks the IS, as confirmed by the second harmonic generation. Crucially, upon applying an out-of-plane
magnetic field (B), the SDE exhibits even-in-B behavior, implying the absence of explicit TRS breaking. This finding challenges the prevailing theoretical paradigm and demonstrates that a
magnetic-field-free SDE can emerge without explicitly breaking TRS. Thereby, our work establishes pressure engineering as a powerful tool for inducing nonreciprocal superconductivity and designing versatile,
magnetic-field-free superconducting devices.
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All authors Shihao Zhu, Tian Le, Cuiying Pei, Changhua Li, Yi Liao, Yi Zhao, Lingxiao Zhao, Qi Wang, Juefei Wu, Qilian Zhang, Yueshen Wu, Tonghuan Fu, Xujie Lü, Wenge Yang, Jie Shen, Jun Li, Yulin Chen, Xiao Lin, Wen-Yu He, Yanpeng Qi
General Relativity and Quantum Cosmology
A generalization of the Fredenhagen-Haag derivation of Hawking radiation for a class of Vaidya space-times
Felipe Dilho Alves
We develop a quantitative Fredenhagen–Haag like approach for describing Hawking radiation using massless scalar fields on controlled spherically symmetric Vaidya space-times. The local thermal character of the system is supplied by the universal scaling limit of Hadamard two-point functions at an outer trapping horizon \cite{KurpiczPinamontiVerch2021}. On regular detector–horizon windows, we construct globally
hyperbolic developments and compare the nonautonomous Vaidya
evolution with a frozen Schwarzschild propagator on Sobolev energy spaces. We derive an explicit Duhamel estimate that is uniform in angular momentum, calculate the exact linear null-peeling coefficient, and bound the quadratic remainder of the ray map. Combining these estimates with positivity gives a two-sided detector-response inequality relative to the local thermal reference. Its error terms quantify operator variation, stationary scattering tails, finite Hadamard scaling, horizon localisation, and the outgoing channel. The inequality is valid at finite parameters because each of these contributions is retained. Under the decay hypotheses, the detector response converges to the corresponding Fredenhagen–Haag form for asymptotically stationary
accretion and for evaporation–
accretion turnaround profiles. We also construct a Hadamard state by Cauchy transport from an eventually stationary Unruh covariance and show that a finite evaporating slab does not determine a late-time response without a prescribed future extension. For asymptotic evaporation with $m(u)>0$ at every finite time and $m(u)\to0$, a mass-rescaled conformal formulation yields a scale-covariant finite-window estimate for scale-following detectors.
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Chaotic Dynamics · Cross-listed from cs.RO
Passively Safe Convex Guidance for Cislunar Rendezvous and Proximity Operations
Ian M. Down, Connor Plaks, Matthew Bolliger et al. (+1 more)
This paper presents purely convex programs for passively safe impulsive rendezvous and proximity operations in cislunar orbits. Approach, arrival, and abort maneuvers are all designed and validated in the context of maneuver execution error and
navigation uncertainty, and formulated for efficient onboard execution in the autonomous scenario. The outlined methods form the baseline onboard guidance routines for NASA's CAPSTONE 02 mission planned to demonstrate autonomous rendezvous and proximity operations capabilities in the southern 9:2 synodic near rectilinear
halo orbit. High fidelity closed loop Monte Carlo simulations using the planned relative
navigation sensor suite and measurement cadence verify the intended maneuver design performance.
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All authors Ian M. Down, Connor Plaks, Matthew Bolliger, Michael Caudill
Superconductivity
Pressure-induced Superconductivity in Thermoelectric Semiconductor Mg3Sb2
Cuiying Pei, Yasong Wu, Airan Li et al. (+14 more)
The intrinsic electronic structures of narrow bandgap thermoelectric (TE) materials serve as a platform for the investigation of coupling effects of quasi-particles under high pressure, enabling the exploration of emerging electronic and
phonon transport, superconductivity, and topological transition. Here, we report the discovery of pressure-induced superconductivity in the TE
semiconductor Mg3Sb2. Upon the increased pressure, the metallization occurs at 8.7 GPa, followed by a superconducting transition concomitant with a carrier-type crossover from p- to n-type. This phenomenon arises from a pressure-induced structural phase transition from the semiconducting P-3m1 to the metallic C2/m-I phase. The superconducting critical temperature (Tc) exhibits a dome-shaped pressure dependence, peaking at 3.3 K at 12.6 GPa. Combined theoretical calculations, high-pressure Raman spectroscopy, and X-ray diffraction (XRD) measurements reveal an additional structural transition above 20 GPa, yielding a distinct C2/m-II phase. Our findings establish the high-pressure phase diagram of Mg3Sb2, elucidate its pressure-dependent electronic properties, and provide valuable insights for future investigations of TE materials under high pressure.
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All authors Cuiying Pei, Yasong Wu, Airan Li, Juefei Wu, Qi Wang, Yifan Zhu, Yi Zhao, Lingling Gao, Changhua Li, Weizheng Cao, Shihao Zhu, Mingxin Zhang, Yulin Chen, Chenguang Fu, Tiejun Zhu, Jiong Yang, Yanpeng Qi
Quantum Physics
Heralded Free-Electron Writing of the Most Subradiant State in an Atomic Array
Tong Shen, Zhexin Zhao and Meng Xiao
The most subradiant eigenstate of a finite subwavelength atomic chain in free space, protected by strongly suppressed radiative decay, offers a powerful resource for
photon storage,
quantum sensing, and many-body
quantum optics. Yet its optical preparation is hindered by the simultaneous need to match a wave vector outside the light cone and a nonuniform envelope. Here, we show that a free electron can overcome these constraints: its velocity sets the imprinted wave vector, while the trajectory of the diffracting wave packet shapes the excitation envelope. This simultaneous momentum and envelope matching enables heralded preparation with near-unity conditional fidelity ($F>99.5\%$) even in a deeply subwavelength regime that is difficult to access with propagating free-space
photons. We further show that a path-superposed free electron can excite an antisymmetric state in two closely spaced parallel chains, whose interchain destructive interference yields stronger subradiance than a single chain with the same total number of atoms. These results establish free electrons as
quantum writers for collective excitations that are difficult to access with propagating optical fields.
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Mesoscale and Nanoscale Physics
Xuzhe Ying and Benjamin T. Zhou
When an electron-doped layer is stacked with a hole-doped layer with approximately equal carrier density, inter-layer Coulomb interaction turns the
bilayer system into an
exciton condensate (EC). In this Letter, we reveal a fundamental property of
bilayer ECs: the excitonic order gives rise to nontrivial hidden
quantum geometric effects in the correlated electron-hole bands, even when the non-interacting bands are trivial. Such peculiar EC-driven
quantum geometry manifests itself in a characteristic out-of-plane polarization response upon applying an in-plane AC electric field to the
bilayer EC system. In particular, the second-order response exhibits a characteristic inverse square scaling with the
bilayer EC order parameter. Our finding reveals a fundamental hidden Berry phase effect driven by electron-hole correlations, and establishes
bilayer EC as a promising platform for rich nonlinear physics.
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High Energy Astrophysical Phenomena
EP241113a: dissipative photospheric emission from a dirty fireball
Cui-Yuan Dai, Xiang-Yu Wang and Bing Zhang
EP241113a, a soft X-ray transient detected by the Einstein Probe (EP), has an isotropic-equivalent energy ($E_{\gamma,\rm{iso}}\sim 10^{51}{\, \rm erg}$) comparable to classical gamma-ray bursts (GRBs) but an exceptionally low peak energy ($E_{\rm{p}} \lesssim 1 \, {\rm keV}$), placing it off the canonical $E_{\rm{p}}$–$E_{\gamma,\rm{iso}}$ (Amati) relation at $>3\sigma$ confidence. The afterglow of EP241113a is also unusual, with an extremely low plateau luminosity and no jet break up to the latest observation. Such properties have been interpreted as arising from an energetic “dirty fireball,” i.e., a relativistic jet with energy comparable to classical GRBs but much higher
baryon loading, leading to a bulk Lorentz factor of $\Gamma\sim 20$. In this Letter, we propose that low $E_{\rm{p}}$ arises from dissipative photospheric emission in such a low-$\Gamma$ jet. As $\Gamma$ decreases, the photosphere shifts outward while the internal shock radius moves inward, causing dissipation to occur well below the photosphere and making the
prompt emission photosphere-dominated. Meanwhile, the thermalization radius also moves outward, reducing the comoving radiation temperature where the spectral peak is established. Combined with weaker Lorentz boosting, these effects naturally shift the observed $E_{\rm{p}}$ into the soft X-ray band. We further suggest that such a low-$\Gamma$ jet may be powered by
neutrino–antineutrino ($\nu\bar{\nu}$) annihilation in a hyperaccreting disk formed during the core collapse of a massive
star. Compared with the Blandford–Znajek process,
neutrino annihilation can produce a dirtier jet through
baryon entrainment from a
neutrino-driven wind. EP241113a-like events therefore offer new insight into the dissipation physics and launching mechanisms of jets from collapsing massive
stars.
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Optics
Breaking the trade-off between invisibility and sensitivity in electromagnetic sensing
Yichao Liu, Jiaxue Zhou, Weifeng Han et al. (+6 more)
Weak electromagnetic signals demand highly sensitive sensors, yet increasing a sensor's sensitivity inevitably strengthens its interaction with the surrounding field, producing scattering that perturbs the very signals being measured. Conversely, existing cloaking strategies suppress scattering only by isolating the sensor from incident waves, thereby compromising signal reception. Resolving this long-standing trade-off between invisibility and sensitivity has remained an outstanding challenge. Here we overcome this dilemma through an integrated transformation-optical architecture that co-designs the entire sensing system, including the electrically large sensor body, the subwavelength sensing probe, and their electrical interconnection. The proposed multifunctional core-shell structure guides incident waves around the sensor body while simultaneously concentrating them into the sensing region without disturbing the external electromagnetic field. A deep-subwavelength aperture preserves electrical connectivity without degrading either cloaking or field concentration, enabling invisible sensing within a single platform. A microwave prototype based on practical optic-null-medium metamaterials experimentally demonstrates broadband scattering suppression exceeding 3 dB together with an average sixfold enhancement of the detected signal over 4.9-5.1 GHz. By simultaneously eliminating measurement-induced field perturbation and amplifying the local sensing field, our approach establishes a general framework for invisible yet highly responsive electromagnetic sensors, opening new opportunities for weak-signal detection in biomedical diagnostics, secure communications,
quantum technologies, and deep-space exploration.
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All authors Yichao Liu, Jiaxue Zhou, Weifeng Han, Hanchuan Chen, Fei Sun, Qin Liao, Hengxiang Zhang, Xiaofan Ji, Yawen Qi
Atmospheric and Oceanic Physics
Recent Sharp Rise in Inhomogeneous Hydrological Extremes Stress Vegetation Growth in China
Shengyuan Liu, Jeremy Cheuk-Hin Leung, Jianjun Xu et al. (+6 more)
The intensifying spatial inhomogeneity of rainfall under greenhouse warming implies that more inhomogeneous hydrological extremes (IHEs), i.e., coexistence of extreme rainfall or drought, may be triggered. While vegetation growth in China is sensitive to hydrological hazards, the variability of IHEs and their ecological impacts remain underexplored. Here, we find a significant increase in IHEs during China's growing season since 2000 (+2.1 events or +14.52 days per decade), with a rapid sharp rise to an annual average of 6.4 events or 42.0 days in the past five years. The primary driver is the enhanced inhomogeneity of moisture-dynamic coupled weather conditions, overlapping with a northward shift of climatological precipitation distribution. This results in a "Wet-North and Dry-South" pattern of IHE impacts, which poses severe and asymmetric threats to vegetation growth in China, with the expansion of drought areas exerts stronger stress on vegetation than the compensatory effects of rainfall. Our findings suggest that the sharp rises of IHEs tend to yield net negative impacts on vegetation growth, highlighting the need for stronger hydrological management to reduce future risks.
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All authors Shengyuan Liu, Jeremy Cheuk-Hin Leung, Jianjun Xu, Kunlun Xiang, Shifei Tu, Meiying Zheng, Daosheng Xu, Yi Li, Banglin Zhang
Fluid Dynamics
Statistical Analysis of Droplet Size Distributions in Liquid-Jet-in-Crossflow Atomization
Tom Johny, Bharat Bhatia, Zafar Alam et al. (+1 more)
This study investigates the droplet size distribution (DSD) and atomization characteristics of a
liquid jet injected into a crossflow (LJICF) under varied momentum flux ratios, Weber numbers, and flow conditions. Numerical simulations are performed using the validated compressible Volume of Fluid-Lagrangian Particle Tracking (VOF-LPT) coupled framework to capture both the primary and secondary atomization processes. Key parameters, including momentum flux ratio, Weber number, crossflow pressure, and velocity, were analyzed to assess their impact on droplet size characteristics, including Sauter mean diameter (SMD) and standard deviation (STD) in the downstream region. The discrete size distribution of droplets comprising probability density and cumulative distribution reveals a shift toward finer, more uniform droplets under enhanced breakup conditions. The findings emphasize the critical role of aerodynamic forces and instabilities in driving efficient atomization, with higher momentum flux ratios and Weber numbers leading to finer and more uniform droplets. Increased crossflow pressure promotes finer droplet formation but is found to reduce droplet density in the downstream domain due to a confined spray plume, delayed particle conversion, and reduced droplet residence time. The log-normal and Rosin-Rammler distributions effectively capture droplet size trends, with the former closely representing the skewness and tail behavior and the latter accurately representing intermediate and larger droplets. However, both have limitations in replicating sharp peaks and the smallest droplet sizes, respectively.
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All authors Tom Johny, Bharat Bhatia, Zafar Alam, Ashoke De
Quantum Physics
Physics-Informed Quantum Machine Learning with Hard Constraint Embedding for Nonlinear Differential Equations of the First Order
Mengke Xu, Xi Li, Xiao Chen et al. (+4 more)
Quantum algorithms based on linear-system approaches for solving differential equations demand
qubit and precision resources beyond near-term capabilities. To address these challenges, this work proposes a physics-informed
quantum machine learning (PIQML) framework with hard constraint
embedding, specifically designed for NISQ era. Within this framework, parameterized
quantum circuits serve as machine learning models, where the input variable is encoded into a high-dimensional feature space via a
Fourier feature map. Subsequently, to eliminate approximation errors in critical physical conditions, the solution is constructed through a rigorously designed function mapper that analytically enforces initial conditions as hard constraints. Crucially, we compute derivatives with respect to the input variable using the parameter-shift rule—a
quantum native gradient evaluation technique that avoids classical discretization. Unlike generic loss functions that target abstract data patterns, our loss function focuses on the differential equation residual and reference data. This design ensures that the trained model not only approximates the data but also intrinsically satisfies the physical constraint expressed by the DE itself. Our method is validated on several differential equations, including highly oscillatory ones, demonstrating its capability to tackle challenging nonlinear dynamics. Results demonstrate that our
quantum model successfully learns the solution, showing close agreement with a high-precision classical numerical
benchmark.
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All authors Mengke Xu, Xi Li, Xiao Chen, Xunan Wang, Wanli Huo, Long Ma, Weiqi Yan
Fluid Dynamics
Flame Dynamics of Air-Diluted Methanol spray Combustion in Confined Swirling Vitiated Hot Coflow
Zafar Alam, Bharat Bhatia and Ashoke De
This study employs swirling hot coflow to ensure improved fuel-air mixture and stable flame, which are essential for designing low-emission, swirl-stabilized combustors. The present study introduces a swirling confined hot coflow around an air-diluted methanol spray. We have used the Eulerian-Lagrangian approach for multiphase simulation, resolving the dispersed
liquid phase via the Lagrangian framework while addressing the continuous gas phase through the Eulerian framework. The Modified Flamelet Generated
Manifold (FGM) model facilitates accurate and computationally efficient simulation of gas-phase reactions. The swirl numbers (SN), which are 0.2, 0.6, 1.0, 1.4, 2.0, and 3.0, are employed in this study to evaluate their impact on flame stability and auto-ignition. A higher lift-off height is observed as the swirl number rises from lower to moderate (SN = 0.2, 0.6, and 1.0). It decreases after the lift-off height reaches the critical swirl number (SN=1.0). These large swirl numbers also cause the time-averaged flame structure to change from a sharp columnar flame to an evenly spread combustion region. It also produces a more compact and widely dispersed flame for higher swirl numbers. Particle statistics, Flame Index, proper orthogonal decomposition (POD), and the mean gas-phase flow field distribution are used to study these impacts on flame dynamics in detail.
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Strongly Correlated Electrons
Exotic superconductivity in the doped Kitaev quantum spin liquid
Takahiro Misawa and Kota Ido
We investigate superconductivity in a doped Kitaev
quantum spin liquid by applying the many-variable variational Monte Carlo method to the hole-doped $t$-$J$-type Kitaev model. Using a projected pair-product wave function that can exactly represent the Kitaev
quantum spin liquid, we examine the stability of superconducting phases on isotropic two-dimensional clusters. For the
ferromagnetic Kitaev interaction, robust triplet $p$-wave superconductivity coexists with ferromagnetism in the low-to-intermediate doping regime but is suppressed as the system approaches the fully polarized
ferromagnetic phase. For the
antiferromagnetic Kitaev interaction, superconductivity exhibits a change in the dominant pairing
symmetry from
spin-dependent triplet $p$-wave at low doping to singlet $d+id$ at intermediate doping. By varying the strength of the
ferromagnetic Kitaev interaction at fixed doping, we show that the triplet superconductivity increases together with the
ferromagnetic moment and becomes strongest slightly below full polarization. Our results provide a theoretical basis for experimental searches for unconventional superconductivity, such as triplet superconductivity coexisting with ferromagnetism, in carrier-doped Kitaev candidate materials.
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Nuclear Theory
Does strange meson condensation reduce the moment of inertia of massive proto neutron stars? insights at S = 1 and YL = 0.4
Nie-Cheng Jian and Xian-Feng Zhao
We investigate the effects of strange
mesons (sigma-
star and phi) on the structural and rotational properties of massive proto
neutron stars (PNSs) within the relativistic mean-field (RMF) framework. Using the TW99 parametrization with
entropy per
baryon S=1 and
lepton fraction YL=0.4, we solve the TOV equations and compute the moment of inertia via the Hartle-Thorne approximation. Among eight parametrizations, TW99 is chosen as it gives the largest maximum mass. Our results show that strange
mesons soften the equation of state at high densities, reducing both the maximum mass and radius. The moment of inertia peaks at a lower central density than the maximum mass, and strange
mesons shift this peak toward higher densities while slightly lowering its value. The relative change in I is negligible for PNSs below 2.1
solar mass, but decreases to about -0.6 at 2.7
solar mass, indicating that strangeness effects are most relevant for the most massive
stars. Our findings provide useful constraints on the rotational
evolution of massive PNSs and their potential gravitational-wave signatures.
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