Mesoscale and Nanoscale Physics
Layer-Number-Controlled Symmetry Breaking and Surface-State Transport in Rhombohedral Graphene Multilayers
Bosai Lyu, Jian Zheng, Kai Liu et al. (+12 more)
Rhombohedral multilayer
graphene hosts layer-polarized flat bands, providing an intriguing platform for correlated and topological electronic states; however, the role of layer number in governing
symmetry breaking and surface screening remains elusive. Here we prepare rhombohedral
graphene multilayers and systematically conduct electrical transport measurements. We uncover an unconventional layer dependence of phase transitions: the critical displacement field (D$_{c}$) for the layer-
antiferromagnetic (LAF)-to-semimetal transitions remains constant across tetralayer to hexalayer
graphene, whereas the D$_{c}$ for semimetal-to-layer-polarized-
insulator (LPI) transition increases with layer number, defying unscreened Coulomb interaction models. In hexalayer
graphene, surface-state-dominated transport emerges, with Landau levels (LLs) and resistive peaks selectively controlled by adjacent gates, a signature of strong interlayer screening absent in thinner stacks. High
magnetic fields reveal valley-layer-locked LLs and dissipative states possibly from interlayer backscattering, highlighting the presence of decoupled surface states. Our findings establish layer number as a key tuning knob for engineering correlated and topological phases in rhombohedral
graphene multilayers.
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All authors Bosai Lyu, Jian Zheng, Kai Liu, Yulu Ren, Size Wu, Yating Sha, Shuhan Liu, Youngju Park, Kenji Watanabe, Takashi Taniguchi, Jinfeng Jia, Zhiwen Shi, Jeil Jung, Weidong Luo, Guorui Chen
Chemical Physics
A Perspective on Phase Space Electronic Structure Theory : From Its Surface Hopping Origins Through To Its Future Promise
Joseph E. Subotnik, Ethan Alguire, Nicole Bellonzi et al. (+20 more)
We trace the history of phase space electronic structure theory (PSEST), high- lighting how this powerful approach emerged from fundamental questions in semi- classical surface hopping dynamics and evolved into an alternative to standard Born- Oppenheimer based electronic structure theory (with moving instead of frozen
nuclei). Our goal herein is not to recapitulate the mathematical details of phase space electronic structure calculations, and few equations are presented so as to maximize readability. Instead, our goal is to provide intuition for those new to the field both (i) regarding the physics present when solving the Schrodinger equation in a non-inertial frame as well as (ii) regarding why PSEST is a necessary step forward towards understanding chemical problems involving
spin (with limited practical alternatives). We further high- light some of the many open questions in this fast developing area, which will hopefully inspire new practitioners in this field. This intuitive perspective lacks many equations and is meant to complement (rather than replace) the more technical review given in Bian et al, Chem. Phys. Rev. 7, 011303 (2026)
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All authors Joseph E. Subotnik, Ethan Alguire, Nicole Bellonzi, Xuezhi Bian, Mansi Bhati, Nadine Bradbury, D. Vale Cofer-Shabica, Ben Curlee, Titouan Duston, Shervin Fatehi, Gaohan Miao, Zheng Pei, Linqing Peng, Tian Qiu, Zhen Tao, Hung-Hsuan Teh, Xinchun Wu, Yanze Wu, Zain Zaidi, Yihan Shao, Jonathan Rawlinson, Neil Shenvi, Robert Littlejohn
Materials Science · Cross-listed from cs.CE
Predicting Mechanical Properties of Lignin-Containing Polyurethane Rigid Foams from Microstructure Using Convolutional Neural Networks
Ilige S. Hage, Charbel Y. Seif, Jose Enrico Q. Quinsaat et al. (+5 more)
Bio-based alternatives for conventional rigid foams have proven to be good substituents owing to their enhanced sustainability and competitive performance. However, because their manufacturing processes are complex and destructive testing is often impractical, this study investigates whether microstructural features can be correlated with mechanical properties in lignin-containing rigid polyurethane (PU) foams using machine-learning approaches. Various types and percentages of lignin-based polyols were investigated as a partial polyol replacement. Scanning electron microscopy (SEM) images and corresponding mechanical compression data were used to train a custom state-of-art dual-head convolutional neural network (CNN) targeting the specific prediction of density, specific compression modulus, specific yield strength, and specific compression strength. The CNN was optimized with a weighted multi-output loss function, achieving strong predictive performance R2 values ranging from 0.850 to 0.91 and correlation coefficients above 0.92 while maintaining mean absolute error percentages below 9%. This proves the trained network capability to predict and capture morphological features governing load bearing responses. On the other hand, Grad-CAM visualization revealed that the network focused its predictions on physically meaningful microstructural regions such as
cell walls and strut junctions, which confirm that the proposed network can be classified as an interpretable, non-destructive and data-driven framework for predicting and understanding bio-based PU foams mechanical behavior, hence reducing the inconvenience caused by time consuming manufacturing and destructive testing.
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All authors Ilige S. Hage, Charbel Y. Seif, Jose Enrico Q. Quinsaat, Daniel J. van de Pas, Richard Vendamme, Walter Eeversd, Karolien Vanbroekhovend, Elias Feghalid
Fluid Dynamics
Anisotropic Thermalization in Far-from-Equilibrium Flows
Arnab Debnath, Timothy Breitzman and Kaushik Dayal
We present a deterministic discontinuous Galerkin (DG) finite-element solution of the Boltzmann equation, without moment-closure approximations, under a class of far-from-
equilibrium deformations. Specifically, we consider affine flows which reduce the Boltzmann equation to a purely velocity-space problem for the reduced distribution function in a reduced velocity field. We solve the reduced equation using a tensor-product Lagrange DG discretization for four representative flows: simple shear, pressure shear, bi-directional shear, and a
vortex flow. Our principal finding is that the velocity distribution is well-approximated by an anisotropic Gaussian throughout the
evolution, despite the non-
equilibrium conditions. Further, we show the
evolution of the covariance tensor of the Gaussian distribution is equal to the inverse of the right Cauchy-Green tensor in the free-streaming limit without collisions. This prediction compares very well with the numerical solution at short times; at longer times, they grow apart, reflecting the influence of particle collisions.
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Solar and Stellar Astrophysics
Numerous bow shocks in the outer Helix Nebula
Pieter van Dokkum, Roberto Abraham, William P. Bowman et al. (+5 more)
Near the end of their lives, low- and intermediate-mass
stars expel metal-enriched material in winds and
outflows, ultimately producing planetary nebulae (PNe). The ejected material is expected to fragment and mix into the interstellar medium (ISM), but this final assimilation step has been difficult to observe directly. Here we report evidence for this process in the form of twenty-two bow shocks in the eastern outskirts of the Helix Nebula, detected in H$\alpha$ emission with the partially completed MOTHRA
telescope. Unlike the large-scale wind-ISM bow shocks commonly observed around evolved
stars, the shocks are compact and associated with individual clumps of gas. Going outward from the central
star, the radius of
curvature $R_c$ decreases by a factor of ~100 over the radial range r=0.4-1.4 pc. This is accompanied by a morphological transition from thin, well-defined bows to fuzzy, patchy structures. We interpret these changes as progressive stripping and fragmentation of AGB-shell remnants as they interact with the ISM. The slope of the observed $R_c - r$ relation implies a loss of fragment coherence on a timescale of ~10,000 yr, providing a rare direct constraint on the time-scale for disruption and entrainment of fragmented
stellar ejecta into the ISM.
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All authors Pieter van Dokkum, Roberto Abraham, William P. Bowman, Seery Chen, Steven R. Janssens, Deborah M. Lokhorst, Imad Pasha, Carter Rhea
Solar and Stellar Astrophysics
Diameters and Temperatures VII: High-angular resolution measurements of Solar-type stars with the CHARA Array
Tabetha S. Boyajian, Ashley A. Elliott, Emelly D. Tiburcio et al. (+8 more)
We present interferometric measurements of angular diameters for 27 nearby
solar-type
stars obtained with the Precision Astronomical Visible Observations (PAVO) beam combiner at the CHARA Array. The sample spans a broad range of
metallicities, includes several known
exoplanet hosts, and covers evolutionary stages from the zero-age main sequence to mildly evolved subgiants. Uniform-disk and limb-darkened angular diameters were measured for each target and combined with bolometric fluxes and
Gaia parallaxes to determine precise, model-independent
stellar radii, effective temperatures, and luminosities. We achieve typical uncertainties of $\sim1$% in radius and $\sim1.5$% in effective temperature. Comparisons with multiple
stellar evolutionary model grids yield mass and age estimates and enable assessment of grid-to-grid systematics, highlighting sensitivities to abundances, evolutionary stage, and proximity to grid boundaries. Our results provide empirical
benchmarks for testing
stellar evolutionary theory, refining surface brightness-color relations, and improving the characterization of
exoplanet host
stars.
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All authors Tabetha S. Boyajian, Ashley A. Elliott, Emelly D. Tiburcio, Kaspar von Braun, Gail Schaefer, Timothy R. White, Daniel Huber, Michael Ireland, Jeremy Jones, Tyler Ellis, Eliot Hiegel
Atomic Physics
Compact Actively-Shielded Magnetic Field Coil within Mu-Metal Shields for ACME Electric Dipole Moment Measurements
S. Liu, M. Watts, C. Diver et al. (+13 more)
A system of actively-shielded coils and mu-metal shields is devised, constructed and shown to provide the stable and spatially uniform
magnetic field needed for the ACME III electron electric dipole moment (eEDM) measurement. Two layers of current-carrying coils, enclosed within three layers of
ferromagnetic shields, produce a field that varies by less than 1 nT (10 $\uG$) within the 1 m $\times$ 4.2 cm $\times$ 4.2 cm interior volume in which a beam of ThO molecules are probed as they precess. The demountable shields are constructed from rectangular mu-metal plates. The largest, with a mass of 19 kg and an area of 2.18 m $\times$ 0.75 m, is easily carried by two people and just fits within a large available annealing oven. The assembly design facilitates low-stress mounting and handling to suppress changes in the
magnetic properties of the mu metal, and also provides modular access to apparatus within the coils for maintenance and upgrades. The nearly static external ambient field is reduced within the shielded precession volume by up to a factor of $10^5$. During the
magnetic field reversals that ACME uses to suppress systematic uncertainties, the “actively-shielded” coil largely cancels out its external fringing field to minimize the magnetization of the mu metal. Even though the shields are only 10 cm outside the coils, shield degaussing after every
magnetic field reversal is not required. The non-reversing residual field stays below 1 nT for up to 17 hours when the field is reversed every 30 seconds, for example. The measured performance, compared to the previous generation ACME II apparatus, suggests that the
magnetic-field-related systematic uncertainties for ACME III will be smaller by an estimated factor of 40 despite a five times longer precession volume and the use of three
magnetic shielding layers rather than five.
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All authors S. Liu, M. Watts, C. Diver, D. G. Ang, C. Meisenhelder, X. Fan, B. Hao, D. Lascar, A. Hiramoto, T. Masuda, P. Hu, Z. Han, X. Wu, D. DeMille, J. M. Doyle, G. Gabrielse
Solar and Stellar Astrophysics
Solar-Cycle Modulation and Photospheric Magnetic Control of Turbulence in the Young Solar Wind
Yanwen Wang, Rohit Chhiber, Arcadi V. Usmanov et al. (+2 more)
The
solar wind is an
outflow of
solar plasma that expands from the corona to fill the heliosphere. Its
turbulence provides a pathway for non-adiabatic heating and acceleration, and is therefore central to understanding the thermodynamic and magnetohydrodynamic (MHD)
evolution of the young
solar wind. However, the variation of its
turbulence properties over the
solar activity cycle and the connection of these properties to
solar source regions remains incompletely understood. Here we analyze observations from 25
solar orbits of NASA's Parker
Solar Probe (PSP) mission, in combination with a global MHD model, photospheric magnetograms, and extreme ultraviolet maps of the low corona, to investigate the
solar-cycle dependence and the
solar sources of
turbulence in the very inner heliosphere. The observations reveal pronounced
solar-activity variation in fluctuation amplitude, cross helicity, and related
turbulence properties. By tracing PSP-connected
magnetic flux tubes to their
solar sources, we demonstrate that high turbulent-energy intervals are preferentially connected to coronal-hole sources with unipolar
magnetic topology, whereas low turbulent-energy intervals are associated with multipolar
topology and active-region environments. Our study combines in-situ measurements with numerical modeling and remote sensing observations to reveal how
solar-cycle-dependent source structure determines
turbulence variability and
plasma heating in the young
solar wind.
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All authors Yanwen Wang, Rohit Chhiber, Arcadi V. Usmanov, Marc Swisdak, William H. Matthaeus
Computational Physics · Cross-listed from cs.LG
Variational Parameter Calibration with Physics-Aware Latent-Space Surrogates
Qiyao Zhou, Xujia Zhu, Pierre Joli et al. (+2 more)
Forward and inverse modeling of parametric dynamical systems requires surrogate models that are not only accurate for state prediction, but also informative for parameter calibration. However, a systematic end-to-end differentiable formulation for coupling deep-learning-based reduced-order surrogates with variational parameter estimation remains underdeveloped. In this work, we introduce a physics-aware neural-network-based latent-space framework for reduced-order forward modeling and variational parameter estimation. The proposed autoencoder-based approach yields a differentiable surrogate that maps physical parameters to predicted flow fields through a latent representation. The observable supervision is used during offline training to encourage the latent variables to retain information correlated with system parameters, while the online inverse problem is solved in the parameter space through the surrogate-induced observation operator. The method is evaluated on two computational-fluid-dynamics
benchmarks. The results show that reconstruction accuracy alone is insufficient for inverse modeling, owing to the lack of end-to-end differentiability or physics awareness for variational parameter calibration. Quantitative latent-space analysis further shows that observable supervision improves case-level separability and temporal organization of latent representations. Experiments with realistic measurement settings, including noisy, low-resolution, randomly masked, and block-wise partial observations, demonstrate the robustness of the proposed framework and show that it generally reduces calibration error and variability compared with the standard surrogate models.
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All authors Qiyao Zhou, Xujia Zhu, Pierre Joli, Yu Cong, Sibo Cheng
Other Condensed Matter
Giant Effective Permeability in Drude Thin Films Probed by THz Time-Domain Spectroscopy
Gian Paolo Papari, Zahra Mazaheri, Antonio Vettoliere et al. (+7 more)
The electromagnetic response of metallic films is commonly analyzed in terahertz spectroscopy by assuming unit relative
magnetic permeability. In this work we show that this assumption introduces significant distortions in the electrodynamic
retrieval of highly conductive films. Aluminum and copper films, 10 nm thick, were investigated by terahertz time-domain spectroscopy in both transmission and reflection configurations. By applying a self consistent
retrieval method that independently determines the complex permittivity and permeability, we show that the Drude-type dielectric response is systematically accompanied by a permeability that strongly departs from unity. This deviation is intrinsically linked to the reactive impedance of the films, which clarifies the light induced onset of large screening currents within a transversally confined geometry. A phenomenological interpretation based on the Faraday Neumann Lenz mechanism and a lumped-element model of the film impedance accounts for the observed trends. These results indicate that the common assumption $\tilde{\mu}=1$ in non-
magnetic Drude films can lead to an incomplete or biased electrodynamic characterization in the terahertz regime.
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All authors Gian Paolo Papari, Zahra Mazaheri, Antonio Vettoliere, Carmine Granata, Roberto Russo, Giovanni Ausanio, Umar Farooq, Junaid Yaseen, Can Koral, Antonello Andreone
General Relativity and Quantum Cosmology
Imprints of core/cusp dark matter distributions on black hole signatures in galaxies
Hassan Hassanabadi, Che-Yu Chen, Soroush Zare et al. (+1 more)
In
galactic environments, a host dark matter (DM)
halo can imprint weak but coherent corrections on black hole (BH) strong-field observables. We construct an exact family of static and spherically symmetric BH spacetimes sourced by a generic core/cusp DM
halo, described by an anisotropic stress-energy tensor with nonvanishing radial pressure. The resulting geometry is determined self-consistently from the Einstein equations for a broad $\{\alpha,\beta,\gamma\}$ density profile, including the NFW, Moore, Hernquist, Jaffe, and core/cusp Dehnen models as special cases. We discuss the asymptotic structure, horizon location,
curvature scale, and energy conditions of the corresponding geometries, emphasizing that the inner logarithmic slope $\gamma$ controls the amount of DM probed by the relativistic region. We then obtain perturbative analytic estimates for the characteristic circular geodesics, demonstrating that the leading strong-field corrections are controlled by the dimensionless compactness $q_\gamma$, rather than by the total
halo mass alone. To leading order in $q_\gamma$, we derive analytic expressions for the light ring radius, angular frequency, critical impact parameter, Lyapunov exponent, innermost stable circular orbit (ISCO) radius, and ISCO frequency. For cuspy profiles, the light ring and ISCO are displaced outward, while the corresponding orbital frequencies are redshifted; for cored profiles, the light ring radius is unchanged at this order, although its frequency and capture impact parameter still carry finite environmental corrections. We also investigate the weak- and strong-deflection angles and their dependence on the
halo's inner structure. We further discuss how these environmental corrections may affect ringdown physics, in particular through the perturbative imprint of the
halo on quasinormal-mode
redshifts and late-time wave propagation.
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All authors Hassan Hassanabadi, Che-Yu Chen, Soroush Zare, Volker Perlick
Quantum Physics
On the Swapping Capacity of a Quantum Repeater
Van Sy Mai, Richard J. La, Abdella Battou et al. (+2 more)
We study the capacity of a
memory-based
quantum repeater in
entanglement swapping between two
quantum links with either single or multiple
memories, which we refer to as the end-to-end (E2E)
entanglement throughput, subject to a constraint on the minimum fidelity. In order to approximate the E2E
entanglement throughput, we adopt queueing models, where
quantum links can have different characteristics:
memory capacities,
entanglement attempt rates and success probabilities, as well as classical communication latencies. We develop a model for estimating E2E
entanglement fidelity, while taking into account the heterogeneous dephasing and depolarizing dynamics of
quantum memories and Bell-state measurements in
entanglement swapping as well as classical communication delays and noises. Finally, with the help of our models for approximating the E2E
entanglement throughput and fidelity, we use the maximum waiting times of entanglements in
quantum memories at the repeater as optimization variables to maximize the E2E
entanglement throughput while ensuring required minimum E2E fidelity.
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All authors Van Sy Mai, Richard J. La, Abdella Battou, Abderrahim Amlou, Cory Nunn
Superconductivity
Yttrium Superhydrides Revisited: Advanced Experimental and Theoretical Studies of YH$_6$, YH$_9$ and YH$_{10}$
Dmitrii V. Semenok, Pedro N. Ferreira, Di Zhou et al. (+10 more)
Yttrium polyhydrides are
benchmark materials in high-pressure superconductivity, yet several key properties of the Y-H system remain insufficiently characterized. Here we combine contact transport, contactless
radio-frequency measurements, pulsed-field experiments, and first-principles calculations to reinvestigate YH$_6$, YH$_9$, and YH$_{10}$ in the pressure range 140-213 GPa. Yttrium hydrides YH$_6$ ($\textit{$T_c$}$ = 218-221 K) and YH$_9$ ($\textit{$T_c$}$ = 235-237 K) demonstrate narrow superconducting transitions ($\textit{${\Delta}$T$_c$}$ = 2-5 K), approaching the limit imposed by thermal fluctuations. Pulsed-field measurements on YH$_6$ up to 60 T establish an extended superconducting phase diagram with a linear slope $\textit{dB$_{c2}$/dT}$ = -0.52 T/K, pronounced transition broadening above 30 T, and negligible normal-state magnetoresistance. We report the
radio-frequency AC susceptibility study of YH$_6$, providing evidence for superconductivity via high-frequency field screening in a contactless geometry. Experiments involving Pd incorporation, Pd thin-film sputtering, and Al alloying show strong suppression of high-temperature superconductivity, with no transitions detected above 78-120 K. Finally, using density-functional theory with the
stochastic self-consistent harmonic approximation, superconducting density-functional theory, and full-bandwidth Migdal-Eliashberg calculations, we show that anharmonic effects substantially reduce the predicted $\textit{$T_c$}$ of cubic YH$_{10}$ to approximately 260-270 K. These results strongly disfavor room-temperature superconductivity in binary yttrium superhydrides.
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All authors Dmitrii V. Semenok, Pedro N. Ferreira, Di Zhou, Fabian Jőbstl, Andrey V. Sadakov, Kirill S. Pervakov, Burkhan I. Massalimov, Toni Helm, Ryosuke Akashi, Vladimir M. Pudalov, Viktor V. Struzhkin, Christoph Heil, Ivan A. Troyan
Chemical Physics
Second-Derivative-Corrected FANPT for Robust Continuation of Nonlinear Wavefunction Equations
Rugwed Lokhande, Krisztina Zsigmond, Paul W. Ayers et al. (+1 more)
We present a second-derivative-corrected extension of the Flexible Ansatz for N-body Perturbation Theory (FANPT) for solving nonlinear Flexible Ansatz for N-body Configuration Interaction (FANCI) wavefunction equations. The original quasilinear FANPT approximation neglects second- and higher-order derivatives of the determinant overlap with respect to wavefunction parameters. In this work, we retain the overlap Hessian and neglect only third- and higher-order parameter derivatives, thereby including the leading nonlinear response of the wavefunction ansatz while preserving the same response-
matrix structure used in the original FANPT formulation. The resulting additional terms enter only through the constant vector of the response equations and are implemented for coupled-cluster wavefunctions in the FanPy/FANCI framework. The new approximation is tested on the Lithium Hydride molecule and the insertion of Beryllium into H$_2$ using seniority-restricted coupled-cluster wavefunctions in the STO-6G basis. The main advantage of the second-derivative correction is that it provides a better initial guess for solving the projected FANCI equations at the next point along the adiabatic connection. This improvement is diagnosed by comparing the FANPT-propagated parameters with the independently optimized FANCI parameters at the same value of $\lambda$. For nonlinear coupled-cluster ansatzes, especially when larger $\lambda$-steps are used, the corrected approximation reduces the same-$\lambda$ parameter deviations and suppresses large parameter-space excursions. These results show that the leading nonlinear overlap correction improves the reliability of FANPT as a continuation strategy for nonlinear wavefunction equations.
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All authors Rugwed Lokhande, Krisztina Zsigmond, Paul W. Ayers, Ramón Alain Miranda-Quintana
High Energy Physics (Theory) · Cross-listed from math.DG
The $L^2$ metric for hyperbolic 2-monopoles
Guido Franchetti and Derek Harland
It has been recently shown that the notoriously divergent $L ^2 $ metric on the
moduli space of
hyperbolic monopoles can be made finite by the introduction of a modified gauge fixing condition \cite{franchetti:2024}. In this paper we compute this modified $L ^2 $ metric for the mass $\tfrac{1}{2}$ 2-monopoles. The resulting metric is actually a complex non-degenerate bilinear form, which restricts to a Riemannian metric on the 4-dimensional subspace of inversion symmetric 2-monopoles. Remarkably, we have been able to compute the $L ^2 $ form explicitly in terms of elementary functions and
elliptic integrals. Its asymptotic form matches what was expected on the basis of previous results in the literature.
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Materials Science
Symmetry-Dependent Mechanical and Vibrational Response of Formamidinium Lead Halide Perovskites: A DFT Study
Mahdi Faghihnasiri, Carmine Autieri and Sara Memarzadeh
Formamidinium-based hybrid halide perovskites (FAPbX3, X = Cl, Br, and I) have attracted considerable
attention for optoelectronic applications owing to their outstanding optical and electronic properties. However, the influence of
crystal symmetry reduction on their mechanical behavior and stability has not yet been comprehensively understood. In this work, density functional theory (DFT) calculations were performed to investigate the structural, elastic, dynamical, and nonlinear mechanical properties of the cubic and ps-cubic phases of FAPbX3. The elastic constants, bulk, shear, and Young's
moduli, Poisson's ratio, sound velocities, and Debye temperature were evaluated and correlated with the second Piola-Kirchhoff stress-strain response under tensile and compressive loading. The results reveal that the effect of
symmetry reduction is strongly dependent on the halide composition. For FAPbCl3 and FAPbBr3, the transition from the cubic to the ps-cubic phase reduces the
lattice stiffness, decreases the acoustic
phonon velocities, and lowers the Debye temperature, whereas the opposite trend is observed for FAPbI3. The stress-strain analysis further reveals pronounced nonlinear, anisotropic, and asymmetric mechanical behavior, demonstrating that
symmetry reduction can either activate or suppress strain-accommodation mechanisms depending on the halide species, thereby governing the mechanical stability and the onset of structural softening. These findings provide microscopic insight into the relationship between
crystal symmetry,
lattice dynamics, and nonlinear mechanical response in formamidinium-based halide perovskites, offering useful guidance for the design of mechanically robust optoelectronic materials.
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Quantum Physics
Flood of multipartite Rains entanglement
Hailey S. Murray, Sagnik Bhattacharya, M. Cerezo et al. (+2 more)
Multipartite
entanglement admits phenomena such as the activation of genuine multipartite
entanglement (GME) and the existence of inequivalent classes of
entanglement, and existing bipartite
entanglement measures have no unique generalization to this regime. In this work, we define the Rains, monsoon, hurricane, and squall
entanglement as generalizations of the bipartite Rains relative
entropy, and we establish various properties of these
entanglement measures. We also prove that the Rains
entanglement is monotone under selective
quantum operations that completely preserve the positivity of the partial transpose. We establish single-letter upper bounds on the one-shot and asymptotic rates at which a fixed pure state can be distilled from an arbitrary state in both the standard and probabilistic approximate
distillation scenarios. Among the
entanglement measures we define, the tightest upper bound on the one-shot pure-state
distillation rate is in terms of the Rains
entanglement. However, the activation of GME (or, equivalently, the tensor instability of biseparability) makes it unclear if the one-shot bound in terms of the Rains
entanglement can be extended to a single-letter asymptotic bound. Instead, we establish upper bounds on the asymptotic pure-state
distillation rate in terms of the hurricane and squall
entanglement. Upper bounds on the GHZ- and W-distillable
entanglement follow as a consequence. Additionally, we define the multipartite max-Rains
entanglement, write it as a semidefinite program, and derive a dual program for it. Finally, we analyze these measures for
quantum pairwise independent networks, and we establish a conditional gradient (Frank-Wolfe)
algorithm for computing the Rains
entanglement.
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All authors Hailey S. Murray, Sagnik Bhattacharya, M. Cerezo, Liuke Lyu, Mark M. Wilde
Physics and Society
Technology interactions reshape the economics of China's coal power decarbonization
Yun-Long Zhang, Jia-Ning Kang, Xiaoming Kan et al. (+5 more)
Decarbonizing existing coal-fired power plants can contribute to near-term
climate mitigation, but identifying cost-effective retrofit strategies is complicated by interactions among mitigation technologies. Here we develop an interaction-aware optimization framework that jointly evaluates energy conservation, biomass co-firing, and carbon capture across 1,885 coal-fired power plants in China while accounting for plant heterogeneity and shared biomass and CO2 storage resources. We find that technology interactions alter both mitigation costs and the emission reductions attributable to individual measures, thereby changing cost-optimal technology portfolios and marginal abatement cost curve at the fleet level. Approximately 1.2 Gt CO2 yr-1 can be mitigated at negative marginal cost, while reaching carbon neutrality requires a marginal abatement cost of US$56 t CO2-1. Progressively deeper mitigation shifts the cost-optimal portfolio from energy conservation toward biomass co-firing and ultimately carbon capture, with biomass combined with carbon capture enabling net-negative emissions. Explicitly accounting for interactions among mitigation technologies therefore provides a more consistent basis for evaluating coal-power decarbonization and coordinating retrofit investment, infrastructure development, and
climate policy.
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All authors Yun-Long Zhang, Jia-Ning Kang, Xiaoming Kan, Lan-Cui Liu, Zhimin Huang, Song Peng, Biying Yu, Yi-Ming Wei
Astrophysics of Galaxies
Magnetic fields in extreme primordial halos: turbulent collapse and implications for early quasar formation
V.B. Díaz, D.R.G. Schleicher, M.A. Latif et al. (+1 more)
It is sometimes suggested that the most massive
quasars at high
redshift may have formed from rare high-sigma peaks in the
cosmic density field. We explore here the
evolution in a massive
primordial halo corresponding to one of these rare sigma peaks, employing cosmological high-resolution magneto-hydrodynamical zoom-in simulations with initial field strength of $10^{-14}-10^{-8}$ G. The dark matter
halo forms at the intersection of strongly convergent flows, leading to the formation of highly supersonic
turbulence already on intergalactic scales, with turbulent Mach numbers of order $10-20$ also within the
halo. Turbulent
magnetic field amplification has never been explored in this regime and we therefore investigate whether this gives rise to effects similar to those observed in more typical
halos. While the weaker initial field is somewhat more strongly amplified as a result of the shear flows, overall the
evolution in the different simulations is rather similar and the flows are dominated by supersonic
turbulence. We show in particular that the turbulent Jeans mass always dominates over the thermal and
magnetic Jeans masses, and only on scales of $10^{-2}-10$ pc, the
magnetic Jeans mass may become comparable to the thermal one. Our simulations thus strongly suggest the
evolution to be dominated by the large-scale dynamics. As established in previous work, we thus expect the formation of central massive objects of a few times $10^4$ M$_\odot$ also in the presence of
magnetic fields. The situation is somewhat different from more typical atomic cooling
halos, where previous results have indicated a larger relevance of the
magnetic Jeans mass on intermediate scales, potentially enhancing the mass of the massive object.
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All authors V.B. Díaz, D.R.G. Schleicher, M.A. Latif, R. Banerjee
Quantum Physics
Generative Learning for Quantum Measurement Design
Jun Dai, Olivier Nahman-Lévesque, Guillaume Rabusseau et al. (+2 more)
Extracting
quantum information from a
quantum state is a fundamental task of
quantum computation, often requiring the estimation of many non-commuting observables under a finite measurement budget. For both near-term and early fault-tolerant settings, the measurement protocol must balance statistical efficiency against implementation resources such as
circuit depth, connectivity, and entangling-gate count. Many existing strategies focus on two extremes: hardware-friendly product measurements with high sampling cost, and fully commuting measurements with deep
circuits. Here we recast resource-constrained measurement design as a generative learning problem. We introduce FlowMeas, which uses a generative flow network to directly sample finite ensembles of shallow Clifford measurement
circuits subject to a prescribed shot budget and hardware constraints. At zero entangling depth, FlowMeas learns
qubit-wise commuting measurement schedules and already matches or improves leading product-measurement methods on nearly all molecular
benchmarks. Allowing one or two entangling gate layers yields further reductions in energy estimation error of up to $27\%$ relative to the strongest state-independent product-measurement baseline. The learned policy can also be reused across related
Hamiltonians, substantially accelerating retraining along a molecular potential-energy surface. We further obtain results for molecular
Hamiltonians with up to 20
qubits and apply the framework to a compactly encoded 54-
qubit interacting fermionic model, extending the demonstrated scale beyond prior molecular
benchmarks. These results establish generative learning as a flexible and unified framework for
quantum measurement design under practical resource constraints.
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All authors Jun Dai, Olivier Nahman-Lévesque, Guillaume Rabusseau, Hong-Ye Hu, Cunlu Zhou
Optics
Few-cycle electro-optic light on thin-film lithium niobate
Xinyi Ren, Chun-Ho Lee, Ian Christen et al. (+6 more)
The twin fields of ultrafast optics and nonlinear photonics enable applications ranging from attosecond science [1, 2] and ultrafast electronics [3] to molecular spectroscopy [4, 5], nonlinear optics [6-8],
quantum nanophotonics [9] and precision metrology [10]. However, bringing these capabilities-including ultrashort pulse generation, dispersion control, and strong nonlinear interactions-together within a scalable photonic integrated platform requires exceptional performance and cooperation between components while preserving sufficient optical power across the
circuit. Here we demonstrate an integrated multi-functional nonlinear photonic system that transforms continuous-wave (CW) light into high-peak-power femtosecond pulses and harnesses them for pulse-driven nonlinear optics on thin-film lithium niobate (TFLN). Microwave-driven electro-optic (EO) broadening followed by integrated dispersive compression generates 230-fs
Fourier-transform-limited pulses with energies up to 3.3 pJ at 30.7 GHz, representing orders of magnitude higher pulse energy than previous integrated pulse synthesis at comparable repetition rates [11]. In a 0.3-meter dispersion-engineered TFLN waveguide,
soliton dynamics compress the pulses to 35 fs (6.7 optical cycles), accompanied by coherent spectral broadening exceeding 330 nm. In a fully-monolithic architecture, EO synthesis, dispersive compression and a high-Q nonlinear resonator are integrated on a single TFLN chip, enabling resonantly-enhanced pulse pumping and coherent spectral broadening at pulse energies as low as 400 fJ. By unifying microwave-controlled pulse synthesis and pulse-driven nonlinear interactions, our work establishes a direct path from CW excitation to few-cycle nonlinear optics on chip, with opportunities spanning microwave photonics [12], optical frequency synthesis and metrology, and mid-infrared and terahertz generation [13, 14].
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All authors Xinyi Ren, Chun-Ho Lee, Ian Christen, Clayton Cheung, Reshma Kopparapu, Yue Yu, Lian Zhou, Zaijun Chen, Mengjie Yu
Mesoscale and Nanoscale Physics
Large bias-tunable magnetoresistance from spin-dependent interlayer hybridization in van der Waals antiferromagnet CrSBr-based heterostructures
Sadeed Hameed, Aditya Kumar, Chengjie Yu et al. (+5 more)
We explore the large magnetoresistance (MR) in \ce{hBN}/few-layer-
graphene/\ce{CrSBr}/few-layer-
graphene heterostructures and reveal the mechanism behind its non-monotonic bias dependence. Using bias voltage and temperature as independent tuning knobs, we achieve MR up to \SI{350}{\percent} at \SI{20}{K}, characterized by symmetric M-shaped maxima around $\pm 0.5\,\mathrm{V}$. Continuous tuning of the magnetization angle $\theta$ via a hard-axis
magnetic field shows that the barrier band-edge offset varies linearly with $\cos(\theta/2)$, a first-order signature of
spin-dependent interlayer hybridization. This linear relationship rules out the Jullière model and a
spin-filter projection. We conclude that the
magnetic-configuration-dependent band edge, rather than electrode
spin polarization, dictates the large magnetoresistance in \ce{CrSBr} junctions.
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All authors Sadeed Hameed, Aditya Kumar, Chengjie Yu, Aravind P. Balan, Xinran Wang, Lichuan Zhang, Yuriy Mokrousov, Mathias Kläui
Materials Science
Many-Body Destabilization of Intermediate Oxygen-Hole States
Anirudh Adavi, Kayahan Saritas, Ming Lei et al. (+3 more)
Oxygen holes in transition-metal
oxides can appear as localized polarons,
symmetry-delocalized ligand holes, or intermediate states whose stability is controlled by subtle electron-correlation effects. In layered Na$_{2-x}$Mn$_3$O$_7$, hybrid density functional theory (DFT) predicts an unusual bond-centered split oxygen-hole polaron stabilized near ordered Mn vacancies. Here we resolve the nature of this state using
diffusion Quantum Monte Carlo (QMC). Although hybrid DFT favors the split configuration, QMC reverses the energetic ordering and identifies the localized oxygen polaron as the lower-energy state. The result is robust to the class of trial wavefunctions used, including hybrid and generalized-gradient DFT wavefunctions. Many-body
spin densities further show that the nominal split state partially collapses toward a localized polaron. Because localized and split configurations produce similar O K-edge spectral features, this qualitative failure is not resolved by conventional X-ray absorption signatures alone. These findings identify Na$_{2-x}$Mn$_3$O$_7$ as a stringent
benchmark for oxygen-hole polarons and reveal a failure mode of hybrid functionals in correlated
oxides.
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All authors Anirudh Adavi, Kayahan Saritas, Ming Lei, Das Pemmaraju, Paul R. C. Kent, Iwnetim I. Abate
High Energy Astrophysical Phenomena
Long-duration GW Searches for Sub-solar NSs and Superkilonovae using CoCoA
Abby Tejera, Divyajyoti, Alessandra Corsi et al. (+3 more)
On 2025 August 18, the LIGO-Virgo-KAGRA collaboration reported a sub-threshold gravitational-wave (GW) candidate, S250818k, consistent with a binary
neutron star (NS) merger potentially involving a sub-
solar-mass compact object. Follow-up electromagnetic (EM) observations identified a Type IIb
supernova, SN 2025ulz within the broad localization area of the GW signal. This potential link between a sub-
solar GW event candidate and a Type IIb SN, while not confirmed given the low statistical significance of S250818k, has nonetheless sparked renewed interest in the "superkilonova" scenario, where sub-
solar-mass NSs form through processes like the fragmentation of an
accretion disk or core fission in a collapsing
star. In this picture, the in-spiral and merger of a sub-
solar NS-NS binary is followed by the merger of the NS-NS remnant with the central black hole (BH), producing chirp-like GW signals. For sub-
solar NSs with masses in the (0.1-1)M_sun range and BH masses in the so-called lower mass gap range of ~(3-5) M_sun, these signals can persist in the 20 - 1024 Hz frequency band of ground-based GW detectors for (10^2-10^3)s, potentially offering an opportunity to probe the superkilonova scenario, as well as the lower mass gap between NSs and
stellar-mass BHs. However, the complexity of the underlying astrophysics may yield waveforms that deviate from standard templates, limiting the use of matched filtering in real GW searches. We therefore explore the detectability of such signals using the Cross-Correlation
Algorithm (CoCoA), a more robust though less sensitive cross-correlation method. We discuss general strategies for implementing CoCoA superkilonova searches via either targeted follow-up of candidate chirps identified in matched-filter searches, or EM-triggered searches of stripped-envelope core-collapse SNe.
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All authors Abby Tejera, Divyajyoti, Alessandra Corsi, Yossef Zenati, Robert Coyne, Logan Cote
Quantum Physics
Evaluating QAOA expectation values can be as hard as counting optimal solutions
Stuart Hadfield
Evaluating expectation values is a critical task for variational
quantum eigensolvers, parameterized
quantum circuits, and many other
quantum algorithms. We consider the well-studied case of the
Quantum Approximate Optimization
Algorithm (QAOA) for the MaxCut problem. Recent work of Wang et al. [arXiv:2511.20212] showed this task to be NP-hard in general for any QAOA depth $p\geq 2$, complementing past results showing efficiently computable formulas for $p=1$ with arbitrary problem graphs. We sharpen this dichotomy showing that for $p\geq 2$ exact or exponentially precise cost expectation value evaluation is #P-hard under deterministic
polynomial-time Turing reductions. Hardness at $p\geq 2$ is shown to remain even for evaluating single pairwise correlators $\langle Z\otimes Z\rangle $, as well as for highly restricted sets of
algorithm parameters. Our proof refines the NP-hardness construction of Wang et al. that recovers the maximum cut value from the largest exponent of a QAOA Laurent
polynomial, utilizing a distinct and simpler construction that extracts a value proportional to the total number of maximum cuts, in addition to the optimal cut value. Thus we show that the QAOA expectation value hardness transition from $p=1$ to $p=2$ is not only from tractability to optimization hardness, but to that of counting optimal solutions. As an application we show our results imply analogous hardness results for computing gradients and Hessians of QAOA
circuits.
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Physics and Society
Unlocking CCUS-Ready Coal Power Investments: A Spatial Real Options Approach
Yun-Long Zhang, Jia-Ning Kang, Lan-Cui Liu et al. (+3 more)
New coal-fired capacity may still be needed in some economies to support energy security, yet tightening carbon constraints increasingly threaten its long-term investment viability. Designing new plants to be Carbon Capture, Utilization and Storage (CCUS)-ready is therefore critical, but existing investment studies largely neglect the spatial factors that shape CCUS investment viability. In this study, we propose a Spatial Real Options (SRO) framework that couples national-scale siting screening with site-level real-options valuation. A national inventory of technically feasible sites across China (n = 194,027) is linked to a real-options model that incorporates temporal uncertainty together with province-specific conditions, CO2 transport distance, and alternative policy instruments. Results show that the nationwide investable window for conventional coal closes by the early-to-mid 2040s. CCUS integration materially reshapes project economics, but outcomes differ substantially across storage options and transport distances: oil-reservoir storage remains economically attractive at short distances, whereas saline-aquifer storage requires operational incentives to become competitive. Generation-hour compensation substantially outperforms investment-cost subsidies, indicating that operating costs, rather than upfront capital, constitute the binding constraint. The resulting spatiotemporal maps provide a practical decision-support tool for identifying where and when CCUS-ready coal investments are most attractive under progressive decarbonization.
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All authors Yun-Long Zhang, Jia-Ning Kang, Lan-Cui Liu, Yi-Zhuo Ji, Song Peng, Yi-Ming Wei
General Relativity and Quantum Cosmology
Analysis of the equations of motion of fictitious matter in embedding theory
A.J. Ziyatdinov and S.A. Paston
Embedding theory is a possible modification of general relativity that provides a framework for explaining the observed effects typically attributed to dark matter. The idea of this modification is to consider our spacetime as a four-dimensional surface in a ten-dimensional flat ambient space. The equations of motion in
embedding theory can be reformulated as a set of Einstein equations with the contribution of some additional fictitious matter and of equations describing this matter. We analyze static solutions of these equations, which are reduced to fictitious-matter configurations of the wall, string, and ball types. The string case is ultimately described by the Liouville equation, and the ball case is described by its three dimensional analogue. For the string case, we show that as the density contribution decreases at infinity, all solutions to the Liouville equation are rotationally symmetric. For the case of the ball, we show that under the assumption of spherical
symmetry, there exists a unique one-parameter family of solutions that are smooth at the center.
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Nuclear Theory
Projected shell model description of nuclear level density: Collective, pair-breaking, and multiquasiparticle regimes in even-even nuclei
Jiaqi Wang, Saumi Dutta, Long-Jun Wang et al. (+1 more)
There is overwhelmingly experimental evidence indicating that excited
nuclear states are dominated by quasiparticle (qp) excitations, which form many-body configurations with broken nucleon-pairs from different orbitals. By using these multi-qp states as building blocks for a shell-model basis, we propose a novel shell-model method to calculate the
nuclear level density (NLD) in deformed
nuclei. The shell-model diagonalization with two-body residual interactions yields a large ensemble of eigenstates of angular momentum and parity. We demonstrate that NLD as a statistical quantity depends sensitively on the structure of deformed single-particle states. As the first example to introduce this method, we take a well-deformed rare-earth
nucleus, $^{164}$Dy, for which NLD has been studied extensively by the Oslo method. By a quantitative comparison with discrete levels from spectroscopic measurements, we show that while the pronounced stepwise structure in the low-energy NLD curve can be understood as the collective excitation and nucleon-pair breaking, the exponential growth of levels in the higher-energy NLD can be described by the combination of the broken-pair states, subject to the Pauli principle. According to the nature of NLD with increasing excitation, we divide the entire NLD curve into (1) collective regime, (2) pair-breaking regime, and (3) multi-qp regime. We discuss the formation mechanism and characteristic features of NLD for the three regimes. In addition, the parity dependence and angular-momentum dependence in NLD are investigated with a strong emphasis on the structure effect.
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All authors Jiaqi Wang, Saumi Dutta, Long-Jun Wang, Yang Sun
Quantum Physics
Benchmarking Quantum and Classical Machine Learning Models on Oncological Data
Sydney Leither, Thomas Lubinski, Michael Kubal et al. (+1 more)
Machine learning is being increasingly used for the detection, diagnosis, and treatment of cancer. However, models often struggle with biological data due to high dimensionality, limited sample diversity, and complex feature interactions. Recent works have investigated the potential for
quantum machine learning models to exhibit improved performance over classical models on this kind of complex data, but have often lacked rigorous empirical evaluation of
quantum advantage. In this work, we develop a methodology for fair benchmarking of
quantum and classical machine learning models, based on the Red Cedar
quantum machine learning and resource estimation framework and AutoML-optimized classical neural networks. We assess the potential for
quantum advantage in machine learning across tabular, omics, and spatial oncological
datasets drawn from the existing
quantum machine learning literature, with a range of preprocessing methods, and find no evidence of
quantum advantage. Our results suggest that the field should prioritize analyzing higher-dimensional, more biologically realistic
datasets to make meaningful progress toward practical
quantum advantage in oncological classification problems.
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All authors Sydney Leither, Thomas Lubinski, Michael Kubal, Sonika Johri
High Energy Physics (Theory)
False-vacuum bubbles in sphaleron scattering
Manuel A. Martínez Sánchez, Christoph Adam and Danial Saadatmand
We investigate the collision dynamics of two bright sphalerons in a (1+1)-dimensional deformed $\phi^6$ scalar field theory with a symmetric potential possessing false
vacua. Two one-parameter realizations of the model, referred to as the barrier and well models, are considered and their static and linear instability properties are first reviewed. We then study head-on collisions of boosted sphalerons over a broad range of initial velocities and deformation parameters. The scattering dynamics exhibit a rich variety of final states, including the production of kink-antikink pairs, long-lived oscillons in true and false
vacuum, multiple oscillons propagating in false-
vacuum regions, and radiative decay. A particularly remarkable outcome is the emergence of a long-lived bubble of the false broken
vacuum bounded by a kink-antikink pair, which repeatedly collapses and re-expands before eventually decaying into an oscillon. These results demonstrate that deformed $\phi^6$ theories with false
vacua exhibit considerably richer sphaleron dynamics than previously known and provide new insight into the role of unstable localized configurations in nonlinear field theories.
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