High Energy Astrophysical Phenomena
Molecular and Atomic Gas Associated with the Gamma Ray Supernova Remnant RCW 103
H. Inoue, Y. Asano, R. G. Bhuvana et al. (+15 more)
We present a study of the interstellar molecular and atomic gas associated with the gamma-ray
supernova remnant (SNR) RCW 103 using the Mopra $^{12}$CO($J$ = 1-0), Atacama Large Millimeter/submillimeter Array $^{13}$CO($J$ = 1-0), and the Australia
Telescope Compact Array & Parkes HI data. We find that CO clouds in the velocity range from $-58.7$ to $-43.5$ km s$^{-1}$ show a clear spatial correspondence with the X-ray shell of RCW 103, particularly extending from the northwestern to the southeastern regions. The position-velocity diagram of the CO emission reveals an expanding gas motion with an expansion velocity of $\Delta V \sim$$7.5$ km s$^{-1}$, which may have been produced by shock waves and/or
stellar winds from the progenitor system. We estimate the total
cosmic-ray
proton energy to be $\sim$$3.0^{+1.1}_{-0.6} \times 10^{47}$ erg, adopting a total interstellar
proton density of $\sim$$810$ cm$^{-3}$. This value is more than an order of magnitude lower than those inferred for other gamma-ray emitting SNRs of comparable age. Given that a substantial amount of dense gas remains within the interior of RCW 103, where thermal X-ray emission is dominant, our results possibly suggest that a significant fraction of the shock energy may have been converted into thermal energy via gas heating, thereby reducing the efficiency of
cosmic-ray acceleration.
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All authors H. Inoue, Y. Asano, R. G. Bhuvana, R. Z. Alsaberi, R. Yamada, K. Tsuge, T. Murase, Y. Fukui, E. M. Reynoso, K. Tachihara, N. Izumi, M. Yamagishi, K. Furuya, N. Harada, K. Tokuda, G. Rowell, M. D. Filipović, H. Sano
High Energy Astrophysical Phenomena
X-ray Polarization of Inverse Compton Scattering by Thermal and Nonthermal Electrons
Boting Wang, Jirong Mao, Jieying Liu et al. (+1 more)
X-ray emission from
accretion-powered astrophysical systems is widely interpreted as inverse Compton (IC) scattering between energetic electrons and soft
photons. Besides the emitted intensity, the polarization of this radiation provides important information about the physical properties of the electrons involved. We investigate how different electron populations shape both the spectrum and polarization of IC emission in the X-ray band. We consider three electron populations: purely thermal, purely nonthermal power-law, and a hybrid population combining both components. We take both numerical simulations and semi-analytic calculations. We first attempt the cases for thermal and nonthermal electrons, respectively. We then focus on the hybrid population, which is expected to be realistic in high-energy object environments. For the case of hybrid electrons, the scattered emission separates into three energy regimes. At low energies ($\lesssim 0.1$ keV), it is dominated by thermal electrons; at high energies ($\gtrsim 4$ keV), it is governed by the nonthermal component. Between these limits, a transition band ($\sim 0.1$-$4$ keV) appears in which both components contribute. The degree of polarization varies smoothly across these regimes, and the behavior in the transition band directly traces the relative importance of thermal and nonthermal electrons. We further show that for partially polarized seed
photons, the scattered polarization scales linearly with the incident polarization while its frequency dependence remains unchanged. These results show that X-ray polarimetry provides a powerful diagnostic of the electron energy distribution in
accretion-powered systems.
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All authors Boting Wang, Jirong Mao, Jieying Liu, Fei Xie
Exactly Solvable and Integrable Systems
The transformations of the mToda hierarchy in tau functions
Wenchuang Guan, Shen Wang, Bailin Zhang et al. (+1 more)
In this paper, we investigate the modified Toda (mToda) hierarchy, which can be regarded as the 2-component first modified Kadomtsev-Petviashvili (mKP) hierarchy. We first investigate the connection between the Toda and mToda tau functions. Based on this, we construct the transformations for the mToda tau functions and Lax operators. Furthermore, we present the mToda squared eigenfunction
symmetries and derive the Adler-Shiota-van Moerbeke (ASvM) formula, which plays a crucial role by connecting the actions of the additional
symmetries on the wave functions with the Sato–Bäcklund transformations of the tau functions. Finally, by establishing the equivalence between the actions of vertex operators on the mToda tau functions and the multi-step mToda transformations, we derive the mToda addition formulas, also known as the generalized Fay identities.
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All authors Wenchuang Guan, Shen Wang, Bailin Zhang, Jipeng Cheng
Materials Science
Depth-Resolved Evolution of Buried Polar Topologies in a PbTiO3/SrTiO3 Superlattice
Xinxin Hu, Penghan Lu, Noa Varela-Dominguez et al. (+9 more)
Polar
topologies in complex
oxides gives rise to a rich spectrum of emergent functionalities and are fundamentally governed by three-dimensional (3D) atomic structures. However, direct experimental determination of buried 3D polar configurations remains a longstanding challenge because conventional (scanning) transmission electron microscopy ((S)TEM) provides primarily projected structural information with limited depth sensitivity. Here, we combine depth-sectioning low-angle annular dark-field (LAADF) STEM, high-angle ADF (HAADF) STEM, and multislice electron ptychography (MEP) to directly visualize the depth-dependent atomic structure and polarization
topology in a PTO/STO superlattice. Depth-sectioning STEM reveals pronounced focal-depth-dependent contrast variations and apparent splitting of Pb atomic columns, indicating significant structural heterogeneity along the beam direction. MEP reconstruction simultaneously resolves the Pb, Ti, and O sublattices with nanometer-scale depth resolution, enabling quantitative mapping of atomic displacements throughout the reconstructed volume. The resulting 3D atomic model reveals substantial depth-dependent displacements of Pb, Ti, and O atoms and a corresponding
evolution of the polarization
topology.
Vortex-like polarization structures are observed near the specimen surfaces but become strongly suppressed within the interior, where distinct polarization configurations emerge. These findings show that polarization patterns observed in conventional projection images can arise from the superposition of multiple depth-dependent polar states and may obscure the underlying 3D polarization texture. Our findings establish a direct experimental link between local atomic displacements and depth-dependent polarization
topology, opening new opportunities for investigating and engineering buried functional states in complex
oxide nanostructures.
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All authors Xinxin Hu, Penghan Lu, Noa Varela-Dominguez, Anthony Edgeton, Chang Beom-Eom, Francisco Rivadulla, José Santiso, Yingzhuo Lun, Zhihua Sun, Rafal Dunin-Borkowski, Gustau Catalan, Jordi Arbiol
High Energy Astrophysical Phenomena
Observations of ionized carbon towards the $\gamma$-ray-bright supernova remnant RX J1713.7-3946
A.R. Thakur, G.P. Rowell, R. Higgins et al. (+7 more)
The origin of
Galactic Cosmic Rays (CRs), particularly at sub-GeV energies, remains uncertain due to their difficulty in being traced. One possible tracer of low-energy CRs is ionised carbon ([C II]), which may be enhanced in regions affected by CR-induced ionisation. We present observations of [C II] 158 $\mu$m line emission across the $\gamma$-ray-bright
supernova remnant (SNR) RX J1713.7-3946 obtained with SOFIA. These data are compared with molecular and atomic gas from Mopra ($^{12}$CO), Nanten ($^{12}$CO) and SGPS (HI), and high-energy emission from TeV $\gamma$-ray H.E.S.S. and X-ray XMM-Newton. We find [C II] emission follows the atomic gas more closely than molecular gas, particularly in regions near the SNR shock front. Ratios of [C II] intensity to gas column density vary across the remnant, with peak values coinciding with regions of enhanced TeV $\gamma$-ray emission. To put the [C II] in a wider context, we examined pointings from the Herschel GOT C+ survey. Our analysis of the GOT C+ data shows no significant difference in the I[C II]/I[$^{12}$CO] ratio for observations towards
star formation regions, HII regions and SNRs. To assess the origin of carbon ionisation, we model [C II] emissivity using the photoionisation code CLOUDY. We find UV
photons and CRs can produce comparable levels of [C II] emission, assuming low-energy CRs (< 1 GeV) are accelerated and trapped within the SNR shock. These results highlight the potential of [C II] as a tracer of CR ionisation and the importance of combining multi-wavelength observations to probe CR interactions in SNRs.
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All authors A.R. Thakur, G.P. Rowell, R. Higgins, M. Burton, Y. Fukui, S. Einecke, H. Sano, G. Wong, M.D. Filipović, C. Braiding
Optics
An Ab initio Framework for Simulating Ultrafast Nonlinear Cavity Quantum Electrodynamics Spectra
Luis Vasquez, Kewei Sun, Haibo Ma et al. (+1 more)
In this letter we introduce a theoretical framework for the simulation of ultrafast transient absorption pump-probe spectra of molecular polaritons. We derive and implement the cavity
quantum electrodynamics (QED)
evolution equations of polaritonic states within the framework of the quasi-classical doorway-Window pproximation, hereto referred cQUEDA /sikeda/. This framework uses outputs from mixed
quantum-classical dynamics simulations in the absence of the cavity. Then by including cavity parameters accounting for cavity rate loss, coupling strength, and frequency detuning, we simulate transient absorption pump-probe spectra. Consequently, we address one of the main standing problems of cavity QED, the simulation of polaritons ultrafast dynamics and nonlinear optical properties. We demonstrate the performance of our method by computing the ground-state bleach (GSB), stimulated emission (SE), and excited-state absorption (ESA) contributions of transient absorption pump-probe spectra of pyrazine strongly coupled to a cavity. The cQUEDA is an on-the-fly computationally efficient framework with low computer requirements: the pyrazine calculations, for example, took minutes on modern laptops. cQUEDA offers wide-ranging applicability and can be generalized to model diverse nonlinear spectroscopic signals and
quantum optics responses.
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All authors Luis Vasquez, Kewei Sun, Haibo Ma, Maxim F. Gelin
Physics and Society
Spatiotemporal organization in bike-sharing systems using gravity model parameters
Hanbo Zhang, Qi Rao and Bo Yang
Gravity models describe bike-sharing origin-destination (OD) flows as increasing with origin and destination activity and decreasing with distance. Yet how these relationships change within a day and across observation areas remains unclear. We examine temporal and spatial variation in origin, destination and distance exponents $\alpha$, $\beta$, and $\gamma$, together with $R^2$ and mean absolute error (MAE), across eight bike-sharing systems. Temporal modeling uses sliding windows, while spatial modeling expands a circular area and separates intra-zonal, cross-zonal
outflow, cross-zonal inflow and extra-zonal trips. We find recurring patterns across cities: morning and evening peaks differ in origin and destination dependence, while cross-zonal
outflow and inflow across the same boundary show opposite changes in their relative origin and destination dependence as radius increases. Model performance and distance dependence also vary with time and radius. A full-day, citywide fit therefore combines time periods and flow types with different
gravity relationships.
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Strongly Correlated Electrons
Frustration-induced degenerate spin state with up-up-down-down ordering in corner-connected Heisenberg square-plaquettes
Pritam Manna and A. K. Bera
We investigate frustrated magnetism of a corner-connected square plaquette Heisenberg model with exchange interactions along the edges $(J_1)$, along inter-plaquette links $(J_2)$, and along square diagonals $(J_3)$. Using Luttinger–Tisza (LT) minimization of the
Fourier interaction
matrix $\mathcal J(\mathbf q)$ together with large-scale Monte Carlo (MC) simulations, we obtain a classical low-temperature
magnetic phase diagram in the normalized plane $(J_1/|J_2|, J_3/|J_2|)$. The two methods play complementary roles: the LT analysis provides the zero-temperature candidate ordering wave vectors, while the MC simulations elucidate the resulting ordering tendencies under the hard-
spin constraint at low but finite temperatures. Three regimes emerge at low temperatures, an
antiferromagnetic phase (AF), a
ferromagnetic phase (FM) and a degenerate
spin state with up-up-down-down (uudd) ordering (DS). For the frustrated degenerate spinstate, LT exhibits line-like minima along $q_x=\pm q_y$ in the $hk$-plane, revealing a highly degenerate
spin configuration which violates the hard-
spin constraint. The MC results uncover a state with quasi-two-dimensional ordering. The DS regime is intrinsically multi-$\mathbf{q}$: the ordered texture assembles itself from
symmetry-related modes on the lines, producing a “uudd”
spin arrangement comprising of distinctive strong
antiferromagnetic correlations on diagonals,
ferromagnetic correlations on corner links, and highly suppressed correlations on the edges. The field-temperature phase diagram for a representative parameter point in the DS regime, determined by MC simulations, yields field induced distinct regions of negatively and positively correlated layers. These two regions are separated by a curve corresponding to negligible inter-layer correlations.
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Classical Physics
Electromagnetic Radiation from a Neutralized Polarized Sphere with Two Conserved Currents for One Charge History
Natan Rentzber
Can a source radiate when its total charge density vanishes identically? Consider a uniformly polarized sphere coated with free surface charge that cancels the bound surface charge at every point and time. Then $\rho_{\mathrm{tot}}=0$, so every electric charge multipole vanishes. Continuity determines only $\nabla\cdot\mathbf{J}$, which allows the same charge history to be supported by different conserved currents. A compensating interior current gives $\mathbf{J}_{\mathrm{tot}}=\mathbf{0}$ and produces no $\mathbf{E}$ or $\mathbf{B}$ at any frequency. The minimum-norm tangential sheet current instead leaves $\mathbf{J}_{\mathrm{tot}}$ nonzero and divergence-free. Its radiation-zone field is exact in $kR$ and proportional to $j_2(kR)$. At long wavelength the radiated power is suppressed by $(kR)^4/100$, and it vanishes exactly at the positive roots of $j_2$. The same calculation gives the interior field and a closed-form energy balance. The average work supplied by driving equals the radiated power and falls to zero at those roots even though interior fields remain. For comparison, the bare sphere has the factor $3j_1(kR)/(kR)$ and is silent at the roots of $j_1$.
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High Energy Astrophysical Phenomena
The impact of circumstellar wind-blown bubbles on the dynamics of pulsar wind nebulae and supernova remnants
Lioni-Moana Bourguinat and Pierrick Martin
The core-collapse
supernova explosion of most massive
stars is followed by the development of a
supernova remnant (SNR) and
pulsar wind nebula (PWN) system whose
evolution is in part dictated by its surrounding environment. The latter is frequently assumed to be the typical interstellar medium (ISM). However, massive
stars emit powerful winds during their lifetime and carve extended circumstellar cavities known as wind-blown bubbles (WBBs). We investigated the impact of WBBs on the dynamics, energetics, and thermal X-ray emission of a SNR-PWN system. We performed numerical simulations of a 1D hydrodynamical analogue of the system, for different
stellar progenitors and
pulsar parameters, in a WBB or ISM environment. The system initially expands to large sizes in the low-density interior of a WBB, until the SNR fills the entire bubble. The PWN grows to $\gtrsim10~\mathrm{pc}$ ($30~\mathrm{pc}$) after $\sim5~\mathrm{kyr}$ ($\sim25~\mathrm{kyr}$) for a $M=8~\mathrm{M}_\odot$ ($M=20~\mathrm{M}_\odot$) progenitor, $5-6$ times larger than in an ISM environment. The impact of the SNR on the massive outer shell of the WBB generates a strong reflected shock that efficiently returns energy to the inner parts of the system. At late times, after a strong compression of the PWN by an order of magnitude in size, back-and-forth shock crossings of the cavity maintain the SNR at very high temperatures and drive a vigorous reverberation of the PWN, with changes in radius by up to $3-4$. In this stage, the PWN is on average $2-4$ times larger than in an ISM environment and contains up to an order of magnitude more energy. Thermal radiation from the system occurs in few very localised emission bursts, as low-velocity shocks are transmitted across the bubble shell when it is hit by blast waves. WBBs offer a possible explanation for the large sizes of many PWNe and the non-detection of their parent SNRs.
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High Energy Physics (Theory)
Unification of Gravity with Internal Interactions: the SO(2,16) Scheme Revisited
Stelios Stefas and George Zoupanos
The starting point of the present work is the observation that the tangent group of a curved
manifold need not have the same dimension as the
manifold itself. We use this fact to construct Conformal
Gravity and its noncommutative (Fuzzy) counterpart as gauge theories, and then to unify both with internal gauge interactions. Specifically, we present a scheme in which conformal
gravity, based on gauging the SO(2,4) group, and fuzzy
gravity, based on gauging the SO(1,5)$\times$U(1), are unified with SO(10) internal interactions through the parent group SO(2,16), and we work through the resulting spontaneous
symmetry breakings and
fermion content in detail. We also discuss the low-energy phenomenology of the scheme, including
cosmic-string gravitational-wave signals, and close with a brief outlook: a candidate minimal unification group, a dark-matter candidate suggested by the construction, and the ghost problem common to higher-derivative
gravity theories of this type.
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Astrophysics of Galaxies
Decoupling candidate dual AGN from chance superpositions in the GOTHIC survey via a deep-learning framework
Bhavesh Mukheja, Snehanshu Saha, Anwesh Bhattacharya et al. (+3 more)
Dual active
galactic nuclei (DAGN) mark a critical phase in the
evolution of merging
galaxies and the pairing of supermassive black holes, yet they remain difficult to identify in large imaging surveys because of projection effects and limited spatial resolution. Compact foreground
stars and unresolved substructure can mimic dual
nuclei through chance superposition, complicating automated detection. We revisit the 46,061
galaxies flagged but rejected as DAGN candidates by the GOTHIC pipeline, primarily because the two
nuclei fell within the SDSS fibre aperture or exceeded its separation threshold. We train a supervised deep-learning framework based on the YOLOv11 oriented-bounding-box architecture on annotated SDSS imaging to separate genuine dual
nuclei from foreground
stellar contaminants and other spurious
alignments. The final model attains a validation precision of 0.919, recall of 0.905, and $F_1$ of 0.912, and yields 29,605 dual-
nucleus candidates after removing
star-dominated and blended detections. Structured visual inspection indicates that $54.5$–$62\%$ are consistent with genuine dual
nuclei, implying $\sim(1.4$–$1.8)\times10^{4}$ plausible systems. Cross-calibrating the YOLO separation against the deterministic GOTHIC centroid measurement and restricting to the compact regime ($d \le 6.87''$) gives a conservative subset of $\sim 13{,}672$ candidates, reaching calibrated separations of $\sim 0.56''$. Spectroscopy of the most compact ($\le 1$ kpc) systems shows spectra dominated by
stellar absorption, with no resolved double-peaked emission, so confirmation requires higher-resolution follow-up. The catalogue is a statistically refined list of candidates, not confirmed DAGN. Nonetheless, deep-learning detection substantially reduces contamination and expands the plausible DAGN census.
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All authors Bhavesh Mukheja, Snehanshu Saha, Anwesh Bhattacharya, Mousumi Das, Françoise Combes, Sudhanshu Barway
High Energy Physics (Phenomenology)
Searching for Solar-Basin Axionlike-Particle Decay with XMM-Newton Blank-Sky Observations
Bo Zhang, Chi Zhang, Lei Lei et al. (+4 more)
Axion-like particles (ALPs) bound in the
solar gravitational field form the so-called ALP
solar-basin. Since the two-
photon decay of non-relativistic particles is approximately isotropic, this population can be searched for using observations in the anti-
solar direction. In this work, we propose a search strategy for narrow decay-line signals from the ALP
solar basin using XMM-Newton blank-sky observations (XMM-BSOs) stacked spectra data taken in directions opposite to the Sun. By jointly fitting the signal and background model, we obtain limits on $g_{a\gamma\gamma}^{95}$ in the mass range $m_a=1.4\text{--}16~{\rm keV}$, with typical sensitivities of $g_{a\gamma\gamma}\sim10^{-10}\text{--}10^{-11}~{\rm GeV}^{-1}$. We have implemented the first anti-
solar search for the
solar basin, demonstrating that this strategy can exploit the stacked exposure of a large number of X-ray observations and provide a scalable analysis framework for future searches.
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All authors Bo Zhang, Chi Zhang, Lei Lei, Yang Yu, Guan-Shen Wang, Bing-Yu Su, Lei Feng
Statistical Mechanics
Geometric Thermodynamics of Scallop Motion with Two Control Parameters
Hisao Hayakawa
According to Purcell's scallop
theorem, reciprocal single-degree-of-freedom shape deformations cannot achieve net propulsion in a viscous fluid. We show that this limitation is bypassed by thermal fluctuations in a two-parameter driven potential landscape. Formulating the
stochastic shape dynamics via a Smoluchowski equation with position-dependent mobility $M_\mathrm{eff}(x)$, we utilize a generalized inverse operator to evaluate the slow-driving response. Cyclic modulation of the control parameters induces a non-zero Berry-Sinitsyn-Nemenman
curvature $F_{12}(\bm{\theta})$, resulting in directed
geometric propulsion. Simultaneously, the non-adiabatic excess dissipation is dictated by a Riemannian thermodynamic metric $g_{ij}(\bm{\theta})$. Our results provide a unified
geometric foundation that bridges hydrodynamic friction,
stochastic mechanics, and thermodynamic trade-offs in micro-swimmers.
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Quantum Physics
A Dynamic-Kernel/QPacket Executable for Quantum Repeater Chains in Q2NS/ns-3
Adam Pearson, Marcello Caleffi and Angela Sara Cacciapuoti
The
Quantum Internet operates on
entanglement, a non-local, non-copyable, stateful network resource, which motivates protocol organization beyond classical layering. We present a first executable specialization of the Dynamic Kernel/QPacket logic from the beyond-layering protocol suite, targeting
entanglement distribution over a linear
quantum repeater chain. The implementation builds on Q2NS, an ns-3-based
quantum-network simulation module available through the ns-3 App Store. It realizes QPacket meta-headers with service intent and append-only action-commit stamps processed by node-local Dynamic Kernels organized as a Planner–Executor–Engine pipeline, while being deliberately scoped to an analytically verifiable service and policy. Within this scoped setting, we study node heterogeneity through a link-preparation policy that accounts for pre-distributed
entanglement and uneven
entanglement-generation support across nodes, including delegation via QPacket forwarding. Simulations verify analytical link-resolvability models and expose signaling load, forwarding behavior, and QPacket meta-header growth. Results show that QPacket overhead is shaped by more than just encoding, including policy choices and available network resources. Overall, this study demonstrates how the Q2NS/ns-3 substrate can support reproducible, policy-specific evaluation of
quantum-native protocol-suite concepts.
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Quantum Physics
Efficient Treatment of Non-Linearity in Quantum Computational Fluid Dynamics Using Hybrid Tensor Networks
Pia Siegl, Nis-Luca van Hülst, Maximilian Mandelt Buxadé et al. (+2 more)
Nonlinear terms present a fundamental challenge for
quantum computational fluid dynamics, as their implementation on inherently linear
quantum hardware typically requires resource-intensive workarounds that limit scalability to large-scale simulations. We present a hybrid
quantum-classical tensor network
algorithm that addresses this bottleneck by combining variational time-stepping with
quantum tensor programming to efficiently compile operators and time-dependent fields into
quantum circuits. Within a probabilistic framework, we replace prior state-based nonlinear implementations with tensor-based block encodings, stabilizing success probabilities that otherwise decay exponentially with system size. Benchmarking on turbulent flow fields demonstrates that the
algorithm maintains high success probabilities and moderate measurement overhead across increasing Reynolds numbers and grid resolutions. Compared to fully classical tensor network solvers, our hybrid approach yields substantial reductions in both
memory footprint and computational cost, establishing a scalable pathway toward practical
quantum advantage in scale-resolving CFD simulations.
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All authors Pia Siegl, Nis-Luca van Hülst, Maximilian Mandelt Buxadé, Tomohiro Hashizume, Dieter Jaksch
Materials Science
Classification of Metal - Insulator Transitions: Relating characteristic Properties to Quantum Chemical Bonding Descriptors
Tim Bartsch, Carl-Friedrich Schön, Dasol Kim et al. (+3 more)
Pressure induced metal
insulator transitions (MIT) are classified by the
evolution of characteristic optoelectronic and vibrational properties calculated with density functional theory. Three classes emerge: ionic solids metallize continuously at band-gap closure with hardening
phonons; covalent solids show discontinuous changes in atomic arrangement and optical
phonon frequencies; a third class exhibits complete
lattice softening and drastically enhanced electron
phonon coupling. A one dimensional hydrogen chain reproduces this behavior and serves as a toy model of the underlying bonding mechanism, termed metavalent. Two
quantum-chemical descriptors capture the distinct bonding changes behind the three classes. In metavalent solids, competing electron localization and delocalization yield soft optical modes and Peierls distortions on the insulating side, superconductivity on the metallic side, and low
lattice thermal conductivity near the MIT.
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All authors Tim Bartsch, Carl-Friedrich Schön, Dasol Kim, Raagya Arora, Umesh Waghmare, Matthias Wuttig
Superconductivity
Phase-controlled perfect nonlocal spin and charge diode effects in a four-terminal Josephson junction with $p$-wave magnets
Lovy Sharma, Bimal Ghimire and Manisha Thakurathi
We theoretically investigate charge and
spin transport in a four-terminal Josephson junction with a normal-metal barrier. The top and bottom superconducting leads are equal-
spin triplet $p_y$-wave
superconductors, while the left and right leads are $p$-wave magnets with proximity-induced conventional $s$-wave superconductivity. When the transverse macroscopic phase difference between the top and bottom leads is set to zero, a longitudinal phase bias generates a pure transverse
spin current with perfect 100% nonreciprocity. Remarkably, a finite transverse phase difference preserves the perfect
spin-diode effect while simultaneously inducing a perfect charge-diode effect, enabling fully nonreciprocal
spin and charge transport. Moreover, the
spin-diode efficiency exhibits sharp, step-like switching as a function of both the gate voltage applied to the barrier and the crystallographic orientation of the $p$-wave magnet, providing independent and experimentally accessible knobs for controlling the diode polarity. The diode response remains robust against asymmetric interface couplings, nonmagnetic disorder, variations in the relative singlet and triplet pairing strengths, temperature, and junction dimensions, demonstrating that the effect is not a consequence of fine-tuned parameters. These findings establish the proposed four-terminal junction as a highly tunable and structurally robust platform for dissipationless, phase-controlled
spin and charge rectification, with potential applications in superconducting spintronics.
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Quantum Physics · Cross-listed from cs.SC
StabQ: Quantum Program Analysis via Weighted Stabilizer Representations
Shangzhou Xia, Junjie Luo and Jianjun Zhao
Quantum program analysis remains challenging due to the exponentially large state space of
quantum programs and the difficulty of precisely characterizing their execution behavior. In particular, non-Clifford operations introduce additional complexity that limits the applicability of stabilizer-based techniques. Although stabilizer representations provide compact descriptions for Clifford
circuits, their limited expressiveness prevents them from directly supporting general
quantum program analysis. In this work, we propose StabQ, a symbolic execution framework for
quantum program analysis based on stabilizer representations. StabQ extends stabilizer-based symbolic execution beyond Clifford-only programs by introducing a symbolic state representation that captures and propagates
quantum state
evolution while preserving execution semantics. Based on this representation, StabQ constructs a Tableau Chain that represents the
evolution of intermediate symbolic states throughout program execution and enables reusable analysis of
quantum program executions. Furthermore, StabQ incorporates tableau consolidation and global-phase recovery mechanisms to mitigate symbolic state growth during execution. Building upon the Tableau Chain, StabQ supports multiple
quantum program analysis tasks, including
quantum state reconstruction,
entanglement analysis, and Clifford-property detection. We evaluate StabQ on three
benchmark suites—
Algorithms, MQT Bench, and QASMBench. The results demonstrate that StabQ constructs semantically consistent symbolic models, accurately preserves
quantum state
evolution, and effectively supports downstream analysis tasks across diverse
quantum programs.
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Strongly Correlated Electrons
Neutron scattering evidence for two-dimensionally coupled spin-dimerized antiferromagnetic lattice in {\alpha}-Cu2P2O7
B. Ghanta, K. S. Chikara, M. Ghanathe et al. (+3 more)
The microscopic
magnetic model of the low-dimensional
quantum magnet alpha-Cu2P2O7 has remained controversial. We present a comprehensive study of its
magnetic ground state and excitation spectrum using temperature-dependent inelastic
neutron scattering,
neutron diffraction, magnetization measurements, and comprehensive
spin-wave modeling. Our results unambiguously establish alpha-Cu2P2O7 as a two-dimensionally coupled
spin-dimerized
antiferromagnetic (AF)
lattice within the bc plane, with a dominant AF exchange J2 = 7.73 meV (hereafter referred to as "intradimer exchange") and weaker exchange couplings J1, J3, and J4 in the two-dimensional
lattice (hereafter referred to as "interdimer exchange"), in agreement with LDA-based density functional theory and in contrast to previous GGA+U predictions. The dominant intradimer AF exchange is found between seventh-nearest-neighbor Cu-Cu ion pairs [d(Cu-Cu) = 5.125(3) A] rather than nearest-neighbor Cu-Cu ion pairs [d(Cu-Cu) = 3.014(1) A] of the structural dimers. Weak interlayer coupling (J5 = 0.03 meV) stabilizes long-range
antiferromagnetic order below TN = 25 K. We further identify a weak single-ion anisotropy, associated with the distorted CuO5 polyhedra, that opens a gap in the
spin-excitation spectrum and drives a field-induced metamagnetic transition. Systematic
spin-wave calculations elucidate the distinct roles of interlayer coupling J5 and anisotropy term D in producing two distinct energy gaps at different
antiferromagnetic zone centers. Complementary
neutron diffraction and magnetization measurements as a function of applied
magnetic field uncover a previously overlooked metamagnetic transition near 13 kOe and allow construction of the
magnetic phase diagram in the H-T plane.
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All authors B. Ghanta, K. S. Chikara, M. Ghanathe, L. Keller, D. Voneshen, A. K. Bera
General Relativity and Quantum Cosmology
Towards a Connection Formulation of Action-Dependent Palatini Gravity
Callum Bell and David Sloan
Previous work has shown that first-order Palatini
gravity may be cast as a non-conservative Herglotz Lagrangian field theory, which excludes the conformal mode from its space of dynamical variables. In the present work, we analyse the role of the $SO(1,3)$ gauge connection in the construction of this action-dependent theory. The connection may be algebraically decomposed into complementary sectors which we interpret as `shape' and `scale' components. Only the former is retained within the Herglotz theory, while the latter is incorporated into the action-dependent sector. It is shown that the choice of connection decomposition is a space that can be smoothly parameterised. Such an observation leads to the finding that there exists a `
moduli space of frictional field theories', in which each point corresponds to a distinct algebraic splitting of the connection into shape and scale pieces. Movement within the
moduli space transitions between Herglotz Lagrangians whose on-shell dynamics all reproduce first-order Palatini
gravity. The distinction lies in how the reproduction of the scale dynamics of the original theory is partitioned between action dependence and dynamical torsion.
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Materials Science
Bonding Signatures of Incipient Electron Localization in Topological Chiral Semimetals Near the Metal-Insulator Transition
Felix Hoff, Jonathan Frank, Mohit Raghuwanshi et al. (+11 more)
How do electronic localization and delocalization compete in solids beyond the traditional limiting cases of metals and iono-covalent
insulators? Topological
chiral semimetals (TCSMs), characterized by their unique
crystal symmetry, offer an intriguing platform to explore this question. Here, we systematically compare TCSMs with covalent compounds, ordinary metals, and metavalent solids (incipient metals), and show that TCSMs occupy a distinct region in a multidimensional property fingerprint. Atom probe
tomography reveals an unusual bond-rupture signature, consistent with a bonding regime intermediate between electron localization and delocalization. This interpretation is supported by measurements of optical properties showing a transfer of spectral weight from interband to intraband transitions. For highly conductive TCSMs, this transition is accompanied by the disappearance of the Born effective charge, a measure of chemical bond polarizability, while less conductive TCSMs retain a nonzero value. Together, these results identify a property based bonding perspective on TCSMs that distinguishes them from metals, covalent solids, and metavalent compounds. Although metavalent solids and TCSMs both lie near the metal-
insulator transition and exhibit distorted
crystal structures, ultrafast coherent
phonon spectroscopy reveals fundamentally different
lattice-dynamical responses: a
phonon-driven Peierls-like instability in metavalent solids versus a robust
chiral B20 bonding motif in TCSMs.
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All authors Felix Hoff, Jonathan Frank, Mohit Raghuwanshi, Jan Köttgen, Vicky Hasse, Tim Bartsch, Navjot Bamrah, Elias Hildebrand, Carl-Friedrich Schön, Kaustuv Manna, Chandra Shekhar, Claudia Felser, Ricardo P. S. M. Lobo, Matthias Wuttig
Astrophysics of Galaxies
Interplay of Compaction, Quenching, and Black Hole Growth in the Most Massive Galaxies since $z\sim5$: Insights from JWST and Chandra Data
Novan Saputra Haryana, Masayuki Akiyama, Abdurro'uf et al. (+16 more)
The buildup of dense
stellar cores is expected to mark an important transition in the
star-formation and black-hole growth of massive
galaxies. Using spatially resolved spectral energy distribution (SED) fitting of James Webb Space
Telescope near-infrared imaging, combined with stacking analysis of Chandra X-ray data, we trace
stellar mass buildup and average black hole
accretion in the most massive
galaxies at $z<5$, selecting 50 most massive
galaxies per
redshift bin at constant number density of $\sim4.4\times10^{-5}$ cMpc$^{-3}$. To robustly constrain central
stellar populations, we separate active
galactic nuclei (AGN) components affecting the photometry using multi-band morphological decomposition and SED analysis. We find that the sample selected with constant number density exhibits evolutionary trend of rapid central compaction at $z\sim4$, during which the median central 1 kpc
stellar mass increases by $\sim0.60$ dex over $\sim400$ Myr. The majority of X-ray detected AGN ($63\%\pm12\%$) are hosted by
galaxies undergoing the compaction, while we find neither individually detected X-ray sources nor a significant stacked X-ray signal at $z>4$, indicating that substantial average black-hole growth emerges primarily during, rather than before, the compaction. Following the compaction, central specific
star formation rates (sSFR) decline by $\sim1.24$ dex over $\sim700$ Myr at $z\sim3$ while remaining elevated
galaxy-wide, signaling the onset of inside-out quenching. Despite this central suppression, specific black hole
accretion rate remains coupled to the total sSFR. Our results suggest that dense-core formation in the most massive
galaxies marks the onset of inside-out quenching and a transition toward enhanced black-hole to
stellar growth ratio.
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All authors Novan Saputra Haryana, Masayuki Akiyama, Abdurro'uf, Suchetha Cooray, Itsna Khoirul Fitriana, Dian P. Triani, Bovornpratch Vijarnwannaluk, Juan Pablo Alfonzo, Irham Taufik Andika, Muhammad Nur Ihsan Effendi, Ibnu Nurul Huda, Takumi Kakimoto, Anton Timur Jaelani, Ronaldo Laishram, Naoki Matsumoto, Abdurrahman Naufal, Lucky Puspitarini, Ryo Albert Sutanto, Hesti Retno Tri Wulandari
Astrophysics of Galaxies
Comparing the Nebular and Stellar Dust Attenuation Curves in Nearby Star-Forming Galaxies
Jong Chul Lee, Hyunjin Shim, Hyunmi Song et al. (+3 more)
Differences in the spatial distributions of
stars and ionized gas relative to
dust in
galaxies imply that
stellar and nebular
dust attenuation curves need not be identical. Although
stellar attenuation curves have been extensively studied, nebular attenuation curves remain less explored. In this work, we investigate nebular attenuation curves using Balmer line ratios for a sample of 90,958 nearby
star-forming
galaxies from the Sloan Digital Sky Survey with well-constrained
stellar attenuation curves. In the H$\alpha$/H$\beta$ versus H$\alpha$/H$\gamma$ diagram, the nebular attenuation curves are, on average, significantly shallower than typical
stellar attenuation curves, which can be qualitatively reproduced by source-
dust geometric effects. The nebular attenuation curve slopes show weak positive correlations with the
stellar attenuation curve slopes and weak dependences on
galaxy properties that broadly follow those of the
stellar attenuation curve slopes. These results suggest that nebular attenuation curves are distinct from
stellar attenuation curves, while remaining consistent with a connection between them.
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All authors Jong Chul Lee, Hyunjin Shim, Hyunmi Song, Ho Seong Hwang, Woong-Seob Jeong, Jong-Ho Shinn
General Relativity and Quantum Cosmology
Thermodynamics, Joule-Thomson Expansion and Ruppeiner Geometry of a Dyonic NED-AdS Black Hole Surrounded by Quintessence
Djedai Ayang Kamo, Saleh Mahamat, Ragil Brand Tsafack Ndongmo et al. (+3 more)
We investigate the thermodynamic properties, Joule-Thomson expansion, and microscopic structure of a dyonic Reissner-Nordström-AdS black hole in nonlinear electrodynamics surrounded by quintessence. Within the extended phase-space formalism, analytical expressions for the mass, Hawking temperature, equation of state, heat capacity, Gibbs free energy, Joule-Thomson coefficient, and Ruppeiner
curvature are derived. The effects of the nonlinear-electrodynamics parameter $\omega$, the quintessence parameters $(c,\epsilon)$, the dyonic charge $Q$, and the pressure $P$ are systematically investigated. The temperature profiles and equation of state exhibit a Van der Waals–like phase structure, with critical points strongly modified by the quintessence and nonlinear electrodynamivs contributions. The heat capacity and Gibbs free energy further reveal the corresponding thermodynamic stability and phase-transition behaviour. The Joule-Thomson analysis shows distinct cooling and heating regions separated by inversion points. In particular, quintessence generally lowers the critical and inversion temperatures, while increasing the charge and varying the nonlinear parameter significantly deform the inversion structure. The Ruppeiner
curvature exhibits pronounced peaks and sign changes near critical regions, indicating strong thermodynamic correlations and alternating attractive and repulsive effective microscopic interactions. The limiting cases $\omega\sim 1$, $c\sim 0$, and $Q\sim 0$ consistently recover the corresponding Maxwell, no-quintessence, and neutral black hole behaviours. These results demonstrate that the combined effects of nonlinear electrodynamics, dyonic charge, quintessence, and AdS pressure substantially reshape both the macroscopic phase structure and the effective microscopic interactions of the black hole.
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All authors Djedai Ayang Kamo, Saleh Mahamat, Ragil Brand Tsafack Ndongmo, Kamiko Kouemeni Jean Rodrigue, Thomas Bouetou Bouetou, Timoleon Crepin Kofane
Mesoscale and Nanoscale Physics
Weaving Hopfions from Emergent Monopoles in a Chiral Magnet
Shoya Kasai, Kotaro Shimizu, Shun Okumura et al. (+1 more)
Recent advances in three-dimensional magnetization imaging techniques have opened new avenues for exploring topological
spin textures beyond domain walls and skyrmions. Among them,
magnetic hopfions are particularly promising, as their knotted
topology is expected to give rise to unconventional dynamics and responses; however, their controlled creation remains challenging. Here we propose a simple mechanism for generating hopfions from
magnetic torons, three-dimensional textures hosting an emergent monopole-antimonopole pair. Using Landau-Lifshitz-Gilbert simulations, we show that an electric current drives the annihilation of this pair, converting a toron into a hopfion. The initial toron length determines the number of generated hopfions, while the current direction selects the sign of the
Hopf invariant. We further find that the threshold current depends sensitively on material parameters, indicating a close connection to skyrmion dynamics. Our results establish an experimentally accessible route to hopfion creation and reveal a pathway from monopole defects to knotted topological textures.
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All authors Shoya Kasai, Kotaro Shimizu, Shun Okumura, Yukitoshi Motome
High Energy Astrophysical Phenomena
Spatially resolved spectral properties of M87* on event horizon scales
Shan-Shan Zhao, Ru-Sen Lu, Rocco Lico et al. (+2 more)
The supermassive black hole at the center of the nearby
radio galaxy M87 (M87*) is a
prime target for studying black hole physics. Spatially resolved spectral measurements on event-horizon scales can reveal the origin of the emission and probe the
plasma and gravitational environment in the immediate vicinity of the black hole. Here, we present an analysis of spectral properties based on nearly simultaneous high-resolution images at 3.5 mm (86 GHz) and 1.3 mm (230 GHz), obtained in 2018 with the Global Millimeter VLBI Array (GMVA) including ALMA and the Greenland
Telescope, and the Event Horizon
Telescope (EHT). We obtain the first spatially resolved spectral-index map ($S_\nu \propto \nu^\alpha$) within the compact region ($\leq 100\,\mu$as). We further detect a robust radial gradient with a modest rise in the inner $\lesssim 20~\mu$as (slightly inside the 1.3 mm ring), followed by a systematic decline at larger radii. The spectral index transitions from positive to negative values near $\sim 30~\mu$as, close to the 3.5 mm ring radius, consistent with frequency-dependent synchrotron opacity in the innermost
accretion flow. These results provide new observational constraints that can help discriminate between models of the horizon-scale emission and the launching of relativistic jets in M87*.
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All authors Shan-Shan Zhao, Ru-Sen Lu, Rocco Lico, Yuh Tsunetoe, Sijia Peng
General Relativity and Quantum Cosmology
Traversable wormholes in $f(T,\tau)$ gravity: a complete classification of the non-exotic sector
Ayan Banerjee, Takol Tangphati, Safiqul Islam et al. (+1 more)
We study static and spherically symmetric traversable wormholes in $f(T,\tau)$
gravity, where the torsion scalar $T$ is coupled to the trace $\tau$ of the matter energy–momentum tensor. We consider the linear model $f(T,\tau)=T+\beta\tau$ with an anisotropic fluid and the mean-pressure matter Lagrangian $\Lm=\Pmean=(p_r+2p_t)/3$. The field equations are obtained for the Morris–Thorne geometry without fixing the
redshift or shape function at the outset. For a constant
redshift function, the energy-condition problem takes a simple form. On the branch $\beta>8\pi$ and for $b(r)>0$, the energy density together with the null, weak, and strong energy conditions is satisfied throughout the spacetime if and only if $r b(r)$ is non-increasing. The same condition also implies asymptotic flatness, $b(r)<r$ outside the throat, and $b'(r_0)\leq -1$. The allowed geometries can therefore be written as $b(r)=r_0^2 h(r)/r$, where $h(r_0)=1$ and $h(r)$ is positive and non-increasing. For the representative family $b(r)=r_0(r_0/r)^n$, the null, weak, and strong energy conditions hold for $n\geq1$, while the dominant energy condition requires $n\geq3(\beta-2\pi)/(\beta-6\pi)$. We also separate the physical matter from the effective source and show how the trace coupling allows the physical matter to remain non-exotic although the effective source violates the null energy condition. Finally, we examine the marginal case $b(r)=r_0^2/r$ with a non-constant
redshift function. A decreasing
redshift function can improve the tangential null energy condition at the throat, but this improvement cannot be maintained throughout an asymptotically flat exterior. These results show that the matter–torsion coupling can support a broad class of traversable wormholes without requiring exotic physical matter.
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All authors Ayan Banerjee, Takol Tangphati, Safiqul Islam, Safyan Mukhtar
Mathematical Physics
Non-equilibrium modelling of polyatomic gases: generic framework and 11-moment model
Masrakain Ahmad, Anil Kumar and Anirudh Singh Rana
In this study, we present a thermodynamically consistent framework for modelling polyatomic gases by integrating the general equation for non-
equilibrium reversible-irreversible coupling (GENERIC) with an 11-moment description. Our formulation unifies rational irreversible thermodynamics (RIT) and extended irreversible thermodynamics (EIT) into a single GENERIC-compatible structure that guarantees compliance with the second law of thermodynamics through the explicit construction of Poisson and friction
matrices. By including translational and internal temperatures, as well as a temperature tensor, the model offers a well-structured and physically meaningful representation of non-
equilibrium behavior in polyatomic gases. The
entropy production is inherently non-negative, and all closure relations emerge naturally from thermodynamic principles. As a test of applicability, we compute the shock wave structure in nitrogen gas, validating the framework against Direct Simulation Monte Carlo (DSMC) simulations and experiments up to moderate Mach numbers.
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General Relativity and Quantum Cosmology
Reconstruction of the Weyl-Lewis-Papapetrou metric for stationary and axially symmetric gravitational perturbations of a Kerr black hole
David Kofroň and Petr Kotlařík
The study of black hole perturbations typically follows two main approaches: the direct perturbation of the metric, or the perturbation within the Newman-Penrose (NP) or Geroch-Held-Penrose (GHP) formalism. In the latter case, a reconstruction procedure, such as the Chrzanowski-Cohen-Kegeles (CCK) method based on the Debye (Hertz) potential, is required to obtain the corresponding metric perturbation. However, the reconstructed metric is then expressed in the radiation gauge, which is not always optimal. In this paper, we analyze stationary and axially symmetric perturbations of the Kerr black hole within both frameworks. Focusing on the
vacuum part of the spacetime (outside the sources), we derive an explicit gauge transformation between the averaged radiation gauge and the gauge in which the metric takes its standard Weyl-Lewis-Papapetrou (WLP) form, and we express the linearized WLP metric functions directly in terms of the Debye potential. We further discuss perturbations of the Kerr black hole towards general type D spacetimes, and analyze the mass and angular momentum perturbations in more detail. Finally, we illustrate the procedure on two examples beyond the type D class: a perturbation of the Schwarzschild black hole by a thin disk, and a perturbation of the Kerr black hole by a rotating particle.
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