Earth and Planetary Astrophysics
Galactic tides in the Solar System within a non-axisymmetric Milky Way model adjusted to Gaia data
Alexandre Bougakov, Yassin Rany Khalil, Marc Fouchard et al. (+4 more)
Context.
Galactic tides are external differential forces acting on extended systems immersed in the
Galactic potential. They play a key role in the dynamics of comets in the Oort cloud. Aims. We aim to establish the strength of
Galactic tides from the non-axisymmetric potential of the Milky Way revealed by the
Gaia mission, and how this strength evolves along the
Galactic trajectory of the
Solar System. Methods. We derived expressions for
Galactic tide parameters independently of any simplified trajectory for a
star in the
Galaxy or any specific
symmetry of the
Galactic potential. We obtained six parameters, $G_1$ to $G_6$, that quantify the influence of tides. Using the most up-to-date
Galactic potential model, extended here to three dimensions, we studied the time
evolution of these parameters along the Sun's trajectory using a statistical approach. Results. Even for
Galactic trajectories featuring modest radial and vertical excursions, as investigated here, the dominant
Galactic parameter, $G_3$, is found to vary by an order of magnitude along the
solar trajectory. $G_1$ and $G_2$ reach up to about one half and one quarter, respectively, of $G_3$ along the
solar trajectory, whilst parameters $G_4$ to $G_6$ reach up to one tenth of $G_3$. Conclusions. Contrary to what is often assumed, all
Galactic tide parameters vary widely along the
Galactic trajectory of the
Solar System. Two consequences can be expected: First, $G_3$ directly affects the flux of observable long-period comets and the extent of the fossilised Sednoids region; second, $G_1$ and $G_2$, and to a lesser extent, $G_4$ to $G_6$, break the integrability of the dynamics, potentially affecting the long-term structure of the Oort cloud. Additionally, the new parameters $G_4$ to $G_6$, while small for the
Solar System, may strongly impact extrasolar systems with a large out-of-the-plane excursion in the
Galaxy.
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All authors Alexandre Bougakov, Yassin Rany Khalil, Marc Fouchard, Melaine Saillenfest, Benoit Famaey, Paola Di Matteo, Misha Haywood
Soft Condensed Matter
Response of a Model Glass to Athermal Quasistatic Pinching
Takumi Nagasawa, Kirsten Martens, Jean-Louis Barrat et al. (+1 more)
We numerically investigate the mechanical response of amorphous solids to localized force dipoles, referred to as pinching, using athermal quasistatic simulations of model glasses with varying degrees of stability. We employ a control parameter, the imposed extension, corresponding to the increase in rest length between the two pinched particles relative to their initial separation. Increasing this extension allows us to continuously tune the system from the elastic to the plastic regime. For small extensions, the response remains elastic. In this regime, the displacement field induced by pinching is well described by linear elasticity and exhibits a long-range power-law decay consistent with dipolar forcing. Averaged responses display anisotropic, quadrupolar-like patterns, with quantitative agreement between simulations and analytical predictions. This continuum description remains valid down to particle-scale distances. As the imposed extension increases, the response becomes plastic. Pinching can then trigger either localized or system-spanning rearrangements, depending on glass stability. Well-annealed glasses exhibit localized plastic events, whereas poorly annealed systems display delocalized cascades. We introduce a method to extract the principal axis of plastic deformation and analyze the associated displacement fields and plastic activity. Overall, our results demonstrate that pinching provides a minimal local probe of amorphous solids. The resulting response, governed by both glass stability and imposed extension, offers insight into the interplay between elasticity, elementary rearrangements, and the emergence of collective plasticity.
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All authors Takumi Nagasawa, Kirsten Martens, Jean-Louis Barrat, Misaki Ozawa
High Energy Physics (Phenomenology)
Shinya Kanemura and Masanori Tanaka
The concept of
quantum information has provided new ways to investigate the theoretical structure of particle interactions. In particular, it has been shown that extrema of
quantum entanglement in scattering and decay processes can be related to
symmetries and characteristic properties of particles. We focus on a more specific question: whether the minimization of
entanglement entropy generated in scattering processes is systematically related to the suppression of interactions that violate global
symmetries or selection rules. We
conjecture that the minimization of the
entanglement entropy can select the
symmetry-preserving point when a new interaction opens a
symmetry-violating scattering channel. We investigate the plausibility of this
conjecture by considering interactions beyond the Standard Model (BSM) that violate global
symmetries or the corresponding selection rules, including
lepton number violation,
baryon number violation,
lepton flavor violation, and
flavor-changing neutral currents. We show that, when
symmetry-violating interactions open final-state sectors that are orthogonal to the
symmetry-preserving sector, the
symmetry-preserving point becomes a local minimum of the
entanglement entropy. Our results support the possibility that the minimization of
entanglement provides a common information-theoretic principle underlying the suppression of BSM phenomena relevant to
symmetry-violating interactions.
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Quantum Physics
Quantum Meta-Complexity Is All You Need: Characterizing One-Way Puzzles via Time-Bounded Kolmogorov Complexity
Morteza Saberikamarposhti
We initiate the time-bounded meta-complexity program for
quantum cryptography. Recent work characterizes one-way puzzles, the minimal search primitive of
quantum cryptography without one-way functions, by the average-case hardness of approximating the plain, uncomputable Kolmogorov complexity over quantumly samplable distributions; the classical program of Liu and Pass, by contrast, lives at
polynomial time bounds. We define a probabilistic time-bounded
quantum program complexity pKq^t for classical strings and prove two unconditional
theorems. First, a
quantum coding
theorem: any string output by a
quantum polynomial-time sampler with probability delta admits a description of the information-theoretically optimal length log(1/delta) plus logarithmic terms, decodable by a
quantum machine in time O(sqrt(1/delta)) times a
polynomial, via amplitude amplification over the coherently executed sampler. Second, an exact characterization at subexponential time: one-way puzzles exist if and only if the gap problem for pKq at time bound 2^(n/2) poly(n) is weakly
quantum-average-hard, refining the plain-complexity characterizations. We then isolate the
polynomial-time coding
theorem as the single load-bearing open
conjecture of the program, prove that it implies the full
polynomial-time characterization, analyze why the classical derandomization proof resists quantization, and formulate a relativized barrier
conjecture delimiting string-valued meta-complexity at one-way puzzles.
Conjectures are labeled as such throughout.
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High Energy Astrophysical Phenomena
Multiwavelength View of Black Hole X-ray Binary Swift J151857.0-572147
Manoj Mandal, Sachindra Naik, Souvik Manik et al. (+1 more)
We investigate multiwavelength timing and spectral properties of the newly discovered black hole X-ray binary Swift J151857.0-572147 during its 2024 outburst using observations from AstroSat, NuSTAR, NICER, Swift, and MeerKAT. The AstroSat/LAXPC20 power density spectrum reveals a $\sim$8 Hz low-frequency QPO with a quality factor of $\sim2.8$. The broadband X-ray spectrum of the source exhibits prominent reflection features, which are modeled to constrain the geometry and physical properties of the
accretion disk. The spectral analysis indicates that the source was in the soft/intermediate spectral state, characterized by a steep power law with a
photon index of $\Gamma \approx 2.6$ and a relatively high disk temperature of $\sim0.9$ keV. The reflection modeling suggests a disk inclination of $23-31^{\circ}$ and a highly ionized
accretion disk with $\log\xi \sim 3.3$-4.0. The MeerKAT monitoring revealed a strong
radio variability that closely tracked the hard X-ray
evolution, including a bright
radio flare during the hard-to-soft state transition, supporting close coupling between the
accretion flow and jet activity. Using the quasi-simultaneous AstroSat, Swift/XRT and MeerKAT observations, we investigated the
radio/X-ray correlation and found that Swift J151857.0-572147 follows the established $L_{\rm X}$-$L_{\rm R}$ relation for
Galactic black hole X-ray binaries. Its location in the $L_{\rm X}$-$L_{\rm R}$ plane is consistent with that of
Galactic black hole X-ray binaries, further supporting its black hole nature.
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All authors Manoj Mandal, Sachindra Naik, Souvik Manik, Sabyasachi Pal
General Relativity and Quantum Cosmology
Ultralight Bosons Explain the Mass-Spin Correlations in the Merging Binary Black Hole Population
Xiao-Xiao Kou, Vuk Mandic, Ran Ding et al. (+1 more)
Ultralight
bosons could trigger superradiant instabilities in rapidly spinning black holes, forming oscillating clouds while extracting rotational energy. We consider an extended, superradiance-informed
spin distribution model that characterizes possible environment-induced
spin variations and compare its predictions with the observed population of merging black hole binaries in the Gravitational-Wave Transient Catalogs (GWTCs). We find that the mass-
spin relation predicted by a scalar
boson with mass $m_b\sim 10^{-12} \,\rm eV$ is consistent with the GWTCs, with increasing significance from GWTC-3.0 to 5.0. The Bayes factor reaches $\ln B \approx 7.8$ for GWTC-5.0. Intriguingly, this mass range largely coincides with a previous study based on a waveform analysis of the GW190728 gravitational wave event. Our findings provide compelling evidence that a superradiance-informed
spin distribution model is highly compatible with the expanding binary black hole population
dataset.
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All authors Xiao-Xiao Kou, Vuk Mandic, Ran Ding, Chi Tian
General Relativity and Quantum Cosmology
Thermal Quantum Fluctuations in Einstein-Nonlinear Maxwell-Yukawa Black Hole
M. Mangut
This study investigates an Einstein-nonlinear electrodynamic black hole generated by a Yukawa-screened electromagnetic potential and examines its thermal properties through the calculation of the fundamental thermodynamic potentials and variables. The effect of thermal fluctuations on the calculated standard thermodynamic quantities is analyzed through two different correction terms added to the Bekenstein-Hawking
entropy. In this work, the thermodynamic behavior in cases where the black hole has a relatively large event horizon is investigated using a logarithmic correction term representing corrections arising from
quantum fields in constant backgrounds. In addition, thermal fluctuations occurring in cases where the event horizon is small are analyzed through an exponential correction term added to the
entropy, reflecting non-perturbative
quantum effects. Finally, the thermodynamic functions for all obtained cases are examined graphically, and the stability properties of the black hole are discussed in detail.
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Other Condensed Matter
Topological Lithography via External Field: Creating Topological States Anywhere Beyond the Edge
Haoran Nie, Chaoran Jiang, Xiangying Shen et al. (+1 more)
Topological
insulators (TIs), recognized for their robust boundary states and unconventional phase transitions, have emerged as one of the most impactful discoveries in recent decades, attracting considerable interest across diverse fields. However, conventional TIs require topological contrasts between adjacent bulk regions, typically achieved by distinct
symmetries, which limits their flexibility and broader applicability. In this work, we introduce a "lithography" approach to inducing topological states by applying external fields in time-reversal-symmetric systems. These states transcend the conventional bulk
topology design paradigm and offer exceptional tunability: they can exist at
geometric edges, within the bulk, or even be induced remotely. Because the external field is highly controllable, the induced states are programmable, reconfigurable, and can be easily tailored into desirable patterns. Theoretically, we demonstrate that the external field modifies the Jackiw-Rebbi mechanism, inducing a real-space topological transition characterized by a local topological marker (LTM). We further establish an extended valley bulk-edge correspondence, which explains both the conventional scenario and our findings. Our results, validated across mechanical, electronic, and acoustic platforms, highlight the broad applicability of this approach to various systems. This work not only advances the theory of
topology but also enhances the diversity, tunability, and practical implementation of topological states and materials.
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All authors Haoran Nie, Chaoran Jiang, Xiangying Shen, Lei Xu
Superconductivity
Electronic Structure and Superconductivity in La$_{1.55}$Sr$_{0.45}$CuO$_4$/La$_2$CuO$_4$ Artificial High-$T_c$ Superlattices Probed by Hard and Soft X-ray Spectroscopy
U. M. Jayathilake, S. Sheikh, T.-L. Lee et al. (+5 more)
In La$_{1.55}$Sr$_{0.45}$CuO$_4$/La$_2$CuO$_4$ (LSCO/LCO) artificial high-$T_c$ superlattices (AHTS), grown by
quantum material design, the superconducting dome can be tuned by varying the
geometric ratio $L/d$, where $L$ is the LCO layer thickness and $d$ is the superlattice nanoscale period. Here, we combine hard X-ray photoelectron spectroscopy (HAXPES) and polarization-dependent soft X-ray absorption spectroscopy (XAS) to probe how the electronic structure evolves across the $L/d$-tuned superconducting dome. We observe systematic chemical-potential
evolution across the series, together with enhanced spectral weight near the
Fermi level, enhanced local and non-local screening signatures, and increased in-plane orbital polarization near the top of the dome. Together, these spectroscopic signatures provide insight into the emergence of Fano-Feshbach resonant superconductivity in the LSCO/LCO AHTS series.
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All authors U. M. Jayathilake, S. Sheikh, T.-L. Lee, C. Klewe, G. Logvenov, G. Campi, A. Bianconi, A. X. Gray
High Energy Astrophysical Phenomena
Feeding The Little Monster: An Accreting Intermediate-Mass Black Hole In A Minor Merger Secondary Galaxy
Marko Mićić and Julia St. Pierre
We report the discovery of a luminous supersoft X-ray source associated with the secondary
galaxy in a 10:1 minor merger at $z$=0.216. We identified the system in the 3D-HST survey and observed it serendipitously in more than 100 Chandra observations, providing a combined exposure of 6.6 Msec. The secondary
galaxy ($\log$ (M$_*$/M$_\odot$)=8.24) exhibits X-ray emission detected exclusively below 2.0 keV, with no significant hard-band
photons. Because the source is low-count, we characterize its spectrum using
Bayesian hardness-ratio analysis combined with simulations of physically motivated spectral models folded through the Chandra response files. The observed count rates and hardness ratios are reproduced by a thermal
accretion-disk spectrum with rest-frame inner-disk temperatures kT$_{in}$=0.18-0.30 keV and luminosities log(L$_X$/erg s$^{-1}$)=40.5-41.2. Interpreted using a standard thin-disk framework, these properties imply a black hole mass of M$_\bullet$$\approx 8\times10^{2}$–$5\times10^{3}\,M_\odot$ accreting at $\approx$0.2-0.5 of the Eddington rate. Alternative interpretations involving ultraluminous X-ray supersoft sources are disfavored by the source's luminosity, temperature, lack of variability, and the host
galaxy's low
star-formation rate. Numerical simulations predict that black holes in smaller, secondary
galaxies could experience episodic rapid growth during minor mergers. This discovery provides observational support for this scenario and suggests that minor interactions may be an important channel for assembling supermassive black holes in
dwarf galaxies.
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Soft Condensed Matter
Liquid-liquid phase transitions in dipolar liquids. Insights into Supercooled Water
Maria Grazia Izzo
Dipolar
liquids combine two coupled degrees of freedom, translational and dipolar. Intriguingly, these two sectors can reside in distinct thermodynamic states, with the state of one sector possibly favoring a specific state of the other. The onset of ferroelectric order in dipolar
liquids is an example of this mutual stabilization. Since this coupling is often encoded in interaction potentials, projecting out one sector to derive an effective interaction for the other can uncover the microscopic mechanism underlying this phenomenon. A coarse-grained theory in which the distance between nearest-neighbor particles depends on their dipolar interaction through a density-dependent mechanical compliance shows that a ferroelectric transition can trigger a
liquid-
liquid transition. It also predicts a first-order
liquid-
liquid transition in the paraelectric phase that can in turn induce ferroelectric ordering. The anisotropic dipolar-dependent soft-core interaction is shown to lead to an effective Jagla-like isotropic two-length-scale interaction, known to support
liquid-
liquid phase transitions. Here, however, the two-length-scale pattern depends on density and dipolar configuration, becoming sensitive to dipolar order. Analysis of supercooled TIP4P/Ice water numerical simulations shows that first-coordination-shell features of pair correlation functions are sensitive to dipolar interaction, supporting the coarse-grained theory foundations. Comparison of low- and high-density
liquid water reveals enhanced spatial anisotropy of the first coordination shell in the low-density
liquid, with increased effective excluded volume, showing that the
liquid-
liquid transition involves structural changes within the first shell, beyond reorganization of the interstitial region and tetrahedral order. These findings point to a role for dipolar interactions in supercooled water
liquid-
liquid phase transition.
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Statistical Mechanics
Survival in a partially reactive wedge
Denis S. Grebenkov
We investigate the power-law decay of the survival probability of a Brownian particle diffusing in an infinite planar wedge whose two sides are partially reactive and described by Robin boundary conditions. We employ matched asymptotic analysis to relate the long-time asymptotics to a stationary harmonic Robin problem near the apex. This approach determines the persistence exponent for arbitrary opening angles and yields the prefactor explicitly for the family of wedges with $\alpha=\pi/n$ ($n=1,2,\ldots$). A simple extension of the apex prefactor to arbitrary angles is conjectured and supported numerically. This asymptotic behavior describes the crossover to the well-known result for perfectly absorbing wedges. As immediate applications, we also deduce the long-time behavior of the probability density function of the boundary local time on wedge sides, as well as the probability density function of the associated first-crossing time.
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Astrophysics of Galaxies
The Neutral Atomic Hydrogen in the solar neighborhood (NeAtHood) project I. Ghost in the shell: Neutral atomic hydrogen in the extended Orion nebula
J. D. Soler, H. Beuther, S. C. O. Glover et al. (+15 more)
The Orion Nebula is the nearest site of ongoing and recent high-mass
star formation. It is a unique laboratory for studying the mass, energy, and momentum input from high-mass
stars. We present 21-centimeter emission line observations that resolve for the first time the neutral atomic hydrogen (HI) gas in the extended Orion nebula (EON) at a resolution of one arcminute, which corresponds to a physical scale of 0.12 parsecs at the standard distance to the region. Our HI emission maps reveal an expanding shell that matches the EON contours delineated by recent observations of ionized carbon ([CII]) line emission. However, our combination of single-dish and interferometric HI observations suggests 100
solar masses of material for the front hemisphere of the shell, which is lower by roughly a factor of ten than the mass inferred from [CII] observations. This discrepancy suggests that the mass of the nearest wind-blown bubble has been overestimated, although we do not rule out the possibility that a significant amount of molecular hydrogen (H_2) in the shell may account for part of the difference. Our extended 21 cm line maps also reveal uncharted structures in and around the EON. They include a probable secondary bubble and a linear protrusion extending roughly four parsecs from the shell boundary. Our results illustrate the potential of HI interferometric observations to elucidate key aspects of the multiphase structure of
star-forming regions and their connection to their surroundings.
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All authors J. D. Soler, H. Beuther, S. C. O. Glover, R. S. Klessen, J. Ott, M. Rugel, J. W. Teh, S. E. Clark, P. Goldsmith, A. Hacar, A. Socci, M. Heyer, M.-Y. Lee, C. E. Murray, D. Seifried, S. Walch, B. Godard, M.-A. Miville-Deschênes
General Relativity and Quantum Cosmology
Relativistic stellar collapse of initially static configurations
Keshlan S. Govinder, Megandhren Govender and Sunil Maharaj
We study the dynamics of a radiating relativistic
star in the presence of the electromagnetic field and the cosmological constant. The
evolution of the model originates from an initially static configuration. The temporal behaviour of the system is governed by a nonlinear second order equation which is studied using a phase plane analysis. We show that in the general case, with all physical parameters present, fold bifurcations arise which are related to nonzero charge and cosmological constant. Our treatment clarifies earlier results and we extend our study to the general solution space. We obtain a more comprehensive understanding of the temporal
evolution for a shear-free configuration during collapse.
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Fluid Dynamics
Mapping-based exact-integral formulation of skin-friction transformations for zero-pressure-gradient compressible turbulent boundary layers
Xuke Zhu, Xiaoshuo Yang, Yongchao Ji et al. (+2 more)
A long-standing route to efficient surface-drag prediction in zero-pressure-gradient compressible turbulent boundary layers is to map the skin-friction coefficient $C_f$ and momentum-thickness Reynolds number $Re_\theta$ onto their `incompressible' counterparts. Reassessment against an extensive DNS database shows that existing formulations do not consistently recover the reference incompressible skin-friction behaviour, even when transformed data exhibit improved collapse. We define the mapped `incompressible' state as a constant-property counterpart of the physical compressible boundary layer and derive the transformation factors from prescribed mean-velocity and wall-normal-coordinate mappings. This definition-first approach links skin-friction scaling to the full-layer accuracy of the underlying velocity transformation and exposes inherited outer-layer errors. Van Driest's theory is recast in a finite-Re exact-integral form, with the classical vD I and II transformations recovered as leading-order asymptotic reductions. Their limitations at finite Reynolds numbers are quantified, and the historical success of vD II is traced to a fortuitous cancellation of truncation errors. The exact-integral formulation then yields modified transformations assessed through a priori scaling and standalone a posteriori prediction of $C_f$ from prescribed macroscopic and wall-thermal inputs. The VIPL-based modified transformation gives the best overall performance. Across $0.30 \leq M_\infty \leq 13.64$ and $-0.55 \leq \varTheta \leq 2.85$, its prediction errors remain below $11\%$, with a mean error of $3.07\%$. Overall, the analysis places skin-friction transformations on a mapping-based exact-integral footing, relating them directly to prescribed mean-flow mappings while avoiding the leading-order asymptotic truncations that limit classical van Driest theory at finite Reynolds numbers.
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All authors Xuke Zhu, Xiaoshuo Yang, Yongchao Ji, Shiyi Chen, Zhenhua Xia
Astrophysics of Galaxies
Can diffuse X-rays be important in driving photoionisation in molecular clouds?
E. I. Makarenko, A. V. Ivlev, S. Bialy et al. (+5 more)
The ionisation balance in molecular clouds is regulated by several ionising sources, including
cosmic rays, X-rays, and ultraviolet radiation. Their relative importance depends on the local physical conditions and on the shielding column density. We compute the contribution of the large-scale diffuse X-ray radiation field to the ionisation in molecular clouds in the absence of strong local X-ray sources, such as young
stars. Our goal is to quantify its significance relative to the
Galactic cosmic rays. Using measurements of diffuse X-ray emission from the first eROSITA all-sky survey, we estimate the depth-dependent X-ray ionisation rate in molecular clouds across different
Galactic environments. We consider both the observed diffuse field and a deabsorbed field obtained by correcting for foreground
Galactic attenuation using HI4PI line-of-sight column densities in a pixel-by-pixel framework. Diffuse
Galactic X-rays are unlikely to dominate the ionisation balance in well-shielded molecular gas ($N_{\mathrm{H}} > 5 \times 10^{21} \mathrm{cm^{-2}}$), where
cosmic rays remain the primary ionising
agent. At low column densities, the deabsorbed diffuse X-ray field produces ionisation rate of $\zeta_X \sim 10^{-18}\mathrm{s^{-1}}$ at $N_{\mathrm H} \sim 10^{19}\mathrm{cm^{-2}}$, remaining below the lower end of
Galactic cosmic ray ionisation rate ($\sim 10^{-17} \mathrm{s^{-1}}$). The X-ray contribution decreases rapidly with increasing shielding, falling to $\zeta_{X}\sim10^{-19}\mathrm{s^{-1}}$ by $N_{\rm H}\sim10^{21}\mathrm{cm^{-2}}$ and to $\zeta_X \sim5\times10^{-21}\mathrm{s^{-1}}$ by $N_{\rm H}\sim10^{22}\mathrm{cm^{-2}}$. Diffuse X-ray may therefore contribute to the thermal and chemical structure of low-extinction material and should be considered when interpreting ionisation tracers in diffuse or cloud-envelope environments.
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All authors E. I. Makarenko, A. V. Ivlev, S. Bialy, X. Zheng, B. A. L. Gaches, P. Caselli, M. Padovani, M. C. H. Yeung
Soft Condensed Matter
XPCS-Echo and broad relaxation measurements using a bunch-mode data acquisition scheme
William Chèvremont, Thomas Gibaud, Yuriy Chushkin et al. (+1 more)
Echoes observed in the intensity-intensity autocorrelation functions [$g_2(q, \tau)$] is a powerful method for probing nonaffine deformations and yielding behavior of soft viscoelastic materials subjected to an oscillatory shear. Multispeckle X-ray
photon correlation spectroscopy (XPCS) measurements of large number of echoes with high time resolution impose severe constraints in terms of the computational hardware and potential degradation of the sample. These issues are alleviated by implementing a bunch-mode data acquisition scheme in which the highest resolution frames or bunches centered at the echo peaks. In addition, by placing the bunches in an aperiodic Fibonacci sequence, $g_2(q, \tau)$ over a long time span can be measured with orders of magnitude lesser number of frames. The performance of these XPCS acquisition schemes is demonstrated using slowly relaxing model colloidal suspensions. Furthermore, an analytical expression is provided for the quantitative description of full $g_2(q, \tau)$.
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All authors William Chèvremont, Thomas Gibaud, Yuriy Chushkin, Theyencheri Narayanan
Quantum Gases
Dynamical stabilisation of a quantum fluid using a single topological defect
Deborah Capecchi, Paolo Comaron, Antonio Gianfrate et al. (+5 more)
The size and shape of a
quantum fluid in
equilibrium is strongly influenced by the inter-particle interactions. In the attractive interaction regime, atomic
quantum fluids ultimately collapse in a violent process that expels most of the particles from the macroscopically occupied state. Here, we use a
quantum fluid of light in propagating geometry as an analogue to a two-dimensional Bose-Einstein condensate (BEC) with large attractive interactions to show that non-trivial
topology significantly alters the dynamical behaviour of the collapse, enhancing the BEC stability and delaying the collapse time by an order of magnitude. We measure direct experimental signatures of
topology affecting
quantum hydrodynamics, unveiling the inherent competition between attractive nonlinearities, that lead to the collapse, and the preservation of topological charge from a multi-charged
vortex. We fully characterise the collapse process in coordinate space and the eventual `solitonification' of the system and connect it to the mode structure of the excitation spectrum.
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All authors Deborah Capecchi, Paolo Comaron, Antonio Gianfrate, Milena De Giorgi, Dario Ballarini, Daniele Sanvitto, Franco Dalfovo, Dimitrios Trypogeorgos
Quantum Physics
Transversal Gates and Magic State Distillation in an Optimally Synthesized Spin-Qubit Shuttling Bus
Pau Escofet, Andrii Semenov, Niall Murphy et al. (+4 more)
Fault-tolerant
quantum computing requires not only reliable logical
qubit storage, but also the ability to perform high-fidelity logical operations between error-corrected
qubits at scale. While much of the existing literature focuses on optimizing syndrome extraction for a single logical
qubit, the co-design of physical architectures that support both robust error correction and efficient logical computation remains an open challenge. In this work, we propose a multi-
qubit spin-
qubit shuttling bus architecture that addresses both requirements simultaneously. The architecture optimizes the physical
qubit layout for syndrome extraction and supports transversal two-
qubit logical gates between an arbitrary number of logical
qubits, achieving all-to-all logical connectivity through coherent
spin shuttling. We further propose an ancilla-sharing scheme that encodes multiple logical
qubits within a single logical element, compressing the physical footprint of the processor and improving long-range gate fidelity. Extending the architecture from a one-dimensional bus to a two-dimensional grid of shuttling tracks reduces the inter-
qubit distance, yielding consistent improvements in logical error. Finally, we apply the
Quantum Reverse Mapping methodology at the logical level to optimize the layout of a 15-to-1 magic state
distillation circuit, demonstrating how the transversal capabilities of the proposed architecture can be leveraged for universal fault-tolerant computation. Taken together, these results establish a principled co-design framework that bridges the physical, error-correction, and logical computation layers of the
quantum stack, and demonstrate that
spin-
qubit shuttling architectures are a viable and flexible substrate for scalable fault-tolerant
quantum computation.
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All authors Pau Escofet, Andrii Semenov, Niall Murphy, Elena Blokhina, Carmen G. Almudéver, Sergi Abadal, Eduard Alarcón
Medical Physics
The 2024 MRSI Data Processing and Quantification Challenge Synthetic Dataset
John T. LaMaster, Julian P. Merkofer, Dennis M. J. van de Sande et al. (+3 more)
Synthetic data is central to
magnetic resonance spectroscopy method development because they provide ground truths for software validation, reproducible benchmarking, and machine- and deep-learning training. In MRSI, synthetic data must capture spatially varying anatomy, field inhomogeneity, nuisance signals, and measurement effects. The 2024 MRSI Data Processing and Quantification Challenge Synthetic
Dataset is a simulated 3T
brain FID-MRSI resource with ground-truth metabolite maps developed as a controlled testbed for MRSI processing and quantification methods. Subject-specific simulations used anatomical images and field maps from Human Connectome Project subjects. Tissue masks,
quantum-mechanically simulated metabolite basis functions, in vivo-derived macromolecular components, Bloch-simulated post-WET residual water, registered in vivo lipid signals, spectral baseline, $B_0$-dependent frequency shifts, Voigt lineshape variations, and complex Gaussian noise were combined in a forward model. Water and lipid signals were synthesized on a high-resolution grid and
Fourier-truncated to the final echo-planar spectroscopic imaging grid to model the finite spatial point spread function. This resource has 24 training and 8 testing
datasets containing contaminated FID-MRSI data, anatomical images, $B_0$ maps, metadata, and ground-truth metabolite and component signals. Forward-model parameters are documented, including tissue-specific metabolite concentrations and relaxation times, macromolecular amplitude ratios, the water model, noise, and field-inhomogeneity ranges. This synthetic
benchmark supports development and comparison of MRSI processing, nuisance-signal removal, and metabolite-quantification methods, while enabling method evaluation. It illustrates how characterized synthetic data can support rigorous evaluation when ground truth is difficult or impossible to obtain.
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All authors John T. LaMaster, Julian P. Merkofer, Dennis M. J. van de Sande, Brian J. Soher, Bernhard Strasser, Chao Ma
General Relativity and Quantum Cosmology
Frequency-domain extended-effective-source gravitational self-force for eccentric Schwarzschild orbits
Xuchen Lu, Yungui Gong, Bokai Zhang et al. (+2 more)
Effective-source formulations provide a practical route to gravitational self-force (GSF) calculations when singular retarded fields cannot be handled directly mode by mode. Up to now, only frequency-domain first-order GSF for circular orbits in Schwarzschild spacetime was obtained with the effective-source method. We construct and implement a frequency-domain extended effective-source (EES) formulation for first-order Lorenz-gauge GSF on eccentric orbits in Schwarzschild spacetime. The central obstacle is that radial libration forces the physical puncture and effective source to switch between interior and exterior branches, limiting their differentiability and producing slow spectral convergence. We overcome this obstruction by analytically extending both branches across the libration region and solving the coupled Lorenz-gauge perturbation equations for the resulting smooth extended sources. This provides an end-to-end gravitational EES implementation for eccentric motion and validates a computational ingredient needed for extending frequency-domain effective-source calculations toward second order.
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All authors Xuchen Lu, Yungui Gong, Bokai Zhang, Chao Zhang, Wenting Zhou
Quantum Physics
Heuristically optimizing, synthesizing, and prioritizing measurement settings for quantum state tomography
Sumukh S. Moudghalya, Anton Frisk Kockum and Akshay Gaikwad
A key task in many
quantum-computing applications, e.g.,
quantum simulation and
quantum state
tomography (QST), is to partition an arbitrary set of operators into mutually commuting subsets for efficient measurements. However, brute-force approaches to this task quickly become intractable as the number and dimensionality of operators grow. Here, we reformulate operator partitioning as a graph-coloring (GC) problem and develop an efficient computational framework to solve it, balancing accuracy and efficiency. Our framework enables leveraging a range of GC
algorithms, which we
benchmark for operator partitioning. Then, we demonstrate their utility in optimizing QST experiments, where determining non-overlapping data acquisition settings for QST is a major challenge, and prioritizing among these settings, i.e., selecting the experiments that provide the most information. We further show how to perform these experiments by synthesizing Clifford
circuits for joint measurement of commuting Pauli operators in multi-
qubit systems. We validate our framework across multi-
qubit (up to five
qubits), multi-qutrit (up to three qutrits), and hybrid
qubit-qutrit systems. Our results show that heuristic GC methods substantially reduce the number of required measurement settings for QST and enable priority-based scheduling that maximizes the information gain per experiment. The optimization converges within minutes on a student-grade laptop, providing speedups of several orders of magnitude over brute-force methods already for these relatively small
quantum systems. This demonstrates the potential of GC heuristics as a scalable and practical tool for characterization of noisy intermediate-scale
quantum devices. We have made the Python implementation of our GC framework to optimize and schedule QST experiments publicly available at https://github.com/ssm8015/QST_GT.git.
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Materials Science
Stephan Geprägs, Matthias Opel, Johanna Fischer et al. (+4 more)
Antiferromagnetic materials promise improved performance for spintronic applications, as they are robust against external
magnetic field perturbations and allow for faster magnetization dynamics compared to ferromagnets. The direct observation of the
antiferromagnetic state, however, is challenging due to the absence of a macroscopic magnetization. We show that the
spin Hall magnetoresistance (SMR) is a versatile tool to probe the
antiferromagnetic spin structure via simple electrical transport experiments by investigating the easy-plane
antiferromagnetic insulators alpha-Fe2O3 (hematite) and NiO in
bilayer heterostructures with a Pt heavy-metal top electrode. While rotating an external
magnetic field in three orthogonal planes, we record the longitudinal and the transverse resistivities of Pt and observe characteristic resistivity modulations consistent with the SMR effect. We analyze both their amplitude and phase and compare the data to the results from a prototypical collinear ferrimagnetic Y3Fe5O12/Pt
bilayer. The observed
magnetic field dependence is explained in a comprehensive model, based on two
magnetic sublattices and taking into account
magnetic field-induced modifications of the domain structure. Our results show that the SMR effect allows to readout the
spin configuration and to investigate magnetoelastic effects in
antiferromagnetic multi-domain materials. We demonstrate that the SMR amplitude scales with the sum of the absolute sublattice magnetizations in ferrimagnetic and
antiferromagnetic materials. In alpha-Fe2O3/Pt
bilayers, we find an unexpectedly large SMR amplitude of 2.5E-3, twice as high as for prototype Y3Fe5O12/Pt
bilayers, making the system particularly interesting for room-temperature
antiferromagnetic spintronic applications.
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All authors Stephan Geprägs, Matthias Opel, Johanna Fischer, Philipp Schwenke, Matthias Althammer, Hans Huebl, Rudolf Gross
Mesoscale and Nanoscale Physics
Nonreciprocal Magnon Hanle Effect in Antiferromagnetic $\alpha$-Fe$_2$O$_3$
Janine Gückelhorn, Sebastián de-la-Peña, Monika Scheufele et al. (+8 more)
The precession of the
magnon pseudospin about the
equilibrium pseudofield, the latter capturing the nature of magnonic eigenexcitations in an antiferromagnet, gives rise to the
magnon Hanle effect. Its realization via electrically injected and detected
spin transport in an
antiferromagnetic insulator demonstrates its high potential for devices and as a convenient probe for
magnon eigenmodes and the underlying
spin interactions in the antiferromagnet. Here, we observe a non-reciprocity in the Hanle signal measured in alpha-Fe2O3 using two spatially separated Pt electrodes as
spin injector and detector. Interchanging their roles alters the detected
magnon spin signal. The recorded difference depends on the applied
magnetic field and reverses sign when the signal passes its nominal maximum at the so-called compensation field. Our findings unlock the high potential of
antiferromagnetic magnonics towards the realization of electronics-inspired phenomena.
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All authors Janine Gückelhorn, Sebastián de-la-Peña, Monika Scheufele, Matthias Grammer, Matthias Opel, Stephan Geprägs, Juan Carlos Cuevas, Rudolf Gross, Hans Huebl, Akashdeep Kamra, Matthias Althammer
High Energy Physics (Theory) · Cross-listed from math.CO
An Affine Semigroup from Orbifold Boundary Conditions: cut, phylogenetic and hierarchical models in the unit-weight sector, and weighted configurations beyond them
Carles Marín
The equivalence classes of boundary conditions of a gauge theory on a two-dimensional orbifold are the fibres of a marginal map, indexed by an affine
semigroup: one generator per alphabet label, graded by weight, embedded by its local data at the fixed points. This note identifies that
semigroup. Without weights the configuration has a name and a literature, whose results about our cases are attributed here: over $\mathbb{Z}_2$ it is the cut configuration of an explicit graph in the sense of Sturmfels-Sullivant — the four-cycle for $T^2/\mathbb{Z}_2$, the wheel $W_4$ for $S^1/\mathbb{Z}_2\times S^1/\mathbb{Z}_2$ — verified as an equality of configurations; over $\mathbb{Z}_m$ with equal cone orders, the group-based phylogenetic model on a claw tree; with unequal orders, a mixed-order variant we do not find in the literature; for higher products, the binary hierarchical model of a cross-polytope boundary complex. The product orbifold's ring is a row of a 2008 table — codimension, degree, minimal generators, normality — every invariant of which our machinery reproduced without knowing of it. What none of the three covers is the alphabet with weights, which arise from induction to higher-dimensional irreducibles of a non-abelian space group and from conjugate-pair recombination over real or quaternionic ground. That sector is adjacent to, but not identified with, the non-abelian direction Sturmfels and Sullivant raised in 2005, and is where our contributions sit: gluing trees for the weighted alphabets and the orthogonal and
symplectic columns, and the group-based model on the tripod, a complete intersection exactly when the finite abelian group has order at most three. The first group beyond $\mathbb{Z}_3$ separates local from global: the $\mathbb{Z}_4$ tripod is a complete intersection on the Zariski-open set the phylogenetics literature works in, and not globally.
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Materials Science
Colossal reversible conductivity switching by room-temperature oxygen-vacancy ordering in Aurivillius oxide films
Song Zhou, Songge Zhang, Lanting Shi et al. (+11 more)
Oxygen vacancies are central to the functionality of
oxides, yet they typically exist as randomly distributed point defects, limiting the ability to precisely manipulate their collective behavior. Here, we report the room-temperature formation of a long-range-ordered oxygen-vacancy superstructure in single-crystalline Aurivillius-phase Bi2WO6 thin films via a mild nitrogen-
plasma treatment. This structural transformation unlocks a colossal, reversible modulation of electrical conductivity by more than nine orders of magnitude, accompanied by a striking optical transition from transparent to black. Atomic-resolution imaging and spectroscopy reveal that the vacancies selectively order within the perovskite-like tungsten
oxide layers, forming a coherent defect
lattice that is absent in the pristine film. Oxygen-
plasma treatment removes the vacancy superstructure and restores the initial state, whereas subsequent nitrogen-
plasma treatment reconstructs it, enabling repeatable room-temperature switching between distinct structural, electronic and optical states. The phenomenon is also observed in another Aurivillius member, Bi2MoO6, suggesting its generality across the Aurivillius family. These findings establish a new paradigm for atomic-scale defect engineering - using gentle
plasma chemistry to construct ordered defect
lattices, opening avenues for reversible property modulation in complex
oxides.
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All authors Song Zhou, Songge Zhang, Lanting Shi, Ping Zhang, Na Li, Jiawei Huang, Bolin Meng, Chuangye Song, Shaoxiang Sheng, Yang Chai, Lede Xian, Jinxing Zheng, Guangyu Zhang, Kehui Wu
Soft Condensed Matter
Pure FENE Bond Potential for Soft Matter and Biological Simulations: Theory, HOOMD-blue Implementation, and Applications to Polymer, Colloidal, and Membrane Systems
Anirban Polley
The finitely extensible nonlinear elastic (FENE) potential is widely used as a bonded interaction in coarse-grained simulations of
polymers, soft matter, colloids, and biological systems. In the classical Kremer–Grest framework, FENE bonding is combined with a short-range Weeks–Chandler–Andersen (WCA) interaction to provide finite bond extensibility together with excluded-volume repulsion. Although this combination is highly successful, it intrinsically couples bonded elasticity to the nonbonded interaction, limiting the ability to independently control these two contributions. Here, we introduce a standalone FENE bond potential in HOOMD-blue in which finite bond extensibility is implemented independently of the choice of nonbonded interaction. This formulation allows the same FENE bond potential to be combined with WCA, Lennard–Jones, or other pair interactions without modifying the bonded interaction itself. We demonstrate the utility of the standalone formulation in coarse-grained
polymer chains, colloidal networks, and mesh-based biological membrane models. Across these systems, Pure FENE bonding without short-range excluded-volume stabilization produces pronounced structural contraction, whereas the addition of WCA repulsion suppresses this collapse and preserves finite, spatially extended structures. These results demonstrate that separating finite bond extensibility from steric interactions provides independent control over local bond mechanics and collective structural organization. The standalone FENE formulation therefore provides a modular framework for coarse-grained simulations in which molecular connectivity and nonbonded interactions represent distinct physical mechanisms.
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Fluid Dynamics
Vortex promoters in MHD duct flow
Andreu Queralt, Dmitry Krasnov, Yuri Kolesnikov et al. (+1 more)
We use 3D direct numerical simulations to study the effects of
vortex promoters in
liquid metal duct flow to sustain Q2D states which are formed in the presence of strong
magnetic fields, such as those present in cooling blankets of fusion reactors. Both for electrically insulating and conducting walls. In case of insulating walls, disturbances are found to be sustained. For conducting walls, the disturbances may be extinguished immediately and replaced by a Walker- or Hunt-type flow with its own jet-detachment instability. Furthermore, we add heat transfer by imposing constant heat flux at the Shercliff walls. We classify and compare possible configurations with respect to their turbulent transport properties. For conducting ducts, no additional effect is observed. For insulating ducts in horizontal position, we observe a small effect. For vertical ducts, the buoyancy forces have a significant impact due to buoyancy-driven instabilities, which produce intermittent fluctuations. The analysis of the turbulent kinetic energy (TKE) and the Nusselt number show that flows with the largest TKE may not have the best heat transfer performance. This is caused by side jets removing heat faster than mixing the bulk flow. The buoyancy force and wall conductance ratio are found to play a key role in determining the flow structure. Part of our work is a parametric study at fixed Reynolds, Hartmann and Prandtl numbers, which allows us eventually to compose a phase diagram showcasing the different flow regimes.
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All authors Andreu Queralt, Dmitry Krasnov, Yuri Kolesnikov, Jörg Schumacher
Mathematical Physics
Asymptotic long-range order for the XY-model on random geometric graphs
Margherita Disertori and Max Mihailescu
We study the classical $XY$-model on random
geometric graphs $\mathcal{G}_{n, \varepsilon}$, which are obtained by sampling $n \in \mathbb{N}$ independent points in a finite domain $\Omega \subset \mathbb{R}^d$, $d \geq 2$, and connecting two points by and edge if their distance is of order $\varepsilon > 0$. We refer to $\mathcal{G}_{n, \varepsilon}$ as the random environment. Letting $\varepsilon \to 0$ as $n \to \infty$ at a sufficiently slow rate, these graphs capture the geometry of $\Omega$. Denoting the inverse temperature by $\beta$, we show that in the limit $\beta \to \infty$ at a rate depending on $n$ and $\varepsilon$, the $XY$-model on $\mathcal{G}_{n, \varepsilon}$ exhibits long range order in the sense that we prove a lower bound away from zero on the two-point function. Our result is quenched in the random environment: long-range order holds with large probability, converging to one as $n \to \infty$. To prove the statement, we show that with high probability the environment is sufficiently regular to apply a convexity argument and the Brascamp–Lieb inequality.
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General Relativity and Quantum Cosmology
Covariant linear response theory for a photon gas in curved spacetime
Jianan Wang, Long Cui and Bin Wu
To overcome the failure of the conventional non-relativistic description of statistics in strong gravitational fields, we develop a covariant theory for a
photon gas in curved spacetime, starting from the Boltzmann equation and employing the relaxation time approximation. The transport coefficients are computed up to second order, which are not a massless limit of the massive-particle results due to the fundamentally different phase-space geometry of null particles. At second order, the gravitational field renders the coefficients tensor-valued and induces transverse fluxes, analogous to the
Hall effect. Using the first-order results, we derive relativistic generalizations of Fick's and
Fourier's laws and obtain the radiation
diffusion equation for spherically symmetric
accretion disks. This provides a covariant description of radiative transport in strong gravitational fields for high-energy astrophysical applications.
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