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2604.28195 2026-05-01 astro-ph.GA

Chemical Taxonomy of $ω$~Centauri: Ten Populations Reveal a Multi-Phase Enrichment History

Furkan Akbaba, Olcay Plevne, Timur Şahin, Sena Aleyna Şentürk

Comments Submitted to MNRAS. 36 pages, 30 figures, 4 tables

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$ω$~Centauri, the most massive globular cluster in the Milky Way, exhibits a level of stellar population complexity that has long resisted a unified chemical characterisation. We exploit high-resolution near-infrared spectroscopy from the Milky Way Mapper survey (MWM DR19) to construct one of the largest homogeneously analysed samples of $ω$~Cen members to date. Applying Ward-linkage hierarchical clustering in a seven-dimensional chemical abundance space, without prior assumptions on population number or boundaries, we identify ten chemically distinct stellar populations. Their nucleosynthetic signatures trace four enrichment channels: iron-peak, $α$-element, CNO-cycle, and high-temperature proton-capture processes. The populations organise into two dominant groups separated by a large light-element spread at a modest iron baseline, consistent with AGB-driven self-enrichment. This dichotomy reflects distinct enrichment pathways: core-collapse supernovae establish the iron baseline, while AGB stars dominate light-element and $s$-process enrichment. A decoupled rise in $s$-process abundances relative to iron-peak elements, together with sub-dominant Type~Ia contributions across all metallicities, indicates evolution on timescales shorter than the characteristic Type~Ia delay time. One intermediate-metallicity population retains a primordial composition, providing evidence for spatially segregated enrichment within the progenitor. The most metal-rich component may trace star formation continuing after accretion into the Milky Way halo. All populations lie in the accreted regime of the $[\mathrm{Al/Fe}]$--$[\mathrm{Mg/Mn}]$ plane, supporting an ex-situ origin. These results reinforce the interpretation of $ω$~Cen as the remnant nucleus of an accreted dwarf galaxy and provide a framework for future chemo-dynamical studies.

2604.28194 2026-05-01 hep-th gr-qc hep-ph

Covariant Locally Localized Gravity and vDVZ Continuity

Hao Geng, Moritz Merz, Lisa Randall

Comments 5+5 pages, 2 figures

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The Karch-Randall braneworld concerns the physics of an AdS$_{d}$ brane embedded in an ambient gravitational AdS$_{d+1}$ spacetime. The gravitational theory induced on the AdS$_{d}$ brane has a very light but massive graviton. It has been established that the zero graviton mass limit of the $d$-dimensional graviton propagator is smooth at tree-level. Furthermore, this smoothness was conjectured to persist to the quantum level. This conjecture suggests that the massive graviton on the AdS$_{d}$ brane is due to spontaneous symmetry breaking, which is consistent with its holographic dual description. In this letter, we show that the zero mass limit of the partition function is a theory of a massless graviton and a decoupled massive vector. The zero mass limit is not the basic Randall-Sundrum II model, but a theory with these additional decoupled vector degrees of freedom coupled only to gravity. The proof relies on deriving the fully covariant description of the $d$-dimensional gravity theory which enables us to compute the one-loop partition function. At the end, we comment on the implications of this result to the physics of entanglement islands.

2604.28191 2026-05-01 cond-mat.quant-gas cond-mat.other cond-mat.stat-mech quant-ph

Observation of Vinen turbulence during far-from-equilibrium Bose-Einstein condensation

Sebastian J. Morris, Martin Gazo, Simon M. Fischer, Haoyu Zhang, Christopher J. Ho, Nigel R. Cooper, Christoph Eigen, Zoran Hadzibabic

Comments 6 pages, 5 figures

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Relaxation of far-from-equilibrium quantum fluids, intimately related to the emergence of long-range order, is theoretically associated with the decay of a turbulent isotropic tangle of vortex lines. We observe and study such decaying quantum turbulence in a homogeneous 3D atomic Bose gas. Using matter-wave techniques to magnify the gas density distribution, and then imaging a thin slice of the magnified cloud, we observe imprints of randomly oriented vortex lines and measure the vortex line-length density $\mathcal{L}$. The observed decay of $\mathcal{L}$ agrees with the prediction for Vinen `ultraquantum' turbulence. Although our weakly interacting gases are highly compressible, their large-scale dynamics are consistent with the behavior of an incompressible hydrodynamic fluid, with the decay of $\mathcal{L}$ not depending on the strength of the interatomic interactions and being similar to that in the strongly interacting superfluid helium.

2604.28189 2026-05-01 hep-th hep-ph

Towards Systematics of Calabi-Yau Landscape for String Cosmology

George K. Leontaris, Pramod Shukla

Comments 19 pages; Contribution to the BIRS-CMI workshop "Recent Progress in Computational String Geometry" held during January 26-31, 2026 at Chennai Mathematical Institute (CMI), Chennai

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In this review, we discuss the relevance and impact of studying Calabi-Yau threefolds in the context of global model building in string phenomenology. First, taking a phenomenologist-friendly approach, we review how the topologies of the various divisors and curves of the compactifying CY threefolds play a crucial role for generating the various ``suitable" classes of effective scalar potentials, within the framework of the popular moduli stabilization schemes such as KKLT and LVS. Subsequently, we discuss the impact of the specifics of the CY threefold geometries in the minimal LVS inflationary models such as fibre inflation, in particular, along the challenges such as the inflaton field-range bound. In this regard, we discuss a multi-field approach in which several fibre moduli assist to drive successful inflation having a sufficient number of efolds, without getting close to their individual Kähler cone boundaries.

2604.28188 2026-05-01 gr-qc hep-th

Cosmology of fractional gravity

Iván Salvador-García, Gianluca Calcagni

Comments 17 pages + appendices and references, 2 figures

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This is a first study of the cosmology of classical fractional gravity, a nonlocal proposal endowed with self-adjoint fractional d'Alembertian operators which serves as the basis for an ultraviolet-complete theory of quantum gravity. We derive the classical covariant nonlocal equations of motion for an arbitrary fractional exponent $γ$ and reduce them to the Friedmann equations on a homogeneous and isotropic cosmological background. We find that de Sitter is an exact stable solution and that bouncing exact solutions are sustained by phantom ($w<-1$) or ghost ($ρ<0$) fluids, in the latter case with a new type of finite-future singularity in the barotropic index. Different representations of the form factor give exactly the same solutions, thus confirming that the formulation of fractional field theories relies on a universality class of form factors. We compare these preliminary results with what obtained in multi-fractional cosmological models mimicking the spacetime geometry of fractional quantum gravity.

2604.28187 2026-05-01 cond-mat.supr-con cond-mat.quant-gas cond-mat.str-el

Enhancement of superconducting stiffness in hybrid superconducting-metallic bilayers

J. E. Ebot, Lorenzo Pizzino, Sam Mardazad, Johannes S. Hofmann, Thierry Giamarchi, Adrian Kantian

Comments 11 pages, 6 figures

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Boosting superconductivity by metallic reservoirs is the essence of Kivelson's bilayer proposal. One layer provides pairing to the electrons, while the weakly coupled metal provides additional phase coherence to those pairs by mediating extended-range pair-pair coupling. Demonstrating significant and unambiguous performance gains with strong-coupling methods for such set-ups had been difficult. In the present work, we study these systems doped away from half-filling, corresponding to a partially spin-polarized 1D Anderson- or Kondo-lattice. We show that this breaks the coexistence of dominant superconducting and density-density correlations decisively in favour or the former. Consequently, we provide evidence that in this doped regime, superconducting near-long-range order is not precluded by a small charge-gap in the thermodynamic limit, as we have recently shown to be the case at half-filling [JE Ebot $et$ $al.$, arXiv:2602.11153 [cond-mat.supr-con]]. We study the complex manner in which the enhancement of superconductivity in the pairing layer depends on the parameters of the metal, and especially that both pairing-limited and stiffness-limited regimes may appear in these systems. In addition to superconducting bilayers, our results are relevant, via a particle-hole transformation, for heavy-fermion Kondo-lattice materials in magnetic fields, as we provide previously lacking insight on the competition between antiferromagnetic and easy-plane magnetism, as well as a route for comprehensive indirect tests of Kivelson's bilayer proposal well beyond previous capabilities.

2604.28184 2026-05-01 cond-mat.mes-hall

Intrinsic anomalous thermal hall effect as a signature of quantum metric in d-wave altermagnets

Rishi G. Gopalakrishnan, Srimayi Korrapati, Sumanta Tewari

Comments 10 pages, 4 figures

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We investigate the intrinsic anomalous thermal Hall effect in d-wave altermagnets, where a transverse heat current is generated by a longitudinal temperature gradient in the absence of a magnetic field, with the leading response proportional to $(\nabla T)^3$. In these systems, the intrinsic Berry curvature-driven linear and thermal quantum-metric-driven second-order anomalous thermal Hall currents vanish as a consequence of crystalline symmetry. We show that the first nonvanishing contribution arises at third order in the temperature gradient and is governed by a nonlinear thermal Berry-connection polarizability, a quantity introduced in this work. Our analysis reveals a distinctive angular dependence of the anomalous thermal Hall conductance as the applied thermal gradient is rotated with respect to the crystal axes. We also find characteristic temperature and chemical-potential dependences that can be tested experimentally. These results identify unique quantum geometry-induced thermal responses and establish altermagnets as a promising platform for exploring intrinsic (i.e., scattering-time-independent) geometric transport phenomena.

2604.28183 2026-05-01 cond-mat.mtrl-sci cond-mat.mes-hall physics.app-ph

Uniaxial strain-driven ferroelastic domain control in LaAlO3

Matthias Roeper, Robin Buschbeck, Jakob Wetzel, Tobias Ritschel, Anna-Lena Hofmann, Vladyslav Kovtunovych, Mike N. Pionteck, Javier Taboada-Gutiérrez, Alexey B. Kuzmenko, Martina Basini, Vivek Unikandanunni, Iuliia Kiseleva, Jochen Geck, Susanne C. Kehr, Maximilian Lederer, Simone Sanna, Lukas M. Eng, Samuel D. Seddon

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Multiferroic domain walls in functional oxides exhibit properties distinct from the bulk and are increasingly exploited as active elements in nanoelectronic and photonic devices. Deterministic control of domain populations has typically remained limited to local control, or removal with temperature. Here we demonstrate continuous, reversible manipulation of the ferroelastic domain structure in single-crystal LaAlO$_3$ using in-situ uniaxial strain. Combining atomic force microscopy, X-ray diffraction, and Raman spectroscopy with first-principles calculations we map the complete microscopic evolution of the twin domain population through the strain-driven transition from the rhombohedral $R\bar{3}c$ ground state toward the predicted orthorhombic $Fmmm$ phase. Applied strains below $0.5\%$ produce pronounced surface flattening and large-scale domain reorganisation, establishing uniaxial strain as a technically accessible control parameter for ferroelastic domain engineering. These results open a route to active, real-time programming of domain architectures in LaAlO$_3$-based heterostructures, with implications for strain-tunable superconducting interfaces, nanoscale phonon-polariton optics, and ultrafast lattice control.

2604.28176 2026-05-01 quant-ph cs.LG

Defending Quantum Classifiers against Adversarial Perturbations through Quantum Autoencoders

Emma Andrews, Sahan Sanjaya, Prabhat Mishra

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Machine learning models can learn from data samples to carry out various tasks efficiently. When data samples are adversarially manipulated, such as by insertion of carefully crafted noise, it can cause the model to make mistakes. Quantum machine learning models are also vulnerable to such adversarial attacks, especially in image classification using variational quantum classifiers. While there are promising defenses against these adversarial perturbations, such as training with adversarial samples, they face practical limitations. For example, they are not applicable in scenarios where training with adversarial samples is either not possible or can overfit the models on one type of attack. In this paper, we propose an adversarial training-free defense framework that utilizes a quantum autoencoder to purify the adversarial samples through reconstruction. Moreover, our defense framework provides a confidence metric to identify potentially adversarial samples that cannot be purified the quantum autoencoder. Extensive evaluation demonstrates that our defense framework can significantly outperform state-of-the-art in prediction accuracy (up to 68%) under adversarial attacks.

2604.28167 2026-05-01 cond-mat.soft cs.LG

Mapping the Phase Diagram of the Vicsek Model with Machine Learning

Grace T. Bai, Brandon B. Le

Comments 8 pages, 3 figures

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In this study, we use machine learning to classify and interpolate the phase structure of the Vicsek flocking model across the three-dimensional parameter space $(η,ρ,v_0)$. We construct a dataset of simulated parameter points and characterize each point using long-time dynamical observables. These observables are then used as inputs to a K-Means clustering procedure, which assigns each point to a disorder, order, or coexistence phase. Using these clustered labels, we train a neural-network classifier to learn the mapping from model parameters to phase behavior, achieving a classification accuracy of 0.92. The resulting phase map resolves a narrow coexistence region separating the ordered and disordered phases and extends the inferred phase boundaries beyond the originally sampled simulation points. More broadly, this approach provides a systematic way to convert sparse simulation data into a global phase diagram for collective-motion models.

2604.28165 2026-05-01 physics.plasm-ph physics.space-ph

Determination of turbulent heating rate and relaxed states in finite Larmor radius magnetohydrodynamic turbulence with helicity barrier

Ramesh Sasmal, Supratik Banerjee

Comments 1 figure

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Finite Larmor radius magnetohydrodynamics (FLR-MHD) provides a hybrid model of plasma that explains how turbulent energy cascade extends to sufficiently small parallel length scales, potentially leading to perpendicular heating of the ions in the solar corona and the solar wind. In this work, we derive exact laws for the cascades of energy and generalized helicity in fully developed FLR-MHD turbulence. In large and small scale limits, we obtain the exact laws for reduced MHD and electron reduced MHD turbulence respectively. Unlike ordinary or reduced MHD turbulence, a global stationary state is shown to be absent in the case of a strong imbalance between the Elsasser variables. This is due to the so-called helicity barrier, which leads to two separate stationary energy cascades with different cascade rates. Our derived exact laws enable us to calculate these two cascade rates and therefore their difference, which effectively provides the heating rate of the ions. In addition, we also derive alternative Banerjee-Galtier forms for the exact laws and hence obtain the relaxed states of FLR-MHD turbulence using the framework of recently proposed principle of vanishing nonlinear transfer. The relaxed states show alignment between the velocity and magnetic field fluctuations. However, due to strong anisotropy, no Beltrami alignment is possible for velocity and magnetic fields. Similarly to the exact laws, the relaxed states of reduced and electron reduced MHD emerge in the large and small scale limits, respectively.

2604.28160 2026-05-01 quant-ph

Reorganizing Quantum Measurement Records Improves Time-Series Prediction

Markus Baumann, Maximilian Zorn, Thomas Gabor, Claudia Linnhoff-Popien, Jonas Stein

Comments 11 pages, 9 figures

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Near-term quantum computers are accessed through repeated circuit executions, which produce finite measurement records rather than exact deterministic outputs. In quantum reservoir computing, these records are converted to feature vectors for a classical readout. The standard expectation-value approach averages all shots from one labeled time step into a single feature vector. This reduces finite-shot noise, but it also gives the readout only one training example from many circuit executions. We introduce split-ensemble training: the same shots are split into groups, and each group average is used as a separate, partially denoised feature vector for the same target. The quantum circuit, task, and measurement budget remain unchanged. Across simulated forecasting benchmarks and real hardware experiments, this simple reorganization improves prediction when full averaging leaves the readout with too few training examples, with the strongest gains observed on hardware. Our results establish shot-record organization as a simple, broadly applicable algorithmic lever for improving near-term quantum learning without additional quantum hardware cost.

2604.28155 2026-05-01 cond-mat.stat-mech quant-ph

Optimal current-based sensing of phonon temperature using a finite reservoir

Sindre Brattegard, Stephanie Matern, Mark T. Mitchison, Saulo V. Moreira

Comments Comments are welcome

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In realistic nanoscale transport set-ups, electron-phonon coupling leads to the exchange of heat between phonon baths and electronic reservoirs with finite heat capacities. Such exchange affects the finite reservoir's temperature. However, this sensitivity of the finite reservoir temperature to the exchange of heat with the finite reservoir has remained unexplored for thermometry. Here, we fill this gap by combining current metrology techniques with a thermodynamic framework encompassing finite reservoirs. We focus on an experimentally realizable set-up with a quantum dot coupled to a finite reservoir and consider two distinct current-based strategies in the long time limit, namely monitoring quanta exchanged between the quantum dot and finite reservoir and the measurement of the total current flowing from the quantum dot into an infinite reservoir. A third strategy involves measurements of the quantum dot occupation. For a large but finite reservoir, we show that the Fisher information for all three strategies captures the finite reservoir's contribution to sensitivity through common factors. We also demonstrate that monitoring quanta exchanged between the system and finite reservoir in the long time limit achieves optimal precision. Finally, we provide an optimization analysis that explores how maximal precision can be achieved within each of the current-based strategies by tuning the gate voltage.

2604.28154 2026-05-01 hep-ph

Mapping data sensitivities in global QCD analysis with linear response and influence functions

Richard Whitehill

Comments 8 pages, 5 figures

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Global QCD analyses provide the primary framework for extracting hadron structure from experimental data, yet the mechanisms by which data constrain non-perturbative functions remain difficult to interpret due to the high dimensionality and complexity of these fits. Here we develop a framework based on linear response and influence functions, which are gradient-based sensitivity measures that directly quantify how experimental information propagates to fitted quantities and observables. These quantities cleanly expose how data locally determines the central values and uncertainties of quantum correlation functions, as well as the correlations between them, providing a transparent and general framework for diagnosing information flow in inverse problems in QCD.

2604.28152 2026-05-01 math.NA cs.NA physics.flu-dyn

Beyond first-order accuracy in continuous-forcing immersed boundary methods, and their well-conditioned projection-based solution

Diederik Beckers, H. Jane Bae, Andres Goza

Comments 35 pages, 10 figures

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We introduce a refined immersed boundary (IB) methodology that is better-than-first-order accurate in practice, while preserving key properties of "continuous-forcing" IB approaches that retain a singular source term in the governing equations. Our method leverages a smoothed indicator (Heaviside) function, following ideas from multiphase flow and immersed layers formulations, to recast the IB solution as a composite of distinct interior and exterior fields. We demonstrate that, when cast through this composite-solution lens, prior continuous-forcing IB methods can be seen as neglecting terms in the governing and constraint equations that restrict the solution to first-order accuracy. We incorporate these terms to systematically improve accuracy without the need for heuristic corrections. In canonical Poisson problems, we empirically demonstrate second-order convergence, and in incompressible Navier-Stokes simulations the method achieves slightly sub-second-order performance. While our present study focuses on these cases, the framework suggests a path towards second-order accuracy or higher, with further extensions. This perspective reframes accuracy limitations typically attributed to IB schemes. Although continuous-forcing IB methods are often reported to be only first-order accurate, we show that neither smoothing nor interface interpolation inherently restricts attainable order. Moreover, we naturally incorporate this higher-order formulation into a projection-based solution process. The resulting algorithm simultaneously mitigates the spurious surface stresses produced by ill-conditioned linear systems and reduces sensitivity to geometric resolution, addressing both conditioning and accuracy concerns within a unified approach.

2604.28151 2026-05-01 cond-mat.stat-mech quant-ph

Domain-wall melting in all-to-all QSSEP from random-matrix theory

Denis Bernard, Lorenzo Piroli, Stefano Scopa

Comments 31 pages, 6 figures

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We study the melting of a domain wall in the quantum simple exclusion process with all-to-all hoppings (a.k.a. the charged SYK$_2$ model). We show that the real-time dynamics of physical quantities of interest can be obtained exploiting spectral results in random matrix theory. We first show that the eigenvalues of the correlation matrix corresponding to the initially charged subsystem evolve according to a Jacobi process, which is defined in terms of a closed system of stochastic differential equations. In turn, this observation allows us to obtain the real-time dynamics of all the eigenvalue moments. We present two physical applications. First, we study the dynamics of the averaged von Neumann entanglement entropy, arriving at a fully explicit expression in the thermodynamic limit. Second, we compute analytically the full-counting statistics of the charge. Our formula allows us to perform a thorough comparison with the full-counting statistics of the classical simple exclusion process. Notably, we show that, in the thermodynamic limit, the quantum and classical full-counting statistics coincide, with no finite-time corrections.

2604.28148 2026-05-01 cs.RO eess.IV physics.ins-det

Design and Characteristics of a Thin-Film ThermoMesh for the Efficient Embedded Sensing of a Spatio-Temporally Sparse Heat Source

Sajjad Boorghan Farahan, Ahmed Alajlouni, Jingzhou Zhao

Comments 45 pages, 13 figures, 63 references, under review in Sensors and Actuators A: Physical

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This work presents ThermoMesh, a passive thin-film thermoelectric mesh sensor designed to detect and characterize spatio-temporally sparse heat sources through conduction-based thermal imaging. The device integrates thermoelectric junctions with linear or nonlinear interlayer resistive elements to perform simultaneous sensing and in-sensor compression. We focus on the single-event (1-sparse) operation and define four performance metrics: range, efficiency, sensitivity, and accuracy. Numerical modeling shows that a linear resistive interlayer flattens the sensitivity distribution and improves minimum sensitivity by approximately tenfold for a $16\times16$ mesh. Nonlinear temperature-dependent interlayers further enhance minimum sensitivity at scale: a ceramic negative-temperature-coefficient (NTC) layer over 973--1273~K yields a $\sim14{,}500\times$ higher minimum sensitivity than the linear design at a $200\times200$ mesh, while a VO$_2$ interlayer modeled across its metal--insulator transition (MIT) over 298--373~K yields a $\sim24\times$ improvement. Using synthetic 1-sparse datasets with white boundary-channel noise at a signal-to-noise ratio of 40~dB, the VO$_2$ case achieved $98\%$ localization accuracy, a mean absolute temperature error of $0.23$~K, and a noise-equivalent temperature (NET) of $0.07$~K. For the ceramic-NTC case no localization errors were observed under the tested conditions, with a mean absolute temperature error of $1.83$~K and a NET of $1.49$~K. These results indicate that ThermoMesh could enable energy-efficient embedded thermal sensing in scenarios where conventional infrared imaging is limited, such as molten-droplet detection or hot-spot monitoring in harsh environments.

2604.28143 2026-05-01 cond-mat.mtrl-sci

Multi-scale calculation of light-induced structural changes in low-angle twisted bilayer WSe$_2$

Rafael R. Del Grande, David A. Strubbe

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Exciton-phonon interactions in transition metal dichalcogenides (TMD) are strong and lead to phenomena such as coherent phonon generation. When stacked and twisted, their properties can be tuned by the twisting angle. In experiments with 1.1$^\circ$ twisted 2L WSe$_2$, a change of 0.1 Å in the interlayer distance was observed when light was shone on this material, and here we explain the microscopic mechanism behind this. Theoretical works to study such systems are limited because the Moiré unit cell is too large. To overcome this, we combined classical force field relaxations with our implementation of ab initio GW/Bethe-Salpeter excited state forces (ESF). From the relaxations we found that the low-angle twisting induced an in-plane strain field, the AB regions are large enough to be simulated as periodic AB stacked 2L WSe2, and the interlayer force constant becomes softer in relation to the perfect AB stacking. From the ab initio ESF we obtained that the in-plane strain increases the out of plane ESFs. Those two effects combined, the weakening of the interlayer force constant and strain dependence of the ESF, make light-induced changes in the interlayer distance of twisted 2L WSe2 stronger than in the perfectly stacked case, in agreement with experimental observations. Therefore, our results show that the exciton-phonon interactions can be tuned in twisted 2L TMDs and can be observed experimentally, which makes those materials excellent platforms to study light-induced changes in materials.

2604.28140 2026-05-01 gr-qc astro-ph.HE astro-ph.SR

Beyond the Separatrix: Analytic Continuation of Darwin Variables for Plunging Geodesics in Schwarzschild Spacetime

Francisco M. Blanco

Comments 11 pages, 6 figures

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We study geodesic motion of a test particle in Schwarzschild spacetime. Bound and scattering geodesics are commonly described using Darwin variables, which provide a convenient parametrization of the radial motion. However, this description breaks down at the separatrix and does not extend straightforwardly to plunging trajectories. We construct an analytic continuation of Darwin variables that yields a real parametrization of bound, scattering, and plunging Schwarzschild geodesics, thereby providing a unified kinematical description of all types of test-mass motion. As a proof of concept, we then apply these variables to a simple non-geodesic evolution in which the energy and angular momentum are driven by a constant external force. This toy model is not intended to represent a physical radiation-reaction model, but rather to illustrate how the extended variables can be used to follow an orbit through a transition to plunge using a single orbital phase variable across the separatrix.

2604.28137 2026-05-01 quant-ph

Weak-to-Strong Measurement Transition with Thermal Instabilities

Marcos V. S. Lima, Carlos H. S. Vieira, Irismar G. da Paz, Pedro R. Dieguez, Lucas S. Marinho

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Quantum measurement is physically realized through a finite dynamical interaction between a system and a measuring apparatus, giving rise to a continuous transition from weak to strong regimes. While this crossover is well understood under ideal conditions, the combined role of thermal instabilities and pre- and post-selection open dynamics has not been systematically addressed. Here, we develop a general framework to analyze the weak-to-strong measurement transition in the simultaneous presence of environmental decoherence and thermal noise. We model the probe as a thermal Gaussian state, explicitly incorporating temperature-dependent fluctuations in the measuring device, and include open-system evolution of the measured system prior to post-selection. By deriving the apparatus's final state, we show that the measurement statistics are modified in a nontrivial, highly sensitive manner by the temperature regime of the system's thermal instabilities, the probe's thermal properties, and the particular choice of pre- and post-selection. This approach allows us to characterize how thermal effects reshape the weak-value condition and influence the emergence of projective behavior across the full measurement crossover.

2604.28135 2026-05-01 astro-ph.EP

The Influences of Hydrogen-Silicate-Iron Miscibility on the Demographics of Sub-Neptunes and Super-Earths

Edward D. Young, Aaron Werlen

Comments Submitted to ApJ

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Models based on variable miscibility among hydrogen, molten silicate, and molten iron, coupled with atmospheric escape, can reproduce the observed occurrence density structure of sub-Neptunes and super-Earths in mass-radius space. The models are also consistent with the radius gap and the observed radius-period relationship exhibited by these planets. The degree of overlap between predicted and observed planetary occurrences suggests that hydrogen-silicate-iron miscibility may serve as a unifying concept for the formation and evolution of these planet classes. The well-defined equilibrium conditions at the boundary between supercritical magma oceans and the overlying hydrogen-rich envelopes are important features of the models. Planets formed with less than ~1 % hydrogen by mass develop discrete, terrestrial-like metallic cores, while those accreting greater hydrogen concentrations are predicted to have fully miscible interiors and no discrete metal cores. Hydrogen-silicate-iron miscibility provides an overarching explanation for the full range of sub-Neptune and super-Earth architectures based on the accreted hydrogen mass fraction and the phase equilibria governing silicate, iron metal, and H$_2$ miscibility.

2604.28133 2026-05-01 hep-ex hep-ph

The DAMSA Experiment

Prithak Bhattarai, Andrew Brandt, Alan Bross, Bradley Brown, Samriddha Chakraborty, Haohui Che, Bhupal Dev, Bhaskar Dutta, Juan V. Estrada, Eric Garcia, Anthony Gomez, Gajendra Gurung, Brian Joshua Gomez Hernandez, Wooyoung Jang, Jay Hyun Jo, Krzysztof Jodłowski, Doojin Kim, Eunsu Kim, Hyunyong Kim, Shin Hyung Kim, Young-Kee Kim, Jing Liu, Chang-Seong Moon, Donna Naples, David Nygren, Minseok Oh, Vittorio Paolone, Hyangkyu Park, Jong-Chul Park, Nathaniel J. Pastika, Rohit Raut, Juergen Reichenbacher, Paul Rubinov, Eunsuk Seo, Veronika Shalamova, Seodong Shin, Melvin Shochet, Adrian Thompson, Yau Wah, Shawn Westerdale, Guang Yang, Un-Ki Yang, Inseok Yoon, Jaehoon Yu

Comments 35 pages, 26 figures. arXiv admin note: substantial text overlap with arXiv:2601.15255

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DAMSA (DArk Messenger Searches at an Accelerator) is a novel short-baseline accelerator/beam dump experiment aimed at probing short-lived physics processes, including searches for evidence of a dark sector of particle physics and well-motivated rare Standard Model signals. Motivated by open questions in neutrino physics and the absence of conclusive evidence for conventional weakly interacting massive particles, DAMSA targets MeV-to-sub-GeV dark-sector messengers with feeble couplings that can be produced in abundance at a beam dump/target. By employing an ultra-short baseline, DAMSA is uniquely positioned to overcome the beam-dump "ceiling" that limits sensitivity to fast decaying particles in longer-baseline experiments. The conceptual design emphasizes a beam-dump production scheme combined with a compact detector optimized for rare decays while mitigating intense neutron-induced backgrounds, inherent to high-power proton beams. To validate the experimental strategy and detector technologies, the DAMSA Path-Finder (DPF) proof-of-concept experiment is also proposed, focusing on axion-like particles decaying to two photons, as the benchmark physics case and operating with 8 GeV electron beams at SLAC Linac-to-ESA (LESA) facility. Successful realization of DPF will establish the feasibility of the DAMSA approach, enabling a broad and powerful program to explore short-lived new physics and precision Standard Model processes in a previously inaccessible regime. This paper outlines the technical details of DAMSA's physics goals, key experimental challenges, and how to overcome them.

2604.28132 2026-05-01 astro-ph.CO astro-ph.GA gr-qc

Finding the one: identifying the host of compact binary mergers

Alberto Salvarese, Hsin-Yu Chen, Daniel E. Holz

Comments 11 pages, 3 figures, 3 tables. Comments are welcome

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Finding the host galaxies of stellar-mass compact binary mergers will open a new window for studying their formation histories and measuring key cosmological parameters, such as the Hubble constant. To date, only one merger, GW170817, has had its host galaxy confidently identified through electromagnetic counterpart observations. The large localization volumes from the LIGO-Virgo-KAGRA (LVK) network, combined with the lack of electromagnetic emission for most events, make host identification challenging. However, as the sensitivity of the gravitational-wave (GW) detector network improves, events are becoming increasingly well localized. Furthermore, galaxy luminosity traces mass or star formation rate, and thus correlates with the probability of hosting a merger. Focusing on the most luminous galaxies within the localization volumes of the best-localized GW events, we estimate the corresponding Hubble constant for each galaxy by combining its redshift with the luminosity distance inferred from LVK observations. For the well-localized LVK events \texttt{S250207bg}, \texttt{GW190814}, and \texttt{S250830bp}, we find only $1$, $1$, and $4$ galaxies, respectively, when restricting the analysis to the most luminous $1\%$ of galaxies above $L_{\rm th} \sim 10^{11} h^{-2} L_{\odot}$ in each event's localization volume and adopting a broad $H_0$ prior. The probability of these galaxies being random, and not associated with the GW events, is $29$-$36\%$ across the three events. We encourage further follow-up observations of these candidate host galaxies. We expect this approach to become increasingly powerful in future LVK observing runs, enabling constraints on merger formation histories and measurements of the Hubble constant.

2604.28128 2026-05-01 cond-mat.mtrl-sci

Unveiling the potential of NdPO4 magnetocaloric phases in cryogenic refrigeration

M. Balli, L. Attou, S-E. Bouzarmine, S. Oubad, K. El Maalam, P. Fournier, S. Mangin

Comments Paper presented at Intermag2026, Manchester, UK

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英文摘要

The RPO4 orthophosphates (R = rare earth element) have recently attracted a wide interest due to the strong coupling between their electronic, orbital and structural ordering parameters resulting in a variety of functional properties. Herein, we demonstrate that NdPO4 phases synthesized via a facile precipitation growth process unveil promise in low-temperature magnetic cooling. The analysis of their structural properties reveals nanorod forms with diameters of 10 to 20 nm and lengths ranging from 200 to 500 nm while the heat treatment transforms their hexagonal rhabdophane-type structure to a monoclinic anhydrous monazite-type symmetry. Magnetization measurements and DFT calculations show strong antiferromagnetic couplings and the absence of any magnetic ordering in the 2-300 K range. On the other hand, the monoclinic phase of NdPO4 exhibits a large magnetocaloric effect of about 19 J/kg K under 5 T near 3 K, outperforming some reference materials containing more expensive rare-earth elements with high magnetic moments.

2604.28121 2026-05-01 quant-ph physics.comp-ph

Quantum Lattice Boltzmann Solutions for Transport under 3D Spatially Varying Advection on Trapped Ion Hardware

Sayonee Ray, Jezer Jojo, Jason Iaconis, Abeynaya Gnanasekaran, Apurva Tiwari, Martin Roetteler, Chris Hill, Jay Pathak

Comments 11 pages, 11 figures

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英文摘要

The Quantum Lattice Boltzmann Method (QLBM) has emerged as one of the most promising quantum computing approaches for the numerical simulation of problems in computational fluid dynamics (CFD). The dynamics is formulated in terms of mesoscopic particle distribution functions governed by a discrete Boltzmann transport equation, comprising local streaming and collision operations. In this work, the resulting macroscopic behavior corresponds to the advection-diffusion equation, which we adopt as a canonical model problem for transport phenomena. Building upon recent progress in QLBM implementations, we advance towards more realistic problem settings that better reflect conventional CFD requirements. We address, for the first time, transport under the action of non uniform velocity fields on quantum hardware. We implement our demonstration using IonQ's trapped-ion systems including Forte generation systems and a 64-qubit Barium development system similar to the forthcoming IonQ Tempo line. We identify the density readout and subsequent reloading of the fluid density as a potential bottleneck of the current algorithm and discuss several approaches to mitigate this bottleneck. We identify the use of MPS shadow tomography as a promising method to efficiently scale the readout to large system with complex density distributions. Lastly, we introduce and simulate a novel method to implement wall boundaries for advection-diffusion in QLBM, and discuss the prospects of scaling to higher-complexity problems.

2604.28120 2026-05-01 cond-mat.mtrl-sci

Polar Topologies in a Ferroelastic Metal Membrane

Rahil Haria, Noah Schnitzer, T. Ben Britton, Yaqi Li, Tom J. P. Irons, Sophia Linssen Pitsaros, Ella Banyas, Geri Topore, Annabel Hoyes, Mariana Palos, Sinead M. Griffin, Katherine Inzani, Michele Shelly Conroy

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英文摘要

Polar metals, materials in which electric polarisation and metallicity coexist, are exceptionally rare because itinerant electrons screen long-range dipoles and favour centrosymmetric structures. Engineering polar textures in a conducting magnet holds promise for reconfigurable spin orbit coupling and magnetoelectric functionality. Here we show that releasing epitaxial SrRuO3 films from their substrates drives a hierarchy of ferroelastic domain refinement from micrometre to nanometre length scales, and that this structural reorganisation spontaneously generates two distinct classes of emergent polar texture that are ubiquitous across the freestanding membrane. Using correlative microscopy from mesoscale electron channelling contrast imaging (ECCI) to atomic resolution scanning transmission electron microscopy (STEM), we demonstrate that electric polarisation emerges selectively at translation-inequivalent antiphase boundaries (APBs). At these boundaries multicomponent aac tilt field undergoes Neel-like interpolation that preserves the in-phase tilt component and amplifies roto flexoelectric coupling, while translation-equivalent boundaries remain nonpolar. The Neel like interpolation at hard APBs and Ising like collapse of all tilt components at easy APBs is corroborated with ab initio calculations. While embedded 90 ferroelastic walls provide an additional mechanistically distinct source of electric polarisation resulting in polar nanoclusters (4 nm). These distinct nanotextures at 90 walls from via elastic accommodation of strain mismatch between variants and rotostriction as the tilt field interpolates across the boundaries. These findings show that, in a membrane form, metal oxides provide a robust platform for hosting nanoscale ferroelastic domains that generate polar textures.

2604.28117 2026-05-01 cond-mat.stat-mech

Strong Mpemba Effect Through a Reentrant Phase Transition

Kristian Blom, Doron Benyamin, Uwe Thiele, Oren Raz, Aljaz Godec

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We investigate temperature quenches across the reentrant phase transition of the antiferromagnetic Ising model in a magnetic field and show that the strong direct and inverse Mpemba effects arise when quenches terminate in the paramagnetic phase. These anomalous relaxation phenomena originate from the selective excitation of the slowest relaxation mode, which in the paramagnetic phase is purely staggered. Consequently, quenches starting from the paramagnetic phase have zero overlap with the slow mode and exhibit a strong (inverse) Mpemba effect. Quenches from the antiferromagnetic phase excite the staggered mode and display a slow-relaxation tail. By varying the lattice coordination number we show that the strong Mpemba effect disappears in the absence of reentrance. Our results provide the first demonstration of the strong (inverse) Mpemba effect in the antiferromagnetic Ising model based on the pair-approximation, and establish a link between anomalous relaxation and the equilibrium phase behavior.

2604.28114 2026-05-01 hep-th math-ph math.MP

BV quantization of $ϕ^3$-theory on $λ$-Minkowski space: Tree-level correlation functions

Djordje Bogdanović, Marija Dimitrijević Ćirić, Stefan Djordjević, Richard J. Szabo

Comments 16 pages; Contribution to the Proceedings of the Corfu Summer Institute 2025 "School and Workshops on Elementary Particle Physics and Gravity'' (CORFU2025), 27 April-28 September 2025, Corfu, Greece

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英文摘要

We review the quantization of scalar field theory on $λ$-Minkowski space using the Batalin--Vilkovisky (BV) formalism. We consider $ϕ^3$-theory in two different quantization schemes: standard and braided. While standard BV quantization is based on an ordinary $L_\infty$-algebra, braided BV quantization is based on a braided $L_\infty$-algebra. We compare the tree-level three-point and four-point correlation functions in the two approaches. For the four-point function, standard quantization leads to two inequivalent classes of diagrams with different noncommutative contributions, whereas braided quantization yields only a single class of diagrams with noncommutativity entering solely through an overall phase factor depending on the external momenta.

2604.28106 2026-05-01 cond-mat.mtrl-sci physics.chem-ph

Machine Learning and Molecular Simulations Reveal Mechanisms of ZIFs Polymorph Selection

Emilio Méndez, Rocio Semino

Comments 54 pages, 20 figures, 4 tables

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英文摘要

Zn(imidazolate)$_2$ metal-organic frameworks (MOFs) exhibit a remarkable degree of polymorphism. Because of their promising industrial applications, many research groups have investigated phase transitions, phase diagram and relative stability of these polymorphs. There is now wide consensus in the research community that these MOFs are solvothermally formed via non-classical nucleation mechanisms, in which pre-nucleation clusters are first formed, followed by an intermediate amorphous structure that subsequently reorganizes to yield the final crystalline MOF. However, no study up to date has uncovered which part of the synthesis process determines the final polymorph obtained. In this work, path collective variable metadynamics simulations performed with a partially reactive force field give insights into mechanistic and thermodynamic aspects of the self-assembly of these MOFs. Databases of transient and intermediate synthesis structures are built from the simulations. By developing and applying neural network classifiers over these databases, it is found that both pre-nucleation clusters and the amorphous intermediate structures are polymorph-dependent. These results suggest that polymorph selection happens as early as the pre-nucleation cluster stage.

2604.28105 2026-05-01 cond-mat.mtrl-sci cond-mat.other

From Narrow-gap Semiconductor to Metallic Altermagnet: Optical Fingerprints of Co-Doped FeSb$_2$

R. Mathew Roy, M. Povolotskiy, J. Kirschke, C. Prange, Y. Xia, V. Sundaramurthy, P. Puphal, M. Pinteric, M. van de Loo, A. Kreyssig, T. Zhang, A. E. Böhmer, M. Dressel, M. Wenzel

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The realization of bulk metallic altermagnetism has remained elusive despite the growing number of candidate materials. Here, we present evidence that moderate cobalt substitution ($\sim$15%) drives the correlated narrow-gap semiconductor FeSb$_2$ into a metallic altermagnetic state persisting up to room temperature. The infrared optical conductivity reveals low-energy interband transitions near 0.1 eV that emerge upon doping and grow with Co concentration. Density functional theory calculations show that these transitions originate exclusively from altermagnetic spin ordering, with spin split bands ($\sim$0.2 meV) of non-relativistic origin, together with spin-orbit coupling induced band splitting of the order of $\sim$5 meV near the Fermi level. Co substitution further leads to Fano lineshapes and mode mixing in the infrared-active phonons, reflecting enhanced electron-phonon coupling and local inversion symmetry breaking, while leaving the altermagnetic spin symmetry intact. Our results establish carrier-tuned FeSb$_2$ as a platform for exploring metallic $d$-wave altermagnetism and its coupling to lattice degrees of freedom.