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Physics

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Tuesday 6 October

Solar and Stellar Astrophysics

Effects of Magnetic Fields on Solar Inertial Modes in Global Nonlinear Simulations

Conrado S. Finotti, Gustavo Guerrero, Santiago A. Triana et al. (+2 more)

Solar inertial modes are increasingly viewed as probes of the solar interior, with recent helioseismic evidence indicating that these modes may be sensitive to the internal magnetic field. We investigate the role of magnetic fields on inertial mode excitation and dynamics using global nonlinear MHD simulations with differential rotation forced toward a helioseismically derived profile. Initial poloidal fields of varying strengths and topologies self-consistently generate different toroidal field configurations through the $\Omega$-effect. In all cases, baroclinic instability excites high-latitude inertial modes, with weak fields enhancing its growth rate above the hydrodynamic value. For stronger fields, the response depends on topology and depth. As a consequence, the polar vortex emerges earlier and modifies its relative amplitude, handedness, and hemispheric asymmetry. Only magnetic topologies exhibiting toroidal bands at the upper convection zone develop a second, magneto-shear ("edge") instability at the equatorward edges of these bands. Powered mainly by the toroidal field, this instability sets in earlier and grows faster for stronger initial fields. It excites equatorial modes absent in the hydrodynamic simulation, with fast magneto-Rossby signatures approaching the classical Rossby dispersion relation at tachocline depths. Alfvénic signatures and tentative slow magneto-Rossby branches also appear. Inertial-mode excitation and frequencies thus depend on magnetic topology and spatial distribution, not merely field strength.
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All authors Conrado S. Finotti, Gustavo Guerrero, Santiago A. Triana, Mausumi Dikpati, Piotr K. Smolarkiewicz

Materials Science

Analytical Prediction of Buckling Limits in Isotropic Pentamode Lattices

M. Verbicaro, F.Braghin and R.V. Craster

Pentamode lattices are architected materials characterized by an elastic response dominated by a single deformation mode. The low stiffness of the other deformation modes, however, may result in limited stability under compressive prestress, thereby limiting their mechanical performance. In this work, we develop a general analytical framework to determine the buckling limits of prestressed 2D and 3D isotropic pentamode lattices with generic link geometries. Two distinct instability mechanisms are considered: a global instability associated with the loss of stability of the effective medium, and a local instability associated with finite-wavelength modes at the scale of the lattice cell. Closed-form expressions for the corresponding critical pressures are derived, and the buckling limit is obtained as the lower of the two. The analytical predictions are validated through numerical simulations of different PM lattices, showing good agreement over the configurations considered. The results reveal a trade-off between approaching the pentamode limit and maintaining sufficient buckling resistance, but also show that appropriate link designs can substantially increase the buckling limit while retaining the desired pentamode behavior.
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Chemical Physics

Coupled Cluster Amplitude Extrapolation in Geometry Optimization

Jonas Beck, Michele Nottoli, Tommaso Nottoli et al. (+3 more)

In this work, we present an amplitude extrapolation ansatz for geometry optimization that uses calculations from previous steps to construct an initial guess for the quasi-Newton solver at each new geometry, significantly accelerating convergence of the coupled-cluster and Lambda solver alike. The ansatz incorporates a necessary amplitude transformation to mitigate discontinuities associated with orbital energy crossings at the Hartree-Fock level of theory, while remaining computational and memory efficient. The method is tested for a diverse set of medium-sized molecules to demonstrate a systematic and significant reduction in the number of coupled-cluster iterations compared to the conventional method.
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All authors Jonas Beck, Michele Nottoli, Tommaso Nottoli, Luca Melega, Filippo Lipparini, Benjamin Stamm

Mesoscale and Nanoscale Physics

Topological Frenkel excitons in 2D molecular crystals

Quentin Stein, Sidhartha Nayak, Song Jiang et al. (+7 more)

Collective molecular excitations govern energy transport in light-harvesting and optoelectronic materials. Theory predicts that excitonic band topology can generate edge-confined states, offering a route to direct energy flow in molecular systems, yet experimental evidence is lacking. Here we use scanning tunnelling microscopy-induced luminescence to image Frenkel excitons in two-dimensional zinc phthalocyanine molecular crystals with nanometer resolution. By varying cluster size, we observe the transition from discrete quantum-confined excitations to collective excitonic bands and directly resolve their real-space wavefunctions. We identify an excitonic state localized at the crystal perimeter and show, through comparison with microscopic theory, that it originates from the momentum-resolved non-trivial topology of the bulk excitonic bands. Our results establish molecular crystals as a platform for engineering topological excitonic states and provide a strategy for controlling energy transport through excitonic band engineering.
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All authors Quentin Stein, Sidhartha Nayak, Song Jiang, Jakob Kuhlke, Michelangelo Romeo, Thomas Frederiksen, Fabrice Scheurer, Katharina Kaiser, Tomas Neuman, Guillaume Schull

Mesoscale and Nanoscale Physics

Momentum-Locked Edge Excitons in 2D Molecular Crystals

Sidhartha Nayak, Alex Boeglin, Quentin Stein et al. (+4 more)

In molecular crystals, molecular excitations can hybridize into collective Frenkel excitons. Here we show that doubly degenerate excitations in planar two-dimensional molecular crystals generate excitonic bands with nontrivial momentum-resolved topological characteristics and edge states appearing only for selected crystallographic terminations. Using a model inspired by aggregates of zinc phthalocyanine molecules deposited on insulating surfaces, we demonstrate that the existence of edge excitons depends sensitively on the crystallographic orientation of the boundary and is governed by the Zak phase of the underlying bulk bands. The resulting edge states exhibit momentum-locked elliptical polarization textures originating from the internal structure of the molecular excitations, potentially enabling directional optical coupling and excitation transport. Our results establish a route toward topological and polarization-textured excitonic states in two-dimensional molecular materials.
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All authors Sidhartha Nayak, Alex Boeglin, Quentin Stein, Katharina Kaiser, Guillaume Schull, Thomas Frederiksen, Tomáš Neuman

Lattice Field Theory

Sampling SU(N) gauge theory on a 2D lattice from independent plaquettes via holonomies and corner reweighting

Javad Komijani

In the Wilson formulation of lattice gauge theory, the fundamental degrees of freedom are group-valued link variables, while the action is a sum over the trace of the plaquettes, the smallest Wilson loops. For generative sampling methods such as normalizing flows, this poses a challenge: the distribution of an individual plaquette is easy to model, but mapping sampled plaquettes to the links is the obstruction. We explore a statistical way around this in two dimensions for the $\mathrm{SU}(N)$ gauge theory with the Wilson plaquette action. The action can be written in terms of holonomy variables, which determine the links once a consistency condition at the four corners of an extended lattice is satisfied. Using a boundary condition that only affects the holonomies, we trade this consistency condition for a conditional sampling problem, which reduces to sampling $X,Y\in\mathrm{SU}(N)$ given the group commutator $Z=XYX^\dagger Y^\dagger$, where $Z\in\mathrm{SU}(N)$ depends on the four corners. Plaquettes are sampled independently, and the resulting configurations carry weights due to the additional conditional sampling. We obtain the density of $Z$, which determines these weights, in closed form for $\mathrm{SU}(2)$ and $\mathrm{SU}(3)$. A normalizing flow models the single-plaquette distribution for $\mathrm{SU}(2)$ and $\mathrm{SU}(3)$; for the group-commutator problem we use a closed-form sampler for $\mathrm{SU}(2)$ and a trained normalizing flow for $\mathrm{SU}(3)$. In our tests on $2\times2$ and $32\times32$ lattices at two couplings each, per-plaquette acceptance rates exceed $99\%$ and the effective sample size of the final weights is moderate, typically above one half.
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General Relativity and Quantum Cosmology

Intrinsic spatial-strain shortcuts in general relativity

Francisco S. N. Lobo

We analyze spacetime shortcuts generated by longitudinal contraction and transverse expansion of the intrinsic spatial metric at fixed reference volume. Smooth bounded ultrastatic corridors are globally hyperbolic and geodesically complete and produce an exact travel-time advance between exterior clocks. An axial maximum makes the axial light ray globally minimizing; a strict maximum on an interior interval establishes Olum's endpoint-surface criterion for exactly matched corridors. Exact Einstein-source identities distinguish integrated Eulerian matter energy from asymptotic mass: infinite tubes have negative integrated energy, whereas finite corridors admit competing gradient contributions. A transverse Ricci identity proves local null-energy violation in every nontrivial localized finite corridor. The axial averaged null energy is strictly negative for localized axial-maximum profiles, and quantitative bounds relate its magnitude to the reference time advance and peak strain. We also obtain the complete finite-profile Ricci spectrum and the axial passenger tidal tensor. These results provide explicit causal and source constraints on a prepared geometry without specifying its physical formation or matter dynamics.
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Quantum Physics · Cross-listed from cs.LG

A Cognitive-Aware QML-CRL Framework for Detecting Affinity and Romance-Investment Fraud

Bibhas Adhikari and Ramya Srinivasan

We present a hybrid quantum-classical framework that detects affinity and romance-investment fraud by modelling the cognitive biases in a manipulative conversation. In our proposed framework, cognitive biases central to this fraud class are carried by dedicated qubits in a structured parameterized quantum circuit, together with a frame qubit makes the encoding sensitive to the temporal order of manipulative reframing, and a narrative qubit that aggregates co-occurrence through a trainable entanglement layer. The circuit parameters are trained jointly with a classical reinforcement-learning agent that decides, turn by turn, whether to flag the conversation, modeled as an optimal stopping problem. We evaluate the model's performance on synthetic conversations that include hard negatives, legitimate but urgent, and legitimate but pushy sales conversations.
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Cosmology and Nongalactic Astrophysics

The Impact of Galaxy Catalogue Completeness with GLADE+ on Dark Siren Cosmology: A Line-of-Sight Prior Analysis of GWTC-3 Events

Juan Esteban Rivera, Antonio Enea Romano, Rachel Gray et al. (+2 more)

Cosmological parameters can be estimated from dark sirens, gravitational waves events without electromagnetic counterpart, by using inference methods which estimate statistically the source redshift from galaxy catalogs. We study the effects of applying different apparent magnitude cuts to the GLADE+ catalog, analyzing events from the third LIGO-Virgo-KAGRA gravitational wave transient catalog (GWTC-3), consisting of 42 binary black holes, 3 neutron star black hole systems and the event GW190425 associated to a binary neutron star coalescence. We find that the inclusion of fainter galaxies has no significant effects on the joint analysis of almost all the events, while for some single well localized event, the effects can be more important, in particular for the event GW190814. To understand why inclusion of fainter galaxies in general has negligible impact on the estimation of cosmological parameters, we compare the redshift of the events with the redshift distribution of dimmer galaxies, and find that most of them are not located in redshift proximity of the events, explaining the limited impact of their inclusion. The event, GW190814 is an exception, as its distance localization, converted into redshift, overlaps with fainter galaxies, unlike what happens for other events, which are farther away. These results show the importance of event localization and catalog depth in determining the impact of catalog completeness on cosmological parameters estimation. To check quantitatively what is the information gained by adding fainter galaxies we have analyzed its impact on the line of sight prior calculation. Based on the results for GW190814 we expect that fainter galaxies will play a more significant role in the estimation of cosmological parameters also for the joint analysis of multiple events, when deeper catalogs will be available.
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All authors Juan Esteban Rivera, Antonio Enea Romano, Rachel Gray, Sergio Vallejo-Peña, Riccardo Sturani

Earth and Planetary Astrophysics

Detection of escaping magnesium in the upper atmosphere of WASP-76b

Lakeisha M. Ramos Rosado, Leonardo A. Dos Santos, Joshua D. Lothringer et al. (+8 more)

Near-ultraviolet (NUV) observations can uniquely probe low-density, high-altitude gas in ultra-hot Jupiters (UHJs) via strong resonance lines of metals. WASP-76b is a well-studied UHJ with prior detections of refractory metals and complex day-night chemistry, making it a prime target for atmospheric escape diagnostics in the NUV. We present HST/STIS E230M (2274 - 3119 $\mathring{\mathrm{A}}$) transmission spectroscopy of WASP-76b. While broad- (~ 200 $\mathring{\mathrm{A}}$) and narrow-band (4 $\mathring{\mathrm{A}}$) transmission spectra do not show spectral features, a velocity-resolved single line analysis reveals clear excess absorption in both components of the Mg II doublet (2796 $\mathring{\mathrm{A}}$ and 2803 $\mathring{\mathrm{A}}$, $k$ and $h$ lines). The Mg II signal is localized to the blue wing (Doppler velocities [-50, -10] km s$^{-1}$) and is recovered with narrower 0.5 $\mathring{\mathrm{A}}$ bins; the inferred absorption exceeds both the optical continuum radius and the Roche-lobe scale, suggesting a highly extended upper atmosphere. We estimate a mass-loss rate of $\dot{M}\sim10^{12.14}\,\mathrm{g\,s^{-1}}$ from ATES. The present NUV data do not improve constraints on lower-atmosphere properties, and a comparison with upper-atmosphere forward models disfavor scenarios with extreme Mg enrichment. Together with the near-solar metallicity inferred from optical+IR spectra, this suggests that the Mg II absorption can arise in an escaping upper atmosphere without requiring extreme Mg enrichment, qualitatively consistent with hydrodynamic escape. Ongoing HST programs expanding the sample of UHJs focused on NUV observations will enable comparative tests of composition and kinematics in escaping atmospheres.
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All authors Lakeisha M. Ramos Rosado, Leonardo A. Dos Santos, Joshua D. Lothringer, David K. Sing, Johanna Teske, Aline A. Vidotto, David Ehrenreich, Julia V. Seidel, H. Jens Hoeijmakers, Munazza K. Alam, Monika Lendl

Earth and Planetary Astrophysics

Polarimetric Behaviour of (3200) Phaethon: New Observations with Implications for Surface Heterogeneity

Zuri Gray, Mikko Vuori, Eric MacLennan et al. (+4 more)

The near-Earth asteroid (3200) Phaethon exhibits unusually high linear polarisation at large phase angles. Previous observations revealed a significant difference between apparitions: measurements obtained in 2016 showed a polarisation up to $\sim10$ percentage points higher than those obtained in 2017 at comparable phase angles. The distinct surface regions and viewing geometries sampled during the two apparitions have been suggested as possible explanations for this difference. Here, we present new R-band polarimetric observations obtained with the Nordic Optical Telescope, covering phase angles $32^\circ<\alpha<103^\circ$. The 2019 measurements show polarisation intermediate between higher and lower values measured in 2016 and 2017, respectively. Using a recent shape model, we calculate the distribution of reflected flux across the surface during the three individual apparitions and find that the 2019 observations sample the surface more similarly to 2016 than to 2017. We explore several possible explanations for the different polarisation behaviours, including differences in regolith grain size, related surface albedo, and observing geometry. While the available observations do not allow these effects to be uniquely disentangled, our results and analysis suggest that surface heterogeneity is the most plausible underlying cause, with viewing geometry potentially contributing to the observed polarimetric differences.
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All authors Zuri Gray, Mikko Vuori, Eric MacLennan, Mikael Granvik, Karri Muinonen, Antti Penttilä, Mikael Turkki

Chemical Physics

Angular Momentum Fluctuations Induced by Phonon-Rotation Coupling Govern Nuclear Spin Relaxation in a Molecular Rotator Phase

Yanan Li, Florin Teleanu and Alexej Jerschow

Nuclear spin relaxation has been widely used to probe molecular reorientation in solids, yet its interpretation has always required assuming both the relaxation mechanism and the form of the underlying correlation function. In rotator-phase solids more unknowns enter the picture: in ammonium iodide, the proton T$_1$ passes through a maximum and decreases with temperature, a behavior attributed to spin-rotation coupling. Here we model both the dipolar and the spin-rotation contributions to $^1$H relaxation in solid NH$_4$I from first principles, by combining molecular dynamics with machine-learned force fields trained on density functionals and ab initio spin-rotation coupling tensors. The computed rates reproduce the measured values above the order-disorder transition, together with their temperature dependence and frequency independence, and show that fluctuations of the NH$_4^+$ angular momentum dominate relaxation throughout the rotator phase. The orientational and angular-velocity correlation functions obtained directly from the simulations further share an oscillatory component at lattice-phonon frequencies, revealing a coupling between lattice vibrations and cation reorientation that contributes measurably to relaxation. Separating this component yields a reorientational barrier in agreement with neutron scattering. The approach makes nuclear spin relaxation a quantitative benchmark for simulated dynamics in molecular solids and provides direct access to angular-momentum correlations in the solid state.
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Quantum Physics

The coupler Eve did not monitor: a black-box cavity cheat

Yueying Wu

Eve receives two average photon counts, while a monitor watching for external leakage may register nothing. Can she conclude that Alice and Bob's opaque cavity devices did not communicate? We give a constructive counterexample: two independently operated controls activate a shared beam-splitter interaction after the inputs arrive. The parties report genuine sample averages, and a fixed local threshold converts these reports into a CHSH game with expected score $S=13/4$ for four repetitions per block, approaching $4$ for large blocks in the ideal model. This exceeds the usual $2\sqrt2$ quantum benchmark because the devices interact during their response. A separate dispersive-bus model explains how substantial exchange can coexist with a small probability of a click in a specified leakage monitor; an illustrative open-system calculation exhibits both effects without postselection. The output marginals nevertheless reveal signalling. The example separates three questions: whether the reports are honest, whether a monitored port is quiet, and whether the devices are physically isolated.
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Atomic Physics

Achieving a long lifetime synchronized state in a thermal vapor Rydberg time crystal

William J. Watterson, Dixith Manchaiah and Christopher L. Holloway

Time crystals are a unique and recently discovered state of matter in which time-translational symmetry is spontaneously broken. Although this state has been observed across a variety of quantum systems, understanding the nature between driving, dissipation, and noise and the effects of these forces on the state lifetime remains elusive. Here, we study phase diffusion and entrainment of the time crystalline oscillatory state of a thermal-vapor Rydberg atom ensemble. We apply a pulsed rf heterodyne driving field which can entrain the oscillation frequency during the on driving period. During the off period, the entrained ensemble phase diffuses on a 1/$e$ timescale up to 2.3 ms – significantly longer than the Rydberg state lifetime. We additionally study how the entrainment and phase diffusion timescales are affected by the strength and detuning of the rf driving field, and develop a classical Fokker-Planck model with an Adler-based driving term that reproduces the observed experimental findings. These results demonstrate the creation of a long-time synchronized time crystal Rydberg atom ensemble state, which could be utilized in applications requiring frequency and phase stability.
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Lattice Field Theory

A gauge-invariant measure for lattice chiral fermions

Nathaniel Craig

We nonperturbatively construct a gauge-invariant measure for overlap fermions on four-dimensional Euclidean lattices in a class of nonabelian chiral gauge theories that includes the Standard Model. On admissible gauge fields, comparing chiral projectors at successive lattice spacings yields an exponentially local current and establishes the global properties needed for Lüscher's reconstruction of a smooth, gauge-invariant fermion measure. This provides a candidate nonperturbative lattice definition of the Standard Model.
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Exactly Solvable and Integrable Systems

Nonlinear Spectral Computing

Ludovica Falsi, Francesco Coppini and Claudio Conti

Many machine learning algorithms rely on the Fourier transform, which is also the inner core of many analog computing devices and, specifically, of optical computing. The square of the modulus of the Fourier spectrum naturally maps onto pairwise interactions, as in the renowned Ising model, making it applicable to combinatorial optimization. Here we show how the nonlinear Fourier transform, related to integrable nonlinear partial differential equations, significantly widens the computational capability and also enables a wide variety of computing gates. We study specifically the case of the nonlinear Schrödinger equation; we introduce an input composed by “tokens”, i.e., batches of information encoded in a multi-step potential, and we show how the nonlinear spectral computing arising in the wave propagation not only generalizes combinatorial optimization to higher order problems, but also realizes boolean gates. In the weakly nonlinear regime, nonlinearity generates higher-order interactions as perturbative corrections to the pairwise terms. In the solitonic regime, the discrete nonlinear spectrum performs digital computation through soliton generation. By using four input tokens, we demonstrate the programmability of all 256 Boolean functions of three variables, including 3-SAT instances. Our results show that integrable nonlinear propagation provides an unprecedented single physical platform for higher-order and logical computation, opening the way to a rich variety of new algorithms for analog computing, machine learning, and classical and quantum information processing.
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Quantum Physics

Interaction-Assisted Spin Coherence in a Multimode Trapped Atomic Ensemble

Aleksandre Merabishvili and Ebubechukwu O. Ilo-Okeke

In a thermally occupied multimode trapped ensemble, mode-dependent detunings can strongly suppress Ramsey contrast even when the underlying dynamics remains coherent. We develop a weak-axis-resolved Hamiltonian theory in which collective mode spins experience longitudinal detunings and overlap-dependent exchange interactions. Without exchange, the distribution of detunings across thermally occupied modes produces coherent phase mixing and an algebraically decaying Ramsey-contrast envelope in the many-mode continuum regime. At the mean-field level, exchange generates a self-consistent restoring field that reduces phase dispersion and restores collective contrast. The crossover is governed by the competition between the collective exchange scale and the thermally induced detuning spread: when the late-time contrast is expressed in terms of their ratio, results at different temperatures collapse onto a common trend, and the crossover coupling follows the predicted inverse-square thermal scaling, with a numerical exponent of 2.06. Weak irreversible pure dephasing limits, but does not eliminate, this recovery, demonstrating that exchange refocuses coherent inhomogeneous phase mixing but cannot reverse irreversible phase noise.
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Quantum Physics

Geometric heat pumping on a quantum processor

Gerónimo J. Caselli, Luis O. Manuel, Liliana Arrachea et al. (+1 more)

Geometric heat pumping is the transfer of energy between reservoirs at equal temperature where the heat exchanged in an adiabatic cycle depends only on the driving contour in parameter space. We implement this mechanism on a superconducting quantum processor using a collision model, where a driven qubit interacts repeatedly with two ancilla qubits that are prepared in thermal states and emulate the reservoirs. Energy measurements before and after each interaction provide a calorimetric record of the heat exchanged with each reservoir. By reversing the driving contour, we extract a heat contribution associated with pumping. Its dependence on the period and on the contour follows exact simulations of the collision model, without adjustable parameters, and approaches in the slow-driving regime the geometric limit of the corresponding Lindblad dynamics.
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All authors Gerónimo J. Caselli, Luis O. Manuel, Liliana Arrachea, Pablo S. Cornaglia

General Relativity and Quantum Cosmology

Anisotropic Cosmology with Inhomogeneous $SU(2) $ and $SL(2,\mathbb{R})$ Nonlinear $\sigma$-Models

N. Dimakis, A. Giacomini, G. Leon et al. (+2 more)

We investigate the cosmological dynamics of the nonlinear $\sigma$-model in a locally rotational symmetric Bianchi V background geometry. We employ the $SU(2)$ and the $SL(2,\mathbb{R})$ internal symmetries, for which the kinetic metric of the multi-scalar fields is a space of constant curvature. We assume an inhomogeneous ansatz for the scalar fields, such that the $\sigma$-model, which allows the existence of nontrivial solutions in the Bianchi V geometry. For an exponential potential, we perform a detailed analysis of the phase space, we determine the stationary points, and we study their stability properties. The scalar field inhomogeneities prevent both the slow-roll and hyperbolic inflationary epochs. The existence of a cosmological constant is required to describe cosmic acceleration.
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All authors N. Dimakis, A. Giacomini, G. Leon, F. Moncada, A. Paliathanasis

Quantum Physics

Heating and Escape of Confined Atoms Subject to Colored Noise

Joseph M. Ryan, Katherine Jonas and Christopher Monroe

The motion of a particle in a finite-depth confining potential, such as that of an electromagnetically trapped atom or ion, is approximately harmonic at low energy and softens as the escape energy is approached. When the particle is driven by a stochastic force, the heating and escape times depend sensitively on the noise power spectrum. We study escape times of particles in softening potentials driven by power-law colored noise. We identify two nested conditions for weak noise: the particle must execute many oscillations before escape, and noise forces must be small relative to forces exerted by the trap so as not to tilt the potential appreciably. In this regime, we derive expressions for the mean escape time using stochastic averaging techniques and compare them with Monte Carlo simulations of the full equations of motion. We also examine the crossover to regimes where these conditions are not met and large quasi-static forces give rise to additional escape mechanisms. Applying these results to an experimental measurement of lifetimes in a microfabricated ion trap, we find that spectral color alone cannot account for the rapid escape rates observed, whereas quasi-static barrier tilting by a stray field of plausible magnitude could. These results are relevant to the heating and escape of trapped atoms due to noisy force fields, as well as to other nonlinear oscillators subject to colored noise.
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Mathematical Physics · Cross-listed from math.SP

A long time Gutzwiller trace formula for perturbations of Schrödinger operators near Anosov energy levels

Julien Moy

Let $P_h$ be a semiclassical pseudodifferential operator on a closed Riemannian manifold $(M,g)$, with principal symbol $p$. We consider perturbations $P_h+h^\alpha Q$, with $0<\alpha\le 1$, where $Q$ is a semiclassical pseudodifferential operator whose symbol oscillates at scale $h^\beta$, with $2\beta <\alpha$. Assuming that the classical dynamics of the unperturbed system on a regular energy surface $p^{-1}(E)$ is hyperbolic, we prove a Gutzwiller trace formula for the perturbed operator that holds up to times of order $|\log h|$. This formula relates the distribution of energy levels of the quantum system near the energy $E$ to the periodic orbits of its classical counterpart. The perturbation $h^\alpha Q$ affects only the phases appearing in the trace formula.
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Strongly Correlated Electrons

Ambipolar metal-insulator transition in bilayer MoSe2

Ha-Leem Kim, Hyungbin Lim, Terry Wu et al. (+7 more)

When Coulomb interactions dominate kinetic energy, dilute two-dimensional carriers form a Wigner solid. Both its melting and disorder-driven localization can drive density-tuned metal-insulator transitions, but their relative roles and interplay have been debated for decades. Atomically thin semiconductors offer a new test because transport and scanning tunneling microscopy can probe the same material, yet poor contacts impede transport where correlations are strongest. Here we introduce contact-free radio-frequency reflectometry that senses sheet resistance through capacitive gate coupling. It resolves the electron and previously inaccessible hole transitions in the same bilayer MoSe2 device, whose carriers share disorder but not mass. Their critical densities differ fourfold yet correspond to comparable Coulomb-to-kinetic-energy ratios, where tunneling microscopy finds solid-liquid coexistence. Magnetoresistance peaks sharply at each transition, reflecting a Pomeranchuk-like, field-driven expansion of the Wigner solid against the correlated liquid. Our results demonstrate interaction-driven transitions in high-quality two-dimensional semiconductors, opening quantitative transport in contact-limited systems.
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All authors Ha-Leem Kim, Hyungbin Lim, Terry Wu, Amogh Y. Waghmare, Garima Gupta, Takashi Taniguchi, Kenji Watanabe, Archana Raja, Eric Y. Ma, Feng Wang

Other Condensed Matter

Magnon Polarization Textures and Transport in Antiferromagnets and Altermagnets

Konstantin S. Denisov and Igor Žutić

Antiferromagnets (AFMs) host magnons that can exhibit fully circular, elliptic and linear polarizations of sublattice magnetization dynamics. We analyze theoretically different momentum-space magnon polarization textures and magnon transport in collinear AFMs and altermagnets (AMs). The sensitivity of the polarization texture to a magnon momentum direction determines two regimes of magnon polarization kinetics: The Dyakonov-Perel relaxation or its dephasing due to asynchronous Larmor precession. For an easy-axis AFM, magnetic field parallel to the Néel vector leads to the suppression of the magnetic dipolar interaction-induced Dyakonov-Perel relaxation, accompanied by the increase in the magnon spin-diffusion length and its counter-intuitive growth with temperature. For a perpendicular orientation, instead, relaxation of circular polarization of magnons is enhanced due to Larmor precession. Finally, extremely anisotropic relaxation of magnon polarization is predicted for AMs or AFMs having Dzyaloshinskii-Morya interaction.
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Quantum Physics · Cross-listed from cs.CR

Cost of Delay for Post-Quantum Migration: Putting Classical and Harvest-Now-Decrypt-Later Risk on One Ordered List

Animesh Shaw

Organisations deciding which assets to migrate to post-quantum cryptography first, and how that work competes with a backlog of classical findings, lack a common unit: post-quantum scores are dimensionless and quantum-only, while classical risk is annualised loss. We express both threats as a cost of delay in currency per year on the same asset. The quantum term is the rate at which deferring migration commits irreversible harvest-now-decrypt-later loss, computed from required confidentiality duration, recordable traffic share and data turnover, using a quantum-arrival law fitted in closed form to published expert anchors. A competing-risks factor couples the two terms so the same loss is not counted twice. We prove that the construction is not a weighted sum of a classical and a quantum score, give a dominance threshold on the classical hazard that is independent of asset value, and show that the induced order is optimal for sequencing work under constant loss rates. We verify the implementation by simulation, adaptive quadrature and a second implementation. On four public systems with parameters assumed from public documentation, the quantum term reorders the asset list beyond input uncertainty for one system only (signal-to-noise 1.36 against 0.14-0.46), moves specific long-lived, quiet, recordable assets decisively, and otherwise changes magnitudes. Asset value and turnover explain 73-91% of the uncertainty in the quantum term; the arrival date explains 3-17%. The case studies are illustrative and are not validated against outcomes.
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Instrumentation and Methods for Astrophysics

Assessment of sky brightness in central Portugal: the Dark Sky destination "Aldeias do Xisto" case study

Domingos Barbosa, Dalmiro Maia, Bruno Morgado et al. (+5 more)

A combination of remote sensing techniques, open space data and field testing was developed to derive astronomical and meteorological parameters and assess Dark Sky brightness of the hitherto unstudied Schist Villages region in the mountainous Interior Center of Portugal. This study covered the period 2012-2017 and established the methodology for regular light pollution and sky brightness studies in the region using satellite imagery to reduce cost and time and increase accuracy of the final analysis. Long-term Artificial Light At Night (ALAN) data from VIIRS instrument aboard the Suomi-NPP satellite along with cloud cover inferred from MODUS/AQUA satellite data and orographic data, were analyzed in a Geographical Information Systems (GIS) environment. The derived ALAN values were consistent with a preliminary site survey selection, confirming the accuracy of the identified dark sky spots in the region. The analyzed region area spans 1624 Km$^2$ and the darkest site within it showed a sky brightness of 21.4 mag/arcsec$^2$. Ground-based SQM photometer observations of the Night Sky Brightness (NSB) at the zenith validated the satellite derived ALAN data. The devised field testing is itself a low cost solution that can be used by teams in developing countries to easily assess dark sky potential prior to the development of local observatories and astro-tourism activities. This study supported the initial certification of this region as a Dark Sky Starlight Tourist Destination since 2018, an important milestone for dark sky protection in central Portugal.
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All authors Domingos Barbosa, Dalmiro Maia, Bruno Morgado, Pedro Cruz, Bernardo Relvas, Valério Ribeiro, Allan Kardec de Almeida Jr., Timothée Vaillant

Fluid Dynamics

Coupled Thermochemical Ablation and Rarefied Particle Erosion during Mars Entry

Hyeon Woo Nam and Sung Min Jo

Martian dust particles are a few micrometers in diameter, comparable to the mean free path of the gas in the hypersonic shock layer. Their Knudsen number ranges from approximately 0.2 to 100, placing them in the transitional and free-molecular regimes, whereas the flow around the vehicle is a continuum. The two-way flow-particle coupling previously developed by the authors for a two-temperature thermochemical nonequilibrium flow is extended to a receding and pyrolyzing heat shield surface. The gas-surface interaction and the in-depth material response are solved on separate time scales. The surface balances are exchanged at every flow step, while the in-depth response is coupled implicitly over physical time windows. The flow-material coupling is assessed against graphite arc-jet measurements. The framework is applied to the Schiaparelli trajectory from 50 to 30 km. Three surface chemistry models (equilibrium, Park-5, and Zhluktov-Abe) are compared for fixed geometry, char-induced recession, and combined char ablation and particle erosion. At the final trajectory point, the stagnation point heat flux differs by 30-75% among the chemistry models. For the equilibrium model, surface recession changes this heat flux by less than 1% but lowers wall temperature and increases pyrolysis gas injection. Particle erosion contributes 1.73 mm of stagnation point recession, exceeding the char-induced recession, and more than doubles the total recession for all three models. To the authors' knowledge, this study provides the first quantitative comparison of particle erosion between rarefied and continuum drag correlations, and the continuum correlation underestimates the stagnation point erosion rate by 31-35%.
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Quantum Physics

Teleportation of a programmable gate

Nada Ali and Mark Hillery

Alice and Bob each have a qubit, and they would like to perform a two-qubit gate on them with the assistance of Charlie. The action of this gate depends on a parameter, which either Charlie knows, will receive later as classical information, or is encoded in a program state. We discuss both the case in which Alice and Bob send Charlie their qubits, which he entangles with his state, and the case where Alice and Bob use teleportation to entangle their states with Charlie's state. All of these procedures depend on the ability of Alice and Bob to apply local correction operations that depend on the results of measurements that Charlie makes, and we discuss under what conditions such operations are possible.
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Mathematical Physics · Cross-listed from math.PR

Conditional Flat Exponential Directed Last Passage Percolation under a One-Point Upper Large Deviation Event

Rishi Dadlani and Shaotian Sun

Exponential directed last passage percolation is a random maximization model connected to tandem queues and interacting particle systems. We study the line-to-point model of the percolation, in which the starting point is allowed to vary inside a line boundary, conditioned on an atypically large last-passage time to a fixed endpoint. Extending recent results for the point-to-point model where the starting point is fixed, we develop heuristic predictions for the conditional limit shape and prove corresponding fluctuation results in certain regimes through steepest-descent analysis of exact multi-point formulas. Our calculations suggest that the conditional fluctuations near diagonal are described by Brownian bridges coupled through an additional shared Gaussian component.
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Astrophysics of Galaxies

(Monty Python and the) HoliGRALE: A Hybrid GRALE Lens Inversion Methodology Diagnostically Evaluated with Synthetic and Real Data

Derek Perera, Jori Liesenborgs, John H. Miller Jr et al. (+4 more)

We present HoliGRALE (Hybrid, only light included, GRAvitational LEnsing), a hybrid lens modeling extension of the freeform method GRALE. HoliGRALE incorporates physically motivated parametric components within the freeform genetic algorithm GRALE. Using three synthetic clusters from IllustrisTNG, each of varying complexity, we evaluate its performance according to its accuracy in reconstructing the density distribution, image positions, magnifications, and time delays. We find that HoliGRALE generally outperforms GRALE on all fronts, and shows greater accuracy in regions containing a high image number density. We estimate the error budget in projected density to be $<5\%$ for simple, few component clusters, and $\sim5-10\%$ for complex, multi-component clusters in the regions constrained by observed images. We then use HoliGRALE to model three lenses: RX J2129.7$+$0005, MACS J0138.0$-$2155, and Abell S1063. In each case, HoliGRALE is able to accurately reconstruct observed magnifications and time delays. In its predictions, HoliGRALE is found to be more precise than GRALE. We particularly highlight the predicted time delay for the next arriving image of SN Requiem to be $4346.61^{+490.27}_{-818.36}$ days ($\approx$ April 2026 – October 2029), consistent with previous work, albeit with less precision. In Abell S1063, we report the reconstruction of a main dark matter halo core radius of $89.9\pm33.2$ kpc, in excellent agreement with past work and useful in testing theories of dark matter. Our results emphasize the expected error budget of HoliGRALE, which should be mentioned and scrutinized in future applications of HoliGRALE for other lens systems.
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All authors Derek Perera, Jori Liesenborgs, John H. Miller Jr, Ashley Francis, Liliya L. R. Williams, Birendra Dhanasingham, Jose M. Diego

Astrophysics of Galaxies

Euclid Quick Data Release (Q1). Exploring the complexity of quenching processes across time, environment, and mass through recently quenched galaxies

Euclid Collaboration: Z. Mao, L. Pozzetti, A. Enia et al. (+307 more)

Recently quenched galaxies (RQGs) provide insights into galaxy quenching. We present a photometric and spectroscopic analysis of RQGs using the first Euclid Quick Data Release (Q1). Using rest-frame UVJ colours, we classify star-forming (SFGs), quiescent (QGs), and recently quenched galaxies at 0.2<z<3.0, separating RQGs into fast- and slow-quenching types (fRQGs and sRQGs) following model evolutionary tracks. The relative fractions of RQGs and their quenching efficiencies both decrease with cosmic time. At early epochs, fast quenching is more efficient in massive galaxies, whereas it becomes efficient only at low masses at later epochs. Slow quenching becomes more efficient at z<1.5, progressing from high to intermediate masses with cosmic time. Most RQGs at z<0.5 reside in low-density environments, while they also exist in high-density environments at z>0.5, suggesting earlier quenching in dense regions. RQGs show intermediate properties between SFGs and QGs in stellar mass, star-formation rate, specific star-formation rate, Sersic index, and radius. Most RQGs exhibit regular morphologies, excluding merger as a primary mechanism. We find that fRQGs retain disc-like morphologies, whereas sRQGs are more concentrated, suggesting different stages of morphological transformation. Our analysis suggests that multiple mechanisms drive quenching. Stacked spectra of galaxies with spectroscopic redshifts confirm old, passive populations in QGs, while sRQG spectrum shows weak Ha emission, indicating residual star-formation activity or AGN contribution. The recently-quenched nature of RQGs is confirmed by strong Balmer absorption lines in stack DESI spectra. The stacked Euclid QG spectrum agrees with previous templates and stellar population models older than 5Gyr at z<1. These results demonstrate Euclid's potential for studying galaxy quenching, to be further enhanced by future releases.[Abrg.]
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All authors Euclid Collaboration: Z. Mao, L. Pozzetti, A. Enia, S. Quai, W. G. Hartley, M. Bolzonella, F. Gentile, G. De Lucia, M. Moresco, N. Borghi, C. Saulder, C. Nipoti, M. Talia, P. Corcho-Caballero, L. Gabarra, Abdurro'uf, L. Wang, L. Bisigello, E. Daddi, M. Siudek, C. D'Eugenio, G. Zamorani, F. Calura, H. Fu, R. Ragusa, F. Shankar, M. Hirschmann, O. Cucciati, T. Kodama, S. Belli, L. Spinoglio, J. R. Weaver, B. Altieri, S. Andreon, N. Auricchio, C. Baccigalupi, M. Baldi, A. Balestra, S. Bardelli, P. Battaglia, A. Biviano, E. Branchini, M. Brescia, S. Camera, G. Cañas-Herrera, V. Capobianco, C. Carbone, J. Carretero, S. Casas, F. J. Castander, M. Castellano, G. Castignani, S. Cavuoti, K. C. Chambers, A. Cimatti, C. Colodro-Conde, G. Congedo, L. Conversi, Y. Copin, F. Courbin, H. M. Courtois, M. Cropper, A. Da Silva, H. Degaudenzi, C. Dolding, H. Dole, F. Dubath, X. Dupac, M. Farina, R. Farinelli, S. Ferriol, P. Fosalba, S. Fotopoulou, M. Frailis, E. Franceschi, M. Fumana, S. Galeotta, K. George, B. Gillis, C. Giocoli, J. Gracia-Carpio, A. Grazian, F. Grupp, S. Gwyn, S. V. H. Haugan, S. Hemmati, J. Hoar, W. Holmes, A. Hornstrup, M. Huertas-Company, K. Jahnke, M. Jhabvala, B. Joachimi, S. Kermiche, A. Kiessling, B. Kubik, M. Kümmel, M. Kunz, H. Kurki-Suonio, A. M. C. Le Brun, V. Le Brun, S. Ligori, P. B. Lilje, V. Lindholm, I. Lloro, M. Magliocchetti, G. Mainetti, D. Maino, E. Maiorano, O. Mansutti, S. Marcin, O. Marggraf, M. Martinelli, N. Martinet, F. Marulli, R. J. Massey, N. Mauri, S. Maurogordato, E. Medinaceli, S. Mei, M. Meneghetti, E. Merlin, G. Meylan, P. Monaco, A. Mora, C. Moretti, L. Moscardini, R. Nakajima, C. Neissner, S.-M. Niemi, J. W. Nightingale, C. Padilla, S. Paltani, F. Pasian, K. Pedersen, W. J. Percival, V. Pettorino, A. Pezzotta, S. Pires, G. Polenta, M. Poncet, L. A. Popa, F. Raison, A. Renzi, J. Rhodes, G. Riccio, I. Risso, E. Romelli, M. Roncarelli, H. J. A. Rottgering, B. Rusholme, R. Saglia, Z. Sakr, D. Sapone, B. Sartoris, P. Schneider, T. Schrabback, M. Scodeggio, A. Secroun, G. Seidel, E. Sihvola, P. Simon, C. Sirignano, G. Sirri, L. Stanco, P. Tallada-Crespí, A. N. Taylor, H. I. Teplitz, I. Tereno, N. Tessore, S. Toft, R. Toledo-Moreo, F. Torradeflot, I. Tutusaus, J. Valiviita, T. Vassallo, G. Verdoes Kleijn, A. Veropalumbo, Y. Wang, J. Weller, A. Zacchei, F. M. Zerbi, I. A. Zinchenko, E. Zucca, V. Allevato, M. Ballardini, E. Bozzo, C. Burigana, A. Cappi, T. Castro, J. A. Escartin Vigo, R. Maoli, J. Martín-Fleitas, R. B. Metcalf, A. A. Nucita, M. Pöntinen, V. Scottez, M. Sereno, M. Tenti, M. Tucci, M. Viel, M. Wiesmann, Y. Akrami, I. T. Andika, S. Anselmi, M. Archidiacono, F. Atrio-Barandela, L. Bazzanini, D. Bertacca, M. Bethermin, F. Beutler, L. Blot, H. Böhringer, M. Bonici, S. Borgani, M. L. Brown, S. Bruton, A. Calabro, B. Camacho Quevedo, F. Caro, C. S. Carvalho, F. Cogato, T. E. Collett, T. Contini, A. R. Cooray, S. Davini, G. Desprez, A. Díaz-Sánchez, S. Di Domizio, J. M. Diego, P.-A. Duc, V. Duret, M. Y. Elkhashab, Y. Fang, A. Finoguenov, F. Fontanot, A. Franco, K. Ganga, T. Gasparetto, R. Gavazzi, E. Gaztanaga, F. Giacomini, F. Gianotti, G. Gozaliasl, M. Guidi, C. M. Gutierrez, A. Hall, C. Hernández-Monteagudo, H. Hildebrandt, J. Hjorth, L. K. Hunt, J. J. E. Kajava, Y. Kang, V. Kansal, D. Karagiannis, K. Kiiveri, J. Kim, C. C. Kirkpatrick, S. Kruk, F. Lepori, G. Leroy, G. F. Lesci, J. Lesgourgues, T. I. Liaudat, S. J. Liu, X. Lopez Lopez, A. Loureiro, G. Maggio, E. A. Magnier, C. Mancini, F. Mannucci, C. J. A. P. Martins, L. Maurin, M. Miluzio, G. Morgante, K. Naidoo, A. Navarro-Alsina, S. Nesseris, D. Paoletti, F. Passalacqua, K. Paterson, L. Patrizii, A. Pisani, D. Potter, G. W. Pratt, M. Radovich, G. Rodighiero, W. Roster, S. Sacquegna, M. Sahlén, D. B. Sanders, E. Sarpa, C. Scarlata, A. Schneider, M. Schultheis, D. Sciotti, E. Sellentin, L. C. Smith, J. G. Sorce, K. Tanidis, F. Tarsitano, G. Testera, R. Teyssier, A. Troja, A. Venhola, D. Vergani, G. Verza, S. Vinciguerra, N. A. Walton, A. H. Wright