Quantum Physics
When does dissipation help neural surrogates learn open quantum dynamics?
Alauddin Ahmed
Dissipation is usually viewed as an obstacle to predicting
quantum dynamics, yet it can also contract trajectories toward steady states and thereby suppress accumulated prediction errors, leaving it unclear whether dissipation ultimately helps or hinders the learnability of open
quantum dynamics. We investigate this question using Neural Ordinary Differential Equation (NODE) surrogates for open Heisenberg XYZ
spin chains. Closed-system learnability deteriorates rapidly with system size, culminating in a static-prediction collapse at four
qubits; dissipation reverses this trend, creating a broad high-fidelity regime at intermediate system sizes, while at four
qubits a fidelity-aware objective recovers learnable rollout structure that is absent under closed-system training. Comparison against static and steady-state baselines reveals that dissipation improves performance through two fundamentally different mechanisms: at weak-to-moderate dissipation the surrogate captures nontrivial transient dynamics and substantially outperforms trivial predictors, whereas at stronger damping high fidelity increasingly reflects trajectory simplification toward the steady state rather than improved learned dynamics. These results show that dissipation can enhance the learnability of open
quantum dynamics, but that fidelity alone is insufficient to distinguish genuine dynamical learning from steady-state trivialization: dissipative contraction and trajectory simplification are distinct effects that peak in different regimes and should be disentangled when evaluating learned
quantum-dynamical surrogates.
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High Energy Physics (Theory)
Towards OSV in AdS
Nikolay Bobev, Sunjin Choi, Junho Hong et al. (+1 more)
We use supersymmetric localization for 3d $\mathcal{N}=2$ SCFTs to establish a relation of the form $Z_{S^1\times S^2} \sim |Z_{S^3_b}|^2$ between the superconformal index and the squashed three-sphere partition function. This applies to general 3d $\mathcal{N}=2$ SCFTs and is derived using a saddle point approximation in the Cardy-like limit of small $S^1$ radius and large squashing parameter. We also show a similar relation between the topologically twisted index and the squashed sphere partition function. In the context of holography our results lead to a relation between the partition function of supersymmetric asymptotically AdS$_4$ black holes and the large $N$ limit of $Z_{S^3_b}$ of the dual SCFT. Since the latter encodes the gauged supergravity prepotential, this result is akin to the OSV
conjecture for asymptotically flat black holes. We confirm this relation in detail for SCFTs arising from M2-branes using recent large $N$ results from supersymmetric localization. We also briefly discuss a similar relation for 5d SCFTs and its implications for asymptotically AdS$_6$ black holes.
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All authors Nikolay Bobev, Sunjin Choi, Junho Hong, Valentin Reys
Chemical Physics
Charge transfer from ammonia neutralizes propylene oxide cations: Implications for the astrochemistry of chiral molecules
Sanjana Maheshwari, Darya Kisuryna and Leah G. Dodson
To date only one
chiral species, propylene
oxide, has been observed in the interstellar medium but little is known about the chemistry that leads to a detectable abundance of this molecule in Sagittarius B2. We used a glow-discharge ion source and a room-temperature ion trap to study the neutralization reactions necessary to convert propylene
oxide cation (PO$^+$) – the assumed precursor for propylene
oxide in space – into the observed astrochemical. We found that the charge-transfer reaction between PO$^+$ and ammonia (NH$_3$) proceeds with a pressure-independent rate coefficient of $(1.39\pm0.03)\times10^{-12}$ cm$^{3}$ s$^{-1}$ to neutralize PO$^+$ and form the radical cation NH$_3$. Although this measured rate coefficient is much slower than that predicted by capture theories, the high abundance of NH$_3$ in Sagittarius B2 motivates the inclusion of this reaction in astrochemical models. We hypothesize that the low ionization energies of many
chiral molecules important to origin-of-life theories means these species may exist as cations in the interstellar medium.
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Mathematical Physics
Weyl orbit particles
Martin T. Luu
The mass spectrum of affine Toda theory is known to be expressible in terms of a suitable eigenvector of the relevant Cartan
matrix. The particles correspond in a precise manner to the Coxeter element orbits in the set of roots. Recently, variants of affine Toda theory have been constructed for many different Weyl group elements. Again, the particles correspond to orbits in the set of roots and this allows the calculation of the classical mass spectrum. We show how these spectral calculations generalize the affine Toda relation with the Cartan
matrix. As an example, we calculate the spectrum for the unique non-Coxeter infinite family $\textrm{D}_{2n}(a_{n-1})$ of primitive regular conjugacy classes in the Weyl groups of complex simple Lie
algebras.
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Exactly Solvable and Integrable Systems
The KdV vacuum operator and its Katz extension
Martin T. Luu
We define a connection on the formal disc that can be used to single out the
vacuum of the Drinfeld-Sokolov KdV hierarchy associated to a simple complex finite-dimensional Lie
algebra. As a connection, it has a canonical Katz extension from the disc to the sphere. We express this Katz extension in terms of the Kac coordinates of a suitable Weyl group conjugacy class. As a consequence, we show that the Katz extension has meaning in the context of the integrable hierarchy: It describes an additional
symmetry.
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Astrophysics of Galaxies
A Strongly Lensed Ultra-faint Arc at $z \approx 10$ with an F200W excess in Abell S1063
Fujiang Yu, Mingyu Li, Zheng Cai et al. (+4 more)
Strong gravitational
lensing provides a powerful route to probing intrinsically faint
galaxies during the first few hundred million years of
cosmic history. In this Letter, we report the identification of GAR10, a highly magnified F115W-dropout
galaxy at $z\approx10$ in the Abell S1063 cluster field, using deep JWST/NIRCam imaging from the GLIMPSE and GO-1840 programs. The source shows an unusually blue ultraviolet (UV) continuum and a significant F200W excess relative to adjacent bands. Under our high-magnification
lensing solution, we infer a median magnification of $\mu=43^{+78}_{-20}$, corresponding to an intrinsic UV magnitude of $M_{\rm UV}\approx-15.8$. We use exploratory Prospector SED modeling to examine two physically motivated interpretations of the observed photometry. In Case I, GAR10 is described by an extremely metal-poor, continuum-dominated
stellar population at $z=10.75_{-0.34}^{+0.41}$, with a blue UV slope of $\beta=-2.92\pm0.12$ and a low
metallicity of $\log(Z/Z_\odot)=-3.56_{-0.85}^{+0.65}$, consistent with an extremely metal-poor or Pop III-like continuum-dominated interpretation under the adopted priors. In Case II, GAR10 is interpreted as an extremely young (1–3 Myr), high-ionization
galaxy at $z=10.45_{-0.21}^{+0.11}$, in which the F200W excess is produced by intense rest-frame UV emission lines, including CIV, HeII, and CIII]. Both cases can partially reproduce the current photometry within the adopted priors, but they imply distinct ionizing sources, enrichment histories, and possible contributions to
cosmic reionization. GAR10 therefore represents a rare laboratory for studying ultra-faint
galaxy formation at
cosmic dawn. Future JWST/NIRSpec spectroscopy will be essential to distinguishing between the steep continuum and emission-line origins of the F200W excess.
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All authors Fujiang Yu, Mingyu Li, Zheng Cai, Yuduo Guo, Hao Zhang, Jose M. Diego, Sijia Cai
General Relativity and Quantum Cosmology
Energy Extraction via Magnetic Reconnection from a Rotating Dyonic Black Hole in $N = 2, \ U(1)^2$ Gauged Supergravity
Raid M Suleiman, Shanshan Rodriguez, Dominic O. Chang et al. (+1 more)
We study energy extraction via
magnetic reconnection from a rotating dyonic black hole in four-dimensional $N=2$, $U(1)^2$ gauged supergravity. Using the Comisso-Asenjo mechanism in the ZAMO frame, we derive the asymptotic hydrodynamic energy per unit enthalpy $\epsilon^{\infty}_\pm$ and determine when reconnection
outflows attained negative energy at infinity. By varying the
spin $a$, electric and
magnetic charges, NUT parameter $N_g$, and gauge coupling $g$, we compute the cutoff magnetization $\sigma_0^{\rm cutoff}$ and map the region of parameter space that admits $\epsilon^{\infty}_-<0$. We find that $\sigma_0^{\rm cutoff}$ and the very existence of Comisso-Asenjo extraction are tightly controlled by $g$ and the dyonic charges: increasing $g$ or pushing the charges toward extremality raises $\sigma_0^{\rm cutoff}$ and shrinks the CA-active part of the ergoregion. Unlike Kerr, the
spin enters through the normalization factor $\Xi$, and the quartic horizon function $\Delta_g$, so
geometric effects from the AdS/NUT deformation dominate the usual frame-dragging enhancement. As a result, the extracted power and efficiency are non-monotonic in $a$ and peak at intermediate
spin ($a\sim0.8$); near-extremal rotation is not required for high efficiency, provided $g$ is small and $Q$ is moderate. Efficient extraction further demands extreme magnetization and nearly radial
outflows, confining the active reconnection layer to a thin shell, just outside the horizon.
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All authors Raid M Suleiman, Shanshan Rodriguez, Dominic O. Chang, Leo Rodriguez
Instrumentation and Methods for Astrophysics
Astrobiology in the Time of Artificial Intelligence
Caleb Scharf
The Viking missions showcased multiple spaceflight technologies representing state-of-the-art capabilities: from digital line-scan imaging to the operation of complex onboard laboratories and software-controlled process autonomy. Since Viking, there have been extraordinary, and still accelerating, advancements in computing technology impacting science, society, and exploration. These developments have occurred in both hardware and software, resulting in increasingly capable devices, advanced programming tools, and algorithmic innovations. The subset of artificial intelligence known as machine learning has emerged as one of the most transformative of these developments, with major implications for space exploration and for improvements to the search for evidence of life beyond the Earth. Those improvements include the integration of data across different scales and increased sensitivity to complex features in data, as well as the generation of adaptive strategies for sampling environments. In this paper, the present and future nature of space exploration and astrobiological research is examined through the contextual lens of Viking, and through the history and possible future of artificial intelligence.
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Earth and Planetary Astrophysics
Dynamical implications of the recently detected feature around Quaoar and constraints on the presence of additional satellites
Gustavo Madeira, Leandro Esteves, Bruno E. Morgado et al. (+4 more)
A recently reported opaque feature in the Quaoar system, detected during the 25 June 2025
stellar occultation, has been interpreted as either a 15 km-radius satellite or a dense, sharp-edged arc orbiting at about 5600-5900 km. Here, we investigate both scenarios through numerical integrations that include Quaoar, its triaxial shape, and Weywot. If the feature is a satellite, stability maps show that it acquires a forced eccentricity of about 0.002 and has only a minor dynamical effect on the Q1R and Q2R rings. Its main effect is to clear a narrow region around its orbit, associated with the overlap of mean-motion resonances, preventing the long-term survival of kilometre-scale moons within approximately one Quaoar radius of the satellite. If instead the feature is an arc, we test confinement around the triangular
equilibrium point of an unseen coorbital satellite. While azimuthal confinement is readily obtained for satellites with satellite-to-primary mass ratios up to 0.001, Weywot's secular perturbation induces large radial excursions in the arc particles, preventing reproduction of the observed radial extent. The required radial confinement is achieved only for confiners comparable to or more massive than Weywot, which would likely be detectable by direct imaging. We therefore disfavour triangular-point confinement as an explanation for a long-lived dense arc and argue that the feature is more dynamically consistent with a satellite. We identify broad stable zones where additional undetected moons could reside, including near the rings as possible shepherd moons. Furthermore, Quaoar's ellipticity alone is sufficient to induce non-resonant orbital excitation capable of preventing ring coagulation, an effect that may be enhanced by small moons near the rings.
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All authors Gustavo Madeira, Leandro Esteves, Bruno E. Morgado, Paulo V. S. Soares, Silvia M. Giuliatti Winter, Othon C. Winter, Bruno S. Chagas
General Relativity and Quantum Cosmology
Primordial Black Holes: A Review of Formation and Evolution
S. Shankaranarayanan, Soumya Bhattacharya and Archit Vidyarthi
Primordial Black Holes (PBHs) have emerged as a leading non-particulate candidate for dark matter and a unique cosmological probe, a paradigm shift accelerated by the detection of anomalous binary mergers by the LIGO-Virgo-KAGRA (LVK) collaboration. While the literature is rich with phenomenological constraints, the fundamental
quantum and relativistic underpinnings governing PBH genesis and
evolution often receive comparatively less emphasis. This review aims to bridge that gap by systematically detailing the physics of PBH formation and their subsequent evolutionary trajectory. We critically examine the hydrodynamic complexity of the early universe, establishing the relativistic thresholds for collapse, the non-linear race against sound in the
primordial plasma, and the rigorous mathematical utility of the compaction function. Furthermore, by incorporating the dynamic nature of FLRW backgrounds, higher
curvature corrections, and
quantum backreaction via the
memory burden effect, we challenge the standard hawking evaporation and show that extreme-
curvature environments halt evaporation entirely, leaving Planck-scale relics that evade current extragalactic bounds. Finally, we map the multimessenger observational landscape, highlighting how the imminent search for sub-
solar mass inspirals by next-generation gravitational wave observatories such as the Einstein
Telescope and
Cosmic Explorer could yield smoking-gun evidence for the PBH paradigm, ultimately transforming these
primordial relics into unparalleled laboratories for high-energy physics.
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High Energy Physics (Phenomenology)
Polarized Deep-Inelastic Scattering with Spin Correlations in Herwig 7
M.R. Masouminia, A. Papaefstathiou and P. Richardson
We investigate polarized deep-inelastic scattering (DIS) in the context of fully exclusive Monte Carlo simulations for the Electron-Ion
Collider (EIC). We present a next-to-leading-order (NLO) treatment of polarized DIS in HERWIG 7 using the POWHEG matching scheme, including neutral-current $\gamma/Z$ exchange and charged-current scattering. We also construct a
spin-correlation treatment for NLO-matched events, first by initializing the shower from the
spin-density
matrix of the polarized DIS Born process and then by propagating the
spin-density
matrix of the accepted real-emission configuration without changing the POWHEG event weight or hardest-emission choice. We validate the integrated cross sections against fixed-order calculations, use parton-level comparisons without subsequent shower
evolution to isolate the accepted POWHEG real-emission kinematics, and employ shower-level observables to test the numerical importance of the Born-level and real-emission
spin information. We find that the Born-level
spin-density initialization can have a visible impact on shower-sensitive observables, while the additional
spin information from the accepted real-emission configuration is not resolved as a robust separate effect within the independent-sample Monte Carlo precision for the longitudinally polarized observables considered here.
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Atomic Physics
Non-adiabatic Effects Induced by Strong Light-Matter Coupling in Cavity QED
T. Zalialiutdinov, D. Solovyev, J. J. Lopez-Rodriguez et al. (+2 more)
We present a systematic study of the diagonal Born-Oppenheimer correction (DBOC) for atoms and molecules embedded in optical cavities and interacting with a quantized electromagnetic field. By explicitly evaluating the
nuclear kinetic energy operator, we analyze cavity-induced modifications of DBOC within a
quantum electrodynamics configuration-interaction (QED-CI) framework built on
quantum electrodynamics Hartree-Fock (QED-HF) and strong-coupling
quantum electrodynamics Hartree-Fock (SC-QED-HF) reference states. The analysis covers a diverse set of atomic and molecular systems, including He, H-, Be, H2, LiH, HF, ammonia (NH3), and formaldehyde (CH2O). We show that the presence of the cavity leads to shifts in molecular dissociation energies on the order of a few inverse centimeters. For several atomic systems, the inclusion of the DBOC yields a pronounced effect, with the correction magnitude reaching the experimental resolution. These findings reveal finite
nuclear mass effects as an essential component of
nuclear dynamics in cavity QED and suggest their relevance for precision analysis in strongly coupled light-matter systems.
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All authors T. Zalialiutdinov, D. Solovyev, J. J. Lopez-Rodriguez, A. Anikin, A. Kotov
Instrumentation and Methods for Astrophysics · Cross-listed from cs.LG
The Degeneracy Distillery
T. Lucas Makinen, Deaglan J. Bartlett, Niall Jeffrey et al. (+1 more)
When two or more parameters or labels produce similar data, they are degenerate, or hard to distinguish. Degeneracies render both label prediction and inverse problems difficult, since both machine learning
algorithms and probabilistic samplers rely on the distinguishability of data and its gradients with respect to parameters. However, identifying degeneracies in physical models or real-world
datasets can be elucidating about the choice of model or the underlying process that produces the data. We present the degeneracy distillery, a method that (1) detects and (2) resolves degenerate parameter combinations (a) automatically and (b) symbolically, from parameter-data (or parameter-simulation) pairs alone, through estimation and flattening of the Fisher information
matrix. By exploring the information geometry of the likelihood, we characterize degeneracies as an intrinsic property of the physical model, requiring no realised data observation. We demonstrate our approach on a range of synthetic and real-world problems, discovering symbolic coordinate transformations that identify the combinations of parameters of a model which yield independent effects on the data. The resulting coordinates flatten the Fisher information in expectation globally, in contrast to posterior-based methods that flatten only at a single point, and substantially reduce the simulation budget required for downstream neural posterior estimation. In test cases we require up to $10\times$ fewer simulations for posterior estimation at matched validation calibration whilst simultaneously gaining physical insight on the system.
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All authors T. Lucas Makinen, Deaglan J. Bartlett, Niall Jeffrey, Benjamin D. Wandelt
Quantum Physics
Mode-selective nonlinear interference for high-brightness and high-purity fiber-coupled SPDC sources
Carlos Sevilla-Gutiérrez, Purujit Singh Chauhan, Varun Raj Kaipalath et al. (+1 more)
Single-mode-fiber-coupled spontaneous parametric down-conversion (SPDC) sources are a key resource for photonic
quantum technologies, but in single-
crystal geometries brightness, heralding efficiency, and spectral purity remain constrained by intrinsic trade-offs. Here, we show how nonlinear interference in a cascaded two-
crystal type-II SPDC source can be used to engineer the modal structure of SPDC emission, improving the brightness–heralding-efficiency trade-off by more than one order of magnitude beyond the single-
crystal limit. We further demonstrate two routes to near-unity spectral purity while retaining high brightness and/or heralding efficiency, even with standard periodically poled
crystals, and study the additional advantages of aperiodic poling with Gaussian phase matching. Using a spectrally resolved Laguerre–Gauss modal decomposition, we show that these improvements arise from mode-selective interference of spatial-spectral SPDC modes within the nonlinear interferometer. We experimentally validate the model through sum-frequency-generation measurements of the spatial-spectral state.
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All authors Carlos Sevilla-Gutiérrez, Purujit Singh Chauhan, Varun Raj Kaipalath, Fabian Steinlechner
Strongly Correlated Electrons
Domain-wall drift in a ferrimagnet induced by a linearly oscillating in-plane magnetic field
Murod Mirzhalilov and Jacob Freyermuth
We investigate ferrimagnetic domain-wall dynamics under linearly oscillating in-plane
magnetic fields. Starting from a ferrimagnetic Lagrangian that retains the field-dependent contribution to the kinetic energy, we derive collective-coordinate equations for the domain-wall position and azimuthal angle. This formulation makes explicit the field-induced inertial terms, including Coriolis-, Euler-, and centrifugal-like contributions, and clarifies how they couple translational and azimuthal dynamics. For an oscillating in-plane field supplemented by a weak static out-of-plane bias field, we show that periodic switching of the wall angle can be rectified into a finite average domain-wall velocity. At low drive frequencies, where the wall angle follows the oscillating field, the induced drift is proportional to the drive frequency rather than the field amplitude, while above a cutoff frequency the wall angle can no longer follow the drive and the average motion is suppressed. Micromagnetic simulations confirm the analytical predictions and demonstrate that the magnitude and direction of the drift can be tuned by the net
spin density. These results identify linearly oscillating fields as a mechanism for frequency-controlled domain-wall motion in ferrimagnets and highlight the role of inertial
spin dynamics near
magnetic compensation.
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Atmospheric and Oceanic Physics
From stable online coupling to decade-long climate simulations: A machine learning parameterization for cloud microphysics in ICON
Ellen Sarauer, Mierk Schwabe, Philipp Weiss et al. (+3 more)
The representation of cloud microphysics and its nonlinear character and scale-dependence is a remaining source of uncertainty in Earth system models (ESMs). Here, we develop and couple online a machine learning (ML)-based cloud microphysics parameterization with the Icosahedral non-hydrostatic modeling framework (ICON). The primary challenge is achieving numerically stable, long-term online coupling when transitioning from training with km-scale data to application in coarse-scale simulations, where the coupled system encounters atmospheric states and feedbacks not seen during training. The training data is obtained from a global convection-permitting ICON simulation at 5 km resolution. The ML microphysics scheme uses a two-stage design: a classifier to identify active grid
cells and a regressor to predict cloud microphysical tendencies. Physical constraints such as enforcing mass positivity and overshoot prevention prove essential for numerical stability in the coupled system. We demonstrate that achieving stable online coupling requires enforcing physical constraints and careful
dataset curation, and that strong offline performance alone is insufficient. The coupled model maintains numerical stability over decade-long simulations with a performance in reproducing the observed
climate comparable to the classical graupel scheme. The ML-based scheme eliminates two microphysics-specific tuning parameters of the classical graupel scheme, though systematic improvements in long-term mean-state biases are not yet realized. This study demonstrates that stable, decade-long
climate simulations with an ML-based cloud microphysics scheme trained on convection-permitting data are feasible, providing a foundation for future hybrid ESMs.
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All authors Ellen Sarauer, Mierk Schwabe, Philipp Weiss, Axel Lauer, Philip Stier, Veronika Eyring
Statistical Mechanics
Pareto-optimal control strategies in intrinsically nonequilibrium systems
Gustavo A. L. Forão, Carlos E. Fiore and Jonas Berx
Thermodynamic control is typically formulated as the optimisation of a single objective, yet competing costs rarely admit a common optimum, so single-objective control captures only one corner of the achievable performance space. We develop a general framework for multi-objective thermodynamic control of intrinsically nonequilibrium systems that maps out the full Pareto front of optimal control strategies. We show that Pareto-optimal protocols generically consist of smooth branches connected by boundary jumps, and that the relative weights of the objectives combine with the physical parameters into a single intrinsic scale that alone governs the trade-off. Remarkably, this scale plays a double role: it parametrizes a single functional form that generates the entire front, and it defines control equivalence classes, in which systems with different parameters but the same scale share identical optimal strategies. We illustrate the framework for two paradigmatic systems that are experimentally accessible: transport of an active particle in a harmonic trap, and a cyclic
quantum-dot engine. For both, we obtain the Pareto front and optimal strategies in closed form.
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Quantum Physics
Wavelet Matrix Product States for Quantum Fields
Molly Kaplan and Antoine Tilloy
We introduce a variational method to solve continuum
quantum models with discrete tensor network techniques. The method leverages wavelet
matrix product states (wMPS):
matrix product states built on top of sufficiently regular ($N\geq 6$) Daubechies scaling functions. These states live in the continuum field theory Fock space, have finite energy density, and can be optimized with standard
algorithms, without restriction to free theories. Further, exploiting the multi-resolution analysis built into wavelets, and its
quantum circuit description, we can iteratively refine wMPS to obtain accurate approximations at arbitrarily fine length-scales. We showcase the efficiency of the method on the Lieb-Liniger model, computing energy density and correlation functions.
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Quantum Gases
Sayak Bhattacharjee, Mahendra K. Verma, Alexander V. Balatsky et al. (+1 more)
We discuss phenomenology associated with turbulent hydrodynamics in
quantum fluids from a condensed-matter perspective. We begin with weakly-interacting superfluids, often modeled by a mean-field theory governed by the Gross-Pitaevskii equation. Considering the effect of
quantum fluctuations beyond the mean-field approximation, we propose a study of many-body
quantum effects in turbulent hydrodynamics, especially near zero temperature. We motivate examples of
quantum many-body systems where such effects may be uncovered. These include
bosons confined in a periodic potential in low spatial dimensions (one and two), and the associated
quantum critical point of the superfluid-
insulator transition, realized in present-day ultracold-atom and
quantum computing platforms. We conclude by listing a set of (open) questions that may be answered using modern
quantum many-body techniques. This article is part of the theme issue 'Frontiers of
turbulence and statistical physics'.
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All authors Sayak Bhattacharjee, Mahendra K. Verma, Alexander V. Balatsky, Srinivas Raghu
Earth and Planetary Astrophysics
Photochemical Production of CS2 in Temperate-to-Warm Gas Giant Exoplanet Atmospheres
Jeehyun Yang, Vighnesh Nagpal, Michael Zhang et al. (+16 more)
Sulfur chemistry has emerged as an important probe of
exoplanet atmospheres in the JWST era, although observational constraints have thus far been largely limited to SO2 and H2S in warm and hot
exoplanets. Recent JWST observations have revealed CS2 in several cooler gas-
giant exoplanets, yielding a new tracer of sulfur chemistry. However, the detailed chemical pathways responsible for the formation of CS2 remain poorly understood. Here, we use TOI-6894 b, a temperate gas
giant with evidence for CS2, as a test case for one-dimensional photochemical kinetic-transport modeling and sensitivity analyses of CS2 chemistry. We show that CS2 is produced through coupled thermochemical and photochemical processes involving CH4 and H2S as the primary carbon and sulfur reservoirs, with S2 photolysis driving disequilibrium sulfur chemistry. Our models provide a physically consistent explanation for the observed CS2 feature in TOI-6894 b. Extending our analysis to gas
giant exoplanets spanning a wide range of Teq, we find that CS2 abundance peaks in temperate to warm atmospheres (Teq ~ 500 - 700 K), and declines toward both lower and higher temperatures. This temperature dependence provides a unified framework for interpreting current CS2 observations, accounting for reported detections in temperate to warm
planets and the lack of detections in colder and hotter
giant exoplanets. Our results establish CS2 as a complementary probe of sulfur inventories and atmospheric
metallicity in cool gas
giant exoplanets
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All authors Jeehyun Yang, Vighnesh Nagpal, Michael Zhang, Qiao Xue, Eliza M.-R. Kempton, Jacob L. Bean, Michael R. Line, Jonathan J. Fortney, Peter Gao, Matthew C. Nixon, Caroline Piaulet-Ghorayeb, Kevin B. Stevenson, Madison Brady, Joost P. Wardenier, Luis Welbanks, Jean-Michel Désert, Guangwei Fu, Vivien Parmentier, Diana Powell
Solar and Stellar Astrophysics
Calibrating angular momentum transport in intermediate-mass stars from gravity-mode asteroseismology. II. Modelling 2937 BAF-type stars
J. S. G. Mombarg and S. Mathis
Asteroseismology of
gravity (g)-mode pulsators covering BAF-type
stars have shown that angular momentum is redistributed during the main sequence. The efficiency of the transport, however, remains largely uncalibrated. This paper aims at exploiting a sample of 2937 characterized g-mode pulsators (the largest one to-date) to place constraints on the efficiency of angular momentum transport by assuming an effective viscosity or an Eddy-viscosity based on the Tayler-Spruit dynamo within a fully-diffusive framework. We compute grids of rotating
stellar evolution models that we then use to simulate a population of
stars by sampling from these grids with prior distributions on the mass, age and initial rotation rate. We then compare these simulated distributions of rotation frequencies and specific angular momentum ($J/M$) to the ones of the sample of observed
stars. We find that a fully-diffusive framework for the transport of angular momentum during the main sequence is sufficient to explain the observed
evolution of near-core rotation frequencies, the observed differential rotation, and the observed mass-dependence of $J/M$ when the effective viscosity (assumed constant) is $10^6\,{\rm cm^2\,{\rm s^{-1}}}$ or larger. Viscosities predicted by the Tayler-Spruit dynamo are in general far above this value and can explain the data as well. Future observational studies of main sequence g-mode pulsators are encouraged to measure core-to-surface rotation rates, particularly of B-type
stars. In this work we have exploited the constraining potential of near-core rotation frequencies alone, while the contrast with the surface rotation would allow us to unravel the mechanisms driving the transport further.
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High Energy Astrophysical Phenomena
Composition of Radiation-Driven Winds from Type I X-ray Bursts
Jason S. Pero and Nevin N. Weinberg
Recent NICER observations of photospheric radius expansion (PRE) X-ray bursts reveal absorption features consistent with photospheres enriched in intermediate-mass elements. These features may arise from radiation-driven winds that eject freshly synthesized
nuclear ashes, offering a new probe of X-ray bursts and
neutron star properties. Motivated by these observations, we use the MESA
stellar evolution code to simulate PRE bursts from
accretion through the hydrodynamic wind phase. We model a range of ignition depths for both pure helium and mixed hydrogen/helium
accretion and explore several prescriptions for convection during burst rise. We find that the wind abundances depend sensitively on both ignition depth and convective treatment, including the efficiency of semiconvective mixing and the prescription used to define convective boundaries. Bursts igniting at column depths greater than or equal to 5 x 10^8 g cm^-2 produce ash-enriched winds, with ejecta ranging from intermediate-mass to iron-peak elements depending on ignition depth,
accretion composition, and the treatment of convection.
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Quantum Physics
Jayden Webster, Florian Kanitschar, Emanuele Polino et al. (+5 more)
Photons encoded in discrete time bins can be routinely prepared in temporal superposition states, enabling high-dimensional
entanglement and enhanced
quantum communication rates. However, characterizing this high-dimensional
entanglement presents significant challenges, namely due to the involved measurement complexity or reliance on restrictive assumptions that compromise the generality of traditional approaches. Here, we develop and experimentally demonstrate a simple linear-optical scheme based on particle-exchange
symmetry that allows us to probe high-dimensional
entanglement in time-bin-encoded states. Combining Hong-Ou-Mandel interference with suitable transformations, our method not only certifies
entanglement but also lower-bounds its dimensionality using only two dichotomic
symmetry-based measurements. This bound is obtained through a new rigorous theoretical analysis and can be further improved by weak, physically motivated assumptions. The scheme remains effective at any timescale, even far below the temporal detector resolution used. Our work provides a powerful state-characterization tool and demonstrates that we can prove high-dimensional temporal
entanglement on timescales inaccessible to the setup.
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All authors Jayden Webster, Florian Kanitschar, Emanuele Polino, Simon J. U. White, Sven Rogge, Farzad Ghafari, Marcus Huber, Nora Tischler
General Relativity and Quantum Cosmology
A thorough investigation of cross-correlation estimators for stochastic gravitational-wave background searches in ground-based detector data
Haowen Zhong, Joseph D. Romano, Vuk Mandic et al. (+2 more)
Detecting a
stochastic gravitational-wave background represents a crucial yet challenging objective within the field of gravitational-wave astronomy. Ground-based detectors currently rely almost exclusively on cross-correlation methods to detect
stochastic gravitational-wave background signals. Traditionally, these methods define and optimize a broadband
estimator initially constructed in the time domain. However, a growing number of analyses require precise narrowband
estimators to accurately characterize the energy density of the underlying signal in specific frequency bins. Transitioning from time-domain broadband
estimators to frequency-domain narrowband
estimators introduces significant complexities that have not yet been fully explored in the existing literature. In this study, we systematically revisit and rigorously reformulate the cross-correlation method in the frequency domain, explicitly addressing and resolving issues related to non-zero covariances induced by windowing and overlapping of data in the time domain. We provide new expressions for the narrowband
estimators and their covariances, which differ from those used in past searches. Fortunately, we show that the expressions that have been widely used in the field nonetheless lead to correct posterior distributions for parameter estimation and correct log-Bayes factors for model selection. By establishing a robust theoretical framework, our work facilitates more accurate and physically insightful interpretations of
stochastic gravitational-wave background observations, laying an essential foundation for current and future research in this field.
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All authors Haowen Zhong, Joseph D. Romano, Vuk Mandic, Shivaraj Kandhasamy, Arianna I. Renzini
Earth and Planetary Astrophysics
Interpreting the scattering surface in protoplanetary disks
Massimiliano Bolchini, Giovanni Rosotti, Marion Villenave et al. (+5 more)
In recent years, extreme adaptive optics have enabled high-resolution, high-contrast scattered-light observations of protoplanetary disks. Interpreting these observations requires an understanding of the scattering surface, which is shaped by the distribution of small
dust grains and determines how disks appear in scattered light. We aim to exploit measurements of the scattering surface height to directly constrain the masses of small
dust grains in disks. Starting from radiative transfer principles, we developed a semi-analytical model of the
stellar radiation path and its interaction with the disk, deriving the height of the scattering surface as a function of disk parameters such as mass, temperature, and opacity. We validated our predictions against the radiative transfer code MCFOST. Using measured scattering heights, we inferred the mass of
dust in small grains and the particle size distribution for a sample of ten disks. We confirm previous results indicating that the scattering surface coincides with the region where the integrated optical depth along the
stellar path is of order unity. The thermal structure of the disk significantly affects the surface height, while
dust settling and anisotropic scattering have comparatively minor effects. Applying our model to observations, we measure global small-
dust mass fractions of order (10^{-3}). Using
dust-opacity models, we show that these values are consistent with modest grain growth ((a_max \gtrsim 0.1,mm)) and grain-size distribution power-law indices of approximately 3–3.5, as commonly predicted by grain-growth models. Scattering-surface measurements, together with constraints on the disk thermal structure, provide a powerful method for determining the small-
dust content of protoplanetary disks.
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All authors Massimiliano Bolchini, Giovanni Rosotti, Marion Villenave, Antonio Garufi, Myriam Benisty, Tilman Birnstiel, Stefano Facchini, Leonardo Testi
High Energy Physics (Phenomenology)
PDF evolution in alternative factorisation schemes
Stéphane Delorme, Aleksander Kusina, Andrzej Siódmok et al. (+1 more)
Beyond leading order, parton distribution functions (PDFs) require a choice of factorisation scheme to be defined unambiguously. Different choices of factorisation scheme lead to PDFs that satisfy modified DGLAP
evolution equations, relative to the conventional $\overline{\mathrm{MS}}$ scheme. In this paper we derive the NLO DGLAP splitting functions for PDFs in alternative factorisation schemes, including for a parametrised scheme spanning a subspace of the general factorisation-scheme space. We plot their Mellin-space counterparts, the anomalous dimensions, and study the leading large- and small-$x$ behaviour, relevant to resummation. We find that the leading behaviour admits a natural interpretation as a modified effective
evolution scale. This is an essential step towards being able to evolve and fit PDFs in alternative schemes for use within QCD calculations.
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All authors Stéphane Delorme, Aleksander Kusina, Andrzej Siódmok, James Whitehead
High Energy Physics (Phenomenology)
Nuclei in high-energy neutrino sources: A multimessenger study of in-source propagation
AmirFarzan Esmaeili, Arman Esmaili and Pasquale Dario Serpico
The joint observation of astrophysical sources in gamma rays and
neutrinos can provide invaluable insight into the physical conditions of the source, including its size, particle densities, and acceleration and production mechanisms. In this work, we investigate the role of
nuclear composition in high-energy astrophysical environments. Using NGC 1068 as a representative example, we perform detailed Monte Carlo simulations of
nuclear and electromagnetic cascades within the source and study the imprints of the injected
nuclear composition on the resulting
neutrino and gamma-ray emissions. We further discuss the importance of MeV-GeV gamma-ray observations for constraining the source composition in the context of future gamma-ray experiments. A dedicated re-analysis of archival COMPTEL observations is also presented.
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Statistical Mechanics
Universal Dynamical Response to Slow Driving in Chaotic Systems
Nachiket Karve, Nathan Rose, David Campbell et al. (+1 more)
We propose a unified perspective on classical and
quantum chaos based on the sensitivity of a system's stationary states to slow driving. We probe this sensitivity via the system's susceptibility to the average protocol speed, which we call the “speed-Fisher information," and relate it to irreversible
entropy production in the system. We show that chaotic dynamics manifests as a divergence of the speed-Fisher information with the protocol time, and that this response is controlled by the perturbation's low-frequency spectral weight. This approach to chaos applies to both classical and
quantum Hamiltonian systems, and naturally extends to non-
Hamiltonian classical flows. We illustrate this framework with simple classical and
quantum examples, along with a non-
Hamiltonian flow that qualitatively exhibits analogous low-frequency spectral behavior.
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All authors Nachiket Karve, Nathan Rose, David Campbell, Anatoli Polkovnikov
Quantum Physics
Efficient Graph State Purification with Factorized Graph-Preserving Operations across Local Clifford Orbits
Mingyuan Wang, Guus Avis, Kenneth Goodenough et al. (+1 more)
Graph states form a broad class of multipartite entangled states underlying measurement-based
quantum computation,
quantum networks, and stabilizer codes. However, systematic
entanglement distillation for arbitrary graph states remains challenging because the
circuit design space grows rapidly with the number of parties. We introduce a group of Clifford operations that we call "factorized graph-preserving". It enables us to efficiently enumerate and optimize graph-state purification
circuits at finite size for realistic noisy hardware. These operations map products of graph-basis states to products of graph-basis states, so their action can be represented as permutations of graph-basis labels. Moreover, this useful gate set admits a compact factorized description determined by simple graph-theoretic features. This structure also allows, after some initial cached precomputation, drastically lower computational complexity for simulating a gate. We further organize these operations over local-complementation (LC) orbits using minimum-edge representatives (MERs), which let us design purification
circuits that apply to all locally equivalent graph states (up to a basis change). Using this framework, we optimize noisy finite-size multipartite
distillation circuits for several graph-state families. Numerical results show that the resulting graph-preserving
circuits can outperform standard recurrence-based purification protocols under realistic gate and measurement noise. Our results establish LC-orbit structure and factorized graph-preserving operations as practical tools for scalable,
topology-aware and hardware-constrained graph-state
distillation protocol design. Our work can also be interpreted as a graph-based heuristic for finding transversal gates.
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All authors Mingyuan Wang, Guus Avis, Kenneth Goodenough, Stefan Krastanov
Astrophysics of Galaxies
First measurement of narrow-line flux ratios for a lensed quasar with JWST/NIRSpec IFS
Hadrien Paugnat, Tommaso Treu, Anna M. Nierenberg et al. (+3 more)
Strong gravitational
lensing is a powerful probe of dark matter (DM) structure on subgalactic scales: in particular, statistics of flux-ratio anomalies (discrepancies between mass model predictions and observed flux ratios) in quadruply imaged
quasars are sensitive to perturbations by low-mass DM
halos down to $\sim 10^6 M_\odot$. Studies leveraging these anomalies require high-quality flux-ratio measurements from an emission region insensitive to
stellar microlensing. In this paper, we present the first measurement of narrow-line flux ratios for a gravitationally lensed
quasar using JWST/NIRSpec with Integral Field Spectroscopy (IFS), targeting the well-studied system RXJ1131$-$1231. Flux ratios are extracted from the [S III] 9071/9533 $\r{A}$ narrow-line doublet - the first use of this doublet for substructure studies - by performing a full lens model reconstruction to isolate the unresolved
nuclear emission from extended narrow-line emission. The resulting spectra are jointly modeled using $\texttt{lensqso-specfit}$, a publicly available software package introduced in this work for the simultaneous spectral fitting of multiple lensed
quasar images. We achieve $\sim$ 5% uncertainties on the flux ratios, comparable to the precision of JWST/MIRI warm
dust measurements, and detect a clear anomaly in the cusp images relative to a standard smooth lens model. Our results are in good agreement with previous narrow-line measurements and broadly consistent with JWST/MIRI warm
dust flux ratios, with marginal ($\sim 2-3\sigma$) deviations. We illustrate how such shifts between differently sized emission regions may be enhanced by small ($\sim 10$ pc) spatial offsets. Our method is generalizable to other systems with existing or future IFS observations, and the combination of narrow-line and warm
dust flux ratios offers a new avenue for improving DM constraints with flux-ratio anomaly statistics.
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All authors Hadrien Paugnat, Tommaso Treu, Anna M. Nierenberg, Anowar J. Shajib, Shawn Knabel, Daniel Gilman