Papers

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Physics

Saturday 25 July

Atmospheric and Oceanic Physics

Transition to double-cell mock Walker circulations with surface warming explained by periodic convection

Heng Quan, Yi Zhang, Guy Dagan et al. (+1 more)

Idealized mock Walker simulations are widely used to study the interactions between overturning circulation and convection in the tropics. Previous studies documented a transition from a single-cell to a double-cell mock Walker circulation when the average sea surface temperature exceeds 300 K. Here, we ascribe the transition to the emergence of periodic convection with warming due to stronger convectively-coupled waves. In cold simulations, the warm pool is dominated by steady deep convection, which results in a single overturning cell. In hot simulations, the warm pool is alternately dominated by deep convection and a stratiform mode, resulting in lower and upper cells respectively. This study suggests that the Walker circulation in a warmer climate may feature complex structural changes in addition to a weakening in strength, and highlights the profound impacts of convection on overturning circulation.

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All authors Heng Quan, Yi Zhang, Guy Dagan, Stephan Fueglistaler

Quantum Physics

A Resource Estimation Model for the Hardware-Software Co-Design of Distributed Quantum Architectures

Raymond P. H. Wu, Chathurika Ranaweera, Sutharshan Rajasegarar et al. (+3 more)

In distributed quantum computing (DQC), executing monolithic quantum circuits across multiple interconnected quantum processing units (QPUs) requires dedicated communication qubits to generate and distribute entanglement. Because the number of physical qubits within a QPU is finite, a trade-off emerges where allocating more communication qubits increases the capacity of quantum channels for concurrent non-local operations, but reduces the number of computational qubits available for local gate operations. Distributed quantum compilation routinely ignores this channel capacity, while hardware architects lack a method to determine it prior to quantum circuit partitioning. Moreover, scheduling entanglement on demand introduces severe latency, whereas pre-fetching exposes stored pairs to decoherence. We propose an economic order quantity model from perishable inventory theory to optimize the trade-off between entanglement distribution latency and the time cost of decoherence. The resulting estimate is driven by algorithmic demand and physical constraints, offering a dual application for the hardware-software co-design of high-performance DQC: for hardware architects, it gives the optimal allocation of dedicated communication qubits in static heterogeneous architectures; for compiler developers, it gives the optimal number to reserve dynamically in homogeneous architectures.

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All authors Raymond P. H. Wu, Chathurika Ranaweera, Sutharshan Rajasegarar, Ria Rushin Joseph, Jinho Choi, Seng W. Loke

Quantum Physics

Theory of approximate quantum error correction and the error-set model

Dor Elimelech, Victor V. Albert and Alexander Barg

We develop a theory of approximate quantum error correction (QEC) based on the error-set model, complemented by general methods for code construction. Exact QEC has a powerful error-set structure: by the Knill-Laflamme conditions, a code correcting a given error set automatically protects against every channel whose Kraus operators lie in their linear span. This linearity gives rise to code distance, the equivalence between erasures and general errors, and a theory of asymptotically good codes. A longstanding view has been that these features do not extend to AQEC, leaving the theory essentially channel-by-channel. We show instead that, although full Knill–Laflamme linearity fails, a restricted form survives and suffices to extend all three structural features to the approximate setting. Specifically, a common error-set criterion governs families of channels whose Kraus operators are linear combinations of a given error set and whose coefficient matrices satisfy a spectral constraint. Using the Bény-Oreshkov worst-case and Petz average-case frameworks, we derive uniform fidelity guarantees for these families in terms of two new code parameters–the environment-leakage distance, controlling worst-case performance, and the Knill-Laflamme Hellinger distance, characterizing the average-case performance of Petz recovery. To demonstrate the scope of this model, we develop partition-based constructions across diverse quantum systems and geometries, placing exact and approximate correction on equal footing. These constructions lead to a metric–error alignment hierarchy for Hilbert spaces, metrics, and error families, which in turn characterizes the resulting recovery guarantees. They yield the first known asymptotically good code families for fermionic systems, one-dimensional Rydberg-blockaded systems, and deletion errors, and extend to other physical platforms.

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Materials Science

Role of $p$-$d$ Hybridization on Optical Properties of Chalcopyrite Semiconductors

Neunghee Han, Harang Kim, Minjae Kim et al. (+1 more)

Designing quantum materials for coherent optical properties is a central agenda in quantum technology. Semiconductor quantum dots are an emerging approach for controlling coherent optical properties via confinement effects, tunable band gaps, and exciton binding energies, yet their inherent structural and compositional inhomogeneity degrades the coherence of the optical spectra, posing a major obstacle. We show that, for chalcopyrite semiconductors, hybridization between transition-metal $d$ and ligand $p$ electrons in the valence band is key to the coherence of the quantum dot optical spectrum. We demonstrate this using first-principles electronic-structure calculations and optical spectroscopy. The strong $p$-$d$ hybridization in CuInS$_{2}$ induces the Cu($d$) Coulomb scattering channel, giving rise to the incoherent photodoped hole carrier, while the weak $p$-$d$ hybridization in AgInS$_{2}$ induces the delocalized photodoped hole carrier having a predominant S($p$) orbital character. Our experimental results on optical spectra suggest that when the Cu ratio is enhanced in the Ag$_{1-x}$Cu$_{x}$In$_{1-y}$Ga$_{y}$S$_{2}$ quantum dot, Cu atoms at both Ag sites and defect sites experience enhanced $p$-$d$ hybridization, and a coupling begins to develop between the electrons in the quantum dot and the defect electrons at a small Cu ratio. This coupling activates Cu($d$) Coulomb scattering for photodoped holes traversing the defect sites, producing an incoherent optical response that naturally explains the long-standing absence of band-edge spectral signatures in CuIn$_{1-y}$Ga$_y$S$_2$ quantum dots. These results serve as a guideline for designing semiconductor quantum dots. To achieve a coherent optical spectrum, avoid $p$-$d$-hybridized orbital character in the photo-doped carrier.

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All authors Neunghee Han, Harang Kim, Minjae Kim, Woonhyuk Baek

Statistical Mechanics · Cross-listed from math.PR

Mixing times and spectra of non-equilibrium symmetric exclusion processes on general graphs

Leonard J. Schulman and Alistair Sinclair

The symmetric exclusion process (SEP) is a classical model of interacting particles on a graph, in which multiple particles execute random walks subject to the constraint that no two particles may occupy the same vertex. The version of the process in which the number of particles is fixed, is by now very well understood, through the study of reversible Markov chains. In this paper, we study the non-equilibrium version of the SEP, in which some vertices of the graph interact with external heat baths, held at different temperatures, that mediate transport through the graph. The resulting steady-state distribution is still the stationary distribution of a natural Markov chain, but the chain is no longer reversible. This means that even the steady-state distribution is very hard to describe, and indeed is the subject of a rich literature, which has focused almost exclusively on graphs which are finite subsets of the lattice $Z^d$. Very little is known about other important quantities, notably the mixing time. We derive various quantitative results about the non-equilibrium SEP for arbitrary graphs with arbitrary heat baths. Our main result is a bound on the mixing time in terms of the worst-case hitting time of a single particle to any of the heat baths; this bound is tight up to two logarithmic factors in the size of the graph. We then use this result to derive a simple algorithm, running in time roughly $n^{O(k)}$, that computes the steady-state joint occupation distribution for any set of $k$ vertices; since the steady-state distribution is very elusive, this provides a potentially useful tool to study its $k$-wise correlations for small values of $k$. Finally, we prove that the spectrum of the Markov chain associated with the non-reversible dynamics for the SEP is independent of the heat bath temperatures; thus in particular the spectrum is always real.

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Optics

Phonon heat transport with squeezing-based symmetry breaking

Yan Cao, Cheng Yang, Xintong Gu et al. (+3 more)

The controllability of phonon thermal transport is fundamental for numerous technologies, from cooling high-performance chips to managing heat in quantum computing. Despite extensive efforts, on-demand, real-time control of phonon heat flow remains elusive, being fundamentally constrained by the temperature gradient. Here we achieve this long-sought phonon heat transport by introducing a novel mechanism using quantum squeezing in a cavity optomechanical system. We find that phonon squeezing of near-ground-state mechanical resonators via an optomechanically induced parametric process breaks the continuous U(1) rotation symmetry in phase space, and consequently the symmetry in the heat current structure. We reveal that heat flow under a constant temperature gradient can be deterministically amplified, reduced, or even reversed, a capability previously unattainable. With phonon squeezing, we achieve over twentyfold amplification of heat flow and reversal within 30 milliseconds. Importantly, quantum discord analysis reveals a direct connection between heat flow reversal and quantum correlation. Our results establish quantum squeezing as a versatile platform for on-demand phononic thermal control, opening avenues for active heat management in quantum devices and thermal logic circuits.

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All authors Yan Cao, Cheng Yang, Xintong Gu, Shenzhu Wang, Jiteng Sheng, Haibin Wu

Nuclear Theory

Future directions in nuclear $\beta$ decay at FRIB and beyond

Garrett B. King, Ayala Glick-Magid, Grigor Sargsyan et al. (+38 more)

Motivated by the opportunities presented for studies relevant to nuclear structure, astrophysics, and fundamental symmetries with nuclear $\beta$ decay, the Facility for Rare Isotope Beams (FRIB) Theory Alliance topical program “Future Directions in Nuclear $\beta$ Decays at FRIB” was held in September of 2025. This white paper summarizes the main points of discussion over the two-week program, and it aims to provide a snapshot of the current status of the field while also highlighting important questions and opportunities for future work. We provide an overview of the experimental tools and techniques that enable modern $\beta$ decay studies, discuss the current state of nuclear many-body approaches used to study $\beta$ decays, and highlight the important science questions that can be addressed by weak decays.

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All authors Garrett B. King, Ayala Glick-Magid, Grigor Sargsyan, Mark A. Caprio, Kyle G. Leach, John A. Behr, Francesca Bonaiti, Maxime Brodeur, Graham Chambers-Wall, Heather L. Crawford, Maria Dawid, Wouter Dekens, Michael Gennari, Robert Grzywacz, Peter Gysbers, Heather S. Harrington, Heiko Hergert, Lotta Jokiniemi, Brenden Longfellow, Rebeka S. Lubna, Kelsey A. Lund, Giacomo Marocco, Anna E. McCoy, Dan Melconian, Alexis Mercenne, David C. Moore, Oscar Naviliat-Cuncic, Samuel J. Novario, Timilehin H. Ogunbeku, Walter C. Pettus, Ryan Plestid, Bertis C. Rasco, Ante Ravlíc, Yukiya Saito, Dustin P. Scriven, Chien-Yeah Seng, Nadezda A. Smirnova, Artemis Spyrou, Vandana Tripathi, Xing Wu, Zhengyu Xu

Statistical Mechanics

Response Morphologies of a Canonical Fluctuation Diagnostic Across Ehrenfest Phase Transitions

Fangfang Wang, Wei Liu, Ying Tang et al. (+1 more)

Microcanonical inflection-point analysis identifies MIPA-type higher-order transition structures from derivatives of the microcanonical entropy. Until recently, however, there was no canonical formulation for probing the corresponding fluctuation-level behavior directly from measurable energy fluctuations without reconstructing the density of states. Previous work addressed this limitation by introducing a canonical fluctuation diagnostic that quantifies energy-fluctuation asymmetry. Here, we investigate how this diagnostic behaves across representative first-, second-, and third-order phase transitions in the Ehrenfest classification. We consider the eight-state Potts model, the two-dimensional Ising model, and ideal three-dimensional Bose–Einstein condensation. The Potts and Ising systems exhibit a robust paired-extremum structure of the diagnostic near their respective transition regions, whereas ideal Bose–Einstein condensation exhibits a discontinuous response at the condensation temperature in the thermodynamic limit. These results show that a single fluctuation-based observable can display qualitatively distinct response morphologies across thermodynamic regimes, reflecting sensitivity to the nature of the underlying phase transition rather than serving as a direct classifier of Ehrenfest order.

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All authors Fangfang Wang, Wei Liu, Ying Tang, Zengru Di

General Relativity and Quantum Cosmology

Nonlinear electrodynamics in Kerr-Newman-NUT-$\Lambda$ spacetime: exact solutions, horizons, and energy conditions

Oscar Galindo-Uriarte, Nora Breton, Claus Lämmerzahl et al. (+1 more)

We construct two exact nonlinear-electrodynamic generalizations of the Kerr-Newman-NUT-$\Lambda$ spacetime. Imposing alignment between the principal directions of the electromagnetic field and the metric tetrad reduces the Maxwell-Faraday sector to a pair of potentials constrained by a single integrability condition, the key equation. Within the polynomial aligned ansatz considered here, the key equation selects two admissible families, corresponding to electromagnetic potentials that are cubic and quartic polynomials. For each family the Einstein equations reduce to a single radial ordinary differential equation that gives a deformation of the Kerr-like radial metric function which is exactly solved. We derive the corresponding metrics, electromagnetic fields, stress tensors, horizon structure, and we analyze the associated energy conditions. The nonlinear sector breaks conformal invariance and, in the cubic family, can mimic an effective cosmological contribution. The explicit Lagrangians as functions of the electromagnetic invariants are obtained in selected static subsectors. The curvature invariants show that the nonlinear contribution does not remove the Kerr-like curvature singularity, while the solutions present the NUT axial conical singularity.

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All authors Oscar Galindo-Uriarte, Nora Breton, Claus Lämmerzahl, Alfredo Macías

Mesoscale and Nanoscale Physics

Spectral Topology and Non-Bloch Band Theory for Domain-Wall Systems

Mingtao Xu, Rui Wang, Tian-Shu Deng et al. (+1 more)

We study the spectral topology of one-dimensional non-Hermitian models in a domain-wall configuration, where different domains are arranged in a ring geometry. While eigenstates can localize near an interface under the non-Hermitian skin effect, we show that the localization of an eigenstate originates from the difference in the spectral winding numbers, with respect to the corresponding eigenenergy, between the two adjacent domains. We then obtain the conditions for the generalized Brillouin zone (GBZ) in the complex momentum space, by extending the Ronkin-function formalism to the domain-wall configuration. In addition to the conventional skin modes that correspond to standing waves on individual domains under the open boundary condition, a unique type of traveling-wave-like skin modes emerges, whose construction involves all domains. Besides their difference in the spatial profiles, these two types of modes obey distinct GBZ conditions, making them differentiable on the GBZ. Interestingly, the traveling-wave-like modes further carry a finite flux spectral winding number, indicating their boundary sensitivity.

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All authors Mingtao Xu, Rui Wang, Tian-Shu Deng, Wei Yi

Materials Science

AEcroscopyWave: Towards Self-Driving Characterization Platforms for Agentic AI

Yongtao Liu, Jawad Chowdhury, Ganesh Narasimha et al. (+8 more)

The characterization of electronic materials has traditionally been stratified into two distinct regimens: industry-scale automated systems to inspect materials for defects and ensure quality (such as in the semiconductor industry), and highly customized, operator-driven systems requiring human experts. The former offers high throughput but limited flexibility, whereas the latter is heavily bandwidth-limited but provides research-grade discovery capabilities. Recent advances in "self-driving" characterization tools offer the potential to bridge the two stratified regimes, by the creation of application program interfaces (APIs) that can control hardware, and the integration of AI methods to incorporate autonomy into the process. Here, we discuss our latest developments in AEcroscopyWave, a custom-built characterization platform for the agentic-AI era, that provides unified control of scanning probe microscopes with programmable peripheral instrumentation, highlighting the design choices that are necessary for maximizing the capability of the system and the ease of use for both human and AI agents. The benefits of making heterogeneous scientific instruments accessible, composable and usable by agents is demonstrated by test cases.

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All authors Yongtao Liu, Jawad Chowdhury, Ganesh Narasimha, Ralph Bulanadi, Liam Collins, Ruben Millan Solsona, Marti Checa, Asraful Haque, Sumner B. Harris, Stephen Jesse, Rama Vasudevan

Earth and Planetary Astrophysics · Cross-listed from eess.SY

Drift-Aware Multi-Target Space Tug Logistics Using Natural Orbital Precession

Omer Burak Iskender, Leonard Felicetti, Kaan Gokturk et al. (+2 more)

Multi-rendezvous missions for active debris removal and in-orbit servicing incur prohibitive propellant costs when their targets differ in the orientation of their orbital planes, and classical mission design treats the nodal precession induced by Earth's oblateness as a perturbation to be cancelled. This paper presents a drift-aware trajectory optimisation framework that instead exploits that precession as a mission-design resource, benchmarked against the published winning solution to the European Space Agency's Kessler Run trajectory-optimisation competition as a trusted reference. Three methodological contributions are made. First, an enhanced drift orbit shapes the size, shape, and inclination of an intermediate orbit to tune the differential precession rate, substantially cheaper than the altitude-only designs of prior work in the Sun-synchronous regime, where inclination is the dominant lever. Second, a global per-leg time-budget optimiser makes explicit and resolves the coupling between drift-time allocation and downstream nodal geometry that defeats greedy allocation. Third, a sequence-recovery test independently re-derives a removal order consistent with the published reference from the debris catalogue alone. Applied to the full debris campaign on the published mission partition under the competition's transfer-time rules, the framework closely matches the published benchmark cost using only analytical transfer models and minutes of single-core computation. A cross-validation anchored to a widely used flight-dynamics tool quantifies the fidelity limits of the analytic model and bounds the cost of literal execution, and the constructive nature of the algorithm supports rapid in-orbit replanning after a missed manoeuvre.

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All authors Omer Burak Iskender, Leonard Felicetti, Kaan Gokturk, David Tellett, Adam Baker

Atmospheric and Oceanic Physics

Energetics of frontogenesis in simple balanced models

Yue Bai and Jörn Callies

Submesoscale fronts have been proposed to act as conduits funneling kinetic energy from geostrophically constrained mesoscale eddies down to small scales, where the energy can be dissipated. Realistic primitive-equation simulations suggest that the downscale energy transfer at submesoscales is strongly concentrated in sharpening fronts, with convergence on the cyclonic side playing a dominant role. This study explores how much of this phenomenology can be captured by simple quasi-geostrophic (QG) and semi-geostrophic (SG) theories of frontogenesis. An analysis of the kinetic energy budget of classical strain-induced frontogenesis shows that there is downscale transfer in both QG and SG fronts. In QG frontogenesis, the narrowing jet along the sharpening front is powered by buoyancy production, but geostrophic downscale transfer due to the strain field plays an important role. In SG frontogenesis, where frontal sharpening is accelerated by the ageostrophic cross-frontal circulation, ageostrophic advection enhances this downscale transfer on the cyclonic side of the front, where the surface flow is convergent. On the anticyclonic side, where the ageostrophic circulation is divergent, the ageostrophic scale transfer of kinetic energy is upscale and partially offsets the geostrophic downscale transfer. While matching patterns in realistic primitive-equation simulations, the ageostrophic scale transfers remain important but not dominant in the adiabatic and frictionless theory considered here. This suggests that processes absent from these theories may play an important role. For example, mixed-layer turbulence may enhance the ageostrophic circulation and the associated dipole of scale transfers. The advection of ageostrophic momentum may also be important in some circumstances.

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General Relativity and Quantum Cosmology

Quasinormal modes of a quantum inspired black hole in four dimensions with cosmological constant

R. D. B. Fontana, Jeferson de Oliveira, B. Eslam Panah et al. (+1 more)

We study the scalar and Dirac perturbations of quantum-corrected black holes with cosmological constant. Using two different methods (WKB and double-null characteristic integration) we compute the quasinormal modes (QNMs) of de Sitter and Anti-de Sitter solutions considering linear field perturbations in the background geometry. In the limit of general relativity black holes our methods demonstrate good convergence with the available results in literature. In the presence of an extra quantum parameter we verify that all perturbations are stable evolving in towers of quasinormal oscillations. We scrutinize the spectra of both dS and AdS solutions studying the influence of that extra parameter in the frequencies.

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All authors R. D. B. Fontana, Jeferson de Oliveira, B. Eslam Panah, Ángel Rincón

Astrophysics of Galaxies

A quasar hatching from a buried red phase at z = 3.7

Zheng Ma, Yongda Zhu, Zhiyuan Ji et al. (+21 more)

We present JADES-GS 209777, previously cataloged as CANDELS J033238.02-274626.2, hereafter "the Hatchling," a red quasar at $z=3.711$. While the source has been reported in earlier deep-field catalogs, our multiwavelength analysis reveals a visible active nucleus still embedded in a dense gas- and dust-rich environment. Red quasar continua are often attributed to dust attenuation, including non-standard extinction curves, but the highly comprehensive multiwavelength data for this source provide direct constraints on the material being cleared. Using JWST/NIRSpec, NIRCam, MIRI, HST, MUSE, Chandra, ALMA, and VLA data, we detect broad emission lines and strong X-ray emission, showing that the active nucleus is at least partially exposed. We also detect H$\alpha$ and He I absorption, indicating dense gas close to the nucleus. Kinematically disturbed O I, Mg II, Na D, and [O III] features, together with extended Ly$\alpha$ emission over $\gtrsim 20$ kpc, further show that multiphase gas is being accelerated from the nuclear region into the host-galaxy environment. The ALMA detection reveals strong dust emission, with the inferred infrared luminosity placing the system in the ULIRG regime. The continuum is red and sharply declining toward the rest-frame UV, resembling compact red AGNs, and may reflect extreme dust attenuation, gas reprocessing, possible BAL-like absorption, or a combination of these effects. Regardless of which mechanism dominates the continuum shape, the line diagnostics show that the visible nucleus remains partially obscured by nearby material. The Hatchling therefore represents a unique opportunity to explore a poorly known transition phase in which feedback is likely clearing an enshrouded quasar and allowing it to emerge toward a more unobscured active nucleus.

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All authors Zheng Ma, Yongda Zhu, Zhiyuan Ji, Eiichi Egami, Marcia J. Rieke, Xiaohui Fan, Jianwei Lyu, George H. Rieke, Fengwu Sun, Yang Sun, George D. Becker, Andrew J. Bunker, Francesco D'Eugenio, Xiangyu Jin, Ignas Juodžbalis, Weizhe Liu, Roberto Maiolino, Pierluigi Rinaldi, Feige Wang, Christopher N. A. Willmer, Yunjing Wu, Jinyi Yang, Junyu Zhang, Peixin Zhu

Friday 24 July

Physics and Society · Cross-listed from q-fin.TR

Herding and Liquidity in Order-Book Markets. III. Leverage and the Onset of Endogenous Liquidity Crises under Weak Anchoring

Jan Novotny

Fundamental-value anchoring of resting liquidity is a causal stabiliser of an order-book market: while the anchor holds, even a heavily leveraged book stays quiet. We take that anchor strength as a continuous control and characterise the endogenous liquidity crises that appear once it is nearly removed. In a single continuous-double-auction market driven by anchored noise traders, chartist herders, a population of funding-constrained market makers, and leveraged holders subject to margin calls, no exogenous shock is injected, so that any crisis is self-generated. Weakening the anchor turns on both classical leverage stylised facts: the return tail exponent falls from about 6.5 to 2.3 and the integrated volatility autocorrelation roughly doubles, although the clustering is short-memory rather than the long-memory of real markets. Isolating the crisis as a matched-herding levered-minus-unlevered book-depletion increment, we find it confined to a narrow region of weak anchor and intermediate herding, in which more leverage always deepens the crisis. Its onset is governed not by leverage alone but by the margin buffer, the price fall a holder can absorb before a forced sale, set jointly by leverage and the maintenance margin: the two-parameter leverage-margin plane collapses, to leading order, onto this single buffer, so that tightening the maintenance margin is as destabilising as raising leverage. The onset is a smooth, sub-critical crossover: the ignition probability rises gradually, a run-length test reveals no latent sharp tipping, and a branching-ratio proxy stays bounded well below unity.

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General Relativity and Quantum Cosmology

Jordan-like invariant representations of scalar-tensor gravity and the return of imperfect-fluid thermodynamics

David S. Pereira and José Pedro Mimoso

It has been shown that the thermodynamics of frame-invariant scalar-tensor gravity admits an Einstein-frame-like invariant representation, in which the scalar sector is minimally coupled and behaves as a perfect fluid with vanishing temperature. We show that this is not the only invariant thermodynamic organization available. Using instead the invariant matter metric, we construct a Jordan-frame-like invariant representation in which matter is minimally coupled and the gravitational action takes the Brans-Dicke-Bergmann-Wagoner form with invariant fields $\Psi=\mathcal I_1^{-1}$, $\mathcal U(\Psi)$, and $\omega_{\mathrm{inv}}(\Psi)$. In this representation the metric field equations retain the Hessian sector characteristic of Jordan-frame scalar-tensor gravity. A $1+3$ decomposition of the corresponding effective stress tensor yields nonvanishing heat flux and anisotropic stress in a generic congruence. In the $\Psi$-comoving frame, the usual first-order thermodynamic identifications are recovered in invariant form, including $K_{\mathrm J}T_{\mathrm J}=-\dot\Psi/(\kappa^2\Psi)$ and $\eta_{\mathrm J}=\dot\Psi/(2\kappa^2\Psi)$, with the bulk channel obtained in homogeneous and isotropic sectors. Thus, frame-invariant scalar-tensor thermodynamics is not intrinsically restricted to an Einstein-frame-like perfect-fluid description: it also admits a Jordan-frame-like invariant formulation in which the effective imperfect-fluid interpretation is manifest.

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General Relativity and Quantum Cosmology

Radiative losses from unbound orbits at quadratic order in spin from MPM formalism

Donato Bini and Giorgio Di Russo

We study the spinning two-body system in the aligned spin case for hyperboliclike motions computing all radiative losses (at the 2PN absolute accuracy and including spin-squared corrections) using the MPM formalism and generalizing previous results valid at linear order in spin [Phys. Rev. D 108, no.6, 064049 (2023)]. Leading PM order results are checked against existing literature, whereas higher-order PM results (within the 2PN accuracy) are new with this work. As a by-product of our general results we analyze the spinning situation which supports radial fall (at 2PN and including spin-squared accuracy level contributions), showing that as soon as the PN accuracy increases deviations from radial fall appear necessarily.

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Physics and Society

Living Structure + AI: A New Episteme for Liberal Arts and Whole-Person Education in the Era of Artificial Intelligence

Bin Jiang

The rapid integration of artificial intelligence (AI) into higher education signals an epistemic shift in how knowledge is created, taught, and evaluated. This paper argues that Christopher Alexander's theory of living structure offers a timely foundation for liberal arts and whole-person education in the AI era. Living structure is understood through two inseparable dimensions: living, the intuitive perception of wholeness, and structure, the underlying order that can be analyzed through fifteen geometric properties, two fundamental laws, two design principles, and the computable L- and B-scores. Building on this foundation, the paper proposes Living Structure + AI as a new episteme for higher education. The ordering is deliberate: living structure is more fundamental, while AI serves as a tool for perceiving, measuring, and generating it. The argument draws on teaching by LivableCityLAB in partnership with Residential College 1, including architecture and city-science courses, an undergraduate common-core course, and a postgraduate experiential-learning course. Across four campus-renovation projects and two courses involving 89 students, participants learned to read environments structurally, establish a design skeleton, and use AI as a structural mediator. L- and B-scores increased in every renovation, broadly converging with preference tests and visual-attention analysis. Course assignments provided additional, though not psychometrically validated, evidence of student engagement. The paper concludes that the deepest contribution of Living Structure + AI lies not on screens, but in enabling students to feel, measure, and remake wholeness in everyday spaces.

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High Energy Astrophysical Phenomena

Verifying Gamma-Ray Burst Duration Analysis Using the Compton Gamma-Ray Observatory T50 Data

Istvan Horvath

Several authors have shown in the literature that a third type of gamma-ray burst class can be detected in the Compton Gamma-Ray Observatory data using T90. In this paper, I examine whether this can also be found in the T50 variable data from the Compton Gamma-Ray Observatory Burst And Transient Source Experiment observation. According to my calculations, the third group detected in T90 can also be detected in the T50 data.

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Plasma Physics

Physics-informed genetic algorithms (PIGAs) facilitating LIBS spectral normalization with shockwave characteristics

Ying Zhou, Jian Wu, Mingxin Shi et al. (+6 more)

Inspired by physics-informed neural networks (PINNs) inheriting both the interpretability of physical laws and the efficient integration capability of machine learning, we propose a framework based on stoichiometric ablation for LIBS spectral normalization, encoding physical constraints between LIBS intensities and shockwave characteristics (temperature Tshock and pressure P) into optimization algorithms with multiple independent objectives, named physics-informed genetic algorithms (PIGAs). It is characterized by its applicability to the wider laser energy range covering laser-induced breakdown to significant plasma shielding and spectral lines undergoing self-absorption outperforming the widely-used physical linear or multivariate data-driven normalization methods. The home-made end-to-end LAP-RTE codes serves as the benchmark to validate the physical reciprocal-logarithmic transformation and its extensibility to self-absorption spectral lines for PIGAs. Next experimental spectral lines are statistically used to validate PIGAs correction effects, the median RSDs of spectral intensities can be effectively reduced by 85% (corrected by P) and 88% (corrected by Tshock) for 108 Fe I lines, while for 33 Fe II lines, reduced by 77% (corrected by P) and 86% (corrected by Tshock). Seventeen self-absorption lines are also corrected effectively, with RSDs being reduced by 78% (corrected by P) and 89% (corrected by Tshock). Our proposed idea of combining optimization methods to quantify unknown parameters in normalization strategies can also be extended to excavate the correlation between parameters for other low-temperature plasma fields with similar processes.

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All authors Ying Zhou, Jian Wu, Mingxin Shi, Minxin Chen, Jinghui Li, Xinyu Guo, Yuhua Hang, Cuixiang Pei, Xingwen Li

Atmospheric and Oceanic Physics

AIFS-TC: A simple correction competitive with the operational frontier for tropical cyclone intensity forecasting

Anna Allen, Wessel P. Bruinsma, Michael Maier-Gerber et al. (+3 more)

AI weather models are in the process of revolutionising weather forecasting. While these models have been shown to achieve superior performance to physics-based NWP in forecasting tropical cyclone (TC) tracks, they tend to dramatically underestimate intensity. Here we present AIFS-TC, a simple correction to the AIFS-Single model that is competitive with the operational state-of-the-art for forecasting maximum wind speed and minimum central pressure at lead times of 12 h to seven days. This performance also holds for rapid intensification events. Notably, the entire system was autonomously designed and built by a large language model (Claude Fable 5) in a few hours, directed through a small number of natural-language prompts by a single domain scientist. That the operational frontier can be reached with an open-source AI forecast model (AIFS-Single) and relatively simple, cheap post-processing is significant for TC science, and points to agentic coding as a route to rapid exploration and progress in life-saving early-warning systems in other domains.

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All authors Anna Allen, Wessel P. Bruinsma, Michael Maier-Gerber, Harrison Cook, Matthew Chantry, Richard E. Turner

Geophysics

Revisiting a historically suspected impact structure in the Venezuelan Guiana Shield using SRTM topography

Miriam Rengel and Ekko Krumstroh

During the 1980s, aerial observations over the Venezuelan Guiana Shield led to the hypothesis that a circular geomorphological feature might represent an impact structure. Radar imagery was subsequently requested and circulated among researchers, but the interpretation remained unresolved. Recently rediscovered correspondence and imagery enabled a re-evaluation using modern digital elevation models from the Shuttle Radar Topography Mission (SRTM). The higher-resolution topographic data indicate that the structure lacks diagnostic morphologies of impact craters and is consistent with the Nuria ring dike intrusive complex. Comparison with analogous circular intrusive complexes, including the Kondyor massif, illustrates how circular morphology alone is insufficient for impact identification. This study documents a historical episode of geomorphological interpretation prior to the availability of modern digital elevation datasets and illustrates how improved topographic information and geological context can clarify the origin of ambiguous circular landforms relevant to planetary surface analysis.

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Solar and Stellar Astrophysics

SMDET-1: a Nearby Y Dwarf Candidate

Aaron M. Meisner, Dan Caselden, Federico Marocco et al. (+11 more)

We present the discovery of SMDET-1, a red, fast-moving object ($\mu \approx 1.3$"/yr) identified in time-resolved unWISE coadds using a pixel-level deep learning methodology called SMDET. Despite being relatively bright at 4.5 microns compared to many other recent WISE-based brown dwarf discoveries ($m_{[4.5]} \approx 14.6$ mag Vega), SMDET-1 had remained overlooked due to its location in a very crowded Galactic plane field ($b \approx 2.25^{\circ}$) and contamination from brighter background objects. SMDET-1 is also serendipitously detected at 4.5 microns in late-2012 Spitzer Deep GLIMPSE survey imaging. SMDET-1 is undetected in UKIDSS and Palomar/WIRC near-infrared imaging, with the strongest constraint on its temperature ($T_{\rm eff}$ < 391 K) arising from its Deep GLIMPSE color limit of $m_{[3.6]} - m_{[4.5]} > 2.81$ mag, which also implies a very nearby photometric distance < 7.4 pc. The Spitzer color bound corresponds to a Y dwarf phototype. SMDET-1 illustrates the importance of continued searches for nearby brown dwarfs within archival datasets like WISE and Spitzer, as well as the potential of pixel-level deep learning to discover astronomical moving objects that challenge traditional data analysis approaches.

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All authors Aaron M. Meisner, Dan Caselden, Federico Marocco, J. Davy Kirkpatrick, Jonathan Gagné, Adam C. Schneider, Samuel A. Beiler, Sergio B. Fajardo-Acosta, Jacqueline K. Faherty, Stanimir A. Metchev, Sam Barber, Marc J. Kuchner, Thomas P. Bickle, Zafar Rustamkulov

Data Analysis and Statistics

Data Field Theory: Theory and Applications of the Functional Renormalization Group for Signal Detection

Riccardo Finotello, Vincent Lahoche, Dine Ousmane Samary et al. (+1 more)

We review the renormalization group framework for signal detection in high-dimensional data, tailored to the regime where the signal may be of extensive rank and does not separate from the noise bulk as isolated spikes. The framework provides a conceptually simple criterion for distinguishing signal from noise within a quasi-continuous spectral region near a random-matrix universality class. This scenario lies beyond the reach of standard methods such as the Baik-Ben Arous-Péché threshold, which requires eigenvalues to be cleanly separated from the bulk. The renormalization group approach, by contrast, directly tracks spectral deformations and consistently yields a lower limit of detection without relying on spike separation. We review results that identify the presence of a signal by testing the stability of the Gaussian fixed point of an effective field theory for the collective behaviour of the degrees of freedom in the spectral tail, where the signal resides. We also discuss how the scale dependence of the canonical dimension, induced by the signal, manifests as a dimensional phase transition.

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All authors Riccardo Finotello, Vincent Lahoche, Dine Ousmane Samary, Parham Radpay

Plasma Physics

Coupling model of metallic target ablation-plasma evolution-radiation under nanosecond laser irradiation

Ying Zhou, Jian Wu, Hao Sun et al. (+8 more)

The interaction of nanosecond laser pulses with metallic materials involves multiple complex physical processes. It is challenging to construct a self-consistent model capable of uniformly describing all stages. This work establishes a multi-physics coupling model for pure iron, encompassing laser energy deposition, solid-liquid phase transition, gas-liquid interfacial kinetic transport, plasma expansion and ionization, and spectral radiation. The numerical solution adopts a partition method, utilizing an implicit compact difference scheme for the target and a Mac-Cormack explicit scheme for the plasma. The simulations elucidate the emergence of plasma shielding and its inhibitory effect on the evaporation process, thereby confirming that 81.6% of the early-stage ablation products are transported through a supersonic expansion mode. The model successfully captures the complete evolution of the plasma plume from a high-temperature, highly ionized state to a low-temperature, neutral atomic state. Based on this, spectral calculations demonstrate the dynamic evolution of radiative characteristics from an early stage featuring a strong continuum background dominated by ion lines to a later stage where the continuum attenuates, atomic lines become prominent, and self-absorption appears. The emergence of self-absorption proves the ability of the model to effectively capture the optical thickness effects arising from spatial inhomogeneity within the plasma. Through systematic comparison between experimentally measured spectra and calculated results from the PrismSPECT and NIST LIBS spectral programs, the model presented here achieves the highest comprehensive scores in quantitative evaluations of multiple channels. This validates the necessity and superiority of the full-chain self-consistent modeling approach, especially in describing plasma inhomogeneity and radiation transport.

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All authors Ying Zhou, Jian Wu, Hao Sun, Jinghui Li, Xiaoxuan Li, Shuzhi Huang, Jiayao He, Xingyu Liu, Yuhua Hang, Cuixiang Pei, Xingwen Li

Quantum Physics

Quantum Mechanics on Non-Hausdorff One-Manifolds with Finite Graph Resolutions: Analytic Completion, Branching, and Invariant-Sector Scattering

Abhiram Sripat

We develop a systematic framework for quantum mechanics on a finite graph-resolved class of second-countable, T1, non-Hausdorff one-manifolds. The central problem is that local differential expressions do not by themselves determine the quantum theory: non-Hausdorff incidence, bundle transport, smooth extension, and analytic completion can impose additional global constraints on the operator domain. We formulate these constraints using transported jets, Whitney realisability, Sobolev traces, and formal return holonomy, obtaining exact closure results for finite smooth graph resolutions. At first Sobolev order, scalar dynamics reduce to a weighted quantum graph whose edge weights arise from a marked resolving presentation, leading naturally to weighted Kirchhoff Hamiltonians. Multiple-origin lines and circles, branching junctions, finite trees, and split-and-rejoin geometries then yield explicit deficiency indices, reflection and transmission laws, interference conditions, compact dark states, and embedded cavity modes. For finite-rank Hermitian bundles, unitary gluing selects a transmitting fixed subspace, so scattering becomes projection onto the invariant sector of the subgroup generated by the gluing matrices. Compact-group representations therefore turn non-Hausdorff incidence into an invariant-sector selection mechanism; connected compact semisimple groups require at most two relative gluing matrices for full invariant completion, with explicit SU(3) examples. The resulting theory separates topological non-Hausdorff data from the analytic and representation-theoretic structures that remain detectable by quantum dynamics.

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Quantum Physics

Closed-Form Expectation Values of the Damped Kerr Oscillator

Jacob Emerson

We derive a closed-form analytical expression for the expectation values of a damped Kerr nonlinear oscillator initialized in a coherent state. Starting from the exact Liouville-space solution of the Lindblad master equation, we specialize to coherent-state initial conditions, obtaining explicit time-dependent expressions for arbitrary normally ordered expectation values. The resulting expressions depend only on the system parameters and the initial coherent-state amplitude, requiring neither numerical integration nor evolution in a truncated Fock space. We verify the analytical expressions against master-equation simulations over a range of nonlinear interaction strengths. The closed-form solution provides an efficient alternative to numerical simulation while remaining free of Fock-space truncation error. Finally, we note an extension of the underlying Lie-algebraic structure that may provide a useful starting point for obtaining exact solutions to a broader class of open quantum optical systems.

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Quantum Physics

A Difference Operator Approach to Quantum Random Walks: Parseval Identity, Krawtchouk Matrices, and Hermite Limits

Chien-Wen Hwang

We introduce a discrete difference operator D_k to study the one-dimensional quantum random walk (QRW) with the Hadamard coin. Explicit combinatorial expressions are obtained for the probability amplitudes a(n,k) and b(n,k), which encode the final step direction and carry alternating signs that reflect the merging of leftward steps. Removing these signs and the coin-state distinction recovers the classical binomial distribution. The symmetric and antisymmetric combinations $a\pm b$ are shown to coincide with diagonal and sub-diagonal entries of the Krawtchouk matrix. Using cross identities among Krawtchouk matrix elements, we prove by induction that the amplitudes satisfy a Parseval identity sum (a^2+b^2)=2^n-1, establishing probability conservation in the Krawtchouk formulation. The operator D_k acts as a discrete Hermite polynomial generator: the ratios h_m = (n choose k)^{-1} D_k^m (n choose k) admit explicit closed forms and converge to Hermite polynomials in the continuous limit. At the discrete level, D_k connects successive Krawtchouk matrices and acts as a coherence generator and a raising operator. The h_m quantify the position-dependent degree of quantum interference on both halves of the distribution, either individually (for x >= 0) or through an inverse-Pascal combination of several h_m (for x < 0), and the ballistic O(n^2) scaling of the variance emerges from the superposition of all excited states. Numerical illustrations for n=6 and n=10 corroborate the analytical results.

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Quantum Physics

Can a quantum circuit detect the Unruh effect?

Pravin Kumar Dahal, Timothy C. Ralph, William J. Munro et al. (+2 more)

The Unruh effect predicts that an accelerating observer perceives the Minkowski vacuum as a thermal bath, yet direct detection remains experimentally inaccessible. Its timelike counterpart, arising from the entanglement of massless fields between the future and past light cones, offers a more feasible route but requires a detector whose transition frequency follows a specific conformal-time scaling. We propose and analyze a practical implementation of such a detector using superconducting fluxonium circuits, which naturally provide two quasi-degenerate ground states and a tunable excited state, forming an effective $\Lambda$-system. By modulating the excited-state transition frequency in Minkowski time, the detector accumulates a geometric phase associated with the timelike Unruh effect. Open-system simulations predict $\sim 10\%$ shift in the ground-state population within $530$ ns, representing a three-order-of-magnitude sensitivity enhancement over two-level Unruh-DeWitt detectors. These results establish a realistic quantum-circuit platform for experimentally probing the timelike Unruh effect and, more broadly, for testing fundamental nature of quantum fields using engineered quantum systems.

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All authors Pravin Kumar Dahal, Timothy C. Ralph, William J. Munro, Arkady Fedorov, James Q. Quach