Papers

Standard pre-geometric mechanisms reproduce the $\Lambda$CDM model but lack a natural source for inflation. We propose a mechanism for the emergence of scalar-coupled topological terms by extending the Lie algebra of a MacDowell-Mansouri model to a Lie algebroid. These terms are commonly regarded as a source for cosmological inflation in effective string actions. With an additional constraint on torsion imposed, the theory reduces to a scalar-tensor theory belonging to the Horndeski class, and reproduces inflationary dynamics that meet existing constraints (Planck/BICEP/Keck and GW170817).

Probabilistic seismic hazard and risk analyses are backbone to building codes, insurance pricing, and disaster management. Yet their open-engine pipelines remain accessible primarily to experts. We present the first agentic interface to the end-to-end probabilistic seismic hazard and risk chain via an open-source server, addressable through the Model Context Protocol (MCP). MCP wraps the OpenQuake engine and the 2020 European Seismic Hazard and Risk Models using twenty-four typed endpoints. Here, an agent is defined as a large language model (LLM) with tools. LLM is confined to the role of an orchestrator so it plans, translates, and explains, while the OpenQuake engine and custom codes compute hazard values, damage probability, and loss. Each response carries source-model, ground-motion model (GMM), and certified data provenance for transparency. Results are benchmarked against ESHM20 at seventy-three cities, the replicated 475-year spectral accelerations match official values within a median of 5 %, and a full hazard-to-loss estimate runs in minutes. The interface additionally accepts a user-supplied empirical or machine-learning GMM on any tectonic region type of the published tree, and adds additional features that existing web services omit: conditional spectra, deterministic scenarios, surface hazard, per-building loss, retrofit comparison, and record selection with waveform retrieval. The proposed design layers transfer to other regional models, and to other hazards.

Thunderstorm Ground Enhancements (TGEs) provide a direct particle-physics diagnostic of accelerating electric fields within thunderclouds. During 12 15 May 2026, Aragats detectors recorded a compact sequence of TGEs under closely related meteorological and electric field conditions. Ten statistically resolved TGEs were selected for quantitative analysis using STAND3 and SEVAN Light gamma and electron proxy channels. The events were classified into negative (N), transition/disturbed negative (TD N), and positive (P) states based on the stability of the near surface electric field (NSEF). The results show that TGEs occur during both comparatively stable and rapidly evolving charge states. Stable negative events correspond to sustained exposure of the Main Negative (MN) charge region, whereas positive and TD N events reflect Lower Positive Charge Region (LPCR) screening and rapid restructuring of the lower thundercloud dipole during End Of Storm Oscillation (EOSO) like evolution. The analysis demonstrates that the electron/gamma composition depends primarily on the persistence and geometry of the lower accelerating field structure rather than solely on the instantaneous sign or magnitude of the NSEF. Rapid electric field impulses, frequently associated with nearby lightning activity, mark active restructuring of the lower dipole and strongly influence electron transport to the detector level. All analyzed events occurred during persistent low cloud base conditions favorable for electron TGEs at Aragats.

Thunderstorm Ground Enhancements (TGEs) are known manifestations of relativistic runaway electron avalanches (RREAs) developing inside thunderclouds. However, the role of positrons in TGEs and their relationship to thundercloud charge structure remain poorly understood. We report time resolved observations of intense positron fluxes detected at the Aragats Observatory on 16 17 May 2026 during strong thunderstorms. Two of the three events were characterized by a positive near surface electric field (NSEF), graupel precipitation, a low cloud base, and low-to-moderate enhancement of gamma ray and electron fluxes measured by SEVAN and STAND3 detectors. The third event is a classical electron TGE considered for comparative purposes. All events show moderate to strong enhancement of the 511 keV annihilation line, along with enhanced radon progeny gamma ray lines. We observe a temporal separation between the electron and gamma ray TGE peak and the positron flux maximum. To explain these observations, we introduce a dual dipole electrodynamic model. The large scale electron dipole comprises the main negative thundercloud layer and its broad positive mirror charge induced at the Earths surface, producing ordinary TGEs. Simultaneously, a localized positron dipole forms from the LPCR, with its negative mirror charge directly beneath the LPCR footprint. This lower dipole accelerates positrons downward while decelerating electrons entering the same region. These results establish positron TGEs as a new subclass of atmospheric high energy phenomena and provide direct evidence of localized positron acceleration in the lower atmosphere.

We analyze electron rich Thunderstorm Ground Enhancements (TGEs) detected at Aragats using the SEVAN Light spectrometer, which can separate charged and neutral particles and reconstruct their energy spectra. The events exhibit large electron fluxes, with reconstructed energies extending to 45 MeV. Simultaneous meteorological observations reveal that all events occurred within a remarkably narrow atmospheric regime characterized by exceptionally low cloud-base heights, temperatures near 0{\deg}C, strong electric-field disturbances, and lightning. Comparisons with the complete Aragats TGE archive demonstrate that the direct detection of runaway electrons becomes possible only when the active acceleration region approaches within several tens of meters of detector altitude, allowing electrons to survive atmospheric attenuation. These results provide an experimental explanation for the century long rarity of observations of Wilsonian electrons. The findings establish the atmospheric conditions required for direct observation of runaway electrons and contribute to the understanding of particle acceleration in natural electric fields.

We investigate a fractional gravity model in which both the Hubble parameter and the gravitational constant evolve dynamically due to fractional renormalization-group effects. The model incorporates a scalar field coupled to a time-varying $G$, generating nonlocal corrections characteristic of fractional–action cosmology. Analytical and numerical solutions reveal oscillatory regimes, cyclic phases, and rapid variations with implications for BBN and early-universe evolution. A robust numerical framework is developed to integrate the regularized system and compare the resulting $H(z)$ evolution with observational data from the Hubble parameter, baryon acoustic oscillations, type Ia supernovae, gravitational lensing, and black hole shadows, thereby enabling a consistent reconstruction of cosmographic quantities. A Bayesian analysis shows that the Fractional model with $\mu=0$ is the only statistically viable variant. The inferred Hubble parameter is stable across models ($h\simeq 0.72$), while the fractional parameters are significantly better constrained in the $\mu=0$ case ($\alpha=1.20^{+0.25}_{-0.14}$, $\zeta=0.43^{+0.39}_{-0.29}$). The dynamical sector yields $m=30.8^{+28.0}_{-20.9}$ and $\Gamma=108.3\pm1.1$, leading to a positive discriminant and a well-determined relaxation timescale $\tau_{\rm rel}\simeq 9$ Gyr, confirming an overdamped regime. Although the $\mu=0$ model attains a slightly lower $\chi^2_{\min}$ than $\Lambda$CDM, the BIC strongly favors $\Lambda$CDM due to its smaller parameter space. Overall, the model reproduces late-time acceleration and mimics $\Lambda$CDM while introducing distinctive cosmographic signatures. The dynamical systems analysis clarifies the stability structure and parameter dependence, indicating that fractional nonlocal corrections may offer new pathways toward addressing the $H_0$ and $S_8$ tensions.

We investigate the constant-$\epsilon$ limit of a photon-sector modification derived from an early-time interaction between a scalar field and radiation. Starting from the underlying scalar–photon coupling, the parameter $\epsilon$ quantifies the departure of the photon energy density from the standard adiabatic scaling, leading in the constant-$\epsilon$ limit to $\rho_{\gamma}\propto a^{-4+\epsilon}$ and to the modified CMB temperature–redshift relation $T(z)=T_{0}(1+z)^{1-\epsilon/4}$. The standard photon sector is recovered for $\epsilon=0$. We implement the corresponding constant-$\epsilon$ background evolution in CLASS and verify that the numerical photon-density evolution reproduces the analytic scaling. We then examine the resulting changes in the recombination history, visibility function and CMB temperature-anisotropy spectrum. These CMB spectra are used only as diagnostic outputs since the coupled scalar–photon perturbation equations are not implemented self-consistently in the numerical calculation and a full CMB likelihood analysis is beyond the scope of the present work. As a preliminary statistical application, we interface the modified CLASS implementation with MontePython and analyze the Pantheon+SH0ES supernova likelihood together with BAO measurements. Within the adopted constant-$\epsilon$ framework, prior choices, data combination and fixed early Universe parameter setup, we obtain $\epsilon=0.0230\pm0.0065$. The posterior is therefore centered on a positive value within this restricted analysis. Because the BAO predictions depend on the model-dependent drag scale and several early-Universe quantities are held fixed, this result should be interpreted as a conditional and preliminary constraint rather than as a full CMB-level determination or evidence for a resolution of the Hubble tension.

Alzheimer's disease (AD) is characterized by the accumulation of Amyloid-$\beta$ ($A\beta$) plaques and hyperphosphorylated Tau proteins. However, many individuals exhibit substantial $A\beta$ and Tau pathology without developing dementia, suggesting that disease progression may depend not only on pathological burden but also on the spatial organization of these proteins. Motivated by this observation, we adapt Gray-Scott reaction-diffusion model to investigate pattern formation arising from the interactions between $A\beta$ and Tau. % To systematically identify stable spatial configurations, we employ a Companion-Based Multi-Level Finite Element Method (CBMFEM) on both two-dimensional domains and anatomically realistic cortical surface meshes. Numerical simulations reveal a rich landscape of multiple steady-state solutions, which are subsequently classified into representative pattern phenotypes using principal component analysis and clustering techniques. The results demonstrate that the coupled $A\beta$–Tau system admits numerous stable spatial patterns rather than a single pathological endpoint. % These findings provide a potential mathematical framework for understanding the heterogeneity of Alzheimer's disease and the existence of cognitively resilient individuals despite significant pathological burden. More broadly, the proposed framework suggests a pattern-based therapeutic paradigm in which disease dynamics are guided toward favorable stable states rather than solely targeting the elimination of pathological proteins.

The Tomimatsu–Sato (TS) family, characterized by the rotation parameter $q$ and the TS index $\delta=n,$ provides an important class of exact stationary axisymmetric vacuum solutions of Einstein's equations, whose integrable structure is known to be closely related to the $n$-point Toda molecule hierarchy through the Nakamura Conjecture. However, the set of equations appearing in the Nakamura Conjecture contains not only Hirota bilinear derivatives but also ordinary first-derivative terms, and therefore is not formulated entirely within the conventional bilinear algebra. In this paper we introduce a reduced trilinear formulation based on the reduced sector $(a,b,c)\rightarrow(a,b,1)$ of the $Z_3$-symmetric trilinear Hirota operators. We show that both the Hirota bilinear derivatives and the ordinary derivatives appearing in the Nakamura Conjecture can be rewritten completely within this reduced trilinear framework. Consequently, the set of equations admits a formulation in terms of reduced trilinear operators. We further show that the reduced trilinear formulation naturally inherits a Hirota-type direct method. The conventional bilinear spectral factor $k_i-k_j$ is replaced by the $Z_3$-weighted combinations $k_i+\omega k_j$ and $k_i+\omega^2k_j$, providing a direct-method structure characteristic of the reduced trilinear hierarchy. These results suggest that the Toda-molecule description of the Tomimatsu–Sato hierarchy may be viewed as a reduced sector of a broader trilinear framework, and provide a new perspective on the integrable structure of stationary axisymmetric gravity.

We investigate the interplay between thermodynamic phase transitions and the dynamical behavior of quasi-normal modes (QNMs) in weakly nonlinear charged anti-de Sitter black holes. In a non-extended phase space, we identify a reentrant large-small-large(intermediate) phase transition for these black holes. Employing the shooting method to solve the Klein-Gordon equation for a massless scalar field, we compute QNM frequencies across these phases, revealing distinct behaviors in different phases. Specifically, to our knowledge, this is the first report of utilizing QNMs as dynamical probes of thermodynamic phases during reentrant phase transitions including zeroth and first-order transitions. These findings establish QNMs as a powerful dynamical probe for thermodynamic phase transitions, providing new insights into the thermodynamic and dynamical properties of nonlinear charged black holes as well.

This work is a generalization of our previous study [arXiv:2406.17944], which dealt with the coherent and incoherent combination of linearly polarized Gaussian laser beams operating in continuous-wave mode under a $2\pi$ focusing configuration. In the present work, the laser beams are focused within a solid angle that can reach $4\pi$ by using two opposing source planes, where all the lasers from both planes are focused onto the same point in the focal plane. Our results show that the focal spot area obtained with either one or two source planes remains unchanged, despite the fact that, in the two-source-plane configuration, the numerical aperture (NA) of the system is twice that of the $2\pi$ focusing scheme. However, the intensity at the focal point is four times greater than that obtained with a single source plane. In addition, the longitudinal resolution is significantly improved, yielding a focal volume smaller than $0.5 \lambda^3$ for a numerical aperture of NA = 0.895. For incoherent beam combination, the focal volume remains practically the same in both the $2\pi$ and $4\pi$ focusing configurations, while the intensity at the focal point is twice that obtained in the $2\pi$ case. Furthermore, in the incoherent configuration, we observe a depth of focus reaching up to 30,000 $\lambda$ for a system with a low numerical aperture.

A deep defogging pipeline pretrained on controlled laboratory fog and fine-tuned with domain-randomized synthetic fog applied to clear outdoor scenes generalizes across a graded sequence of out-of-distribution settings with no target-domain training, from chamber-free free-flowing fog to iPhone video recorded through an aircraft cabin window in flight, an entirely unseen sensor, scene, and optical path. This directly addresses an open transfer limitation reported for real-world binocular defogging. Two design choices support the transfer. First, a single-camera fog imager photographs a flat-panel display through an artificial-fog enclosure with a fixed 114~mm scattering path, producing 5{,}495 pixel-aligned foggy/clear pairs. Exact registration permits a paired Laplacian ratio that predicts per-image restoration quality far better than single-image proxies (Spearman $\rho = 0.632$ versus $0.399$) and supports pixel-exact $L_1$ reconstruction training that avoids adversarial hallucination. Second, the fog-chamber checkpoint is fine-tuned on Mapillary Vistas crops overlaid with on-the-fly randomized synthetic fog spanning a broad range of strengths, spatial variations, airlights, and noise conditions. On a 552-image held-out split, a uniform comparison of 30 restoration backbones places NAFNet at the top (24.33~dB~/~0.7912~SSIM), with a compact alternative within 1.29~dB at 3% of the parameter count, and a ResNet-50 classifier confirms that the restoration preserves semantic content rather than only pixel-level structure. On unpaired aircraft-window video, NIQE decreases from a mean of 6.22 to 4.97 after fine-tuning, with temporally stable output across full-motion sequences. The same backbone, under paired supervision, also reaches 20.71~dB~/~0.683~SSIM on a non-overlapping O-HAZE/NH-HAZE split (a transferability check rather than a competitive ranking).

The carbonized papyri from Herculaneum preserve the only large-scale library to survive from classical antiquity, but many unopened rolls remain unread because physical opening risks irreversible damage. X-ray computed microtomography ($\mu$CT) and virtual unwrapping offer a non-invasive route to their texts, yet previous work on sealed Herculaneum scrolls has recovered only localized readings or limited surface regions. Here, using high-resolution phase-contrast $\mu$CT acquired on the BM18 beamline at the European Synchrotron Radiation Facility (ESRF), together with improved computational unrolling and machine learning, we achieve the complete virtual unwrapping and reading of PHerc. 1667 under explicit coverage and papyrological-review criteria. This makes PHerc. 1667 the first Herculaneum papyrus to be fully digitally unrolled and read for extended scholarly study without physical opening. In PHerc. Paris 4, the optimized scan protocol makes ink directly visible in the tomographic volume, allowing three-dimensional ink segmentation and independent validation of surface-conditioned ink recovery. In PHerc. 139, we recover title and author-attribution evidence identifying the scroll as Philodemus, On Gods, Book 8. These results move virtual unwrapping of the Herculaneum scrolls beyond isolated demonstrations towards a scalable framework for systematic recovery of the still-unopened library.

Although entangled state vectors cannot be fully described in terms of variables localized in space and time, any given entanglement experiment can be built from basic quantum circuit components with well-defined locations. We analyze such quantum circuits and present evidence that the local weak values comprise a covariant tensor associated with each individual qubit. Even if the state is massively entangled, these tensors do not evolve or collapse when other qubits are measured or pass through distant circuit elements. They can therefore be viewed from different reference frames without contradiction. Furthermore, their evolution through any circuit always obeys covariant dynamical rules. Weak values are subject to both past and future constraints, so the covariant quantities can only be determined by considering the entire circuit "all-at-once", as in action principles, incorporating the future measurement basis to avoid the standard no-go theorems. Because these results hold for a set of universal quantum gates, this work lends support to the claim that any quantum circuit can be assigned a realistic, lower-level description compatible with our understanding of classical spacetime.

Single mass-spring-damper models of vocal folds have been effective in simulating vocal fold vibrations without added complexity. However, single-degree-of-freedom models cannot sustain oscillation in the presence of structural damping unless source-tract interaction is considered. Moreover, existing lumped models struggle to accurately simulate vocal fold closure during phonation. This study aims to develop a reliable and simplified single-degree-of-freedom model of phonation that can simulate sustained oscillation in a damped system without incorporating a vocal tract model. Additionally, the proposed model maintains vocal fold closure in a manner consistent with the physics of phonation, addressing a longstanding challenge in existing lumped models. High-speed videoendoscopy (HSV) data from four normophonic subjects producing sustained vowel /i/ were used to extract glottal area waveforms (GAWs) via deep learning-based image segmentation for particle swarm optimization of the model parameters. An additional resistance force was incorporated to compensate for flow separation and generate the force imbalance required for sustained oscillation. An external structural force was also added during closure to sustain the closed phase. The 4th-order Runge-Kutta method was used to solve the governing equations with enhanced numerical stability and accuracy. The model parameters were optimized for individual subjects, resulting in normalized errors below 3% between experimental and simulated GAWs. The proposed model accurately reproduced subject-specific vocal fold vibrations and vocal fold closure in agreement with experimental data. Overall, the proposed model provides a computationally efficient framework for simulating sustained phonation without requiring complex source-tract coupling while capturing the key biomechanical and aerodynamic mechanisms of phonation.

Grain boundary sliding models of superplastic flow take the elementary event to be the shear of an oblate-spheroidal unit embedded in a solid matrix, whose rate follows transition state theory. The mechanics of this unit, and the assumptions linking it to dislocations and macroscopic flow, have not been stated explicitly. Here the unit is analysed as an Eshelby inclusion, a continuum, mathematical treatment without using physical concepts. The analysis gives closed-form shear and volumetric energy coefficients ($0.4456$ and $0.8889$ for aspect ratio $1/2$ and Poisson ratio $1/3$) and shows that the shear stress of the unit is a force dipole, decaying as $r^{-3}$ and changing sign with direction, unlike a dislocation. The inputs, assumptions and proposals needed to connect this unit of shear to dislocation theory and superplastic flow are then stated and classed as experimentally validated, physically realistic or fitting constants. Under three such proposals, a row of about four units acquires the Peierls-Nabarro profile of a full dislocation, and two to three units that of a Shockley partial; the Peierls and Frank-Read stresses and the stacking-fault energy then follow from experimental inputs. With the unit energy as the free energy of activation and strains fitted to superplastic data, the flow law reproduces all 52 measured strain rates of a Cu alloy within an order of magnitude. Molecular-dynamics calculations for Cu outline the extension to dislocation emission, mesoscopic grain boundary sliding and the inverse Hall-Petch effect. This gives phenomenological models of superplastic flow a mechanical basis.

Dislocation loops are the elementary product of radiation damage in crystals, limiting reactor-component lifetimes, power-electronics reliability and the coherence of solid-state qubits. Their nucleation has been simulated for six decades but never reduced to a thermodynamic law. We show that dislocation-loop formation is a first-order phase transition, and construct its Ginzburg–Landau free energy, with the loop area as order parameter, entirely from atomistic simulation. In diamond, carbon self-interstitials condense into planar precursors that collapse abruptly into a prismatic $\tfrac{1}{2}\langle110\rangle$ loop across a 3.7-electronvolt barrier, with pressure–volume work supplying only 2% of the energy released. The reduced free energy proves material-independent: the vacancy platelet-to-loop collapse in body-centred-cubic iron falls on the same one-parameter family, placing loop nucleation on a transferable thermodynamic footing.

Shearing a packing of solid granular grains can be difficult, especially when the solid fraction is high and the boundary confinement is strong. It was recently shown that embedding voids in grains can make a packing easier to shear when such voids make the grains auxetic. Here, we use finite element simulation to show that auxeticity is not a necessary condition even in a seemingly very constrained setting: shearing dense and ordered granular packings under a constant solid fraction. More specifically, by controlling the geometry of a void embedded in a grain, we induce an apparent elastic anisotropy and softening of the grain under shear, which collectively leads to a significant reduction – up to 90% – of the apparent shear modulus of a packing of these grains. Complementary analysis shows that this reduction correlates well with a decrease in contact-force anisotropy, and is insensitive to system size and contact friction variation. Our results highlight how grain-scale geometry, mediated by multi-body contact mechanics, modulates macroscopic system-scale elasticity, providing a minimal design mechanism towards targeted collective mechanical properties of soft granular metamaterials.

We present a novel unified conditional-probability framework for relativistic systems in which conditioning on additive conservation laws simultaneously yields equilibrium occupation statistics and conservation-induced correlations. In this formulation, equilibrium arises as a conditional limit law of a closed system. The one-mode marginal gives Maxwell–Boltzmann, Bose–Einstein, and Fermi–Dirac statistics at leading saddle order, with the conserved quantities fixing the exponential tilt and the microscopic occupation measure determining the statistics. Expanding the two-mode marginal to Gaussian order gives the leading finite-rank covariance between modes induced by exact conservation. When contracted with observables linear in mode occupations, this covariance gives their leading exact-conservation contribution. We use this structure to define projected observables orthogonal to selected conserved quantities. By construction, their covariance has no leading exact-conservation contribution. In small collision systems, where conservation effects are less suppressed by multiplicity and can survive standard nonflow suppressions, this provides a direct way to isolate conservation-aligned contributions to long-range correlations. We demonstrate this with PYTHIA8/Angantyr-generated p+Pb events at $\sqrt{s_{\mathrm{NN}}}=5.02~\mathrm{TeV}$ by comparing ordinary and projected covariances, showing that the projection removes the conservation-aligned contribution while leaving the conservation-orthogonal covariance essentially unchanged.

The kagome metal ScV$_6$Sn$_6$ has attracted attention as a platform for exploring the interplay between charge density wave (CDW) order and symmetry-breaking phenomena, including a recently reported intermediate phase and a low-field Hall anomaly that has been attributed to an anomalous Hall effect (AHE). The interpretation of both observations has been limited by the modest sample quality achieved by previous growth procedures, which produced crystals with in-plane residual resistivity ratios (RRR) of at most $\approx$9. Here, we report a simple modification of the flux growth procedure that yields ScV$_6$Sn$_6$ single crystals with RRR exceeding 50, more than five times the previous highest reported value, and use this expanded mobility range to revisit both the symmetry and the magnetotransport of the CDW phase. We resolve a sequence of closely spaced transitions in the immediate vicinity of $T_{CDW}$ that emerges above a sharp threshold of RRR $\approx 4$, and demonstrate through elastoresistivity that the intermediate phase breaks the three-fold rotational symmetry of the parent lattice. We examine the Hall response from both the parent samples across the full RRR range as well as Cr-doped samples, and conclude it is quantitatively inconsistent with an intrinsic AHE and is instead explained by ordinary multi-band transport involving small, high-mobility pockets identified through quantum oscillations. These results refine the symmetry-breaking landscape of ScV$_6$Sn$_6$ and establish systematic mobility tuning as a diagnostic for disentangling an intrinsic AHE from multi-band Hall contributions in kagome CDW systems.

Extracting interpretable, localized physical mechanisms from complex spatiotemporal data is a foundational challenge across physics, biology, and engineering, but has remained out of reach on real measurements. The central obstacle is obtaining high-quality gradients of data via numerical differentiation, which amplifies noise, diverges for high-order equations, and falters on irregular geometries, limiting the scope of existing approaches to clean simulations of low-order systems. Here, we present weak dominant balance, a derivative-free framework that projects governing equations into a weak (integral) formulation, offloading differentiation onto smooth analytical test functions and leaving the data untouched. The method sustains accurate regime identification under severe noise where existing approaches categorically fail, delivers the first data-driven decomposition of a third-order partial differential equation applied to turbulent duct flow, and produces matching decompositions across direct numerical simulation and particle-image velocimetry measurements of a wavy channel flow, uncovering a previously uncharacterized dynamical regime. Weak dominant balance brings mechanism-level analysis out of simulation and onto measured data, and opens complex physical systems to direct, equation-grounded interpretation.

Quantum evolution is generally expected to drive a quantum many-body system toward equilibrium. This expectation is often justified by the Hilbert-space ergodicity of generic quantum dynamics, namely, the idea that pure-state evolution explores Hilbert space uniformly up to physical constraints. Such a statement can be made rigorous by requiring the associated state ensemble to form the Haar-random ensemble, or its more structured generalization, the Scrooge ensemble. In this Letter, we report the emergence of exact Hilbert-space ergodicity in a continuously monitored quantum many-body system. For any target density matrix $\sigma$, we construct a continuously monitored system for which we rigorously prove that the Scrooge ensemble of $\sigma$ is the unique late-time equilibrium distribution of quantum trajectories. Remarkably, this requires only that the jump operators in the monitoring form a deformed unitary 1-design, a seemingly much weaker condition than full ergodicity. We numerically demonstrate our predictions by simulating continuously monitored systems whose equilibrium states are thermal states. Our results establish a rigorous mechanism for the emergence of Hilbert-space ergodicity and provide a practical route for its investigation on quantum devices.

ESA's LISA mission will open a new window onto the gravitational-wave sky by detecting signals from a wide variety of sources in the millihertz frequency band. Among these, galactic binaries are expected to be the most numerous sources observable by LISA. Their analysis and parameter estimation represent a significant challenge, as the signals are expected to strongly overlap in both the time and frequency domains. Conventional Bayesian inference approaches, such as Markov Chain Monte Carlo sampling, are difficult to scale to this setting due to the high dimensionality of the problem and the complicated likelihood landscape which can hinder convergence. In this work, we explore simulation-based inference as a means to perform efficient parameter estimation for single galactic binaries, with a potential extension to the analysis of multiple overlapping sources. Our approach relies on a conditional normalizing flow acting as a neural posterior estimator. The model is trained using samples generated according to a dedicated simulation framework that does not require any likelihood computation. Once trained, the neural posterior estimator enables the generation of thousands of posterior samples per second, again without explicit likelihood evaluation. We first present results for a single source in a narrow frequency band, and then extend the analysis to wider frequency ranges. As a proof of concept, we further investigate the more challenging case of two overlapping sources. These results demonstrate the potential of likelihood-free inference as a scalable alternative to conventional Markov chain Monte Carlo sampling for the analysis of LISA galactic binaries.

We present a theoretical study of the evolution of polarization entanglement and quantum coherence in 511 keV photon pairs produced by para-positronium decay during successive Compton scattering events. We start with a maximally entangled Bell state and employ the generalized Stokes-Mueller formalism to derive the two-photon density matrix following single-, double-, and triple-Compton scattering, explicitly considering both polar and azimuthal scattering geometries. Using this framework, we quantify the degradation of quantum correlations through concurrence (as a measure of entanglement) and the $l_1$-norm (as a measure of coherence). Our results demonstrate that entanglement is highly sensitive to the scattering geometry and disappears near right-angle scattering, while quantum coherence remains finite even in regimes where entanglement vanishes completely. These findings provide a unified description of polarization-dependent decoherence in annihilation photon pairs and clarify the distinct roles of entanglement and coherence in realistic two-photon interactions. These results are relevant for quantum-enhanced positron emission tomography and highlight the persistence of quantum resources in scattering-dominated media.

We study the transport of light through dense opaque anisotropic metamaterials consisting of oriented nanowires. The nanowires consist of polymer photoresist that is structured by direct laser writing (DLW) with two-photon induced polymerization, with radii between $a = 0.5$ and $1~\mu \text{m}$. Our flat samples have a thickness up to 9 layers, from $L = 3~\mu \text{m}$ to $20~\mu \text{m}$. Within each layer, the nanowires are parallel and spaced with random nearest-neighbor distances; nanowires in adjacent layers are perpendicular. The diffuse optical transmission at $\lambda = 633~$nm is as low as $T = 12 \%$, typical of optically dense, multiple scattering metamaterials, with a mean free path down to $\ell = 1.1~\mu \text{m}$, much less than the sample thickness. It is striking that the linear polarization of the input light is maintained at the output of the dense nanowire samples, and not scrambled as in dense nanosphere arrays. Moreover, the linear output polarization faithfully tracks the input polarization. We propose that the polarization is maintained in our optically thick samples, since light is predominantly transported perpendicularly to the nanowire layers. The polarization vector then lies in the nanowire plane, consisting of a linear combination of parallel and perpendicular vectors that are both conserved upon subsequent scattering. Hence, the polarization remains independent of nanowire orientation, even after multiple scattering events. We propose that anisotropic scattering samples may find practical uses in white LEDs and its applications in lighting luminaires, optical communication, and encryption systems.

We model Herman Kahn's escalation ladder as an impartial combinatorial game. Reindexing each rung by its distance to the nuclear threshold turns the ladder into a subtraction game, the most tractable class in combinatorial game theory, and the doctrinal fact that no side wishes to fire first selects the misere convention. We prove that single-ladder stability is governed by a congruence (Theorem 4.1) and derive a ladder-design corollary that makes the burden of first escalation a function of ladder length and escalation granularity (Corollary 4.2). For simultaneous theaters we show, under normal play, that joint stability is the Nim-sum of the theater-wise escalation distances (Theorem 5.2), a condition that is neither additive nor dominated by the most dangerous theater. We then show the Nim-sum reduction fails under misere play, introduce the misere quotient as its replacement, and prove by exhaustive backward induction that for two-step escalation the quotient is the order-six monoid with generators a, b satisfying a^2=1 and b^3=b, with loss set {a,b^2} (Theorem 6.3). To our knowledge, impartial combinatorial game theory has not previously been applied to nuclear escalation ladders; the existing game-theoretic literature on escalation is classical and payoff-based.

Applications of the proposed primitive: Quantum Primitive for Output-Hiding Function Sharing are discussed for environments in which the parties may have strategic considerations over the generated function value, and therefore may not be mutually trusted. We show that in environments in which the measurement may not be reliably controlled by either party, the primitive permits the parties to generate private, unbiased coins.

Thin carbon-strip targets provide fast relative hadron beam polarimetry, but their response in intense relativistic bunched beams is not governed by local stopping-power heating alone. We develop a coupled response model that combines beam-target overlap, secondary-electron escape, retained heat, target motion, transient heat transport, RF-induced strip-end heating, beam-induced forces, resistance changes, and slack-strip deformation. RHIC target observations constrain the relevant motion, force, and nonlocal-heating scales and show that target survival depends on both beam-center heating and electromagnetic boundary conditions near the strip ends. Applying the model to Booster, AGS, RHIC, and EIC proton and $^{3}\mathrm{He}$ cases shows that the RHIC proton lifetime scale is reproduced at the order-of-magnitude level, while the RHIC target-holder fin results require the additional RF/end-heating mechanism. For EIC proton flattop operation, carbon-strip polarimetry may remain viable only with reduced dwell time, sufficient detector acceptance, and suppression of RF-induced end heating. For cooled-emittance $^{3}\mathrm{He}$, the calculated sublimation-loss scale is far beyond a straightforward RHIC-like carbon-strip extrapolation. Conventional carbon strips are therefore unlikely to remain viable for the most demanding EIC light-ion cases without major changes in target motion, target technology, or diagnostic concept.

Numerical simulation of quantum computing hardware and open quantum systems governed by the Lindblad equation is challenging due to the high dimensionality of the density matrix and the need to preserve fundamental physical properties. In our previous work, we developed an arbitrary-order, low-rank, completely positive and trace preserving (CPTP) method for the Lindblad equation with time-dependent Hamiltonians by nested Picard iteration (NPI). In this work, we develop Gregory NPI schemes, which are CPTP schemes constructed by Gregory-type quadrature on equispaced nodes. The methods, which are of order up to nine, substantially reduce the computational cost compared to our previously proposed NPI schemes with Gaussian quadrature rules, while retaining high-order accuracy and structure preservation. We analyze the stability of the resulting scheme for a physics-based test equation. Numerical experiments verify the convergence of the method and demonstrate the effectiveness of the low-rank approximation. We study the performance of a previously constructed CNOT gate for both closed and open quantum systems.

The astrometric measurements provided by the Gaia space mission represent a key advancement in the search and characterization of exoplanets, helping in particular to solve the mass degeneracy intrinsic to the radial velocity (RV) method. The fact that a fraction of astrophysical false positives contaminates the current catalog of astrometric candidate solutions requires an RV follow-up to validate and confirm such candidates. Within the GAPS programme, we have observed a selected sample of 14 stars having Gaia astrometric solutions compatible with the presence of a substellar companion. The immediate aim of this survey is to identify astrophysical false positives and provide the first RV validation and confirmation of the remaining candidates. We analysed data collected with the HARPS-N spectrograph to identify stellar binary systems from the spectral cross-correlation function profiles. The remaining astrometric candidates were characterized via Markov chain Monte Carlo analysis searching for the best-fit RV solution. Among the stars in our sample with astrometric candidate solutions, we identify 6 as originating from close binary companions mimicking the astrometric motion of distant substellar companions, from which we can estimate an updated value of $43_{-11}^{+13}\%$ for the binary contamination fraction in the Gaia DR3 catalog of astrometric candidates. We validate and confirm the remaining 8 solutions, corresponding to giant and brown dwarf companions with minimum masses between 8 and 62 $M_{\rm Jup}$ and semimajor axes between 0.76 and 1.42 au, providing the first RV characterization for 6 of these candidates and updated orbital solutions for 2 previously confirmed ones.