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Physics

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Wednesday 23 September

Optics

A native signed incoherent photonic matrix core on thin-film lithium niobate supporting in situ backpropagation

Yuan Ren, Yong Zheng, Ruixue Liu et al. (+2 more)

Artificial intelligence workloads increasingly demand computing architectures combining high throughput, energy efficiency, and physical scalability. Here we present a signed incoherent optical matrix multiplier on thin-film lithium niobate that natively supports signed inputs and weights. We demonstrate closed-loop in situ backpropagation on a 16 X 16 photonic core, including forward computation, nonlinear operations, error propagation, and gradient computation. Measured physical outputs directly participate in optimization, thereby incorporating actual device responses and nonidealities into training. The core achieves 8-bit multiplication and 10-bit accumulation precision across 256 channels, maintains 10-bit accuracy in tiled 256 X 256 matrix computation, and further executes Transformer linear operations in a BERT-mini workload. This work presents a fundamental, scalable building block that addresses key limitations in practical optical computing, thereby opening avenues for large-scale, high-efficiency photonic neuromorphic systems.
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All authors Yuan Ren, Yong Zheng, Ruixue Liu, Min Wang, Ya Cheng

Statistical Mechanics

Multiscale Entropies as Order Parameters for Nonequilibrium Phase Transitions

Gerhard Jung and Misaki Ozawa

We develop a multiscale entropy framework based on the wavelet conditional renormalization group that decomposes the total Shannon entropy into contributions from different spatial scales. Generative modeling enables accurate estimation of these entropies from configurations or snapshots, even in nonequilibrium systems whose underlying probability distributions are unknown. Applications to the equilibrium $\varphi^4$ model and nonequilibrium active Model B+ show that multiscale entropies reveal criticality and spatial organization obscured in the total entropy. These entropies serve as scale-dependent order parameters for characterizing phase transitions and pattern formation.
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Quantum Physics

The winner's curse in hardware VQE: drift-differenced remeasurement of finite-shot selection bias

Julen Larrucea

Finite-shot optimization can make noisy variational quantum eigensolver energies look artificially accurate. We studied six hardware-tractable molecular active spaces on two IBM Heron r3 processors. Seven optimizer-selected values fell below the exact active-space eigenvalue by up to 17.36 mHa. The cell-balanced fraction of the source-observed best-final advantage not retained on later fixed-parameter measurement was 0.989 (approximate 95% session-level interval [0.906, 1.072]); alternative aggregations span 0.892-0.989. Thus little of the selected advantage remained on average. Measurements occurred 5.6-38.4 days later, so parameter-dependent drift remains a competing explanation. Best-observed hardware VQE values require prompt independent confirmation before supporting accuracy claims.
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High Energy Physics (Phenomenology)

Response of Hellinger-distance based coherence to weak decoherence in two-flavor neutrino oscillations

Saurabh Rai, Nilakshi Das and Tejhas Kapoor

We evaluate the Hellinger-distance coherence of the two-flavor neutrino state subject to Lindblad damping of the mass-eigenstate interference term, and obtain a closed expression in terms of the flavor-basis density-matrix elements. In the two-flavor vacuum treatment with negligible wave-packet separation, the undamped state is pure, and the smallest eigenvalue of the damped state grows linearly with $\epsilon=1-\kappa$, where $\kappa=e^{-\Gamma L}$. An expansion about the pure state then yields a nonanalytic $\sqrt{\epsilon}$ correction to the Hellinger coherence, with coefficient $K=2\sqrt{2}\,u\sin2\theta/\sqrt{1-2u}$, whereas the flavor-transition probability, the $l_1$ coherence, the concurrence, the entanglement of formation and the local quantum Fisher information all respond linearly in $\epsilon$. Using representative Daya Bay, KamLAND and MINOS working points together with a current $90\%$ C.L. bound on energy-independent damping, we find fractional changes in the Hellinger coherence of $0.18\%$, $9.40\%$ and $21.51\%$, against $0.0009\%$, $0.43\%$ and $1.81\%$ for the concurrence. The comparison concerns the response of the quantifiers to the damping parameter and carries no implication about experimental resolution. The same mechanism operates, with a different coefficient, for a correlated dephasing channel acting on the flavor coherence, where the non-Markovian regime produces damped revivals.
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General Relativity and Quantum Cosmology

A nonlinear Newtonian approximation to General Relativity

Oliver F. Piattella

We investigate a nonrelativistic approximation to general relativity that does not require the metric coefficients to be weak perturbations of the Minkowski metric. Instead, we assume a differential hierarchy in which the contributions to the curvature containing second derivatives of the metric dominate over those quadratic in its first derivatives, while the metric-dependent coefficients multiplying the retained terms are kept fully nonlinear. Since this separation is not covariant, we formulate the approximation in harmonic coordinates, where it corresponds to retaining the principal part of the reduced Einstein equations. We show that the truncated Einstein tensor satisfies the contracted Bianchi identities up to the order neglected in the derivative hierarchy, ensuring compatibility with energy–momentum conservation at the retained order. The standard Newtonian equations are recovered in the weak-field regime, whereas outside it the dynamics retains a nonlinear dependence on the lapse and spatial metric. In particular, null geodesics probe the spatial geometry at leading order, suggesting gravitational lensing as a natural setting in which observable departures from the standard weak-field description may arise. We illustrate the construction with a static spatially isotropic configuration and discuss the scope and limitations of the approximation.
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High Energy Physics (Phenomenology)

Sensitivity to Higgs Pseudo-Observables in ZH Production at NLO QCD

Makhlouf Chennit and Abdelkader Mohamed-Meziani

We study the sensitivity of the associated Higgs production process $pp \rightarrow ZH$ to anomalous Higgs couplings within the Effective Field Theory framework. Event samples are generated using $ \text{MadGraph5\_aMC@NLO}$ at $\sqrt{s}=13$ TeV using the UFO model HPO\_ewk\_prod\_NLO, and analyzed using a dedicated Python analysis of HepMC events. We investigate several kinematic observables and derive constraints on the EFT parameter $\epsilon_{ZZ}$ using a $\chi^2$ statistical analysis. A 95% confidence level interval $-0.026 < \epsilon_{ZZ} < 0.383 $ is obtained from the simulated data.
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Instrumentation and Methods for Astrophysics

A ready-to-deploy MLOps software platform for satellite and NEO detection at meter-class ground-based observatories

Rafael Carrillo Navarro, Pablo García-Martín, René Duffard et al. (+2 more)

Ground-based astronomical observations frequently contain streaks produced by artificial satellites, space debris, and potentially Near-Earth Objects (NEOs). While machine-learning models can reliably detect these features, their practical adoption in observatory operations is often limited by the lack of integrated tools for visual inspection, validation, workflow management, and structured data storage. This paper presents the StreakMind Workbench, a framework that applies MLOps practices to bridge research-oriented machine-learning pipelines with routine observatory operations. Rather than introducing new detection algorithms, the Workbench addresses a software-engineering challenge in astronomical computing: maintaining a single authoritative source of scientific processing code while providing astronomers with an operational environment for workflow execution and result inspection. Integrated with the reference StreakMind AI model of Carrillo et al. (2026) and implemented in Python using PyQt5, the Workbench supports the complete workflow from FITS ingestion to database storage, including inference, result inspection, database exploration, training management, and Minor Planet Center formatted observations. Validation on 273 images from La Sagra Observatory demonstrates successful end-to-end workflows while maintaining consistency with the underlying StreakMind scientific code. The platform facilitates operational use of a research ML pipeline in meter-class observatories and moderate-scale campaigns, supporting Space Situational Awareness and planetary defence.
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All authors Rafael Carrillo Navarro, Pablo García-Martín, René Duffard, Juan Luis Orellana Montes de Oca, Oscar Ortega Ríos

Materials Science

Direct observation of the electronic structure of even-layer puckered SnTe monolayer films on graphene

Satoru Ichinokura, Shunsuke Tsuda, Kiyohisa Tanaka et al. (+1 more)

We report a direct observation of the electronic structure of monolayer SnTe on graphene by angle-resolved photoemission spectroscopy. By combining low-energy electron diffraction, momentum microscopy, core-level spectroscopy, and first-principles calculations, we show that the observed monolayer-limit electronic structure is consistent with a puckered even-layer biatomic-layer building block rather than a nonpuckered square-flat structure. The observed band dispersion and its polarization dependence are reproduced by a puckered structure with a substrate-renormalized buckling amplitude. We further show that graphene actively interacts with ultrathin SnTe by selecting its in-plane orientational texture, renormalizing the buckling amplitude, and modifying the local interfacial electrostatic environment in the monolayer limit. In comparison, multilayer SnTe exhibits a more ringlike momentum-space distribution, interlayer-split valence bands, and a stronger p-type character, revealing the onset of thickness evolution from an interface-stabilized puckered ultrathin limit toward a more bulklike state.
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All authors Satoru Ichinokura, Shunsuke Tsuda, Kiyohisa Tanaka, Koichiro Yaji

High Energy Physics (Phenomenology)

CP asymmetry and visible decay in $3+1$ neutrino oscillations on a quantum computer

Amartya Sengupta, Sidhartha Samtani, Ani Girgvliani et al. (+1 more)

We use quantum simulation to study how visible neutrino decay modifies the vacuum CP asymmetry in muon-to-electron oscillations within a $3+1$ neutrino scenario. The decay channel preserves CP symmetry, with CP violation arising from phases in the mixing matrix. We track the energy redistribution from visible decay and distinguish how parent attenuation and daughter regeneration modify the CP asymmetry. For the reference benchmark, the regenerated contribution is $4.85\times10^{-4}$, approximately $46\%$ of the total decay-induced shift. The full circuit for an effective two-energy model agrees with independent classical evolution. On an IBM quantum processor, we prepare the daughter state conditioned on decay and restore its physical normalization using fixed source and decay probabilities. After correction for measurement errors, the flavor-probability and coherence measurements both agree with the prediction within one standard error. Null controls test the suppression of the regenerated signal when daughter coherence or the relevant CP-sensitive mixing factor vanishes.
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All authors Amartya Sengupta, Sidhartha Samtani, Ani Girgvliani, Dejan Stojkovic

High Energy Astrophysical Phenomena

Energy estimation of direct and reflected cosmic-ray events aboard balloon-borne radio detectors

Sergio Cabana-Freire, Jaime Alvarez-Muñiz and Matias Tueros

Balloon-borne radio detectors offer a highly effective approach to monitoring immense volumes of the Earth's atmosphere and ice for ultra-high-energy cosmic rays and neutrinos. Because these payloads measure radio emission from a single, highly elevated vantage point, reconstructing the air-shower energy using traditional methods is not possible. In this work, we present a comprehensive, simulation-based energy reconstruction framework tailored to the unique cosmic-ray event geometries observed by balloon payloads. For the first time, we adapt and apply this methodology to direct atmosphere-skimming cosmic-ray showers, accounting for their highly asymmetric development in rarefied air. Furthermore, we provide a major update to the energy reconstruction of reflected downward-going showers by incorporating spherical reflection and ray de-focusing mechanics directly into simulations. We rigorously validate the method across different event geometries, demonstrating a baseline energy resolution of $8-11\%$. Finally, we quantify the systematic effects of finite detector pointing resolution, unknown primary mass composition, and signal-to-noise ratio, establishing a robust framework for the analysis of cosmic-ray events in next-generation balloon missions such as PUEO and POEMMA-Balloon with Radio.
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Pattern Formation and Solitons

Multiprecision computation of bright and dark solitons in the discrete nonlinear Schrödinger equation

Rudy Kusdiantara, Farrell T. Adriano and Hadi Susanto

We study the spectral stability of bright and dark solitons in the discrete nonlinear Schrödinger (DNLS) equation using multiprecision arithmetic. The eigenvalues governing stability are exponentially small in the lattice spacing and cannot be resolved with standard double precision. To address this, we develop a computational framework combining multiprecision arithmetic, an exact Jacobian for the stationary problem, and a squared-operator formulation for spectral analysis. This enables accurate resolution of exponentially small eigenvalues and direct comparison with exponential-asymptotic predictions. Our results show that onsite bright solitons are spectrally stable, whereas intersite bright solitons and both onsite and intersite dark solitons are unstable. Bright solitons require only a few eigenvalues and allow efficient large-scale computations, while dark solitons demand higher precision due to their proximity to the continuous spectrum. Simulations up to \(N=65{,}250\) grid points (31.7 GB RAM) highlight the necessity of multiprecision arithmetic for capturing beyond-all-orders spectral effects.
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Quantum Physics

Geometric perspective on quantum Rabi model: Super adiabatic universality and curvature non-adiabatic effects

Zu-Jian Ying

Quantum Rabi model (QRM) is a fundamental model in light-matter interactions (LMIs), whereas this finite-component system manifests infinite physics to be explored and a full understanding has not yet been reached after a hundred years since it was proposed. In the present work we create a geometric perspective for the QRM by mapping to a curved nanowire system, with curvature-induced spin-orbit coupling (SOC) manipulatable by LMI strength and frequency ratio, which is capable of revealing and perceiving the property universality and diversity from the ground state to the whole spectrum in a unified picture. Indeed, we unveil a super university in the adiabatic regime which manifests a universal scaling of spin texture ubiquitously valid for different couplings, different frequencies and different energy levels. The curve frame also facilitates our finding that a direction changeover of tangential spin swing emerges in the non-adiabatic spin texture in association with the quantum phase transition (QPT) in the QRM, which endows a geometric non-adiabaticity interpretation and connotation to the QPT. We also clarify that, among the curvature-induced effects, the SOC accounts for the spectral bifurcation and oscillations. Our method and analysis, readily generalized to other light-matter models, opens a dialogue between geometry and physics, thus paving a novel way to gain deeper insight into LMIs.
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Optics

Shift-register synchronization of dual-wavelength pulse trains in resonators with quadratic nonlinearity

Stepan Bogdanov, Anastasiya Bednyakova and Sergei K. Turitsyn

Self-organization of nonlinear waves underpins phenomena ranging from hydrodynamic pattern formation to optical frequency-comb generation. We introduce and numerically demonstrate a shift-register synchronization mechanism for pulse trains in quadratic nonlinear resonators. The synchronized state persists despite substantial group-velocity mismatch through continuous parametric energy exchange, resulting in deterministic discrete pulse shifts after each cavity round trip. Nonlinear parametric interaction modifies the effective walk-off, allowing the pulse trains to satisfy the shift-register synchronization conditions. The proposed mechanism reveals a previously unexplored synchronization regime in quadratic resonators and provides a route toward multicolour frequency combs, optical memories, and ultrafast photonic information processing.
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High Energy Astrophysical Phenomena

A magnetar-powered jet-wind outflow in gamma-ray burst-associated supernovae: Application to the thermal components of GRB 060218-SN 2006aj

Yun-Peng Li and Da-Bin Lin

A rapidly rotating magnetar formed in the collapse of a massive star may release its spin-down power through both a collimated polar jet and a quasi-isotropic magnetar wind. With its long-lasting soft X-ray blackbody component and the double-peaked UV/optical light curves of SN 2006aj, GRB 060218-SN 2006aj provides a useful test case for such a two-component energy-injection scenario. We developed a magnetar-powered jet-wind model in which the two outflows interact with homologously expanding SN ejecta, driving forward shocks that produce shock-breakout emission and subsequent magnetar-powered thermal emission. We first used the jet component to fit the 0.3-10 keV blackbody flux and temperature evolution of GRB 060218 and subsequently added the wind component to model the UV/optical light curves of SN 2006aj. We find that the soft X-ray blackbody component can be reproduced mainly by shock-breakout emission from the polar ejecta driven by the jet. The double-peaked UV/optical light curves are instead produced by the interaction between the quasi-isotropic magnetar wind and a more massive ejecta component. The first optical peak is dominated by wind-driven shock-breakout emission, whereas the broader and later emission is powered mainly by the subsequent magnetar-powered thermal component. Our results suggest a two-component magnetar-engine picture for GRB 060218-SN 2006aj, in which the X-ray thermal emission and the UV/optical double-peaked evolution arise from different energy-injection channels of the same central engine.
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Mesoscale and Nanoscale Physics

Charge and spin qubits in interacting quantum dots coupled to Rashba-active leads

Grazia Di Bello, Fabrizio Pavan, Mattia Trama et al. (+3 more)

We present a unified study of charge and spin qubits encoded in a single interacting quantum dot tunnel-coupled to Rashba fermionic leads. The dot is described by an Anderson impurity Hamiltonian with either repulsive or attractive local interactions and a magnetic field of arbitrary orientation. In the repulsive regime, a spin qubit is encoded in the singly occupied spin sector, whereas in the attractive regime, close to the degeneracy between the empty and doubly occupied configurations, these two states define a charge-qubit subspace. We combine a weak-coupling Lindblad master equation in the Markovian secular limit with numerically controlled matrix-product-state simulations of the full dot-reservoir system. In equilibrium, we identify magnetic pair breaking in the attractive regime and a weak Rashba-induced magnetic anisotropy when the magnetic field is rotated relative to the spin-orbit axis. In the dynamical regime, relaxation and decoherence are controlled by the energetic gap between the logical manifold and nearby leakage states, and are further enhanced by Rashba-dependent tunneling. These findings show that even a minimal Anderson-impurity description captures key ingredients for coherent spin and charge qubits: the energetic structure of leakage states and spin-orbit-dependent dot-lead hybridization.
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All authors Grazia Di Bello, Fabrizio Pavan, Mattia Trama, Roberta Citro, Giulio De Filippis, Carmine Antonio Perroni

Mathematical Physics · Cross-listed from math.AP

Homogenization at a polynomial scale in high contrast

Scott Armstrong, Tuomo Kuusi and Amélie Loher

We prove an upper bound on the homogenization length scale which is a fixed power of the coarse ellipticity ratio for coefficient fields that satisfy a finite range of dependence assumption.

Strongly Correlated Electrons

Asymmetric magnetoresistance in 3$d$-5$d$ based La$_{0.67}$Ca$_{0.33}$MnO$_3$/SrIrO$_3$ bilayer: The role of unidirectional anisotropy

A. G. A. Rahman, Subham Naskar, R. K. Patel et al. (+4 more)

The complex interplay between spin-orbit coupling, magnetism, and magnetic field at the interface of a heterostructure consisting of ferromagnet (FM) and heavy metal (HM), often exhibit extraordinary magnetic and electric phenomena where an in-plane Dzyaloshinskii-Moriya (DM) interaction plays a crucial role to stabilize local spin texture in FM layer. Here, we report detailed magnetic and magneto-transport behaviour on an epitaxially grown thin heterostructure with 3$d$ FM La$_{0.67}$Ca$_{0.33}$MnO$_3$ (LCMO) and 5$d$ HM SrIrO$_3$ (SIO). Magnetic measurements show an unusual development of magnetic ordering in SrIrO3 around 42 K, which further leads to a Mn/Ir magnetic coupling at the interface. The magnetoresistance (MR) measurements show an evolution of its value and shape with the magnetic state of this bilayer. While MR is negative at high temperature, it shows a positive to negative crossover with stable magnetic ordering of LCMO, and finally the positive MR exhibits an asymmetry at low temperature with the ordering of SIO. While we ascribe this unusual MR behaviour to interface-driven varying spin scattering between itinerant and localized electrons, our results shed a light to comprehend the complex but tunable interface behavior on charge transport in a particularly designed heterostructure, offering valuable insights for future functional material engineering.
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All authors A. G. A. Rahman, Subham Naskar, R. K. Patel, S. Manna, Chandrani Nath, Kranti Kumar, A. K. Pramanik

Quantum Physics

Near-Optimal Bell Nonlocality with GKP and Entangled Cat States

Özlem Erk{\i}l{\i}ç, Aritra Das, S. Nibedita Swain et al. (+2 more)

Gottesman-Kitaev-Preskill (GKP) states are widely studied as a bosonic encoding for fault-tolerant quantum computing because small displacement errors can be identified and corrected through syndrome measurements. However, fault-tolerant operation requires substantially greater GKP squeezing than is currently available in optical platforms. It is therefore important to identify quantum-information tasks that can be realised with finite-squeezing GKP states. Here, we study Bell nonlocality in finite-energy GKP Bell states under experimentally motivated measurement constraints. Although finite-energy GKP Bell states support Bell nonlocality even at low squeezing, logical Pauli measurements alone cannot reveal it. Accessing the maximum CHSH violation supported by the state generally requires logical non-Clifford rotations. We instead show that the required non-Gaussian resource can reside in the measurement itself. Photon-number-resolving detection combined with Gaussian preprocessing and adaptive feed-forward closely approaches the maximum violation of the CHSH Bell inequality without implementing logical non-Clifford gates. The same measurement principle strongly enhances Bell violations for cat-code Bell pairs and entangled coherent states, demonstrating that its usefulness extends beyond the GKP lattice. Our results identify non-Gaussian measurements as a practical route to revealing Bell nonlocality in finite-energy bosonic states.
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All authors Özlem Erk{\i}l{\i}ç, Aritra Das, S. Nibedita Swain, Simon Devitt, Timothy C. Ralph

Optics

All-Dielectric Ceramic 3-D Printed Unidirectional Leaky-Wave Antenna at mm-Wave Frequencies

Guillaume François, Masoud Sakaki, Henrik Jansen et al. (+3 more)

An all-dielectric leaky-wave antenna, radiating unidirectionally at broadside without the use of a metallic ground plane, is designed and manufactured. It operates in the 70-90 GHz frequency range with a design broadside frequency of 77 GHz. The design process makes use of the theory of photonic bandgaps to position a -1 harmonic at the broadside frequency on the second Bragg-condition point. The structure is then modified to close the bandgap and to simultaneously guarantee maximum total field coupling to the relevant radiating harmonic, ensuring radiation unidirectionality. The antenna is manufactured with an Al2O3 ceramic printing process, demonstrating its manufacturing potential for complex low-loss high-frequency structures. Simulations agree well with measurements, with the main deviation being a 1 GHz frequency shift that could be reproduced in simulation. The antenna prototype shows a scanning range of -18{\deg}-22{\deg} and gain values above 23 dBi. More than 85 % of the radiation power is radiated unidirectionally at broadside, with simulations showing potential to attain 98 %.
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All authors Guillaume François, Masoud Sakaki, Henrik Jansen, Amar Al-Bassam, Niels Benson, Dirk Heberling

High Energy Astrophysical Phenomena

Multi-Band Optical Variability Characteristics of the $\gamma$-ray emitting blazar 1ES 0647+250 during its 2020 flare

K.Subbu Ulaganatha Pandian, C. S. Stalin, S. Muneer et al. (+4 more)

We present a multi-band optical variability study of the $\gamma$-ray emitting high-synchrotron-peaked blazar 1ES~0647+250 during its enhanced optical activity in 2020. The analysis utilizes 107 epochs of high-precision $B$, $V$, and $R$-band photometry obtained with the 75 cm telescope at the Vainu Bappu Observatory, combined with high-cadence $z_g$ and $z_r$ survey data from the Zwicky Transient Facility. The combined light curves reveal coherent variability across all optical filters, with the source reaching a peak $R$-band magnitude of 15.74 mag. We calculated the variability amplitude, finding the highest intrinsic variability in the B- band. Spectral analysis using color–magnitude diagrams reveals a statistically significant “Bluer-When-Brighter” trend, supported by a Pearson correlation coefficient of $r = 0.68$ ($p < 0.001$) for the (V$-$R) index. Furthermore, the discrete correlation function analysis indicates a near-zero time lag between the $V$ and $R$ bands, suggesting simultaneous emission within the observational cadence. The observed spectral hardening is consistent with synchrotron-dominated optical emission, likely associated with enhanced particle acceleration within the jet during the active phase of 1ES~0647+250.
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All authors K.Subbu Ulaganatha Pandian, C. S. Stalin, S. Muneer, S. Umayal, Aditi Agarwal, Amit Kumar Mandal, B. Natarajan

Quantum Physics

Structured Hamiltonian Learning for Multiqubit Conditional Phase Gates

Xiu-Hao Deng

Accurate measurement of an intended conditional phase does not by itself place a multiqubit phase gate in its declared generalized-gate equivalence class. We cast the diagnosis as structured Hamiltonian learning of the diagonal successful block in a known basis: Ramsey measurements on a connected graph reconstruct a target-relative eigenphase map; a Walsh transform then yields the per-cycle stroboscopic error generator in a selected logarithm branch, whose branch-dependent coefficients alone cannot decide global equivalence. For diagonal Pauli-Z dressing of weight at most m we derive an exact branch-independent criterion from multiplicative Boolean-Mobius invariants, converted at finite shot counts into a pass/fail/unresolved decision under prespecified tolerances and simultaneous confidence, separate from model rejection. For shared-control C^mZ gates a circular target-face contrast isolates each intended conditional phase, yet a support theorem exhibits forbidden interactions invisible to every target face once multiple targets or external spectators are present. We derive a Cramer-Rao bound for arbitrary integer phase contrasts, recovering the 4^m attempted-circuit scaling of a uniform (m+1)-body face, and quantify degradation from visibility loss, heralded survival, readout confusion, and correlated noise, while systematic bias triggers model rejection. Seeded simulations implement the 4M-setting multiplexed acquisition end to end: for M=3,4,5 at a common budget its mean phase-map RMSE is 0.689-0.794 times a separately compiled statewise scan, and a blind-interaction test yields 300/300 global-audit rejections versus 1/300 for target faces. These results estimate the error generator of a diagonal successful block under a specified acquisition model; they are not unknown-basis Hamiltonian identification, arbitrary-channel tomography, or hardware certification.
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Quantum Physics

The refractive index of the medium within the volume of deep inelastic $ep$ scattering: I. Group velocity of interaction carriers

B. B. Levchenko

We propose a new method for measuring several characteristics of a fermion-boson medium formed during deep inelastic particle scattering. This method involves measuring the group and phase velocities of the accompanying wave process. The phase and group velocities of a wave process are related by the Rayleigh differential condition. The refractive index of a medium is determined by the phase velocity, while the group velocity characterises the medium's dispersion properties. In the case of deep inelastic $ep$ scattering under consideration, the wave process in an individual event is understood to be the exchange between an electron and a proton of an effective, non-perturbative mediator of interaction (${\cal B}$) with the quantum numbers of a neutral current. In the first report, we present new data on the group velocity of interaction carriers ${\cal B}$. We extracted the group velocity modulus values, $U_{_{\cal B}}^*$, from the HERA collider data using a formula derived from modified Heisenberg uncertainty relations and applying the indirect measurement method. The HERA data demonstrate that in the selected kinematic domain the speed of the mediator ${\cal B}$ exceeds the speed of light $c$ in free space, $U_{_{\cal B}}^* > c$. To compare with the obtained data on group velocity, we analyse a simplest model of dispersion relation occurring due to the relativistic relationship between the energy, mass and momentum of a particle, supplemented by de Broglie relations.
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Earth and Planetary Astrophysics

Probing Exoplanetary Chemistry with Ariel: Scientific Priorities and Observational Strategies

Olivia Venot, Yamila Miguel, Robin Baeyens et al. (+30 more)

Over the past two decades, increasingly precise observations have revealed that exoplanet atmospheres are chemically diverse and often far from equilibrium, with processes such as vertical mixing, photochemistry, and atmospheric circulation producing significant departures from thermochemical expectations. As large surveys across a wide range of planets begin to uncover population-level chemical trends, a coherent interpretation of these patterns remains elusive, particularly for gas giants and Neptune-like planets where disequilibrium processes likely dominate. The ESA Ariel mission will provide the first homogeneous, statistically significant atmospheric dataset for nearly a thousand exoplanets, offering an unprecedented opportunity to investigate the origins of chemical diversity across planetary populations. This white paper highlights central scientific questions for understanding atmospheric chemistry and recognized as priorities for the community. These questions span the mechanisms driving disequilibrium chemistry, the role of sulfur- and phosphorus-bearing species, the influence of stellar activity, the formation of haze precursors, and the chemical evolution of atmospheres around stars of different ages and types. Because these topics connect chemistry, physics, and planetary evolution, they form the core focus of the Ariel Chemistry Working Group, which synthesizes current knowledge and identifies the diagnostics best addressed by Ariel's spectral capabilities. For each theme, we outline observational strategies and representative targets already included in the Mission Candidate Sample, illustrating Ariel's ability to address these questions. By linking large-scale observations to predictive atmospheric models, this work supports refinement of Ariel's target selection and enables population-level studies that will transform our understanding of planetary atmospheres.
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All authors Olivia Venot, Yamila Miguel, Robin Baeyens, Stefano Bellotti, Giuseppe Cassone, Quentin Changeat, Ryan Cloutier, Athena Coustenis, Dwaipayan Dubey, Billy Edwards, Kaustubh Hakim, Eric Hébrard, Christiane Helling, Helgi Rafn Hrodmarsson, Leoni Janssen, Adam Yassin Jaziri, Gaia Lacedelli, Panayotis Lavvas, Jorge Lillo-Box, Amy Louca, Adrien Masson, Zita Martins, Karan Molaverdikhani, Benjamín Montesinos, Harrison Nicholls, Enric Palle, Paul Rimmer, Donna Rodgers-Lee, Jonathan Tennyson, Shang-Min Tsai, Roméo Veillet, Sergey N. Yurchenko, Maria Zamyatina

Computational Physics · Cross-listed from cs.AI

SHRAV: State-Hypothesis-Reason-Action-Verify Framework for Physical Modeling and Inverse Design

Ziheng Guo and Yang Bu

Physical modeling and inverse design require computation that can continue from reusable state. We introduce SHRAV, an architecture-independent computational framework organized around State, Hypothesis, Reason, Action, and Verify. Its central mechanism is a state-continuation core with declared reuse boundaries and explicit roles for learned evolution and numerical quantities. Forward configurations evolve predictive state and read out physical responses; inverse-design configurations additionally generate target-directed modifications and consume evaluator feedback. Electromagnetic world-model studies are mapped to forward configurations, with selected readout and reuse diagnostics reported here. Computational lithography demonstrates an inverse-design configuration: four fixed-weight design updates improve thresholded aerial-image intersection-over-union from 0.5313 to 0.8153 under independent scalar-pupil replay, with a maximum absolute IoU difference of approximately 0.000824 between predictor estimates and independent replay.
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Applied Physics

Thermoreflectance-Based Techniques for Micro- and Nanoscale Thermophysical Property Measurements: Principles, Methods, and Recent Advances

Puqing Jiang, Shanshan Chen, Xiaobo Li et al. (+1 more)

As semiconductor devices shrink toward the nanoscale, heat transport and thermal-energy-storage behavior in materials and interfaces become increasingly dependent on length scale, structure, and interfaces. Accurate characterization of thermophysical properties, including thermal conductivity, interfacial thermal conductance, and volumetric heat capacity, is therefore essential for functional-material design and thermal management of advanced electronic devices. Photothermal thermoreflectance techniques provide noncontact measurements with high spatial and temporal resolution and a broad measurement range, making them important tools for micro- and nanoscale thermophysical characterization. This review examines the physical principles and technical characteristics of transient thermoreflectance (TTR), time-domain thermoreflectance (TDTR), frequency-domain thermoreflectance (FDTR), steady-state thermoreflectance (SSTR), spatial-domain thermoreflectance (SDTR), and the square-pulsed source (SPS) method. A unified heat-diffusion framework is established to compare these methods in terms of parameter sensitivity, measurement uncertainty, and applicability. Representative applications illustrate their suitability for low-thermal-conductivity materials, anisotropic films, crystalline materials, and multilayer heterostructures, as well as their complementary capabilities for characterizing thin-film thermal conductivity, interfacial thermal conductance, and in-plane/cross-plane heat transport. Finally, emerging directions are discussed, including ultrahigh spatiotemporal resolution, multiphysics coupling, in-line industrial inspection, intelligent data processing, and natural-language-driven analysis.
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All authors Puqing Jiang, Shanshan Chen, Xiaobo Li, Ronggui Yang

Materials Science

High-Throughput Photovoltaic Screening and Spacer-Dependent Shift Current in Two-Dimensional Hybrid Perovskites

Vikrant Chaudhary, Fu Li, Yue Zhao et al. (+5 more)

High-throughput first-principles screening of structurally diverse two-dimensional hybrid organic-inorganic perovskites (2D HOIPs) provides a route to systematically explore their photovoltaic properties. Here, we develop a computational workflow with two distinct objectives: spectroscopic limited maximum efficiency (SLME) screening to identify materials with promising photovoltaic potential and nonlinear shift current calculations to characterize their bulk photovoltaic response. Applying this workflow to a curated dataset of experimentally reported 2D HOIPs, we identify more than 25 compounds with SLME values above 25% and more than 25 compounds exhibiting shift current responses exceeding 10~$\mu$A/V$^2$. We then focus on the Pb-I-based 2D HOIPs with $n=1$ to investigate the influence of spacer chemistry on the shift current response, revealing substantial spacer-dependent variations in both its magnitude and spectral peak position. Overall, these results highlight the potential of high-throughput first-principles calculations to accelerate the discovery of experimentally relevant 2D HOIPs with promising photovoltaic properties while revealing how organic spacer chemistry influences their nonlinear shift photocurrent response.
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All authors Vikrant Chaudhary, Fu Li, Yue Zhao, José A. Márquez, Wei Xie, Claudia Draxl, Zhihua Sun, Hongbin Zhang

High Energy Astrophysical Phenomena

Broad-band spectral-timing: simultaneous NICER and HXMT observations reveal an anticorrelation between the softest and hardest X-ray fluxes in MAXI J1820+070

Niek Bollemeijer, Phil Uttley and Bei You

Black hole X-ray binaries (BHXRBs) in the hard state show variable X-ray emission across a wide range of energies. Hard X-rays are thought to be produced through Compton-upscattering of seed photons from the accretion disc by the hot X-ray corona, leading to a spectral component roughly shaped like a power-law with a high-energy cut-off. A complete study of the coronal variability requires a full view of the spectrum, from the low-energy cut-off at the seed photon energy to the high energy cut-off, which may be related to the coronal temperature. We present a detailed spectral-timing study of strictly simultaneous observations by NICER and Insight-HXMT of the bright BHXRB MAXI~J1820+070, covering the 0.3-250 keV energy range. The high data quality allows us to study the lags and coherence across the full X-ray band. We find that at low Fourier frequencies ($\lesssim0.02$ Hz), the soft X-ray flux below 1 keV and hard X-ray flux above 100 keV are anticorrelated, i.e. phase lags of $|\pi|$ rad. No anticorrelation is observed when comparing energy bands above 1 keV. We consider several explanations for the observed complex behaviour, such as a modulation of the coronal cut-off energy by the disc, power-law pivoting and a contribution from non-thermal electrons. Future, more detailed modelling efforts based on the observed effects may place new constraints on the dynamics of the X-ray emitting regions around accreting black holes.
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Mesoscale and Nanoscale Physics

Observation of the orbital Nernst effect

Yuto Masuda, Takamasa Hirai, Daegeun Jo et al. (+5 more)

The Nernst effect, which converts a temperature gradient into a transverse charge current, is fundamental to thermoelectrics. Its spin analogue, the spin Nernst effect, enables thermal generation of transverse spin currents and is central to spin caloritronics. Recently, the discovery of orbital currents, the orbital counterpart of spin currents, has extended angular-momentum transport beyond spin, leading to the prediction of the orbital Nernst effect, in which a temperature gradient drives a transverse orbital current. However, experimental evidence for this effect has been lacking. Here, we report the observation of the orbital Nernst effect in Ti. Using Ni electrodes on Ti, we detect a thermally induced voltage that depends on the magnetization direction and scales linearly with the temperature gradient. This voltage is strongly suppressed both when Ni is replaced with Ni$_{81}$Fe$_{19}$ and when Ti is replaced with Cr, providing strong evidence that the signal originates from the orbital Nernst effect rather than the anomalous Nernst or spin Nernst effect. These results establish thermally driven orbital transport, opening a pathway toward orbital caloritronics.
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All authors Yuto Masuda, Takamasa Hirai, Daegeun Jo, Naoki Yano, Peter M. Oppeneer, Hossein Sepehri-Amin, Ken-ichi Uchida, Kazuya Ando

Quantum Physics

Scalable integration of silicon carbide color centers into nanophotonic structures

Raphael Wörnle, Jonas Schmid, Dennis Grüner et al. (+7 more)

Color centers in silicon carbide are a promising platform for quantum technologies, offering long-coherence electron and nuclear spins for storing and manipulating quantum information, as well as single-photon emission for quantum communication. Low photon collection efficiency is commonly addressed by integrating color centers into nanophotonic devices. Here, we report a scalable method for the deterministic integration of color centers into silicon carbide nanopillars, using the same nanoscale mask for both implantation of oxygen-related color centers (PL5, PL6) and subsequent nanopillar fabrication via dry etching. This approach solves the issue of low color center creation yield in nanostructures, with figures of merit comparable to bulk samples. We demonstrate count rate enhancements of up to one order of magnitude for PL5 and four times for PL6, while preserving spin coherence times. Our method is directly applicable to other solid-state platforms, offering a scalable route to efficiently integrate color centers into nanostructures.
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All authors Raphael Wörnle, Jonas Schmid, Dennis Grüner, Jonah Heiler, Flavie Davidson-Marquis, Georgy V. Astakhov, Vadim Vorobyov, Florian Kaiser, Jonathan Körber, Jörg Wrachtrup