Superconductivity
Papers
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Tuesday 16 June
Josephson diodes are non-reciprocal superconducting devices characterized by different switching currents depending on the current flow direction. They recently attracted considerable theoretical and experimental attention, in view of their possible application as rectifying elements in the field of superconducting electronics, and as probes to investigate symmetry breaking mechanisms in mesoscopic systems. In this work, we show that graphene Josephson junctions provide rectification of supercurrent with an efficiency exceeding 20%. The effect appears applying a mT out-of-plane magnetic field and is enhanced close to the nodes of the Fraunhofer interference pattern. Our theoretical model identifies long-range scattering potentials in the junction as the symmetry-breaking mechanism, which yields supercurrent rectification in highly transparent junctions. While graphene stands as an ultra-clean transmission medium, our work shows that unavoidable residual disorder in a clean two-dimensional system is sufficient to promote this effect. Tailoring of the inversion (mirror) symmetry breaking could be obtained via proper design of external gates.
Optics
Reservoir computing based on multicore fibers
Photonic reservoir computing offers a hardware-efficient route to processing temporal and sequential data, but delay-based implementations often rely heavily on temporal multiplexing, where long temporal masks are required to generate a sufficiently rich reservoir state. Here we show numerically that the spatial degrees of freedom of an active multicore fiber placed inside a delayed optical feedback loop can reduce this dependence on serial temporal encoding. The input signal is encoded by temporal and spatial masks, the pump distribution across the cores controls the reservoir operating point through the core-dependent effective gain and saturation energy, and the detected core intensities serve as readout features for a single trained linear layer. The system is modeled by linearly coupled nonlinear Schrödinger equations with saturable gain and solved using a split-step Fourier method. On the Mackey-Glass one-step-ahead prediction benchmark, a seven-core reservoir with equal temporal masks reduces the validation normalized root mean square error from 0.5956 for the single-core baseline to 0.0651 at a modulation rate of 40 GHz. At 1 GHz, spatial-only encoding reaches an error of 0.0323 using one temporal sample per symbol and no temporal mask. These results show that an active multicore fiber can provide both parallel readout channels and a tunable nonlinear transformation, offering a route to photonic reservoirs with reduced reliance on temporal multiplexing.
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High Energy Physics (Theory)
Hamiltonian formalism for Bose excitations in a plasma with a non-Abelian interaction: plasmon bremsstrahlung
The classical Hamiltonian wave theory describing plasmon bremsstrahlung radiation occurring upon collision of high-energy color-charged particles in a hot quark-gluon plasma is proposed. A generalization of the Lie-Poisson bracket to the case of a hot QCD medium, involving two independent components $a^{\phantom{\ast}(1)a}_{\bf k}$ and $a^{\phantom{\ast}(2)a}_{\bf k}$ of the bosonic normal field variable $a^{\phantom{\ast}a}_{\bf k}$ and two non-Abelian color charges $Q^{\,a}_1$ and $Q^{\,a}_2$ is suggested. The canonical transformations including both bosonic degrees of freedom of the soft collective excitations of the hot quark-gluon plasma and degrees of freedom of two hard test particles related to their color charges are written out. The most general structure of the canonical transformations in the form of integro-power series in the components $c^{\phantom{\ast}(\alpha)a}_{\bf k},\,\alpha = 1, 2$, of the new normal field variable $c^{\,a}_{\bf k}$ and in the new color charges ${\mathcal Q}^{a}_{\alpha}$ up to the terms of sixth order is presented. To construct kinetic equations the multiple-time-scale perturbation theory is used. The notion of the plasmon number density ${\mathcal N}^{\,(\alpha,\alpha^{\prime})aa^{\prime}_{\phantom{1}}}_{\bf k}(\tau)$, which is a nontrivial matrix both in the effective color space and in effective two-particle space, is introduced. The self-consistent system of four Boltzmann-type kinetic equations taking into account the time evolution of the averaged color charges of the hard particles is obtained. In the approximation of the fixed color charges of two interacting particles the exact solution of the system of kinetic equations defining the dynamics of the colorless $N^{(1)}_{\bf k}$, $W^{(1)}_{\bf k}$ and color $N^{(2)}_{\bf k}$, $W^{(2)}_{\bf k}$ components of the plasmon number density, is obtained.
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Strongly Correlated Electrons
Probing La-based nickelates with Ni 1$s$ core-level photoelectron spectroscopy
We present a comparative Ni core level photoemission study of La$_3$Ni$_2$O$_7$, Nd$_3$Ni$_2$O$_7$, and LaNiO$_3$ using both the Ni $2p$ and the Ni $1s$. We address the challenges in analyzing the widely investigated Ni $2p$ spectra arising from the substantial overlap in energy of the Ni $2p$ with the La $3d$. We show that on the other hand the deep Ni $1s$ core level does provide a clean view on the intrinsic electronic excitations and we highlight its potential to resolve detailed differences in the electronic structure within the strongly correlated Ruddlesden-Popper series La$_{n+1}$Ni$_n$O$_{3n+1}$.
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Fluid Dynamics
Stability of Kirigami parachutes in effectively infinite numerical domains
Kirigami, the art of cutting flat sheets into deployable 3D structures, has recently inspired a new class of parachutes which can deploy into a naturally stable inverted canopy. However, the dynamic mechanism, fluid forces, and geometrical parameters that grant this stability have not yet been clearly identified. In this paper, we use a novel Biot-Savart far-field boundary condition to perform prescribed acceleration and free-falling simulations in effectively infinite domains, tracking the descent of a parameterized kirigami parachute. The far-field velocity is reconstructed from the interior vorticity, resulting in less than 0.1% variation in the predicted dynamics as the domain size is doubled. We first show the linear forces drop 2-5 times as the parachute is deployed due to increased permeability, whereas the moments increase due the counterbalancing effect of the increased lever-arm. Next, we find that the kirigami parachute achieves stable flight for deployment heights as small as half its radius, quickly damping out applied perturbations. For smaller deployments, the parachute tumbles due to side-slip and rotational coupling, as in falling disks. These effectively unbounded simulations identify that deployments approximately equal to the radius offer high drag forces with strong dynamic stability, providing a simple design rule for deployable parachutes.
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Materials Science
Ground-state properties of the $S=3/2$ anisotropic triangular lattice antiferromagnet Na$_3$Cr(PO$_4$)$_2$
We report the crystal structure and magnetic properties of a $S=3/2$ anisotropic triangular lattice compound Na$_3$Cr(PO$_4$)$_2$ employing single-crystal and powder x-ray diffraction, magnetization, heat capacity, and $^{31}$P nuclear magnetic resonance (NMR) experiments, supported by the band structure calculations. Magnetic susceptibility exhibits a broad maximum around 3.5 K, indicating the presence of a short-range antiferromagnetic order, typical of a low-dimensional spin system. Magnetization and heat capacity manifest an antiferromagnetic long-range ordering at around $T_{\rm N} \simeq 2.6$ K. This was further confirmed by the drastic NMR line broadening and a peak in the nuclear spin-lattice and spin-spin relaxation rates. The isothermal magnetization data exhibit a field-induced spin-flop transition at around $\mu_0H_{\rm SF} \simeq 1.7$ T reminiscent of an anisotropic two-dimensional magnet, before saturating above $\mu_0H_{\rm sat} \simeq 4.5$ T. The saturation field was further upheld by the field-dependent NMR relaxation measurements at low temperatures. The $^{31}$P NMR spectral shape confirms the commensurate antiferromagnetic nature of the ordering below $T_{\rm N}$. Ab initio calculations reveal a significant deformation of the triangular spin lattice, resulting in triangles with two antiferromagnetic couplings of similar strength and a much weaker coupling along the third side of the triangle.
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Plasma Physics
Schrödinger equations and fluctuation theorems for collisionless plasma systems
The fluctuation theorem and detailed fluctuation theorem are formulated for classical systems whose governing equations can be written in Schrödinger-type equations and which possess either a unitary or an antiunitary time-reversal operator. The initial state vector is treated as a random variable drawn from a time-reversal-symmetric probability distribution, and a stochastic relative entropy defined from its probability density is used to formulate these theorems. The framework is applied to two collisionless plasma systems: the linear Vlasov-Poisson and linear gyrokinetic systems. For the linear Vlasov-Poisson system, the governing equations are recast into Schrödinger form, and Hamiltonian eigenvectors corresponding to Case-Van Kampen modes are derived to construct explicit solutions. The stochastic relative entropy is interpreted as entropy generation associated with Landau damping, in which electric-field energy is transferred from the lowest Hermite state to higher-order Hermite states acting as thermal reservoirs. For a specific class of initial distributions, a new analytical expression for the probability density function of the stochastic relative entropy is derived and validated numerically. For the linear gyrokinetic system in a uniform magnetic field, the governing equations are likewise transformed into Schrödinger form, and the corresponding time-reversal operators are identified. The state-vector space is constructed as a tensor product of species, perpendicular-velocity, and parallel-velocity spaces. The resulting state vectors decompose into two orthogonal components: one coupled to electromagnetic fluctuations and the other corresponding to ballistic modes. These results establish a nonequilibrium statistical-mechanical framework for collisionless plasma dynamics and provide useful examples for future quantum-computing applications to plasma simulations.
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Nuclear Theory
Improving the efficiency of Hartree–Fock–Bogoliubov solvers in 3D space
The solution of the three-dimensional Schrödinger-like single-particle equations that appear in Kohn Sham density functional theory, as well as in other contexts, for large systems and without any symmetry, requires efficient and robust numerical algorithms. Conventional methods suffer from slow convergence and require careful tuning, depending on the spatial discretization. Conjugate gradient methods combined with preconditioning have been proposed to accelerate the convergence of symmetry-unrestricted Skyrme energy density functionals; however, their effectiveness may depend on the design of a preconditioner. In this work, we introduce the generalized conjugate gradient method for the self-consistent solution of the Hartree–Fock–Bogoliubov equations, which eliminates the need for problem-dependent preconditioning and improves the convergence speed of currently available methods. The performance of the proposed algorithm is demonstrated on representative nuclear systems, showing improved convergence behavior compared to standard approaches. The proposed method ultimately provides a promising tool for systematic studies of superheavy, strongly deformed, and drip-line nuclei.
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Quantum Physics
From Period Finding to Lattice Sampling: Experimental Insights into Shor's and Regev's Factoring Algorithms
Quantum algorithms for integer factorization represent one of the most prominent applications of quantum computation, with far-reaching implications for modern cryptography. While Shor's algorithm provides a polynomial-time solution in the ideal quantum model, its practical implementation is severely constrained by the limitations of current noisy intermediate-scale quantum (NISQ) hardware. These constraints have motivated the exploration of alternative factoring algorithms with different structural and resource trade-offs. In this work, we present an experimental study of Regev's quantum factoring algorithm, implemented on real quantum hardware, and compare its behavior with that of Shor's algorithm under analogous conditions. Focusing on the case N = 15, we execute both algorithms on the QMIO quantum computer at the Centro de Supercomputacion de Galicia (CESGA) and contrast the results with one of IBM's open-access quantum computers and ideal simulations. This parallel execution enables a low-level comparison of the two algorithms, highlighting how their respective quantum implementations interact with hardware noise, limited circuit depth, and finite sampling. Our analysis emphasizes the different ways in which Shor's and Regev's algorithms encode arithmetic structure into quantum states through Fourier sampling in one and higher dimensions, respectively, and how these differences manifest in experimental outcomes. Although neither algorithm demonstrates a practical advantage in the small N regime, the results provide insight into their relative robustness and failure modes on contemporary quantum devices. This study illustrates the value of experimental benchmarking of alternative quantum factoring algorithms as a means of understanding the practical implications of algorithmic design choices in the NISQ era.
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Mathematical Physics
Homogeneous Boltzmann-type equations on dense graphs
In kinetic theory, interactions between particles are typically assumed to be "all-to-all", meaning that any pair of randomly selected particles may, in principle, interact. This assumption originates from the theory of colliding gas molecules; however, it may be less appropriate for describing other forms of interaction, such as social interactions. These are more naturally characterised as "some-to-some", reflecting the existence of preferential connections between agents. In this paper, we consider homogeneous Boltzmann-type equations on finite graphs that model such networks of preferential interactions, and we rigorously derive their dense graph limit as the number of agents tends to infinity. We also investigate the long-time behaviour of the limiting equation in the case of linear pairwise interactions, characterising the emergent equilibrium distributions and relating them to their counterparts in the classical "all-to-all" setting.
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Instrumentation and Methods for Astrophysics
A fast spectral-multigrid Poisson solver in non-Cartesian geometries
Accurate and efficient computation of self-gravity is essential in astrophysical fluid dynamics, particularly in spherical and cylindrical geometries where large radial dynamic ranges and non-axisymmetric structures arise. Poisson solvers in such settings must simultaneously achieve high accuracy, scalability, and flexibility across a wide range of grid configurations and physical regimes. We present a robust and scalable Poisson solver for three-dimensional non-Cartesian geometries, supporting both spherical and cylindrical coordinates with either uniform or logarithmic radial discretizations. The method employs azimuthal Fourier decomposition to transform the 3D Poisson equation into a set of independent 2D Helmholtz equations. These are solved using a geometrically consistent multigrid algorithm that preserves second-order accuracy on both uniform and non-uniform grids. Vacuum boundary conditions are implemented through a screening-mass approach, enabling accurate solutions in domains with open boundaries, inner cavities, and strongly non-axisymmetric mass distributions. Owing to the differing convergence rates of Fourier modes – where higher-order modes converge more rapidly – the solver allows efficient mode-by-mode treatment. The combination of spectral decomposition and multigrid acceleration provides an efficient and flexible computational framework. The solver is implemented in the PLUTO code and validated against both analytical solutions and dynamical test problems in spherical and cylindrical geometries. Results demonstrate second-order convergence and excellent agreement with reference solutions. Weak-scaling tests up to 4096 cores show strong parallel performance, with the Poisson solve remaining subdominant to magnetohydrodynamic update cost. This makes the method well suited for large-scale simulations of star formation, accretion disks, and gravitational instabilities.
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Optics
Principle of Entangled-Photon Thermometry for Ultrafast Laser Processing
A quantum-enhanced approach for fast temperature diagnostics in ultrashort laser surface processing is introduced. The goal is to overcome limitations of existing methods, such as plasma emission, emissivity changes during ablation, and the need for time-consuming pump-probe measurements. The proposed method exploits polarization anisotropy in entangled photon pairs. The idler photon interacts with the laser-affected material surface, while its entangled counterpart is detected in a remote optical arm. Temperature-dependent changes in the complex refractive index modify the reflectance of p- and s-polarizations on the idler path, altering the coincidence-resolved polarization statistics of the signal photons. Using a Qiskit-based model incorporating experimental pump-probe reflectometry data, remote reconstruction of rapid thermal dynamics during femtosecond laser ablation is demonstrated. Although based on simulation, the model employs literature data to represent realistic material behavior. Due to the discrete nature of single-photon events, classical sliding-window analysis suffers from shot noise and temporal inertia. To overcome this limitation, a multilayer perceptron (MLP) regression network is applied to extract implicit anisotropy information from the photon bitstream. Compared with the classical approach, the neural-network method improves reconstruction robustness, reduces temperature noise, enhances the signal-to-noise ratio (SNR), and enables nanosecond-scale tracking of thermal dynamics. The results indicate that entangled-photon polarization anisotropy combined with machine-learning analysis is a promising approach for remote, background-rejected, high-speed temperature diagnostics in laser-matter interaction studies.
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High Energy Physics (Experiment)
Better Queries, Cheaper Attention: Adapting Transformers for Efficient Sparse Reconstruction
Query-based transformer decoders are effective for object reconstruction from sparse scientific sensor measurements, but their scalability to high-multiplicity data is limited by fixed, input-independent query sets and costly decoder cross-attention. We introduce a geometry-aware dynamic-query decoder that couples input-conditioned query construction with structured sparse cross-attention. Decoder queries are initialised from selected encoder-level measurement representations that serve as candidate trajectory seeds, making both query content and query multiplicity input-dependent. Local Strided Cross-Attention (LSCA) exploits the induced geometric ordering by replacing learned mask-gated cross-attention with a geometry-defined local support that restricts attention to physically plausible query-hit interactions and exposes sparsity for block-sparse execution. We study this architecture for charged-particle trajectory reconstruction in a simplified High-Luminosity Large Hadron Collider detector, where thousands of trajectories must be reconstructed from tens of thousands of sparse measurements. In the nominal configuration, the dynamic-query (DQ) architecture increases trajectory reconstruction efficiency from 94.1% to 98.1% and reduces the fake rate by more than a factor of two relative to the fixed-query baseline. The DQ+LSCA model reduces end-to-end inference latency by nearly 50% and peak allocated inference memory by more than a factor of 10 relative to the fixed-query baseline.
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Cosmology and Nongalactic Astrophysics
PSZ: The meta-catalogue of Planck Sunyaev-Zeldovich sources
We present the PSZ, a meta-catalogue of 1962 clusters and cluster candidates produced by the Planck Collaboration. The PSZ contains fully-updated validation information for all official Planck catalogue detections, together with redshift estimates for confirmed clusters, with no duplicate entries. The validation is derived from optical and X-ray follow-up campaigns, supplemented by cross-matching with external catalogues with redshift information, and with XMM-Newton archive data. The external catalogues considered include the all-sky X-ray catalogue MCXC-II, the eROSITA X-ray cluster catalogue, the RASS-MCMF and PSZ-MCMF catalogues, and the extended Planck catalogues of Burenin. A total of 281 clusters are newly-confirmed owing to this process; conversely, 262 Planck candidates are invalidated. Of the 1500 confirmed clusters, 274 have updated redshifts, and 278 have newly-assigned redshifts. An MCXC-II counterpart is assigned to 631 clusters, updating the MCXC cross-match published in the Planck catalogues. Differences with the PSZ2 update of Bahk & Hwang are discussed. We further introduce a new, homogeneously-derived mass estimate, corrected for selection effects owing to intrinsic scatter and the properties of the underlying mass function. New posterior probability contours in the $Y_{5R500}-\theta_s$ plane are provided for all sources, in addition to the corresponding $M_{500}(z)$ degeneracy curves. PSZ includes both corrected and uncorrected $M_{500}$ values for confirmed clusters. A methodology for cross-identification between catalogues is presented. We show that simple fixed-distance matching is insufficient for this task, and demonstrate the need for additional consistency checks based on mass proxies, redshifts, and distance versus angular size comparisons. The final PSZ comprises 1500 confirmed clusters, 262 noise-dominated detections, and 200 candidates awaiting validation.
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High Energy Physics (Theory)
Imprints of dynamical phases in semiclassical entanglement entropy in 2D CFT
We study the time evolution of semiclassical entanglement entropy in a class of $sl(2,\mathbb{R})$ driven states in a large $c$ conformal field theory (CFT) in $1+1$ spacetime dimensions. Upon varying the parameters of the drive, we find that the entanglement entropy exhibits the signature of the dynamical phases of the driven CFT. We further study the holographic dual of this CFT where the excited states of a minimally coupled scalar in $AdS_3$ induce a backreaction that modifies the background geometry. We compute the back reacted geometry by solving Einstein's equation with the expectation value of the stress tensor in the coherent state as the source term. Subsequently, we calculate the time evolution of the perturbed minimal area and the bulk entanglement entropy at $O(G_N^0)$, up to the sub-leading order in short distance approximation. These results match the CFT entanglement entropy in the boundary at $O(c^0)$, and serve as a nontrivial check of the Faulkner-Lewkowycz-Maldacena (FLM) conjecture for the first quantum correction of holographic entanglement entropy. The details of the check has been provided in the accompanying ancillary notebook.
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Statistical Mechanics
Work Extraction via Backward Motion in Optimal Closed-Loop Stochastic Control
We experimentally realize finite-time feedback control in an overdamped colloidal system using real-time optical tweezers with in situ reinforcement learning (RL). By varying the protocol duration tf for displacing the optical trap between prescribed positions, the optimal strategies identified by RL reveal a crossover from deterministic dragging toward the target to feedback-assisted exploitation of thermal fluctuations, reducing and eventually overcoming the energetic cost. The resulting policies agree quantitatively with the exact optimal closed-loop solution. By extending the approach to spatially localized external forcing, we further show that RL can identify optimal feedback strategies in heterogeneous stochastic environments where direct analytical control design is challenging.
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Mesoscale and Nanoscale Physics
Atomic-scale sensing of photoexcitation processes in electronically isolated molecules via atomic force microscopy
Atomic-scale insights into light-matter interaction can be obtained using light-assisted scanning probe microscopy techniques. Recently, photoexcited charge carriers have been detected by means of scanning tunnelling microscopy, enabling the study of photo-induced charge transfer with atomic-scale spatial resolution. Here, we propose an approach based on atomic force microscopy (AFM), namely photoexcitation single-charge AFM (PE-AFM), to detect photoexcitation in single molecules adsorbed on non-conductive dielectric films. Synchronizing laser pulses to the oscillation of the tip of an AFM enables the detection of electron tunnelling events that follow photoexcitation. We demonstrate the PE-AFM technique for individual copper phthalocyanine molecules and achieve photoexcitation-driven AFM contrast with ångström spatial resolution. The observed sub-molecular contrast suggests the involvement of a long-lived quadruplet excited state. When combined with the recently developed AFM excited-state spectroscopy including lifetime measurements, PE-AFM enables comprehensive characterization of electronic states involved in photoexcitation and subsequent intersystem crossing, establishing a powerful platform for investigating photophysical processes at the single-molecule level.
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Quantum Physics
Quantum mechanics in configuration space in context
To enhance the way in which wave-particle duality is implemented in the modelling of quantum mechanical systems, Bukhari et al. [New J. Phys. 27, 084501 (2025)] recently introduced an alternative approach to quantum mechanics, namely quantum mechanics in configuration space. This formalism is based on a physically motivated quantisation of Newtonian mechanics and promotes the classical position-velocity states (x,v) to pairwise distinguishable quantum states. The resulting |x,v> states form the basis of the Hilbert space of individual quantum mechanical particles and evolve along classical trajectories. In this paper, we consider the modelling of a mechanical particle in free space and put quantum mechanics in configuration space into context. It is shown that this formalism increases the continuity between quantum and classical mechanics by avoiding a conceptual inconsistency associated with the definition of momentum in canonical quantisation. In addition, we emphasise that standard quantum mechanics and quantum mechanics in configuration space are based on two distinct formulations of classical mechanics.
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Quantum Physics
Quantum Computing Algebra (QCA), the theory and implementation
We present a real geometric algebra framework designed for the direct translation of the Dirac formalism into geometric algebra representations. Unlike previous approaches based on positive-definite signatures, QCA employs a split-signature construction that enables a natural realization of quantum states and operators while simplifying computational implementation. We further present an implementation of QCA using the GAALOP software and show how quantum gates and multi-qubit systems can be efficiently represented and generated computationally. As an application, we demonstrate the use of QCA in quantum game theory, where the real-algebraic formulation provides computational advantages for modeling entangled strategies and quantum interactions. The proposed framework establishes a practical bridge between the abstract formalism of quantum computation and efficient geometric algebra implementations.
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Quantum Physics
Photon anti-bunching in high harmonic generation
Photon anti-bunching is the direct evidence for the existence of photons without having a classical counterpart. Unlike bunching of photons, which can have a semi-classical description, the effect of photon anti-bunching can only be understood with quantized electromagnetic fields. However, for the process of high harmonic generation (HHG), where many photons of the driving field are upconverted to a single photon of higher energy, there is yet no clear evidence for the presence of individual photon emission. The key result of this work is the prediction of photon anti-bunching in the process of HHG, marking it the first theoretical discovery of non-classicality in the temporal correlations of HHG photons. While other non-classical signatures in HHG, such as sub-Poissonian statistics or squeezing, have been discussed for an ensemble of photons, the anti-bunching signature reported here is a signature of a single photon. This is achieved by using the recently developed Heisenberg picture approach for quantum optical HHG, revealing clear anti-bunching signatures in the intensity correlation function across the entire harmonic spectrum.
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Quantum Physics
Helical Dirac Current with Local Coupling to a Chiral Potential
We show that a propagating electron wave in the lowest cylindrical channel carries a spin-resolved helical conserved current, and connect this current texture to its local chiral coupling. In a weakly relativistic positive-energy Dirac projection, the two sectors have the same azimuthally symmetric charge density and opposite circulation superposed on longitudinal flow, even though their nonrelativistic orbital harmonic is $l=0$. The current is radially distributed and extends into the evanescent tail. A scalar screw potential couples these modes through a derived vertex expressed by the chiral current overlap, $\mathcal J_\chi$. Both spatial textures determine the coupling: the environmental radial profile weights the electronic circulation, while the screw harmonic selects correlated changes of spin sector and longitudinal momentum. For a uniform static harmonic, elastic energy conservation makes the first-order spin-flip amplitude vanish within the same transverse mode. Environmental energy exchange is therefore required to activate these selected channels. The same current overlap supplies the spatial kernel for heliciton-assisted inelastic scattering in a companion study and for a subsequent transport treatment of chirality-induced spin selectivity (CISS).
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Cosmology and Nongalactic Astrophysics
Synergy between CSST and future gravitational-wave detectors: Probing primordial black holes by cross-correlating dark sirens with galaxies
Gravitational-wave (GW) events and galaxies both trace the cosmic matter distribution, but the mergers of astrophysical black holes and primordial black holes (PBHs) are expected to populate different environments and therefore to cluster with different biases. The GW clustering bias is thus a statistical observable that can separate the two populations. We assess how well this can be done by cross-correlating the photometric galaxy survey of the Chinese Space-station Survey Telescope (CSST) with mock GW catalogs from two future detector networks: the third-generation ET2CE network (the Einstein Telescope and two Cosmic Explorer detectors) and the multi-band BDET2CE network, which adds the space-based baseline Decihertz Interferometer Gravitational-Wave Observatory. We find that CSST combined with 10 years of ET2CE observations can reveal a PBH contribution once its fraction in the total merger rate exceeds about $40\%$, while the much sharper sky localization of BDET2CE lowers this threshold to about $20\%$. The improvement comes from recovering the small-scale clustering information that localization errors would otherwise erase. These results show that combining future GW detector networks with CSST galaxy clustering offers a promising and largely independent route to identifying PBHs statistically.
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Cosmology and Nongalactic Astrophysics
Joint reconstruction of $H(z)$ and $f\sigma_8(z)$ with physics informed neural networks
We present a model-independent joint reconstruction of the Hubble parameter $H(z)$ and the growth rate $f\sigma_8(z)$ using a dual-head physics-informed neural network trained on four complementary late-universe datasets: Cosmic Chronometers, Redshift-Space Distortions, the DESI DR2 BAO mean vector and full covariance, and the Pantheon$+$SH0ES supernova compilation. The two output heads share a backbone and are coupled through the linear growth equation of general relativity, penalizing the ODE residual at 1000 collocation points per training step via automatic differentiation. Uncertainty is quantified by an ensemble of 100 networks, each trained on an independent parametric-bootstrap resample of the data and its own draw of the fiducial cosmological parameters from Planck 2018 priors, so that the ensemble spread captures data-noise, initialization, and fiducial-cosmology systematics simultaneously. The physics coupling weight $\lambda$ is selected via an L-curve analysis over six values; the curve is nearly flat in total data $\chi^2$, indicating that the joint dataset is intrinsically consistent with the growth ODE. Without any $H_0$ prior, the free reconstruction yields $H_0 = 69.0 \pm 4.7$\,km\,s$^{-1}$\,Mpc$^{-1}$, consistent with the Planck 2018 CMB value and with the DESI DR2 inverse distance-ladder determination, and approximately $0.9\sigma$ below the SH0ES local measurement. The reconstructed $H(z)$ lies systematically below the flat $\Lambda$CDM prediction at $z \sim 0.7$-$0.8$, consistent with the dark energy evolution suggested by DESI DR2. As conditional analyses, we also anchor $H_0$ to the SH0ES value $73.04 \pm 1.04$\,km\,s$^{-1}$\,Mpc$^{-1}$ and the Local Distance Network consensus $73.50 \pm 0.81$\,km\,s$^{-1}$\,Mpc$^{-1}$; both anchored reconstructions yield a suppressed $f\sigma_8$, illustrating the propagation of the $H_0$–$\sigma_8$ link through the ODE coupling.
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High Energy Physics (Theory)
Lorentzian Regularization of the Type IIB Superstring Torus Vacuum
We study the one-loop torus vacuum of Type IIB Superstring theory through sector-resolved modular integrals. Building on the i\varepsilon-prescription and the E_s-regularized modular-integral framework of Manschot and Wang [1], we construct regularized sector functionals for the closed oriented torus before the final GSO projection. The construction keeps the unprojected spin-sector data explicit and fixes the compact-domain and cusp contributions within a single modular prescription. We also independently cross-check the result with the Lorentzian-inversion reconstruction of modular integrals by Baccianti et al. [2] This provides a first direct regularized construction of the unprojected sectors of the Type IIB Superstring torus vacuum.
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Astrophysics of Galaxies
OQ~208: A New Fe~II Changing-look Active Galactic Nucleus and Implications for the Nature of the Changing-look Phenomenon
In addition to the traditional hydrogen Balmer emission lines, here we extend the optical changing-look (CL) phenomenon occurring in some active galactic nuclei (AGNs) to the optical FeII complex. Multiepoch spectroscopy allows to identify OQ~208, a local flat-spectrum radio source, as a new FeII CL-AGN owing to the disappearance of both its strong FeII complex (RFe $\equiv$ FeII/H$\beta =0.64$) and its Balmer broad-line emission on a timescale of $\sim14$\,yr. The simultaneous disappearance implies that in this object, both the FeII and Balmer emission come from the same region exposed to the ionizing continuum. We further identify an anticorrelation between the FeII strength and the continuum (and also Eddington ratio) during the CL events in dozens of CL-AGNs recently studied by Panda & Sniegowska (2024), suggesting a negative response of RFe to both $L_{5100}$ and $L_{\mathrm{bol}}/L_{\mathrm{Edd}}$; this can be understood by the Comptonization process in a hot, optically thin accretion flow.
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Classical Physics
A posteriori study of Thermal-Large Eddy Simulation in solar receiver operating conditions
This study investigates Thermal-Large Eddy Simulations (T-LES) of anisothermal and turbulent channel flows under physical conditions representative of solar receivers. Solving the low-Mach number Navier-Stokes equations, T-LES results are evaluated a posteriori against Direct Numerical Simulation (DNS) data. We assess 12 subgrid-scale models. All models are based on the Anisotropic Minimum Dissipation (AMD) model. After computing a global error rate to evaluate all models, we select four for a detailed analysis regarding the effects of mesh resolution, numerical schemes, and model formulations. Results demonstrate that a two-layered mixed model combining the AMD/AMD-scalar with the Gradient model yields the best agreement with DNS.
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Soft Condensed Matter
Defect Localization by Vanishing Deviatoric Stress in Active Nematics
Collective stress generation in cellular monolayers is a key phenomenological process governing coordinated migration and emergent multicellular dynamics. We employ a generic active nematics model to investigate stress generation and its associated properties. By analyzing the maximal principal stress and its correlation with the nematic director across different activity strengths, we find that the principal stress aligns perpendicular (parallel) to the nematic director for extensile (contractile) activity. In the turbulent regime, we identify a rotation-invariant scalar measure of the in-plane deviatoric stress whose zero-level contour coincides with the locations of all $\pm 1/2$ topological defects (both nematic and principal stress defects) are localized. This feature is robust and remains unchanged with variations in both the magnitude and nature (extensile or contractile) of activity. Our findings thus open up a new route to probe the spatial alignment from the mechanical and rheological properties of confluent cell layers, where stress measurements are more accessible than detailed cell shape or size characterisation.
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Quantum Physics
Asymptotically Optimal Circuit Depth for Diagonal Unitary Synthesis and Compilation on Two-Dimensional Grids
Diagonal unitaries are a fundamental but resource-intensive class of quantum operations, arising as the phase separators of QAOA and the time-evolution blocks of Hamiltonian simulation. Under all-to-all connectivity their optimal depth is established, but on nearest-neighbor hardware general-purpose compilers fall back on heuristic search, which yields no analyzable cost bound and becomes intractable at the very sizes where depth is the bottleneck. We address synthesis and compilation jointly. On the synthesis side, we develop a Gray-Path Framework (GPF) that realizes any $n$-qubit diagonal unitary in asymptotically optimal $R_z$ and CNOT depth $O(2^n/n)$ without ancillas. Our main result is that compiling GPF onto a two-dimensional nearest-neighbor grid preserves this optimality: routing adds depth $\Theta(2^n/n)$ and gate count $\Theta(2^n)$. Because GPF fixes its entire interaction structure in advance, routing reduces to scheduling a known sequence, with no heuristic search. We give the construction both with and without ancillas: the ancilla-free, cost-optimized layout is a two-row grid, and a $2k$-row layout introduces a space–time tradeoff that cuts depth by $1/k$ while remaining asymptotically optimal for the enlarged register; both are deterministic and analyzed in closed form. The same complexity is also attained on a linear nearest-neighbor chain, so the preservation is topology-independent, holding on any architecture that contains such a chain. All routing bounds are closed-form, giving the concrete resource estimates that heuristic compilers cannot provide at scale.
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Quantum Physics
On the entanglement induced by the deformation of phase-space
Most quantum gravity theories propose that the fundamental concept of space-time is mostly compatible with quantum theory in noncommutative (NC) space. In the present paper, we revisit the notion of entanglement induced by NC deformations of phase space. The positive partial transpose (PPT) criterion for separability of bipartite Gaussian states is extended to a general class of Bopp's shift. In particular, we have considered both the position-position and momentum-momentum noncommutativity, with deformation parameters $\theta$ and $\eta$, respectively. It turns out that $\theta$ and $\eta$ induce the entanglement. We have directly applied the formalism for an anisotropic two-dimensional harmonic oscillator. Peres-Horodecki separability condition leads to a constraint equation for the parameter values of the oscillator in NC space. It turns out that the bipartite Gaussian state is almost always entangled in deformed space. To implement the theoretical idea, we provide an outline for a gedankenexperiment to identify the signature of phase-space noncommutativity, i.e., quantum gravity. In particular, the gedankenexperiment is devised to test the separability of supposedly separable Gaussian states in the usual commutative space, through the covariance matrix, which is constructed via measured output photocurrents after interaction of input Gaussian states and reference states. If the experiment shows that the supposedly separable states are actually entangled, then the entanglement is created through the intermediate background noncommutative space, which is a signature of the quantum nature of gravity.
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General Relativity and Quantum Cosmology
The Pre-geometric Origin of Geometric Trinity of Gravity
The so-called Geometric Trinity of Gravity is based on three distinct geometric features of spacetime, i.e.\ curvature, torsion and non-metricity, which give rise to equivalent dynamics for General Relativity (GR), Teleparallel Equivalent of General Relativity (TEGR) and Symmetric Teleparallel Equivalent of General Relativity (STEGR). Pre-geometric gravity, on the other hand, offers a unifying framework from which all metric-affine theories can emerge. Starting from a gauge formulation \textità la} Yang–Mills with a Higgs-like field, a mechanism of spontaneous symmetry breaking can give rise to an effective metric as well as to the classical dynamics of the gravitational field. In particular, the emergence of gravity in the spontaneously broken phase is shown to be consistent with all the different formulations of the Geometric Trinity of Gravity, in terms both of actions and of gauge choices for the affine connection. This general result is achieved by deriving and analysing suitable expressions in the unbroken phase for pre-geometric actions and for pre-geometric gauge-fixing conditions respectively.