Quantum Physics
Thermal screening and critical scaling of quantum energy teleportation in a harmonic chain
Taisanul Haque
We develop a finite-temperature Gaussian-state formulation of
quantum energy teleportation in the one-dimensional harmonic chain. For Gibbs states, the optimized measurement-feedback protocol reduces to thermal two-point functions. In the single-site protocol, the extracted energy is governed by a single correlator, which makes the thermodynamic and near-critical limits analytically tractable. At fixed finite temperature, the extracted energy is exponentially screened with distance and is controlled by a thermal correlation length for both critical and non-critical $\alpha$. In the zero-temperature critical limit taken after the thermodynamic limit, we derive the exact asymptotic law $E_{\mathrm{ext}}\sim d^{-4}$. Numerical results confirm both regimes and resolve the crossover responsible for the apparent drift of the effective decay exponent at intermediate distances. We also analyze squeezed Gaussian measurements and show that they modify the extraction prefactor: $p-$squeezing enhances the extracted energy, whereas $q-$squeezing suppresses it, without changing the large-distance scaling.
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Mesoscale and Nanoscale Physics
Francesco Buonemani, Massimo Balmelli and Olesia Dmytruk
We theoretically study a hybrid
superconductor-
semiconductor platform hosting Majorana bound states coupled to a single mode photonic cavity. Starting with a one-dimensional wire coupled to a bulk $s$-wave
superconductor embedded in a photonic cavity, we derive an effective light-matter
Hamiltonian for such a platform. Assuming that the photonic vector potential is aligned along the tunneling between a wire and a
superconductor, we find that the cavity coupling enters only in the effective superconducting pairing term. By solving the coupled electron-
photon Hamiltonian using different approaches, such as exact diagonalization in case of zero or large number of
photons, high-frequency expansion, and mean-field decoupling, we find that the phase boundary between the topological trivial phases is shifted to smaller values of the Zeeman energy compared to the uncoupled case. Cavity
embedding has the strongest effect on the phase diagram in the semiclassical regime, corresponding to a large number of
photons. In all cases, we find that at large values of the light-matter coupling strength the effective superconducting pairing is suppressed, driving the system into the gapless phase. We demonstrate that even small light-matter coupling strength allows for entering the topological phase at values of the Zeeman energy compared to the uncoupled platform.
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High Energy Physics (Phenomenology)
Electric Dipole Moments in the CP-violating Generational Three-Higgs-Doublet Model
Hao-Ran Ma, Ti-Bin Hou, Jin-Lei Yang et al. (+1 more)
Motivated by the Yukawa interactions in the CP-violating Generational Three-
Higgs-Doublet Model (G3HDM), we investigate the electric dipole moments (EDMs) of the $b$
quark, $c$
quark, electron,
neutron, and mercury atom, imposing constraints from the observed $125~\mathrm{GeV}$
Higgs signals,
flavor physics, and rare $B$-
meson decays. We find that the $b$
quark,
neutron, and mercury EDMs are predominantly controlled by top-enhanced charged-
Higgs amplitudes, whose internal cancellations are generally weak. Meanwhile, pronounced pairwise cancellations between nearly degenerate neutral
Higgs states occur in the $c$
quark, electron,
neutron, and mercury EDMs. Using degenerate perturbation theory, we show that these cancellations originate from approximate relations among the neutral-
Higgs mixing-
matrix elements, which enforce the anti-
alignment of the corresponding CP-odd coupling invariants.
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All authors Hao-Ran Ma, Ti-Bin Hou, Jin-Lei Yang, Tai-Fu Feng
Materials Science
Element priors and target support shape chemical transfer in materials graph networks
Ran Zhao and Kangming Li
Materials graph neural networks must often transfer to chemical regions weakly represented in training data. Such transfer can rely on predefined relations among elements or supervised evidence from target-containing structures, but these pathways are usually entangled. Here, held-out-element splits and incremental target support separate their roles. Without target-containing training structures, formation-energy errors depend strongly on the element representation, particularly for H, O and F. Matched perturbations show that representation-induced sharing matters beyond input dimension or numerical form, while a label-free similarity-graph prior reduces selected zero-shot errors. Adding a few target-containing structures sharply lowers errors and contracts differences among one-hot, k-hot and continuous inputs across ALIGNN and CGCNN. Calibration explains only part of this recovery, and freezing the initial element projection preserves most gains in five of six ALIGNN splits. Target support therefore shifts chemical transfer from reliance on static element relations toward learning from target-containing environments.
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High Energy Physics (Phenomenology)
Radiative pion-pair production in disperon QED
Yizhou Fang, Sophie Kollatzsch, Adrian Signer et al. (+1 more)
Based on the previously developed disperon QED method for incorporating data input into loop processes in Monte Carlo codes, we calculate $ee\to\pi\pi\gamma$ at NLO and include the pion vector form factor within the form-factor scalar QED approximation wherever it is physically justified. By also considering contributions beyond, for which the form-factor scalar QED approach is less well justified, we gain insight into the associated theory uncertainty for selected experimental scenarios. All calculations are implemented and made available within the Monte Carlo framework McMule.
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All authors Yizhou Fang, Sophie Kollatzsch, Adrian Signer, Max Zoller
Adaptation and Self-Organizing Systems
Explosive Synchronization in Inertial Kuramoto Models: Determining Resilience in Power Grids
Cook Hyun Kim, Jihye Kim, Sangjoon Park et al. (+2 more)
Maintaining power-grid stability is essential for a sustainable energy supply. Using empirical power-grid data, we show that the inertial Kuramoto model with correlated powers and coupling strengths provides a relevant framework for analyzing explosive synchronization and grid stability. We identify two distinct synchronization pathways, initiated by population-driven or coupling-driven seed rotors, that yield different order-parameter behaviors. Inertia, in turn, determines whether the resulting seed clusters retain distinct angular velocities. Similar mechanisms govern recovery from external disturbances, linking power-grid resilience to these two nucleation pathways. Our findings provide a microscopic framework for understanding synchronization and recovery, with implications for stable power-grid operation.
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All authors Cook Hyun Kim, Jihye Kim, Sangjoon Park, Jürgen Kurths, B. Kahng
High Energy Physics (Phenomenology)
Neutrino masses and mixing angles in the Plan B Model
Ben Allanach and Prabhoda Chandra Sarjapur
The Plan B Model was proposed to improve the global fit quality of the Standard Model to observables involving the $b\rightarrow s \ell^+ \ell^-$ transition whilst simultaneously providing a qualitative explanation for the small magnitudes of some off-diagonal
quark mixing
matrix entries. The model is based on applying an additional spontaneously broken $U(1)_{3B_3-L_e-2L_\mu}$ gauge
symmetry to the Standard Model with family-dependent
fermion charges. Right-handed
neutrino fields are present and cancel gauge anomalies. We investigate the implications of the Plan B Model for
neutrino masses and mixing angles. The model naturally suggests a Froggatt-Nielsen mechanism for
neutrino masses and mixing hierarchies. We find that an implementation of the Froggatt-Nielsen mechanism works when additional suppression is present from a clockwork mechanism. We show how current
neutrino oscillation data can be fit with order unity fundamental dimensionless couplings.
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Astrophysics of Galaxies
H II region filling factors in NGC 628: Luminosity-size relation and connection with polycyclic aromatic hydrocarbon emission
Lorena Aragüete Riesco, José M. Vílchez, Salvador Duarte Puertas et al. (+7 more)
Understanding the internal structure of H II regions is fundamental for constraining
star formation processes in
galaxies. We investigated how the filling factor (FF) relates to luminosity, size, electron density, and H$\alpha$ equivalent width (EW(H$\alpha$)) in H II regions, and explored its connection with polycyclic aromatic hydrocarbon (PAH)-to-
dust emission as a possible tracer of evolutionary stages. We analyzed 622 H II regions in NGC~628, combining 475 regions from SIGNALS and 147 from PHANGS-MUSE. We derived their luminosities, emission-line fluxes, radii, electron densities, and FF, and used PHANGS-JWST/MIRI imaging to quantify the PAH-to-
dust ratio $R_{\rm PAH}$ from the 7.7, 11.3, and 21~$\mu$m bands. Higher FF and EW(H$\alpha$) values are found in luminous regions, whereas more extended regions with lower EW(H$\alpha$) exhibit lower FF. We show that the H II region radius definition significantly affects the $L_{\rm H\alpha}$–$R$ relation. Low-luminosity compact H II regions appear to mark a transition from cluster-powered regions to nebulae ionized by single massive
stars, around $\log(L_{\rm H\alpha}) \sim 37~{\rm erg \ s^{-1}}$. The PAH-to-
dust ratio correlates with the volumetric H$\alpha$ luminosity density, $L_{\rm H\alpha}/R^3$, with a transition around $\log(L_{\rm H\alpha}/R^3) \sim 32~{\rm erg \ s^{-1}}$, corresponding to $\log({\rm FF}) \approx -4.4$. Regions with lower FF exhibit higher $R_{\rm PAH}$, suggesting less efficient PAH processing in more porous structures. These results are consistent with an evolutionary scenario in which FF decreases with
stellar cluster age as
giant H II regions evolve toward fainter and more extended states. The volumetric H$\alpha$ luminosity density reduces covariance between $L_{\rm H\alpha}$ and $R$ induced by region-definition methods, enabling more consistent cross-catalog comparisons.
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All authors Lorena Aragüete Riesco, José M. Vílchez, Salvador Duarte Puertas, Laurie Rousseau-Nepton, Carmelle Robert, René Pierre Martin, Philippe Amram, Robert Kennicutt Jr., Christophe Morisset, Ray Garner III
Materials Science
Fourier Neural Operators for Composition-Driven Crystal Structure Discovery
Zhijie Yu, Jingyu Li, Yang Huang et al. (+1 more)
Crystalline materials discovery is essential for energy, electronics, and catalysis, but the vast chemical and structural space makes exhaustive screening infeasible. Existing voxel-based methods are limited by the local receptive fields of three-dimensional convolutional neural networks and the posterior collapse of high-dimensional variational autoencoders. Here, we develop a
Fourier Neural Operator (FNO)-based
crystal-field solver that maps a prescribed chemical formula and
lattice parameters to periodic number-density and electron-density fields. By operating on global
Fourier modes, the solver captures long-range correlations in periodic
crystal fields beyond conventional local convolutions. Building on this solver, we construct a coupled generation-solving framework in which a conditional variational autoencoder generates diverse candidate
lattice parameters in a low-dimensional basis-coefficient space, followed by density-field prediction and atomic reconstruction through peak detection, position optimization, and weight optimization. The reconstructed structures are further screened using voxel-level filtering, machine-learning interatomic-potential relaxation, and first-principle calculations. The framework generates novel structures across 104 chemical formulas with competitive reconstruction accuracy, demonstrating high generative diversity and structural validity. By extending
Fourier neural operators to periodic
crystal fields and coupling them with composition-conditioned
lattice generation, our approach provides a scalable route to
crystal structure discovery from prescribed chemical compositions.
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All authors Zhijie Yu, Jingyu Li, Yang Huang, Jingrun Chen
Optics
Direct Optimization of a 3D Finite-Source Reflector via Neural-Network Parameterization
Roel Hacking, Lisa Kusch, Martijn Anthonissen et al. (+1 more)
We present a direct optimization method for three-dimensional freeform reflectors that transform the light of a finite-étendue source into a prescribed far-field angular intensity distribution. The reflector profile is represented by a small neural network (a multilayer perceptron), which is trained end-to-end through a differentiable ray-tracing objective. We furthermore parameterize the emission directions in gnomonic coordinates, and show how we use this to ensure that every emitted ray intersects the reflector. At each iteration, the network is converted to a bicubic spline representation for ray-tracing efficiency, and intersections with this smooth surface are solved by a damped Newton solve, with gradients computed via the implicit function
theorem. The traced output distribution is compared with the desired target on a 'soft' histogram, under an $H^{-1}$-type spectral weighting that emphasizes long-range transport of flux to improve convergence. Optimization is performed using a BFGS method with self-scaled Broyden updates and a plateau-perturbation rule to prevent stalling. The method converges reliably within seconds on a single GPU for all examples tested.
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All authors Roel Hacking, Lisa Kusch, Martijn Anthonissen, Wilbert IJzerman
Nuclear Theory
Femtoscopy as a New Probe of the Nuclear Equation of State
Xialei Jiang, Jiaxing Zhao, Yingjie Zhou et al. (+1 more)
Femtoscopic correlations are widely regarded as precision probes of hadronic interactions through
vacuum final-state interactions after kinetic freeze-out. Here we demonstrate that, in
baryon-rich heavy-ion collisions, the
nuclear mean field generates an additional dynamical contribution to femtoscopic correlations during the transport
evolution. Using the Parton-
Hadron-
Quantum-Molecular Dynamics (PHQMD) transport approach, we investigate
proton-
proton,
proton-$\Lambda$, three-
proton, and
proton-
proton-$\Lambda$ correlations in Au+Au collisions at $\sqrt{s_{\rm NN}}=3$, 4.5, 7.7, and 19.6 GeV. We find that the
nuclear mean field produces a characteristic low-$k^*$ enhancement that is strongest at the lowest beam energies and gradually disappears with increasing collision energy. Furthermore, both the stiffness and the momentum dependence of the
nuclear equation of state leave distinct signatures in the femtoscopic correlation functions, with higher-order correlations exhibiting substantially enhanced sensitivity compared with conventional two-particle observables. Our results demonstrate that femtoscopy extends beyond its traditional role as a tool for studying hadronic interactions and serve as a new class of microscopic observables for the
nuclear equation of state, complementary to collective flow and subthreshold strangeness production, thereby opening a new avenue for exploring dense baryonic matter in low-energy heavy-ion collisions.
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All authors Xialei Jiang, Jiaxing Zhao, Yingjie Zhou, Xiaofeng Luo
High Energy Physics (Phenomenology)
The Type-I Seesaw as a Relativistic Fermionic Proximity Effect: Spectral Moments, EFT Consistency, and Sterile-Sector Reconstruction
Jianlong Lu
We formulate the type-I seesaw as a relativistic fermionic proximity effect in the exact active-sector two-point kernel. Active
neutrinos have no renormalizable gauge-invariant Majorana mass and couple by
lepton-number-conserving Yukawa hybridization to a sterile Majorana pairing kernel. Integrating out the sterile fields gives a nonlocal Nambu-Gorkov
embedding self-energy. In a sterile Takagi basis its anomalous and normal
flavor responses are $\mathcal{A}(Q^2)=\sum_i M_i y_i y_i^T/(Q^2+M_i^2)$ and $\mathcal{B}(Q^2)=\sum_i y_i y_i^\dagger/(Q^2+M_i^2)$, respectively. Their low-energy expansions generate correlated
lepton-number-violating and
lepton-number-conserving moment towers. The leading moments reproduce the Weinberg coefficient and the dimension-six kinetic operator. Both towers share one sterile mass set; its positive normal support supplies a common annihilator, although anomalous residues can cancel at exact degeneracy. We prove normal block-Hankel positivity and positivity of a dimensionally rescaled mixed Nambu-Hankel sequence. The latter gives
matrix Cauchy-Schwarz inequalities between
lepton-number-conserving and
lepton-number-violating data and can reveal paired directions hidden by a degenerate normal residue. Isolated nondegenerate pole residues satisfy an additional nonlinear compatibility identity. These results yield tree-level EFT consistency tests and a
matrix-pencil reconstruction of visible pole and aggregate-residue data; selecting a unique ultraviolet Lagrangian requires additional information about sterile-basis multiplicities. An exact one-generation example distinguishes the static Schur-complement kernel from the physical Takagi pole mass. The proximity structure applies without a
Fermi surface or condensate, and Nambu doubling introduces no new physical degrees of freedom.
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Materials Science
Large Exchange Magnetostriction in a Kagome Antiferromagnet at Room Temperature
Jie Du, Liang Yao, Hang Li et al. (+5 more)
The pursuit of high-performance magnetostrictive materials is crucial for advancing technologies in sensing, actuation, and microelectromechanical systems. Although pronounced magnetostrictive effects have been observed in a few ferromagnets, a systematic exploration of magnetostriction across a broader range of antiferromagnets remains limited. Here, we report the observation of large magnetostriction in the kagome antiferromagnet YMn6Sn6. Under a
magnetic field, the system undergoes a field-induced
evolution from a helical
magnetic ground state toward a collinear field-polarized state, accompanied by a large anisotropic
lattice strain and a substantial volume magnetostriction exceeding 400 ppm at room temperature. Remarkably, the magnetostrictive response remains nearly fully reversible up to 9 T with nearly hysteresis-free behavior, effectively minimizing the energy dissipation commonly associated with domain-wall pinning. Combined experimental measurements and theoretical calculations reveal that the large, nearly hysteresis-free magnetostriction originates from the competition between intralayer
ferromagnetic and interlayer exchange interactions. This exchange-driven magnetoelastic coupling further gives rise to a strongly direction-dependent
lattice distortion pathway. This work establishes kagome helimagnets as a tunable platform for low-dissipation magnetoelastic functionalities and responsive magnetomechanical applications.
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All authors Jie Du, Liang Yao, Hang Li, Xiaodong Zhou, Yuan Yao, Xuekui Xi, Yong-Chang Lau, Wenhong Wang
Data Analysis and Statistics · Cross-listed from cs.LG
iPINN for Broadband CARS Phase Retrieval: A Framework for Function Approximation and Inverse Modeling Problems in Nonlinear Spectroscopy
Ravi Teja Vulchi, Carl Messerschmidt, Mohammadsadegh Vafaeinezhad et al. (+4 more)
Phase
retrieval in broadband coherent anti-Stokes Raman spectroscopy (BCARS) is an ill-posed inverse problem. The Raman-like signal is encoded in the imaginary part of the resonant susceptibility, which mixes coherently with a non-resonant background (NRB) that varies across acquisitions. We introduce an inverse physics-informed neural network (iPINN) that predicts Lorentzian peak parameters from raw BCARS spectra and reconstructs the resonant susceptibility through a differentiable analytical forward model. A
transformer encoder assigns spectral features to 24 learnable peak slots, and a multi-view consistency loss enforces invariance across NRB pattern, NRB strength, and noise. Unlike direct spectral regression approaches, the method retains accuracy under varying acquisition conditions. On a public
benchmark, iPINN achieves the lowest error among the tested baselines (MAE 0.016 vs. next-best 0.046). On 28 zero-shot test spectra acquired across seven solvents and four focal positions, accuracy is depth-invariant in five of seven solvents. These results show that inverse parametric prediction with a differentiable physical decoder supports robust phase
retrieval across measurement conditions.
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All authors Ravi Teja Vulchi, Carl Messerschmidt, Mohammadsadegh Vafaeinezhad, Rajendhar Junjuri, Tobias Meyer-Zedler, Juergen Popp, Thomas Bocklitz
General Relativity and Quantum Cosmology
Reissner-Nordstrom in the Bertotti-Robinson-Bonnor-Melvin electromagnetic field
Marco Astorino
The
magnetic Reissner-Nordstrom black hole embedded into the Bertotti-Robinson
magnetic field is presented. Then it is used, as a seed, to generate, through the Harrison transformation of the Ersnt's equations, the Reissner-Nordstrom metric in the Bertotti-Robinson-Bonnor-Melvin
magnetic field. Special cases generalising, the
vacuum hairy type I Schwarzschild solution is discussed. The local equivalence between various forms of the Schwarzschild-Bertotti-Robinson is shown by exhibiting the explicit diffeomorphism.
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Quantum Physics
Towards Natural Gas Contract Selection via Quantum-Guided Independent Set Reduction
Vivek Dixit, Vaibhaw Kumar, Kentaro Ohno et al. (+2 more)
Selecting mutually compatible natural gas transportation contracts is a practically important optimization task in which operators must choose from many candidate agreements subject to temporal, infrastructural, and flow-related constraints. As the number of candidates grows, the resulting search space becomes difficult to explore exhaustively. We study a pairwise abstraction of this task, formulated as a Maximum Clique problem on a contract-compatibility graph, or equivalently as a Maximum Independent Set (MIS) problem on the complement graph. Building on recent work, this paper studies a
quantum-classical framework for solving large-scale MIS instances within the limitations of noisy
quantum hardware. The approach combines iterative classical graph reduction with
quantum-guided optimization to progressively simplify the search space while maintaining high solution quality. This enables large candidate spaces to be reduced to smaller subproblems that are more suitable for execution on current
quantum computers. We evaluate the approach on fifteen
benchmark instances from the
Quantum Optimization Benchmarking Library (QOBLIB), obtaining an average approximation ratio of 0.996 and recovering optimal solutions for fourteen instances, including graphs with up to 186 vertices. We further evaluate the
algorithm on six synthetic pairwise contract-compatibility graphs containing up to 900 contracts, where the proposed method achieves an average approximation ratio of 0.989 and obtains optimal solutions in four cases. These experiments demonstrate the ability of the hybrid MIS solver to reduce industrially motivated graphs. The pairwise abstraction serves as the first step of a two-stage screening procedure that narrows the candidate contracts to a smaller set of mutually compatible ones, which can then be verified against pipeline-capacity constraints.
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All authors Vivek Dixit, Vaibhaw Kumar, Kentaro Ohno, Alberto Maldonado Romo, Larry Bowden
Mathematical Physics
A general improbability result for non-collision singularities as subsystems with at most four particles
Manuel Quaschner
Non-collision singularities of the $n$-body problem are initial conditions for which no global solution exists and which, however, do not lead to a collision in the limit; i.e., the moment of inertia of the system diverges. The question of whether the set of initial conditions leading to non-collision singularities in the $n$-body problem is improbable is open and is the first on Barry Simon's list of fifteen problems in mathematical physics from the year 1984. So far, this question has only been answered positively in the case $n=4$. Using a final cluster decomposition into subsystems whose particles interact strongly with each other and exert only small forces on particles from different subsystems, we can prove the improbability of the set of all singular orbits with the following conditions: -There may be arbitrarily many subsystems undergoing total collision at their center of mass. - There may be subsystems exhibiting a non-collision singularity, i.e. the respective moment of inertia of the subsystem diverges. These subsystems consist of exactly four particles each and the asymptotic directions of these subsystems have to differ (which is only a mild condition). This result includes all known statements and indicates a way how the general problem could be solved.
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Computational Physics · Cross-listed from math.OC
Stochastic Optimization of Tree Tensor Networks
Marius Willner, Maximilian Scharf, André Uschmajew et al. (+2 more)
Tensor networks, originally developed for
quantum many-body physics, are promising models for machine learning. We derive
stochastic Riemannian optimizers for tree tensor networks (TTNs) on both their parameter and quotient
manifolds, including adaptive and learning-rate-free schemes suitable for minibatch training. Using a hybrid CNN-TTN architecture, we evaluate the methods on Fashion-MNIST, CIFAR10, and Imagenette. The proposed optimizers achieve predictive performance comparable to unconstrained optimization while enabling numerically stable downstream compression.
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All authors Marius Willner, Maximilian Scharf, André Uschmajew, Timo Felser, Marco Trenti
High Energy Physics (Phenomenology)
Understanding IR singularities in the Loop-Tree Duality
Germán Rodrigo, Leandro Cieri, Prasanna K. Dhani et al. (+11 more)
One of the main advantages of the Loop-Tree Duality representation of scattering amplitudes is that it makes the origin of infrared and threshold singularities particularly transparent. This talk reviews recent progress in describing how singularities emerge and cancel at the level of scattering and
vacuum amplitudes, discusses a novel strategy to efficiently construct finite integrals, and presents a complementary perspective based on encoding the underlying causal and singular structure in terms of
qubits and
quantum circuits.
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All authors Germán Rodrigo, Leandro Cieri, Prasanna K. Dhani, Roger J. Hernández-Pinto, Jorge J. Martínez de Lejarza, Salvador A. Ochoa-Oregon, Konstantinos Pyretzidis, Selomit Ramírez-Uribe, David F. Rentería-Estrada, Andrés E. Rentería-Olivo, José Ríos-Sánchez, German F.R. Sborlini, Surabhi Tiwari, Juan P. Uribe-Ramírez
Mathematical Physics · Cross-listed from math.PR
Uniform Partition-Function Estimates for Coulomb Modulated Energy at All Positive Temperatures
Zhenfu Wang and Xianliang Zhao
We prove uniform-in-$N$ partition-function estimates at all positive temperatures for the centered modulated energy of logarithmic, Riesz, and Bessel–Riesz kernels on $\mathbb R^d$ in the locally square-integrable range $0\le s<d/2$. They yield finite-particle exponential integrability, quadratic behavior at small parameter, explicit kernel-dependent growth at large parameter, and uniform
entropy control of the associated Gibbs measures. As applications, we obtain uniform Rényi-divergence and relative-
entropy bounds for interacting Gibbs
equilibria and entropic mean-field convergence near thermal
equilibrium; the optimal $N^{-1}$ normalized relative-
entropy rate for the three-dimensional Coulomb flow; and an $N^{-1/2}$ Gaussian approximation for fixed-time finite-dimensional fluctuations. Finally, the modulated energy converges to a random variable in the second Wiener chaos, and for every positive parameter the partition functions converge to its Laplace transform, represented by a Carleman–Fredholm determinant. This formula identifies the sharp small-parameter behavior and, when the reference density is bounded below on a ball, the sharp large-parameter growth.
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Materials Science
Independent Tuning of Surface Acoustic-Waves and Spin-Waves via Buffer-Layer Engineering in Co2FeGe Heusler Thin Films
A. V. Achuthan, A. Vovk, S. Bunyaev et al. (+7 more)
Understanding and controlling acoustic and
spin-wave excitations in
magnetic thin films is critical for the development of magnonic and
spin-acoustic devices. We report on the use of Cr and W buffer layers to independently modify the acoustic and
magnetic excitations in Co2FeGe full-Heusler thin films grown on MgO(001). Using Brillouin light scattering (BLS) spectroscopy and
ferromagnetic resonance (FMR), we probed Rayleigh and Sezawa surface acoustic waves (SAWs) alongside Damon-Eshbach and perpendicular standing
spin-wave (PSSW) modes. Our results show that acoustic dispersion depends strongly on the buffer material; W-buffered films exhibit a pronounced 16% reduction in Rayleigh SAW frequency compared to buffer-free films, primarily due to mass loading and acoustic impedance shifts. While the buffer layers significantly shift acoustic frequencies, they simultaneously modify the dynamic
magnetic response (increasing
spin-wave group velocity by ~34%) through different physical mechanisms. Finite-element simulations show excellent agreement with the experimental acoustic data. These findings demonstrate that buffer-layer engineering is an effective strategy for the independent tailoring of elastic and
magnetic excitations, providing a versatile platform for hybrid
spin-acoustic technologies.
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All authors A. V. Achuthan, A. Vovk, S. Bunyaev, B. Postolnyi, P. Štrichovanec, P. A. Algarabel, K. Załęski, J. P. Araujo, G. N. Kakazei, A. Trzaskowska
Solar and Stellar Astrophysics
On the photospheric abundances of the B-type fast rotator Regulus
Yoichi Takeda
A spectroscopic study of Regulus (late B-type rapidly-rotating
star) was conducted with an aim of investigating its photospheric chemical abundances (especially for light elements), which has barely been challenged so far because of the considerable difficulty of abundance determination for such a very fast rotator (>~300 km/s). The atmospheric parameters were determined to be T_eff = 12345K (effective temperature) and log g = 3.58 (surface
gravity) based on the spectral energy distribution, while the microturbulence was estimated as v_t = 0.5 km/s. The abundances of 14 elements (He, C, N, O, Ne, Mg, Si, S, Ca, Ti, Cr, Mn, Fe, and Ni) were derived by applying the spectrum-fitting technique, where the non-LTE effect was taken into account for lighter elements from He to Ca. The resulting relative-to-the-Sun abundances ([X/H]) revealed a remarkable trend that, while most elements indicate near-
solar abundances (within +/-<~0.3dex), only C shows a marked deficiency ([C/H]~ -1.4) which is hard to explain. For example, a simple scenario of C underabundance caused by mixing of CN-cycled product (e.g., due to rapid rotation or binary mass transfer) is unlikely because any N enrichment is not observed. This problem remains yet to be further investigated.
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Optics
Spatio-temporal coherent molding and retrieval of pulsed signals in optical waveguides
Nika Durishvili, Ramaz Khomeriki, Vakhtang Jandieri et al. (+3 more)
Optical waveguides are key elements for high fidelity, long distance optical communications. Coupled waveguide arrays allow for higher information density, steerting the propagation direction, and for encoding information. However, due to the mixing of relative phases for short pulses containing multiple waveguide-mode frequencies, a process for retrieving an encoded input state once these signals undergo coherent propagation remains elusive. A concept is presented to extract with high fidelity the phase-encrypted input signal from spatio-temporal propagated states. As a realization, an array of coupled waveguides is suggested with the
retrieval mechanism being realized by local phase shifts that comply with the identified
retrieval concept. Three dimensional full-wave electromagnetic simulations for broadband optical signals in coupled dielectric waveguides confirm the validity of the scheme and the high fidelity of information
retrieval pointing to potential applications, for instance in ultrafast coherent coding and decoding of information imprinted on pulse sequences.
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All authors Nika Durishvili, Ramaz Khomeriki, Vakhtang Jandieri, Douglas H. Werner, Daniel Erni, Jamal Berakdar
Quantum Physics
Structure-Aware Placement and Routing of Multi-Controlled Toffoli on Bivariate Bicycle Code Architectures
Anik Basu Bhaumik, Suman Dutta, Siyi Wang et al. (+1 more)
The multi-controlled Toffoli (MCT) gate is a fundamental primitive in
quantum circuit design, with applications in
quantum arithmetic, cryptanalysis, and algorithmic implementations. Being a high-level logical operation, the efficient decomposition of MCT gates into lower-level netlists has remained a major optimization challenge for decades. While emerging
quantum error-correcting codes such as bivariate bicycle (BB) codes drastically reduce fault-tolerance overhead, realizing non-Clifford
circuits on modular BB-code architectures introduces complex compilation bottlenecks governed by inter-module routing, factory density, and layout. Consequently, the mapping of MCT gates onto BB-code architectures remains relatively unexplored. In this paper, we overcome these challenges by mapping optimal-Toffoli-depth MCT decompositions (Dutta et al., PRA, 2025) onto BB-code-based fault-tolerant architectures via direct $\lvert \mathrm{CCZ} \rangle$ state injection from an external magic state factory. We introduce a targeted placement strategy that exploits the binary-tree structure of MCT decompositions to co-locate interacting subtrees. This approach reduces inter-module instruction counts by up to $\mathbf{16.02}\%$ compared to a naive sequential first-fit placement. We also evaluate the impact of factory placement across different
topologies, demonstrating that grid-based layouts yield up to a $\mathbf{23.7}\%$ reduction in inter-module instructions relative to linear architectures (Yoder et al., arXiv, 2025). Finally, we validate the practical viability of our compiled
circuits by analyzing aggregate execution errors and logical failure probabilities using the bicycle-ISA error
estimator bicycle_numerics provided by the Qiskit community, https://github.com/qiskit-community/bicycle-architecture-compiler.
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All authors Anik Basu Bhaumik, Suman Dutta, Siyi Wang, Anupam Chattopadhyay
Nuclear Theory
Hyperonic Softening versus Nucleonic Three-Body Repulsion in Hypernuclear Matter within a microscopic approach
Mahboubeh Shahrbaf
We investigate cold homogeneous matter composed of
neutrons,
protons, and $\Lambda$ hyperons within our hyperonic extension of the lowest-order constrained variational (LOCV) method, hereafter denoted LOCVY. Our earlier LOCVY calculation, based on two-
baryon interactions, is extended by supplementing the Argonne $v_{18}$ nucleonic interaction with the Urbana IX three-nucleon force, reduced within the variational framework to a correlation-weighted density-dependent effective two-nucleon interaction. The $N\Lambda$ and $\Lambda\Lambda$ interactions are kept unchanged, allowing the present calculation to isolate the competition between hyperon-induced softening and nucleonic three-body repulsion. The energy per
baryon is calculated for fixed $\Lambda$ fractions $Y_{\Lambda}=0$, $0.1$, and $0.2$ in matter with a symmetric nucleonic component and in the
proton-free
neutron–$\Lambda$ limit. Direct differences between calculations with and without the three-body force quantify its density-dependent contribution, while a complementary decomposition into $NN$, $N\Lambda$, and $\Lambda\Lambda$ terms identifies the microscopic origin of the stiffening. The Urbana contribution becomes increasingly repulsive with density and opposes, but does not generically remove, the softening associated with a finite $\Lambda$ content. We further investigate the saturation properties for several prescribed $\Lambda$ fractions, with and without the nucleonic three-body force, to clarify how strangeness and many-body interactions modify the saturation point and the agreement with empirical
nuclear-matter properties.
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Fluid Dynamics
Assessment of Numerical Lift Coefficient Data for a Circular Cylinder with Application to Bladeless Turbines
L. Ridgway Scott and Henry von Wahl
We assess computed lift coefficient data for flow past a circular cylinder to evaluate their suitability for practical applications. Specifically, we consider lift coefficient data for a circular cylinder over Reynolds numbers from 120 to 8000. The results are obtained from two-dimensional finite element simulations of the incompressible Navier-Stokes equations using pressure robust discretizations. We compare the computed lift coefficients with published experimental and numerical results, finding good agreement in some cases but significant disagreement in others. Because lift fluctuations are central to
vortex-induced vibration concepts, these data therefore provide input for the analysis and preliminary design of bladeless turbines.
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Soft Condensed Matter
Optimizing diffusion-limited transport, with applications to electrochemical systems
Manu Mannattil and L. Mahadevan
Transport in certain systems fails when
diffusion cannot replenish or remove material from a boundary rapidly enough, causing the boundary concentration to reach a critical minimum or maximum. Motivated by experiments in electrochemical systems that demonstrate this
diffusion-limited failure of charge transport, we determine dynamic current protocols that maximize charge transfer subject to a prescribed concentration constraint. The optimal protocol has a "bang-ride" structure: the maximum feasible current is used until the boundary concentration reaches its critical value, after which the current is progressively reduced to maintain that value. For semi-infinite domains, we derive the optimal currents analytically and obtain system-independent upper bounds on their improvement over constant-current operation. We also extend the framework to finite and multilayer domains and show that the same formulation applies to both charging and discharging.
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Quantum Physics
Ontic and epistemic states in the theory of spacetime-local beables
Nathan Argaman
Bell's
theorem rules out developing a locally causal theory to describe
quantum phenomena. Many take this to imply that any model of
quantum entanglement must employ variables (called beables by Bell) which follow nonlocal rules, even though signaling is local. The alternative is to adopt an all-at-once (block universe) approach, with beables which may depend on both past and future inputs, even though signaling is causal. Within this lenient-causality approach (a.k.a. retrocausal), simple cases of
entanglement have been successfully described by locally mediated
stochastic toy models, i.e.,~toy models which are local in a sense which generalizes Bell's local causality. Developing a widely applicable reformulation of
quantum mechanics along these lines is a grand challenge. This work presents a general framework for such models and theories, and identifies the corresponding ontic and epistemic states. The epistemic state is closely analogous to the
quantum state, yielding an explanation for the collapse of the wavefunction. In the case of the models of the framework, it is clear what the information is about. The expression for the empirically verifiable predictions of the models in terms of the ontic and epistemic states displays remarkable parallels to the Born rule. A toy-model example is discussed.
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Atmospheric and Oceanic Physics
A Checklist to assess the energy and carbon impacts of ML/AI applications in Earth System Modeling
Filippo Dainelli, Amirpasha Mozaffari, Marina Castaño et al. (+5 more)
As machine learning and artificial intelligence find their way into nearly every aspect of
climate, weather, and Earth system modeling, it is worth pausing to consider what our design decisions imply for the science and for the computational resources we consume. A growing body of literature addresses the ethical and sustainable development of ML/AI, yet translating these principles into day-to-day research practice remains a challenge as most of best practices are dispersed across multiple studies and commentaries. Here, we distill these discussions into a practical checklist that ML/AI and Earth system science practitioners can use to assess and reduce the environmental footprint of their own applications, organised around the successive stages of the model development pipeline. We complement the checklist with a selection of metrics drawn from the literature for estimating the energy consumption and carbon footprint of a project. For each question, we point to concrete examples and actionable suggestions from recent literature, aiming to bridge the gap between aspirational principles and the decisions researchers face at every stage of the development cycle.
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All authors Filippo Dainelli, Amirpasha Mozaffari, Marina Castaño, Aina Gaya i Àvila, Lluís Palma Garcia, Alessio Melli, Oscar Dimdore Miles, Amanda Duarte
High Energy Physics (Experiment)
Neutrino Experiments at the LHC and the HL-LHC
Chayanit Asawatangtrakuldee and Albert De Roeck
High energy
neutrinos are copiously produced in
proton-
proton collisions at the Large
Hadron Collider (LHC), located at CERN, near Geneva, Switzerland. In particular, a large
neutrino flux is expected in the far-forward direction. This flux is concentrated near the beam axis, reaches energies up to the TeV scale, and for electron and tau
neutrinos can be dominated by heavy flavour decays at the highest energies. These features open a new experimental window for studying
neutrino interactions with dedicated forward detectors, in an energy range beyond the reach of traditional accelerator-based
neutrino experiments. The new FASER and SND@LHC experiments reported the first direct observations of
neutrino interactions at a
hadron collider using the first data from Run 3, which started in 2022. Since then, the programme has advanced to the first measurements, including charged-current
neutrino-nucleon cross sections and the detection of different
neutrino flavours. This article describes the forward
neutrino flux at the LHC, the acceptance and detector concepts of the Run 3 experiments, and summarises the current status of
collider neutrino measurements. It also discusses prospects for extending this
neutrino programme towards the HL-LHC era. The collected data will also provide constraints on very forward
hadron production, and enable searches for feebly interacting particles.
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