Materials Science
In-situ total scattering investigation of crystalline ordering in amorphous ion-beam sputtered thin films for interferometric gravitational wave detectors
Alberto Martinelli, Giulio Favaro, Giacomo Ciani et al. (+9 more)
Amorphous tantala is an important optical material used in a number of high-precision optical applications, including gravitational wave interferometry. In this paper, we study in-situ the structural changes that occur in amorphous ion-beam sputtered coatings during an annealing treatment by means of a synchrotron radiation scattering experiment. The scattering signal is measured as a function of time on a large range of the Q-space. X-Ray diffraction and Rietveld analysis are used to study crystallization during the annealing treatment, whereas pair distribution function analysis allows to inspect the structural changes occurring during the amorphous to crystalline transition. Our findings indicate that several structural rearrangements occur in parallel, namely a first quick establishment of a backbone structure in the cationic substructure appearing on a rather extended range (up to 100 Angstrom), followed by a progressive rearrangement of the oxygen atoms environment which gradually increases the crystallinity of the structure.
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All authors Alberto Martinelli, Giulio Favaro, Giacomo Ciani, Livia Conti, Jean-Pierre Zendri, David Hofman, Massimo Granata, Angela Trapananti, Flavio Travasso, Laura Silenzi, Valeria Milotti, Marco Bazzan
Physics and Society
The social consequences of AI delegation
Henrique Ferraz de Arruda and Yamir Moreno
A substantial body of recent work has debated whether large
language models (LLMs) can serve as substitutes for human participants in behavioural research. This debate, however, captures only one direction of a rapidly changing relationship. The more consequential question is not simply whether researchers should use LLMs as human surrogates, but whether - and under what conditions - humans are beginning to use LLMs as surrogates for their own deliberation. Across domains including health, law, finance, education, and personal guidance, increasing numbers of people consult generative AI systems before, alongside, or instead of human experts, peers, or independent judgment. Although evidence for actual delegation remains uneven, this uncertainty makes the phenomenon an urgent social-scientific object of study. We argue for a research programme that treats LLMs as consequential social actors in a functional sense: systems whose outputs shape human decisions, social norms, and collective dynamics.
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Superconductivity
On pseudogap phase as precursor to a superconducting dome in high-Tc cuprates: Non-analytic T* as a function of doping
Felix A. Buot
We generalize the condition under which a
quantum material exhibiting a pseudogap phase is a precursor to a superconducting (SC) dome. The result reveals the non-analytic T* as a function of doping. A well-known example is the high-Tc cuprates. Essentially, the SC dome is generated under two conditions: (1) that the pseudogap T* is a decreasing function of doping, due to the decrease in size of extended pairing of doped holes with doping, and most importantly, (2) that the rate of configurational-ordering parameter is an increasing function of doping as a result of the decrease in extended length of the disordered pairs. The theory behind these hinges on a novel strong
entanglement and confinement hole pairing (ECHP) mechanism that unravels the microscopic features of the entire phase diagram of both electron and hole-doped high-Tc cuprates, recently discussed in the by Buot et al. The ECHP configurational ordering (CO) at the underdoped and overdoped regions qualitatively agrees with
spin texture experiments, and strongly suggests that strange metal phase can only occur in the overdoped region, in agreement with experiments.
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Fluid Dynamics · Cross-listed from math.AP
Exponential mixing and enhanced dissipation on the unit sphere with Rossby-Haurwitz flows
Augusto Del Zotto and Marc Nualart
We exhibit a family of smooth incompressible velocity fields on the two-dimensional unit sphere such that the time
evolution of any mean-free initial data passively advected by any of them is mixed exponentially fast. In the presence of molecular diffusivity, we show that the solution to the associated advection-
diffusion equation experiences enhanced dissipation with optimal decay rates. Each member of this family is an alternating combination of two Rossby-Haurwitz flows with random amplitudes and constitutes a spherical analogue to the sine shear-alternating example of Pierrehumbert.
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Atomic Physics
Colloquium: Nuclear clocks
Andrei Derevianko, R. Elwell and Eric R. Hudson
The Th-229
nuclear isomeric state has the lowest energy of all known
nuclear excited states, placing it within the reach of current table-top
laser technology. This extraordinary property has made this
nuclear isomer an attractive candidate for a
nuclear optical clock of incredibly high precision and accuracy, both as isolated trapped Th-229 ions and embedded into solid-state platforms. Activity around Th-229 has surged in recent years, driven by breakthroughs in its direct
laser excitation. The underlying
nuclear physics that gives rise to this unique isomer will be elucidated, as well as the nearly half-century of efforts that led to its direct excitation. The design and systematics of a Th-229
nuclear clock will be discussed, both in ion traps and in the solid-state. These systematics, such as frequency shifts and quenching channels, can be leveraged both to probe the local chemical environment, and as a control knob during clock operation. Finally, the
nuclear clock's high sensitivity to the variations of fundamental constants will be discussed.
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Statistical Mechanics
Extensible links in a broad class of single polymer chain models
Michael R. Buche, Matthew J. Grasinger and Jason P. Mulderrig
The physics of
polymer chains is often probed using molecular stretching experiments and various idealized single-chain models. The majority of these models consist of a discrete sequence of links, which may be treated as rigid or extensible. Although such models are well established and many specific extensible variants have been proposed, no generally applicable theory has been presented. Moreover, most existing treatments are heuristic rather than systematically and rigorously derived. This critical gap is closed here through the development of a generally applicable asymptotic theory for including link extensibility in a broad class of discrete models for single-chain thermodynamics. The theory is verified analytically using the freely jointed chain and validated numerically using the freely rotating chain. The resulting approximation is first-order accurate in inverse link stiffness, with quadratically decreasing error, and recovers extensible behavior across all link stiffnesses from a single rigid-link reference calculation.
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High Energy Physics (Experiment)
The SHiP/NA67 experiment at the ECN3 high-intensity beam facility at the CERN SPS
Matei Climescu
The Search for Hidden Particles (SHiP/NA67) is a general-purpose, high-intensity beam dump experiment approved in 2024 for the future exploitation of the ECN3 experimental
hall at the CERN Super-
Proton-Synchrotron in conjunction with the new Beam Dump Facility (BDF). It will collect $6\times10^{20}$
protons on target over $\sim$15 years of operation. SHiP is designed to probe the largely underexplored domain of feebly interacting particles with masses in the $\mathcal{O}(100~\mathrm{MeV})$ to few-GeV range, providing leading sensitivity to most models predicting particles within this range, notably heavy neutral
leptons, dark
photons, dark scalars,
axion-like particles and light dark matter. The intense flux of
neutrinos of all flavours produced in the dump additionally enables a rich Standard Model and
neutrino-physics programme with notably $\mathcal{O}(10^3)$ $\nu_{\tau}$ per year of operation, thus bringing forward a study of $\nu_{\tau}$ phenomenology. This contribution summarises the physics motivation, the experimental concept and the detector subsystems, and outlines the expected sensitivity and timeline.
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Materials Science
Synthetic pre-training of graph-network models for predicting solid-state NMR parameters
Chiheb Ben Mahmoud, Carlos Bornes, Christopher J. Heard et al. (+3 more)
Nuclear magnetic resonance (NMR) is a powerful probe of atomic structure, but accurate
quantum-mechanical predictions of tensorial NMR parameters are computationally demanding. This creates a bottleneck both for direct
quantum-mechanical studies and for collecting high-quality training data for machine-learning (ML) models. Here, we introduce a synthetic pre-training and fine-tuning protocol for graph-based ML models of solid-state NMR parameters. We first pre-train models on synthetic tensorial data, as obtained using an existing ML model, and subsequently fine-tune those models on new ground-truth data. We observe a pronounced improvement in data efficiency when pre-training and fine-tuning span the same compositional and configurational space, and we carry out initial experiments regarding chemical transferability. Our work outlines a route toward future data-efficient training workflows for tensorial ML models for solid-state NMR, combining inexpensive synthetic supervision with targeted first-principles refinement.
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All authors Chiheb Ben Mahmoud, Carlos Bornes, Christopher J. Heard, Lukáš Grajciar, Jonathan R. Yates, Volker L. Deringer
Astrophysics of Galaxies
The Small-scale Structures in the Wind of Messier 82
Yucheng Guo, Timothy Heckman, Sanchayeeta Borthakur et al. (+10 more)
Small-scale multiphase structure plays a central role in
galactic-wind
evolution, yet the parsec-scale morphology and excitation of the warm ionised gas remain poorly constrained. We present deep HST narrow-band imaging of the southern wind of Messier~82 (M82) in Halpha, [OIII], [SII], and [NII], designed to resolve the warm ionised phase on parsec scales. The Halpha emission is detected to 2.1 kpc above the disk, while the fainter emission lines are detected over smaller radial extents, with [OIII] reaching 1.5kpc. We develop a filament-finding pipeline for the Halpha image and construct a quantitative catalogue of the filamentary structures. The wind forms a highly connected network of strands and
knots, dominated by compact filaments with typical projected widths of 5.3pc and lengths of 9.5pc. Both the projected covering fraction and the line-flux contribution of the filamentary component decline with height, showing that the outer wind becomes increasingly dominated by diffuse emission. Optical line-ratio diagnostics indicate that the warm ionised gas occupies an intermediate excitation regime: photoionisation by the central starburst can energetically power the observed Halpha luminosity, while the systematic separation between filamentary and diffuse emission, together with the
evolution of the line ratios with vertical distance, suggests an increasing contribution from shocks or other similar heating in the diffuse outer wind. These results show that separating filamentary and diffuse emission in high-resolution imaging provides a powerful way to connect the morphology, excitation, and multiphase structure of
galactic winds.
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All authors Yucheng Guo, Timothy Heckman, Sanchayeeta Borthakur, Peixin Zhu, Rosalia O'Brien, Ralph S. Sutherland, Lisa J. Kewley, Lee Armus, D. B. Fisher, Sebastian Lopez, Brant E. Robertson, Evan E. Schneider, Patrick L. Shopbell
Materials Science
Influence of CeO$_2$MnO$_x$ heterostructure on Hydrogen Peroxide Electrogeneration on Carbon-Based Catalysts
Caroline de O. Carrilho, Juliana M. S. de Jesus, João Paulo C. Moura et al. (+7 more)
The sustainable electrogeneration of hydrogen peroxide (H2O2) via the two-electron oxygen reduction reaction (2e$^-$ ORR) represents a promising alternative to conventional production methods. In this study, CeO2 and CeO2MnOx nanoparticles were synthesized and supported on Vulcan XC-72 carbon at varying loadings (1, 3, and 5%), aiming to assess the lowest metal loading and high H2O2 electrosynthesis. Physicochemical characterizations confirmed the successful formation of CeO2 nanowires and the effectiveness of the MnOx surface modification. XRD, TEM, XPS, EPR, and contact angle analyses revealed that CeO2 loading increased surface hydrophilicity through the presence of oxygenated functional groups, thereby favoring electrochemical activity. On the other hand, all CeO2MnOx loadings were statistically equivalent to Vulcan XC-72 in terms of contact angle. Electrochemical evaluations using a rotating ring-disk electrode (RRDE) demonstrated enhanced ORR activity and high H2O2 selectivity for the 1% CeO2MnOx/C and 3% CeO2/C catalysts, achieving up to 90% selectivity and elevated ring currents. The results suggest that low metal loading and surface modification via MnOx improve the balance between active site exposure, oxygen adsorption, and intermediate stabilization, thus favoring the selective 2e$^-$ pathway. These findings support the development of cost-effective, non-noble-metal catalysts for green H2O2 production via electrosynthesis.
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All authors Caroline de O. Carrilho, Juliana M. S. de Jesus, João Paulo C. Moura, Dara Silva Santos, Aline B. Trench, Caio Machado Fernandes, Aila O. Santos, Odivaldo C. Alves, Júlio C. M. Silva, Mauro C. dos Santos
Chemical Physics
Fe3O4 Nano-octahedra/Vulcan XC72: Optimization and Combination with Solar-Based Electro-Fenton for Progestins Degradation
Juliana M. S. de Jesus, Caroline de O. Carrilho, João P. C. Moura et al. (+4 more)
The widespread presence of synthetic progestins, such as levonorgestrel (LNG) and gestodene (GES), in aquatic environments poses significant ecotoxicological risks due to their endocrine-disrupting properties. In this study, nano-octahedral magnetite (Fe3O4-NO) was synthesized via a hydrothermal route and incorporated into gas
diffusion electrodes (GDEs) supported on Vulcan XC72 to enhance the in-situ electrogeneration of hydrogen peroxide (H2O2). High-resolution transmission electron microscopy, X-ray diffraction, SEM, X-ray photoelectron spectroscopy, and contact angle measurements thoroughly characterized the physicochemical and morphological properties of the materials. The 3% Fe3O4-NO/C catalyst provided a two-fold increase in H2O2 selectivity compared with Vulcan XC72. Electrochemical performance was optimized using a 2^3 factorial design and principal component analysis (PCA), with current density, pH, and Na2SO4 concentration as variables. The optimized GDE (3% Fe3O4-NO/C) achieved a maximum H2O2 production of 0.44 +/- 0.02 g L-1 with a current efficiency of 43.1 +/- 0.23% and a specific energy consumption of 0.012 +/- 0.009 kWh g-1. The electrode was further applied to the degradation of LNG and GES using
solar and anodic-assisted electro-Fenton processes. Under optimal conditions, over 70% removal of both progestins was achieved, with stable performance across three operational cycles. These findings demonstrate the potential of 3% Fe3O4-NO/C-GDEs as efficient, reusable cathodes for sustainable electrochemical advanced oxidation processes (EAOPs) in water treatment.
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All authors Juliana M. S. de Jesus, Caroline de O. Carrilho, João P. C. Moura, Aline B. Trench, Caroline C. Augusto, Bruno L. Batista, Mauro C. dos Santos
Materials Science
Direction-Dependent Quantum Transport Properties of MoS$_2$ Integrated into Biphenylene Configuration
Gözde Özbal Sarg{\i}n
Motivated by the experimental realization of the two-dimensional (2D) carbon biphenylene network (BPN), the theoretical extension of the BPN
topology to various groups of elements was successfully implemented. In this work, we conducted first principles and
quantum transport calculations to reveal the electronic, thermal, thermoelectric performance and current-voltage (I-V) behavior of the pristine MoS$_2$-BPN by using density functional theory (DFT) combined with Non-
Equilibrium Green's Function (NEGF) formalism. At room temperature, the
phonon thermal conductance is remarkably low along both the armchair and zigzag orientations, with values of 0.28 nW/K and 0.23 nW/K, respectively. The directional dependence of the electronic and thermal transport properties is clearly reflected in the thermoelectric figure of merit ($zT$) values, which reach first peaks at 0.27 and 0.19 along the armchair and zigzag directions, respectively. The current-voltage ($I-V$) characteristics demonstrate an exceptionally strong transport anisotropy, characterized by a substantial current ratio of $I_{\text{armchair}}/I_{\text{zigzag}} \approx 7 \times 10^4$. Furthermore, while the current along the armchair direction increases steadily with the applied bias, transport along the zigzag direction is characterized by a pronounced intrinsic negative differential conductance (NDC). This contrast highlights fundamentally distinct charge transport mechanisms along the two orthogonal axes. Consequently, different directions of this BPN phase of MoS$_2$ can be tailored for distinct nanoelectronic applications, where the armchair and zigzag axes serve as a reliable current switch and an active NDC device, respectively.
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Solar and Stellar Astrophysics
MINDS survey of silicates in T Tauri disks: Correlation between dust and gas
J. Varga, Th. Henning, L. B. F. M. Waters et al. (+20 more)
Context. Silicates are key constituents of
planet-forming disks and major building blocks of rocky
planets. Mid-infrared spectral features of micron-sized silicate grains trace grain growth, mineralogy, and disk chemistry. Aims. We characterized the
dust mineralogy in T Tauri disks using James Webb Space
Telescope (JWST)/Mid-Infrared Instrument (MIRI) observations and investigated the connections between the
dust and molecular gas compositions. Methods. We analyzed JWST/MIRI spectra of 26 disks from the MIRI mid-Infrared Disk Survey (MINDS). Using our DustComp spectral decomposition tool, we inferred the mass fractions of individual
dust species. The fits included Mg$_2$SiO$_4$ (forsterite), MgSiO$_3$ (enstatite), and SiO$_2$ (silica), together with amorphous silicates of corresponding stoichiometry. Results. Mg-rich (and Fe-poor) silicates reproduce the data well, with residuals typically within $\pm3\%$. Grain size distributions are skewed toward sizes larger than $2\mu$m, indicating significant growth. The average
dust composition is dominated by Mg$_2$SiO$_4$-stoichiometry grains ($\sim60\%$), followed by MgSiO$_3$ ($\sim30\%$) and SiO$_2$ ($\sim10\%$). Crystalline mass fractions are typically in the $5$-$24\%$ range, with a mean of $14\%$. Annealed silica is robustly detected in nine objects, with cristobalite as the main polymorph. We found a correlation between
dust and molecular gas composition: disks with strong annealed silica features show stronger CO$_2$ emission, while forsterite-rich disks display stronger H$_2$O emission. Disks with annealed silica features may also have elevated gas-phase C/O ratios. Conclusions. The observed
dust-gas correlation may provide the first indication that the molecular gas composition regulates the availability of
dust species in the inner disk.
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All authors J. Varga, Th. Henning, L. B. F. M. Waters, I. Kamp, Á. Kóspál, P. Ábrahám, O. Absil, A. M. Arabhavi, D. Gasman, S. L. Grant, M. Güdel, H. Jang, T. Kaeufer, J. Kanwar, N. T. Kurtovic, P.-O. Lagage, G. Perotti, A. Somigliana, L. M. Stapper, B. Tabone, M. Temmink, E. F. van Dishoeck, M. Vlasblom
High Energy Physics (Experiment)
ALETHEIA: Autonomous Loop for Experimental Theory and HEP Inference Across-data
Vincent Alexander Croft
ALETHEIA is a self-completing tool for monitoring the learning of
manifolds in physics foundation models from data. It provides a method to automatically build physics foundation models for permutation-invariant per-event representations of unknown physics
manifolds. This process is demonstrated here for dimension-six Standard Model Effective Field Theory (SMEFT) content of four operators in neutral-current Drell-Yan, whose input is unordered event-level features, and we drive it with an active-learning loop that separates two jobs that the literature usually conflates. Active learning completes a representation: given a fixed operator content, an acquisition rule chooses the working points that pin the model's coefficients fastest. The physics expands it: which new operator to switch on is read from the residual structure, ordered by SMEFT power counting, never guessed by the acquisition. The representation is the ManifoldInformer, a permutation-invariant per-event encoder $\psi_\theta$ pooled into a closed-form ridge head; its latent recovers the analytic morphing tangents ($R^2=0.999$) and
curvatures ($R^2=0.954$) of the SMEFT cross section. The loop monitors a residual-operator fingerprint: when a single out-of-span direction dominates, it appends that direction to $\psi_\theta$ ($\psi$-extension) and refits. The acquisition arm unlocks new operators through an Arize-Phoenix span, such that the concepts of “learning correctly”, in which each extension collapses $\sigma_1$; and “learned completely”, in which $\sigma_1$ is below the noise floor; are read directly off the monitored trace.
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Instrumentation and Detectors · Cross-listed from eess.SP
Multi-Channel Soil Moisture Measurement: High Accuracy and Low Crosstalk Through Optical-Semiconductor Based Differential Sensing
Thomas Maier, Charlotte Rohleder, Lukas Kamm et al. (+3 more)
Soil moisture measurement plays a key role in irrigation and environmental management. Yet it remains unreliable due to heterogeneous soils, limited sensing volumes, temperature drift, and parasitic inter-channel coupling. This work presents a compact multi-depth capacitive probe that extends a parallel-plate geometry from previous work with differential activation to suppress stray capacitances and improve accuracy. An equivalent-
circuit model quantifies parasitic effects, and optically coupled transistor bridges isolate each sensing layer. Raw capacitance is converted to volumetric water content and plant-available water using established calibration models. Laboratory results show a fourfold reduction in temperature sensitivity, strong confinement of the sensing volume, and improved repeatability in heterogeneous soils. Field validation against reference sensors demonstrates high accuracy and precision comparable to widely used instruments, enabling a practical and scalable solution for agricultural and urban soil-moisture monitoring.
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All authors Thomas Maier, Charlotte Rohleder, Lukas Kamm, Philipp Dauner, Jan Pinski, Bjoern M. Eskofier
Quantum Physics
Bosonic Cyclic Codes: Trading Stabilizers for Gaussian Non-Clifford Phase Gates
Owen C. Wetherbee, Yijia Xu, Victor V. Albert et al. (+2 more)
Bosonic codes offer hardware-efficient approaches to
quantum error correction, with the best encodings offering effective protection of idle
quantum information against loss and dephasing - particularly rotation-symmetric codes, which include the cat and binomial code families. However, rotation-symmetric codes are only naturally endowed with a single logical Pauli gate, while other logical gates require the use of non-linear operations, obstructing the utility of these codes for realizing
quantum algorithms. Here, we balance error protection with controllability by introducing bosonic cyclic codes: a generalization of rotation-symmetric codes that enable the measured tradeoff of error protection properties for fault-tolerant logical phase gates. Through our general construction, we find that sacrificing the detectability of a single
photon loss relative to a rotation-symmetric code can yield a number of logical phase gates commensurate with the original rotation
symmetry order of the code, all achievable via passive Gaussian rotations. Giving the corresponding generalizations of cat and binomial codes - which we dub cyclic cat and Vandermonde codes, respectively - we further find that many of the desirable properties of these codes transfer to the bosonic cyclic code setting. We go on to discuss the larger $SU(2)$
symmetry and rotation gates of the codes, which yield additional stabilizers and logical Pauli gates, as well as new non-Clifford gates for the smallest `kitten' binomial code, and provide a new error detection protocol. Finally, we introduce a general paradigm for converting higher-order stabilizers to logical gates, as in our generalization of rotation-symmetric codes, and apply it to several multimode bosonic codes.
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All authors Owen C. Wetherbee, Yijia Xu, Victor V. Albert, Baptiste Royer, Valla Fatemi
Nuclear Theory
Gaussian vs. Real Wavefunction of Nuclear Clusters and Hypernuclei
Jiaxing Zhao, Joerg Aichelin and Elena Bratkovskaya
We compare realistic $N$-body wave functions obtained from solutions of the Schrödinger equation with Gaussian ansätze constrained to the same rms radius. The microscopic wave functions exhibit significantly broader spatial distributions, revealing pronounced non-Gaussian structures. In addition, we investigate possible production channels for $A=4$ clusters using a phenomenological two-body interaction. This study provides a potential mechanism that may help alleviate the underestimation of $A=4$ cluster yields in theoretical models compared to experimental data.
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Solar and Stellar Astrophysics
Spectroscopic analysis of RGB stars in nine open clusters
Saulo de Oliveira Cantanhêde, Alan Alves-Brito, Rodolfo Smiljanic et al. (+4 more)
Stellar clusters are crucial tools for studying the age, spatial distribution, dynamics, kinematics, and chemical composition of different
Galactic stellar populations. In this work, we used red
giant stars from open clusters to better understand the extra-mixing process through the CNO abundances and $^{12}$C/$^{13}$C, $^{16}$O/$^{17}$O and $^{16}$O/$^{18}$O isotopic ratios determined using high-quality spectra in the visible and near-infrared regions. We analysed the radial velocities and chemical composition of 22 K-type
giant stars from nine open clusters (NGC188, NGC2682, NGC3680, NGC5822, IC4756, NGC6633, NGC3532, NGC6281, and NGC5460). High-resolution and high signal-to-noise spectra of
stars in the NGC188 cluster were obtained with the ESPaDOnS spectrograph at the CFHT in the visible region. The
stars in the other clusters were observed with the CRIRES spectrograph at the VLT. We used IRAF to compute radial velocities and Turbospectrum and MOOG for the chemical analysis. The values obtained for the radial velocities and abundances of the sample are similar to those found in the literature. The results in the visible and infrared support the occurrence and predicted mass dependence of thermohaline mixing on the red
giant branch and of rotation-induced mixing on the main sequence. Variations of the initial abundances of $^{17}$O and $^{18}$O may be needed to explain the dispersion of the oxygen isotopic ratios in red
giant stars.
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All authors Saulo de Oliveira Cantanhêde, Alan Alves-Brito, Rodolfo Smiljanic, Beatriz Barbuy, Nadège Lagarde, Corinne Charbonnel, Pierre North
Quantum Physics
Revealing the topology of quantum states via Kirkwood-Dirac quasiprobabilities
Stefano Gherardini and Luca Lepori
We discuss a theoretical approach to discriminate whether two states of a many-body
quantum system belong or not to different
topology classes. This approach is based on expressing a strange correlator - a recently established tool for
quantum topology discrimination - between the states as a function of Kirkwood-Dirac quasiprobabilities (KDQs). KDQs provide a first-principles representation of two-time
quantum correlators. The link between strange correlators and KDQs allows to establish that strange correlators are weak values of an observable converting an initial trivial state into a topologically non-trivial one. We thus propose a
quantum topology witness that is achievable measuring the prior and subsequent effects on a many-body system of a sudden quench transformation that realizes the transition between trivial and topological phases. The witness is evaluated on a probe
quantum state whose main features are detailed within the paper. Finally, directly exploiting schemes that allows for the complete reconstruction of KDQs, we address an interferometric protocol for
topology discrimination, along with a general discussion of the main lines and challenges towards its implementation.
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Quantum Physics
Analog Quantum Asynchronous Event-Based Graph Neural Network
Kristian Sotirov, Shaheen Acheche, Antonio A. Gentile et al. (+1 more)
Asynchronous, event-based graph neural networks (AEGNNs) have recently emerged as an efficient paradigm for processing the sparse and high-temporal-resolution data from event cameras. In this paper, we propose
quantum analog AEGNNs (QA-AEGNNs), a novel framework to implement an AEGNN on a neutral-atom
quantum computer. Neutral-atom
quantum processors offer a programmable analog
quantum computing platform based on controllable Rydberg-atom interactions. To this end, we map the streaming event data to an array of trapped neutral atoms, where each atom represents a graph node (event) and is positioned such that
geometric proximity reflects the spatio-temporal neighborhood of events. The native Rydberg
Hamiltonian of the
quantum processor is programmed to mirror the message-passing computations of the AEGNN, with atomic
qubit states serving as node feature
embeddings and inter-atom interactions realizing graph edges. Furthermore, we propose a hybrid
quantum-classical training scheme in which the analog
Hamiltonian parameters (e.g.,
laser pulse amplitudes and detunings) are optimized using classical feedback to learn the
quantum AEGNN model from data. Our approach leverages the continuous
Hamiltonian dynamics and massive parallelism of neutral-atom
quantum systems to natively execute event-based graph computations with potential accuracy improvements
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All authors Kristian Sotirov, Shaheen Acheche, Antonio A. Gentile, Osvaldo Simeone
Mesoscale and Nanoscale Physics
Optical fingerprints across the strain-driven semi-Dirac transition in Kekulé-O graphene
Yawar Mohammadi
We show that the strain-driven semi-Dirac transition in Kekulé-O
graphene gives rise to a sequence of anisotropic optical fingerprints associated with band structure reconstruction. Across the transition, optical spectral weight is continuously redistributed among the dominant interband transitions, leading to a pronounced enhancement of the optical anisotropy. Combining numerical four-band calculations with analytical low-energy results, we identify three low-energy fingerprints that emerge with increasing strain: gapped absorption peaks, semi-Dirac critical scaling, and a pronounced van Hove optical resonance. At the semi-Dirac critical point, where the Kekulé gap closes at the $\Gamma$ point, the low-energy optical conductivity is characterized by $\sigma_{xx}(\Omega)\propto\Omega^{1/2}$ and $\sigma_{yy}(\Omega)\propto\Omega^{-1/2}$. Beyond the transition, the semi-Dirac point splits into two anisotropic Dirac cones, accompanied by the emergence of saddle points near the $\Gamma$ point. The resulting saddle-point excitations produce a pronounced van Hove optical resonance at energies well below those of
graphene, while the split Dirac cones give rise to an anisotropic constant optical conductivity. We further show that the low-energy optical fingerprints can be traced to the continuous
evolution of a dominant optical transition channel driven by strain-induced band reconstruction. Moreover, the fingerprints remain identifiable in the presence of moderate disorder broadening and finite-temperature effects, indicating their potential observability under experimentally realistic conditions.
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Materials Science
Ab initio study of magnetism in pristine and defective MnBi2Te4
Ana Beatriz Pedro Fontes, Jiaqi Zhou, Simon M.-M. Dubois et al. (+1 more)
The
magnetic material MnBi2Te4 (MBT) has garnered significant
attention due to its unique combination of long-range antiferromagnetism and nontrivial topological electronic properties. However, experimental measurements report inconsistent magnetizations, which could be attributed to a variety of intrinsic defects. To date, a comprehensive investigation of defect-engineered MBT systems has not yet been established. Employing state-of-the-art $ab~initio$ techniques, this work systematically investigates the influence of various experimentally reported defects on the
magnetic properties of bulk and monolayer MBT at different concentrations. Mn-vacancy and Mn-rich defects are found to enhance the ferromagnetism of bulk MBT. The investigation of Mn-rich and intermixing defects in the monolayer reveals that subtle structural and electronic modifications can alter the
magnetic coupling. Projection onto a Heisenberg
Hamiltonian demonstrates that defects modify exchange interactions, thereby giving rise to distinct
magnetic ground states. This work sheds light on
magnetic coupling mechanisms and provides guidelines for the experimental control of magnetism in MnBi2Te4.
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All authors Ana Beatriz Pedro Fontes, Jiaqi Zhou, Simon M.-M. Dubois, Jean-Christophe Charlier
Quantum Physics
Adaptive identification of low-degree polynomials in quantum singular value transformation: application to nonlinear quantum properties estimation
Jumpei Kato, Akira Tanji, Hiroyuki Harada et al. (+3 more)
Estimating properties of unknown
quantum states via
quantum singular value transformation (QSVT) often requires high-degree
polynomials to handle small
eigenvalues of density
matrices. Specifically, the existing approaches determine the
polynomial degree by relying on overly conservative worst-case bounds based on the minimum non-zero
eigenvalue or the rank of the density
matrices. In this work, we propose a spectral cutoff method that truncates the negligible
eigenvalue tail depending on the task, the target accuracy, and the state, which enables the use of significantly lower-degree
polynomials. To implement this, we develop a two-stage
algorithm to estimate nonlinear properties, particularly von Neumann
entropy and Rényi
entropy. In the first stage, we execute a search
algorithm to identify the spectral cutoff directly from the unknown
quantum state. In the second stage, we estimate the nonlinear properties utilizing QSVT with the degree of
polynomial adaptively determined by the cutoff. This two-stage
algorithm significantly improves the overall estimation cost compared to known bounds, even without knowing the minimum
eigenvalue or the rank.
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All authors Jumpei Kato, Akira Tanji, Hiroyuki Harada, Kaito Wada, Kosuke Ito, Naoki Yamamoto
High Energy Physics (Phenomenology)
The Gravitational Form Factor of the Pion in Perturbative QCD with a Dilaton Interaction
Claudio Corianò, Hsiang-nan Li, Dario Melle et al. (+1 more)
We investigate the pion gravitational form factors (GFFs) at intermediate and large momentum transfer within the framework of QCD factorization. Our analysis centers on the non-Abelian $TJJ$ correlator, which couples the local QCD energy-momentum tensor to two external
gluon fields and explicitly encodes the perturbative effects of the trace anomaly. We demonstrate how this
quantum anomaly induces a scalar, dilaton-like contribution to the hard-scattering kernel. To ensure field-theoretic consistency, a careful separation of the
quark and
gluon sectors is performed, accounting for the modifications introduced by gauge-fixing terms and Slavnov-Taylor identities on the off-shell gluonic structure. To obtain realistic phenomenological predictions and regulate soft-
gluon endpoint divergences in the hard kernel, we implement the Sudakov resummation framework coupled with a Gaussian model for the pion's transverse-momentum-dependent wave function. We show that the resulting anomaly-induced corrections significantly modify the behavior of the pion GFFs at large momentum transfer, leaving a unique imprint on the trace sector and the $D$-term.
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All authors Claudio Corianò, Hsiang-nan Li, Dario Melle, Leonardo Torcellini
Geophysics
Surface Crevasse Evolution Observed Using Matched Field Processing and Source Relocation at Hansbreen, Svalbard
Wojciech Gajek, Ugo Nanni, Ali Gholami et al. (+3 more)
Crevasses control glacier dynamics through fracture and meltwater routing, yet their propagation rates remain observationally scarce and poorly constrained across brittle-to-viscous regimes. Cryoseismology offers a powerful means to capture dynamic processes within glacial ice, with recent advances in novel processing methods like Matched Field Processing (MFP) applicable to dense seismic arrays. However, precise localisation of cryoseismic sources remains challenging in sparse or irregular seismic arrays. We propose a two-step workflow for metres-scale resolution mapping of glacial seismic activity that integrates MFP and discrete arrival times relocation under a limited instrumentation constraint. We apply this approach to analyse seismic activity at the ice surface on the Hansbreen glacier, Svalbard. Using MFP, we detect surface icequakes and characterise meltwater noise regardless of the limited instrumentation. The relocation procedure increases the accuracy of surface icequakes localisation and reveals ongoing crevasse opening episodes. The precise locations of the icequakes allow for the estimation of the crevasse propagation rate and the determination of the
diffusion coefficients of 0.47 to 0.55 m2 per s. Based on the obtained results, we discuss brittle-to-viscous regime transfer and interpret the crevassing mechanism as sustained subcritical crack propagation, where viscous stress relaxation governs rates of orders of magnitude below elastic limits.
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All authors Wojciech Gajek, Ugo Nanni, Ali Gholami, William D. Harcourt, Danni M. Pearce, Louise Steffensen Schmidt
Statistical Mechanics
Transverse geometry reshapes current and tracer fluctuation amplitudes in quasi-one-dimensional single files
Olivier Bénichou and Aurélien Grabsch
Single-file transport means no overtaking: particles move in a narrow channel while preserving their longitudinal order. This simple constraint has profound dynamical consequences, most notably tracer subdiffusion, and has made single-file transport a paradigmatic form of confined many-body motion, observed from molecular transport in zeolites to single-file
diffusion of colloids in narrow channels. A common modelling approach assumes that, once overtaking is suppressed, finite-width effects can be discarded or represented by an effective particle size in a strictly one-dimensional model. Starting from the Brownian dynamics in the full confined geometry, we instead derive the exact large-scale one-dimensional fluctuating-hydrodynamic equation governing the coarse-grained line density. Its transport coefficients are fixed by the confined
equilibrium equation of state, through which the transverse geometry remains encoded in the one-dimensional description. Consequently, transverse geometry leaves the $t^{1/2}$ single-file scaling unchanged but can qualitatively reshape the density dependence of the current and tracer fluctuation amplitudes. In the minimal hard-core setting, this yields a collective diffusivity that can become non-monotonic in density for sufficiently wide no-passing channels. This
geometric non-monotonicity propagates to exact large-scale predictions for the amplitudes of integrated-current fluctuations and tracer-displacement fluctuations. The effect is robust to the interaction potential, channel geometry, initial preparation and microscopic dynamics. Quasi-one-dimensional single-file transport therefore defines a distinct regime in which forbidding overtaking does not erase geometry from collective transport.
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High Energy Physics (Phenomenology)
Revisiting Cherenkov radiation in anisotropic chiral matter: exact calculation reveals threshold-free emission
R. Martínez von Dossow and Luis F. Urrutia
We explore Cherenkov radiation in anisotropic
chiral matter within the framework of Carroll-Field-Jackiw electrodynamics, where the
axion angle exhibits a linear dependence on position. By deriving closed-form expressions for the polarization modes of electromagnetic fields in cylindrical coordinates and the space-frequency domain, we solve the modified Maxwell's equations. To enforce causality, we impose outgoing wave boundary conditions at a cylindrical surface at infinity, which yields the dispersion relations. Our analysis uncovers the specific angles and frequency ranges that allow for zero, one, or two Cherenkov cones. We also obtain the spectral energy distribution of the radiation in all cases. Notably, one sector of the model exhibits a novel phenomenon: Cherenkov radiation can be generated by slowly moving charges without a threshold, but only within a specific frequency range. This behavior is not observed in standard materials. Using our exact calculations, we also investigate the reliability of an approximate method previously proposed based on the calculation of the Green's function for the system.
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Quantum Physics
Nonreciprocal quantum rotation sensing via virtual-excitation enhancement in a spinning cavity
Lu-Qi Yang, Yu-Meng Ren and Peng-Bo Li
Quantum sensing with high precision and sensitivity plays an important role in
quantum technologies and
quantum information processing. Here, we propose a nonreciprocal
quantum metrological scheme for estimating rotational angular velocity in a hybrid light-matter platform, where the setup consists of a spinning ring cavity coupled to a two-level system and an auxiliary bosonic mode. Through the Sagnac effect, the angular velocity is converted into a direction-dependent detuning, which modifies the effective light-matter dressing of the hybrid system. As a result, the angular velocity is encoded not only into the renormalized hybrid-mode spectrum, but also into the virtual excitations generated by ultrastrong coupling. These virtual excitations modify the polaritonic frequency response to rotation and enhance the
quantum Fisher information (QFI) associated with angular velocity estimation, without requiring direct extraction of virtual excitations. Moreover, since the Sagnac-Fizeau shift enters the virtual-transition energy denominators, the metrological response becomes intrinsically different for opposite driving directions, leading to a tunable nonreciprocal sensitivity contrast. In addition, we also discuss a readout scheme and show that bundle emission coincidence counting can serve as an auxiliary direction-dependent readout channel. Our results provide a route toward exploiting nonreciprocal light-matter dressing and virtual excitations as resources for
quantum rotation sensing.
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Quantum Physics
Robust self-testing based on Gisin's arbitrary-input Bell inequality
Rajdeep Paul and Alok Kumar Pan
Self-testing refers to the strongest device-independent (DI) certification method that validates the nature of a
quantum system and devices solely based on the observed statistics. We demonstrate the self-testing of state and measurements based on the Gisin Bell inequality (GBI) featuring arbitrary inputs for both parties. We introduce a systematic and elegant sum-of-squares (SOS) approach that enables the dimension-independent derivation of the optimal
quantum violation of GBI. We derive the state and the interrelation between the local observables directly from the optimization condition. Since the practical experimental scenario involves inevitable noise and imperfection, we present a comprehensive strategy for robust self-testing.
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Solar and Stellar Astrophysics
Dimming and pulsation shock of the coalesced star V838 Monocerotis
T. Kamiński, C. E. Woodward, T. Liimets et al. (+3 more)
V838 Mon is the remnant of a
stellar merger that occurred in 2002. Twenty-four years after the merger, the remnant closely resembles a red supergiant, but its luminosity is sustained by core H burning and continued contraction toward hydrostatic
equilibrium. In late 2025, the system entered the deepest dimming event observed since 2006. We characterize the 2026 dimming using multiband photometry and high-resolution spectroscopy spanning from the dimming minimum through the recovery phase. The photometric color
evolution during the dimming can be well reproduced by
dust extinction with $A_V=1.26$ mag and $R_V=1.8$, consistent with a transiting clump of freshly formed circumstellar
dust composed of small silicate or alumina grains. The photospheric effective temperature changed by no more than ~200 K during the event. During the recovery phase, H recombination lines from the Balmer, Paschen, and Brackett series appeared in emission, with anomalous line ratios matching those of pulsating Mira
stars near maximum light. These features are interpreted as arising from a sub-photospheric pulsation shock. Simultaneously, low-ionization metal lines appeared blueshifted by 90 km/s relative to the
stellar rest frame, tracing shock-affected gas on the near side of the
stellar disk. The spectroscopic sequence suggests that the 2026 dimming was itself triggered by a preceding pulsation shock that occurred earlier in 2025. We present the first observational evidence for pulsations in a
stellar merger remnant. Twenty-four years after the coalescence, V838 Mon exhibits pulsation shocks qualitatively identical to those of red supergiants and Mira
stars, confirming predictions of pulsational instability in post-merger objects. A further dimming event, triggered by the observed shock, is predicted to start in northern summer 2026.
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All authors T. Kamiński, C. E. Woodward, T. Liimets, M. R. Schmidt, A. A. Djupvik, I. Ilyin