Quantum Physics
Quantum Federated Learning Based on Bures–Uhlmann Geometry for Heterogeneous Noisy Clients
Haruki Emori, Masaki Uchihara and Yuuki Tokunaga
Quantum federated learning enables collaborative model training across
quantum devices without sharing raw data, and it faces the data and hardware heterogeneity inherent to noisy
quantum devices. Utilizing the
quantum geometric tensor is a natural remedy, yet pure-state approaches and diagonal approximations discard the correlations that encode parameter incompatibility. To address this, we extend the parameter-space geometry to the mixed states that noisy clients actually prepare. The real part of the resulting mixed-state
geometric tensor is the Bures metric, which measures how fast the physical state changes under parameter variation, and the imaginary part is the mean Uhlmann
curvature, which quantifies the incompatibility of estimating multiple parameters simultaneously. Accordingly, we employ the Bures metric as a local preconditioner and use the mean Uhlmann
curvature to develop an achievable-precision aggregation rule that dynamically down-weights unreliable clients. Furthermore, we establish theoretical guarantees by proving a convergence
theorem and a variance-dominance proposition. Empirical evaluations on a trapped-ion
quantum emulator demonstrate that the proposed method maintains high accuracy across diverse device-heterogeneity conditions and outperforms standard
federated averaging, whose accuracy degrades under strong noise.
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High Energy Physics (Experiment)
Search for scalar leptoquarks produced via muon-quark scattering in proton-proton collisions at $\sqrt{s}$ = 13 TeV
CMS Collaboration
The first search for TeV-scale scalar leptoquarks (LQs) produced in
muon-
quark ($\mu$q) interactions is presented. It is based on
proton-
proton collision data recorded at a center-of-mass energy of 13 TeV with the CMS detector at the LHC, corresponding to an integrated luminosity of 138 fb$^{-1}$.
Quantum fluctuations inside the
proton generate charged-
lepton components, enabling the study of
lepton-induced processes. In particular, the interaction of a
muon from one colliding
proton with a
quark from the other
proton enables the study of resonant production of a single LQ and its subsequent decay. The final state includes one or two
muons and a jet that can come from the hadronization of either a light
quark (u) or a b
quark. The primary observable is the invariant mass of the
muon-jet system, whose distribution peaks at the LQ mass. The data are found to be in agreement with the background predictions. Upper limits are set on the product of the LQ production cross section and its decay branching fraction to the $\mu$q final state. The results exclude broad regions in the parameter plane of the LQ mass and the LQ-$\mu$q coupling, improving upon previous CMS searches by extending the coverage for LQs with masses between 1.5 and 3.6 TeV, and couplings between 0.2 and 0.6 for the LQ(u$\mu$) scenario; and masses above 1.8 TeV, and couplings above 1 for the LQ(b$\mu$) scenario.
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Mathematical Physics
Critical Points of Line Restrictions of Signed Point-Charge Potentials
Xiuqing Duan
Let $\alpha>0$ and restrict a finite inverse-power potential with arbitrary real coefficients to a line. Combine terms having the same projected centre and squared height $\left(a, b^2\right)$, delete classes whose coefficient sum is zero, and let $m$ be the number of remaining classes. We prove the following dichotomy. If $m=0$, exact cancellation occurs if and only if every class sum vanishes, and every ordinary point of the original domain is critical. If $m \geq 1$, there are at most $2 m-1$ critical points: when all effective heights are positive the zeros are counted with analytic multiplicity, while in the presence of effective sources on the line the assertion is one global distinct-point bound. This proves the signed line
conjecture of Gabrielov-Novikov-Shapiro, valid throughout their range and in fact for every $\alpha>0$. The structural input is a projective paired Haar
theorem: for finite $\beta>1$, the full $2 m$-dimensional space $\sum L_j / Q_j^\beta$, with pairwise nonproportional positive-definite binary quadratics and arbitrary real linear numerators, has at most $2 m-1$ projective zeros counted with multiplicity. For positive charges, the substitution $p=2 \alpha$ proves
Conjecture 3 of Edelsbrunner-Fillmore-Oliveira throughout its stated range $p \geq 1$ and extends the same conclusion to every $p>0$. For every $n$, an explicit positive $n$-charge configuration attains $2 n-1$ simple critical points.
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Data Analysis and Statistics · Cross-listed from stat.ML
Localizing Global Discrepancies: Marginal Contributions and Contextual Anomaly Detection
Tommaso dorigo
Global goodness-of-fit and discrepancy statistics can establish that a sample departs from a reference distribution without identifying which observations drive the departure. We develop a framework for this localization problem by assigning to each observation its conditional or marginal contribution across random statistical contexts. This connects resampling diagnostics and data valuation to projection theory and event-level anomaly detection. For symmetric statistics, fixed-size replacement is exactly equivalent to centered conditional localization. For U-statistics, the addition score equals the first Hoeffding/Hájek contribution; for smooth distributional functionals it is related at leading order to the influence function; and for unbiased known-background MMD it reduces exactly to the MMD witness. This viewpoint also yields more efficient
estimators. Matched-context subtraction removes fluctuations unrelated to the observation, while for pairwise MMD the event-containing terms give a simple localizer. On the LHC Olympics anomaly-detection
benchmark, the pair
estimator converges to the direct empirical MMD witness with the predicted 1/(Rm^2) scaling, where m is batch size and R the number of batches. At m=1000 and R=5x106 it reaches correlation 0.9993 with essentially identical AUC. We also ask when context contains information beyond an event's own features. In a shared-latent toy model, the full single-event signal and background distributions are identical by construction, forcing isolated-event AUC=0.5. Discriminating information survives only in cross-event dependence induced by the shared latent parameter; the ensemble recovers this information, whereas an independent-latent control does not. This separates two roles of context: efficient localization of a global discrepancy and genuinely additional class information when the alternative contains shared structure.
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Cosmology and Nongalactic Astrophysics
PIFFLE: Characterizing the Foreground Contributions from 4 Decades in Halo Mass to the FRB20230907D Dispersion Measure
Qi Guo, Khee-Gan Lee, Sunil Simha et al. (+10 more)
We characterize the foreground environment of FRB20230907D, localized to a
galaxy at $z=0.464$, which has an observed dispersion measure of ${\rm DM}_{\rm obs}=1031~{\rm pc~cm^{-3}}$. At its
redshift, FRB20230907D lies above the Macquart relation, the expected relation between cosmological dispersion measure and the source
redshift, indicating a substantial excess DM along this line of sight. We use Subaru/PFS and SDSS spectroscopy, published group catalogs, Rubin/LSST imaging, and eROSITA X-ray data to characterize the foreground structures that may account for this excess. A friends-of-friends search identifies a massive foreground system at $z\simeq0.09$ with $M_{200}\simeq5.2\times10^{14}~M_\odot$, while low
redshift catalogs reveal an additional group at $z\simeq0.02565$. Assuming that the
halo gas follows a modified-NFW
halo density profile, we estimate observer frame contributions of $150^{+110}_{-70}~{\rm pc~cm^{-3}}$ and $80^{+60}_{-40}~{\rm pc~cm^{-3}}$ from these systems, respectively. Together with the Milky Way, diffuse intergalactic medium, Virgo cluster, M49 group, and host
galaxy contributions, these foreground structures can account for the excess dispersion measure of FRB20230907D within uncertainties. This highlights the importance of dense foreground spectroscopy and multi-wavelength data.
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All authors Qi Guo, Khee-Gan Lee, Sunil Simha, Chenze Dong, Ilya S. Khrykin, Nicolas Tejos, J. Xavier Prochaska, Kevin McCarthy, John D. Silverman, Ines Pastor-Marazuela, Ben Stappers, K. M. Rajwade, Manisha Caleb
Solar and Stellar Astrophysics
A high-frequency type II radio burst associated with an X2.3 class flare
Divya Paliwal, Anshu Kumari, Vishwa Vijay Singh et al. (+3 more)
Radio observations provide a powerful diagnostic of the
solar corona, enabling investigations of dynamic phenomena associated with
solar flares, coronal mass ejections (CMEs), and shock waves. We present a multiwavelength analysis of a rare high-frequency type II
radio burst (starting frequency of $\sim$750 MHz and frequency drift rate of $\sim$0.5 MHz s$^{-1}$) associated with the X2.3-class
solar flare that occurred on 6 November 2024. A propagating EUV disturbance was observed shortly after the
flare onset in the SDO/AIA field of view, while
radio spectrographs recorded the type II burst between 13:46 and 13:56 UT over a frequency range of $\sim$750 to 45 MHz.
Radio imaging observations from the Nançay Radioheliograph (NRH) show that the
radio sources propagate southward during the event. X-ray spectroscopy from HEL1OS onboard Aditya-L1 and imaging observations from STIX onboard
Solar Orbiter reveal signatures of efficient non-thermal electron acceleration associated with the
flare. An NLFFF extrapolation identifies a pre-eruptive
magnetic flux rope in the source region, while white-light coronagraph observations obtained during the event show no detectable large-scale CME. The speed of the erupting flux rope, derived from stereoscopic EUV observations, is consistent, within measurement uncertainties, with the shock speed inferred from the
radio dynamic spectrum. Together, these observations suggest that compact flux rope eruptions, even in the absence of a detectable white-light CME, can generate low-coronal shocks capable of producing high-frequency type II
radio emission.
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All authors Divya Paliwal, Anshu Kumari, Vishwa Vijay Singh, Dinesh Mishra, Pritam Das, Nadiya K
Plasma Physics
Electromagnetic pressure-gradient-driven instabilities with moderate high mode numbers in tokamak plasmas
Yann Narbutt, Ksenia Aleynikova, Matthias Borchardt et al. (+6 more)
Pressure gradient-driven instabilities are investigated in tokamak
plasmas using the global gyrokinetic code EUTERPE emphasizing the role of moderate high mode numbers. As the normalized
plasma pressure $\beta$ is increased, there is a well-known, sudden transition from ion-temperature-gradient (ITG) instabilities to kinetic ballooning modes (KBM), if the magnetohydrodynamic (MHD) geometry is held fixed. However, if the
equilibrium field is recomputed for each value of $\beta$, so that the
equilibrium is consistent with the stability calculation, the transition can disappear. In a number of cases, we are only able to find an ITG-KBM transition if inconsistent
equilibria are used. In the MHD unstable regime, gyrokinetic simulations and MHD stability calculations show good agreement for moderate ratios of ion temperature gradient to density gradient and small values of the ion gyro-radius. Otherwise, non-MHD contributions are important, such as the diamagnetic stabilization and ion wave–particle resonant effects.
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All authors Yann Narbutt, Ksenia Aleynikova, Matthias Borchardt, Thomas Hayward-Schneider, Ralf Kleiber, Axel Könies, Alexey Mishchenko, Carolin Nührenberg, Edilberto Sánchez
Computational Physics
Real-Time Monitoring of MHD Liquid Metal Flows with Shallow Recurrent Decoders
Claudio Scardino, Stefano Riva, Carolina Introini et al. (+4 more)
State estimation in magnetohydrodynamic flows is critical for real-time monitoring of
liquid metal blankets in tokamak fusion reactors. Due to the multiphysics nature of these phenomena, high-fidelity simulations are computationally prohibitive for real-time applications. This work investigates a data- driven Reduced Order Model framework: the Shallow Recurrent Decoder (SHRED) coupled with Principal Component Analysis, to map sparse temperature measurements to the full thermo-hydraulic system's state. The major contribution of this work lies in the two-parameter analysis of a fully three-dimensional domain representative of the DEMO breeding blanket configuration. Here, the flow is subjected to an external
magnetic field varying in direction and intensity and is hindered by two cylinders acting as a water-cooling system, which impose a temperature boundary condition on their surfaces. This double-parametric
magnetic variation induces nonlinear transitions in the flow dynamics, ranging from chaotic behavior at low
magnetic field intensities to laminarized regimes at high intensities, characterized by the formation of asymmetric side layers at an inclination angle of 30 degrees. SHRED reconstruction maintains a mean relative error of approximately 5% for the temperature, pressure, and velocity fields. This accuracy is maintained across both weak and strong
magnetic fields, ranging from 0.075 T to 0.300 T, and for inclination angles from 5 to 30 degrees, reflecting its dominant toroidal component. These errors are only slightly larger than the lower error bound dictated by low-rank truncation. The results establish SHRED as a reliable state
estimator for complex and realistic engineering applications involving completely unseen parametric scenarios and validate it as an accurate real-time state estimation technique suitable for online monitoring and control of real facilities.
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All authors Claudio Scardino, Stefano Riva, Carolina Introini, Matteo Lo Verso, Eric Cervi, Antonio Cammi, Laura Savoldi
Materials Science
Topological Signatures of Hardness and Structural Order in Network-Forming Materials
Yair Augusto Gutiérrez Fosado, Ayobami Daramola, Davide Marenduzzo et al. (+1 more)
Understanding how the
topology of network forming materials influences their physical properties remains a longstanding challenge. Here, we investigate the
topology of experimentally compatible atomistic models of amorphous silica together with the crystalline polymorphs cristobalite and quartz. By comparing multiple atomistic models of amorphous silica that equally reproduce
neutron-scattering data, we show that different microscopic descriptions can imply different topological interpretations of glass stability. To characterize the network beyond conventional
geometric descriptors, we introduce the linking valence, which quantifies the average number of topological links per network loop. This topological descriptor separates silica into two distinct classes: the mechanically harder quartz exhibit values more than an order of magnitude larger than those of amorphous silica and cristobalite, despite their common tetrahedral building blocks. Spectral analysis of the loop-linking networks provides a complementary distinction, separating amorphous from crystalline phases and revealing differences in the long-range organization of topological constraints. These results establish topological linking as a new framework for connecting the structure and physical properties of network-forming materials.
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All authors Yair Augusto Gutiérrez Fosado, Ayobami Daramola, Davide Marenduzzo, Ciprian G. Pruteanu
High Energy Astrophysical Phenomena
Three-dimensional Core-Collapse Supernova Simulations: From shell burning to shock revival
Haakon Andresen, Evan P. O'Connor, C. E. Fields et al. (+1 more)
The outcome of core-collapse
supernova simulations depends sensitively on the multi-dimensional structure of the progenitor
star at the onset of collapse. We perform three-dimensional simulations of the final ~10-15 minutes of
stellar evolution for five non-rotating
solar-
metallicity progenitors with zero-age main-sequence masses of 20, 21.5, 24.5, 26, and 29
solar masses, mapped from one-dimensional MESA models into the FLASH hydrodynamics code. Convection develops in the oxygen-rich layers of all five models, with convective velocities reaching several hundred km/s, and in some models strong convection also develops in the inner silicon- and oxygen-burning shells. For the 24.5
solar mass progenitor, we carry out three core-collapse simulations: one initialised from the fully three-dimensional model, one from its angle-averaged counterpart, and one from the original one-dimensional MESA progenitor. We find that the multi-dimensional progenitor leads to 35 to 50% higher non-radial kinetic energy in the post-shock region and an average shock radius 5 to 10% larger than in the angle-averaged model, and shows the earliest shock revival of the three. The gravitational-wave emission is similar in all three models and strengthens after shock revival, driven by a change in the downflows reaching the protoneutron
star rather than by progenitor asymmetries.
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All authors Haakon Andresen, Evan P. O'Connor, C. E. Fields, Sean M. Couch
Quantum Physics
Variationally Optimized Imaginary-time Polynomial Filters for Ground State Projection
Bahman Seifi, Ibsal Assi and J. P. F. LeBlanc
In this work, we develop a variational imaginary-time
evolution (ITE) framework based on
polynomial filtering, derived from an operator-level action principle, which yields an optimized non-
unitary projector expressed as a
polynomial in the
Hamiltonian. Starting from a single-ancilla, first-order imaginary-time update defined by a Taylor expansion and Trotter-Suzuki (TS) decompositions, we show that replacing these approximations with alternative variational formulas substantially improves both accuracy and stability at larger time steps, leading to up to an order-of-magnitude enhancement in the final success probability. We further derive rigorous error bounds that depend only on static properties of the
Hamiltonian, providing practical guidance for selecting the simulation time step.
Benchmarks on the transverse-field Ising model demonstrate faster convergence to the ground-state energy and improved robustness compared to standard TS–Taylor ITE, highlighting variational
polynomial filtering as a practical route to higher-fidelity ground-state preparation on near-term
quantum devices.
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Instrumentation and Detectors
Development of a high-granularity, high-precision timing readout electronics system for large-area MRPC detectors
J.N.Tang, W.H.Wu, Y.Q.Tan et al. (+4 more)
Multi-gap Resistive Plate Chamber (MRPC) detectors offer excellent time resolution and detection efficiency, creating a strong demand for high-precision, highly scalable timing readout systems. In this work, a readout electronics system is designed for a large-area 100*100 cm MRPC detector containing 2400 high-granularity 2*2 cm pad channels. The system consists of two Front-End Boards (FEBs), a central clock distribution module, and a back-end DAQ aggregator. Each FEB is equipped with 40 32-channel PETIROC2B ASICs mounted directly behind the sensing pads. An automated S-curve calibration procedure equalizes the baseline dispersion across all 2400 channels, reducing the FWHM of the baseline voltage distribution from 50 mV to 12 mV and establishing a uniform triggering threshold. Signal-injection measurements confirm an intrinsic single-channel electronic time resolution of 33 ps RMS, alongside inter-chip and inter-board time resolutions of 43 ps RMS and 45 ps RMS, respectively. This high-granularity, high-precision timing readout system can be widely applied to Time-of-Flight systems,
cosmic-ray
muon imaging, as well as other fast-timing detector systems.
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All authors J.N.Tang, W.H.Wu, Y.Q.Tan, W.Zhi, H.J.Yang, Imad Laktineh, Q.P.Shen
Mesoscale and Nanoscale Physics
Crystal-phase quantum dots in AlGaAs nanowires
Rohan Radhakrishnan, Rodion Reznik, Gilles Patriarche et al. (+6 more)
Crystal-phase
quantum dots (CPQDs)$\unicode{x2014}$
quantum dots in nanowires defined by
crystal structure rather than material composition$\unicode{x2014}$constitute the only platform capable of fabricating
quantum-dot arrays with the ultimate precision of a single atomic layer. This intrinsic control yields perfectly aligned
quantum dots with atomically sharp interfaces, providing a unique pathway toward scalable
quantum-dot-based photonic
quantum technologies. To date, CPQDs have been studied primarily in binary
semiconductors, such as InP and GaAs, where their emission linewidths are typically in the meV range, thereby limiting their technological potential. Here, we report, for the first time, CPQDs in AlGaAs nanowires and show bright single-
photon emission with linewidths as narrow as 61 $\mu eV$ and low background emission, demonstrating optical quality well beyond typical CPQDs. We attribute this performance to a type-I band
alignment, as suggested by an
exciton lifetime of 1 ns, significantly shorter than that typically observed in type-II CPQDs. Additionally, we observe an
exciton fine-structure splitting and a Zeeman splitting, as commonly observed in standard type-I self-assembled
quantum dots.
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All authors Rohan Radhakrishnan, Rodion Reznik, Gilles Patriarche, Lorenzo Leandro, Igor Ilkiv, Anna Andreeva, Artem Khrebtov, George Cirlin, Nika Akopian
Earth and Planetary Astrophysics
Inversion Framework of Internal Mass Distribution Parameters of Asteroid Apophis from Dynamical Observations
Yiting Li, Chenyang Huang, Yang Yu et al. (+2 more)
The detection of the internal mass distribution of asteroids is of great significance for understanding their origin,
evolution, and mission planning for exploration. Previous approaches rely on indirect density estimates or close-range spacecraft
gravity inversion, which have limited applicability. This paper presents a proof-of-concept framework to infer the internal mass properties of asteroid (99942) Apophis during its close Earth flyby in 2029 using dynamical observations collected during the encounter. We establish a dynamical mapping from the
evolution of orbital and rotational states to internal structural parameters, formulate it as an inverse problem, and solve it using Particle Swarm Optimization. The
algorithm is first validated on a regular ellipsoidal model and then applied to three mass distribution models based on the actual shape of Apophis. Under ideal observation conditions, the relative error of the inverted moment of inertia ratios can be below 0.001%, and the absolute error of the center-of-mass position reaches the order of 10-5 meters. The
algorithm successfully distinguishes among different internal structures. When realistic measurement noise is introduced, the inversion accuracy degrades. A sensitivity analysis reveals that the accuracy of the inertia tensor inversion is primarily limited by angular velocity measurement noise, whereas center-of-mass determination is highly sensitive to the precision of position and velocity data. This study provides a proof-of-concept for a technically feasible and cost-effective approach to infer asteroid internal structure during close encounters, and also highlights the critical data accuracy requirements for practical application, offering guidance for future observation campaigns.
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All authors Yiting Li, Chenyang Huang, Yang Yu, Shengping Gong, He Zhang
Materials Science
Work Function and High-Coverage Adsorption Energy as Hydrogen-Evolution Descriptors on Ag-Au-Pd-Pt Alloys
Zacharias Liasi, Ridha Zerdoumi, Felix Thelen et al. (+8 more)
Hydrogen-
evolution activity is commonly rationalized through hydrogen adsorption energies and the Sabatier principle, yet this descriptor picture becomes ambiguous on multimetallic surfaces, where each composition exposes a distribution of local adsorption environments. Here we investigate whether the bare-surface work function, previously shown to add predictive information for monometallic surfaces, remains an activity descriptor for compositionally complex surfaces. We test this on three combinatorial Ag-Au-Pd-Pt thin-film materials libraries screened for acidic hydrogen
evolution by scanning electrochemical
cell microscopy. Graph neural networks provide adsorption-energy distributions and work functions for each measured composition. A work-function-only model explained most of the activity variation (mean $R^2_\mathrm{log}$ = 0.903), as did a coverage-corrected adsorption model (mean $R^2_\mathrm{log}$ = 0.955), outperforming dilute adsorption (mean $R^2_\mathrm{log}$ = 0.758). Combining work function and coverage-corrected adsorption yielded the highest fit quality (mean $R^2_\mathrm{log}$ = 0.969), but only a small gain over coverage-corrected adsorption alone. For these four metals the coverage-corrected adsorption energy and work function follow a similar trend, producing similar activity rankings, hence including both adds little beyond either one individually, although both are strong predictors.
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All authors Zacharias Liasi, Ridha Zerdoumi, Felix Thelen, Geovane Arruda de Oliveira, Rico Zehl, Natalia Pukhareva, Leonardo H. Morais, Henrik H. Kristoffersen, Alfred Ludwig, Wolfgang Schuhmann, Jan Rossmeisl
Solar and Stellar Astrophysics
On the Origin of a Dusty Circumstellar Medium around Red Supergiants
Das Sujit, Arkaprabha Sarangi and Sutirtha Sengupta
Red supergiant (RSG)
stars are widely recognized as significant sources of
dust, enriching the interstellar medium. However, the physical conditions that regulate
dust nucleation in their winds remain poorly constrained. We investigate the formation of molecules and
dust in RSG and explore how enhanced mass loss can produce a dense,
dust-rich circumstellar medium (CSM) before core collapse. We couple time-dependent mass loss with non-
equilibrium chemistry to model the formation of molecules and
dust precursors using mass loss rates ranging from 10$^{-6}$ to 10$^{-2}$ \Mdot\ and both constant and accelerating wind profiles. Molecules such as CO, H$_2$O, SiO, HCN, CS, SO, NH$_3$, H$_2$, and O$_2$ form efficiently in the CSM, with masses varying between 10$^{-15}$–10$^{-2}$ \Ms. O-rich
dust, namely silicates and alumina, dominates the
dust composition. The total
dust mass ranges between 10$^{-8}$ and 3$\times$10$^{-3}$ \Ms. Accelerated winds produce more
dust and allow
dust formation closer to the
stellar surface. The resulting fluxes exhibit strong mid-infrared excesses. The 9.7 and 18 \mic\ silicate features appear in either emission or absorption depending on the optical depth of the circumstellar medium. The time-dependent mass-loss history of our SN~2023ixf progenitor models results in a gradual increase in CSM
dust mass toward explosion. A clumpy CSM provides a substantially better match to the observed optical and infrared fluxes, demonstrating the importance of time-dependent mass loss, CSM structure, and wind acceleration in shaping the observable properties of red supergiant progenitors.
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Mesoscale and Nanoscale Physics
Evidence for Three-component Interlayer Coherent Exciton Condensation
Subi Du, Xiaohan Zhang, Hongxi Song et al. (+8 more)
Increasing the number of internal components in a
quantum many-body system can host collective orders inaccessible to simpler settings.
Quantum Hall bilayers provide a canonical realization of interlayer
exciton condensation, yet extending such coherence across three independently addressable electronic fluids has remained elusive. Here we report evidence for three-component interlayer coherent
exciton condensation in triple-layer
graphene system. Using Rydberg
excitons in an adjacent WSe2 monolayer as a layer-sensitive optical probe, we resolve interaction-induced incompressibility at zeroth-Landau-level crossings for all three pairwise layer combinations, establishing top-middle, middle-bottom and top-bottom
exciton condensate channels within the same device. Independent control of displacement field and interlayer bias continuously tunes these pairwise states towards a regime where Landau levels from all three layers approach simultaneous degeneracy. At their convergence, incompressibility persists while the
exciton energy and spectral weight evolve smoothly between the pairwise limits, suggesting coherent participation of all three layers in a single three-component state. More broadly, the ability to independently control layer potentials and engineer interlayer interactions establishes multilayer
graphene as a programmable synthetic dimension for exploring higher-component
quantum Hall order and simulating strongly correlated
quantum matter.
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All authors Subi Du, Xiaohan Zhang, Hongxi Song, Siyu Fan, Yiduo Wang, Zhenyu Wang, Song Liu, Kenji Watanabe, Takashi Taniguchi, Jiangping Hu, Yang Xu
Cosmology and Nongalactic Astrophysics
Explicit gauge-invariant variables in multifield inflation beyond linear order and Hamiltonian dynamics
Julien Grain, Hugo Holland and Lucas Pinol
General relativity coupled to multiple scalar fields is a diffeomorphism-invariant constrained system. Consequently, a naive counting of the perturbative degrees of freedom unavoidably overestimates the true number of physical modes propagating in the theory, as gauge redundancies and constraint equations remove non-dynamical ones. While this problem has been solved for linear fluctuations, this work presents the first explicit calculation of all large-scale gauge-invariant phase-space variables in multifield inflation and at second order in perturbation theory, in a
Hamiltonian language. Building upon the well-known Sasaki-Mukhanov variables, we show how to construct a finite-dimensional basis of quadratic corrections which are invariant under gauge transformations. Although our procedure is generic to any number of fields and at any scale, we restrict to super-Hubble scales for their explicit solution, which we deliver. Henceforth, we prove that it is possible to recover the usual flat-gauge and comoving-gauge fluctuations as large-scale gauge-invariant combinations, making for a robust consistency check of the gauge-fixed procedure to connect theoretical predictions above the horizon to observations. We derive the quadratic and cubic
Hamiltonian of multifield inflation in a gauge independent manner, then we gauge fix our theory by going into the flat gauge, and we show perfect agreement with the literature on this topic, usually based on a Lagrangian approach. After these concrete steps, we propose a more formal proof of the existence of gauge-invariant variables at quadratic order, and we provide a sketch of the procedure that should allow to go to higher orders in perturbation theory.
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High Energy Physics (Theory)
Stress-Testing Swampland Bounds with Class S Theories
Gabriel Fenati, Miguel Montero and Irene Valenzuela
We test the Sharpened Distance
Conjecture (SharpDC) for CFTs, as well as the Refined Distance
Conjecture (RDC), in AdS$_5$ gravitational spacetimes, using the CFT dual. The former provides a lower bound on the exponential mass decay rate of the tower of states becoming light at infinite distance in the conformal
manifold, while the latter bounds the bulk field range that can be traversed before the exponential behaviour of the tower kicks in. We prove the SharpDC for any large $N$ Lagrangian supersymmetric gauge theory with a finite number $M$ of gauge factors and vanishing one-loop $\beta$-function. We also investigate whether it universally holds in the limits of large central charge, finding that it does not: We exhibit concrete examples in Class S theories where the
conjecture is violated in the $M\rightarrow\infty$ limit with $N$ fixed, where the size of the bulk internal geometry is much larger than the AdS
curvature scale. We also test the RDC in the
moduli space of Class S theories without punctures in the large $N$ limit, showing that it amounts to a precise upper bound on the Weil-Petersson diameter of the
moduli space of Riemann surfaces of genus $g$. This bound is consistent with all the mathematical literature up to date, but so far remains unproven.
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Nuclear Theory
Spin-State Teleportation and Tests of EPR Correlations Using 151 MeV Entangled Protons
H. Witała
We discuss the feasibility of
quantum spin-state teleportation in a three-
proton system at an energy of 151 MeV, where, similarly to the low-energy case, a single Bell-state term dominates the
proton-
proton scattering
matrix. We find that, in contrast to the low-energy regime, where unpolarized
proton-
proton scattering produces strongly entangled outgoing
proton pairs, at higher energies a pair of
protons, each with an energy of $151$~MeV, must be produced in an unpolarized, exclusive
proton-deuteron breakup reaction under complete final-state-interaction kinematics. The subsequent interaction of one of the entangled
protons with a polarized hydrogen target triggers, as in the low-energy case, the teleportation process, whereby the polarization of the target
proton is transferred to the second member of the entangled pair within the very narrow angular region of strong
entanglement centered around a laboratory scattering angle of $45^\circ$. We also find that scattering one member of a strongly correlated
proton pair forming a Bell state from an unpolarized hydrogen target leads to Einstein-Podolsky-Rosen-like correlations between the polarization of the scattered
proton and that of the unscattered second entangled
proton. The polarization of the scattered
proton varies with its scattering angle. An identical polarization, following the angular dependence of thepolarization of the first
proton, is induced in the second member of the pair, whose initial polarization was zero and whose momentum remains unchanged. The sign of the polarization of the second
proton is determined by the sign of the
spin correlation in the Bell state.
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Astrophysics of Galaxies
Deep VISTA observations of the Magellanic Clouds (VMCDeep)
M.-R. L. Cioni, A. O. Omkumar, N. J. G. Cross et al. (+28 more)
The central regions of
galaxies challenge observers with a high density of
stars, gas and
dust. The LMC hosts a dense
stellar bar whereas the SMC hosts a dense core, which have eluded even the most sensitive large-scale wide-field surveys of individual
stars from the ground and from space. This work describes deep imaging observations obtained with VISTA of the inner regions of the Clouds. They were obtained to resolve
stars fainter than the red clump, that due to crowding were missed in previous observations, and to quantify features associated with the
star formation, kinematics and structure of the
galaxies. These studies will allow us to establish how the dynamical interactions between the LMC and the SMC, and the interaction between the Clouds and the Milky Way have influenced the most gravitationally bound regions. Multiple near-infrared images were obtained in the J and Ks filters during excellent weather conditions. The data were reduced using the VDFS which provides single-filter and band-merged calibrated images and catalogues, with associated confidence maps, for individual observations and combined observations for deep tiles. Approximately one million sources, with only minor quality issues and about 40 epochs per filter, are detected in the central 1.77 sq. deg. They provide a more contiguous spatial area coverage than sources in the VMC survey, which covers the same regions by overlapping two VISTA tiles per
galaxy. The catalogues, which are made available with this work, contain attributes to select unique good quality detections for which we provide examples of ongoing scientific applications. These data represent valuable complementary information to deep imaging observations at other wavelengths and provide additional epochs for proper motion and photometric variability studies extending the time baseline to 11 yr, as well as targets for spectroscopic observations.
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All authors M.-R. L. Cioni, A. O. Omkumar, N. J. G. Cross, F. Cusano, F. Dresbach, F. Ficara, F. Niederhofer, J. M. Oliveira, V. Ripepi, S. Vijayasree, G. Clementini, R. de Grijs, L. Girardi, M. A. T. Groenewegen, V. D. Ivanov, N. Kacharov, M. Marconi, A. Mazzi, G. Pastorelli, C. M. Pennock, M. Petr-Gotzens, J. Storm, S. Subramanian, J. Th. van Loon, R. P. Blake, M. J. Holliman, J. Irwin, M. J. Irwin, R. G. Mann, M. Read, E. Sutorius
Instrumentation and Methods for Astrophysics
JWST telemetry combined with active coronagraphy: raw contrast predictions for exoplanet imaging with the Habitable Worlds Observatory
Raphaël Pourcelot, Laurent A. Pueyo, Emiel H. Por et al. (+6 more)
We provide a quantification of the technological gap between the James Webb Space
Telescope (JWST) and the Habitable Worlds Observatory (HWO) for the goal of exo-Earth imaging around Sun-like
stars at the $10^{-10}$ raw contrast level. We use JWST's in-flight telemetry of the primary segmented mirror to simulate a JWST-like
telescope equipped with a modern coronagraph instrument, inspired by the Roman Space
Telescope (RST) Coronagraphic Instrument (CGI), featuring an Apodized Pupil Lyot Coronagraph and active deformable mirror wavefront control on a segmented, unobstructed, off-axis
telescope. We show that it can achieve around $10^{-10}$ raw contrast for very bright
stars (brighter than magnitude 4) for fast control frequencies of 100 Hz, but that this level of control still lacks sufficient signal to correct JWST-amplitude errors for fainter
stars. We show that an improvement of a factor of ten in wavefront stability is sufficient to extend this capability to a $10^{-10}$ raw contrast across all considered control frequencies (1 Hz to 100 Hz), assuming no reaction wheel vibrations, for
stars up to a magnitude of 11. These results establish a new quantitative
benchmark linking JWST's demonstrated thermo-mechanical stability to HWO's requirements, showing that active wavefront control relaxes the structural stability demands on the observatory, and identifying wavefront stability as the critical technological gap that must be closed for HWO to achieve its exo-Earth imaging goals.
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All authors Raphaël Pourcelot, Laurent A. Pueyo, Emiel H. Por, Marshall D. Perrin, Iva Laginja, Bryony Nickson, Sarah Steiger, Rémi Soummer, Rendal Telfer
Optics
Structural perturbation theory for bound states in the continuum via bifurcation of zeros and extrema of the dispersion relation
Lijun Yuan and Ya Yan Lu
In a lossless periodic structure, a bound state in the continuum (BIC) corresponds to a real zero and a local maximum of the imaginary part of a complex dispersion relation $k = k(\beta)$, where $\beta$ is the Bloch wave number. A perturbation of the structure deforms the dispersion curve and may destroy, move or split the BIC, as demonstrated in existing studies involving lossless
symmetry-preserving perturbations,
symmetry-breaking perturbations and dissipative perturbations. We present a comprehensive perturbation theory, emphasizing the
evolution of the real zeros and extreme points of $\mathrm{Im}[k(\beta)]$ under various structural perturbations. In particular, our theory reveals the existence of lasing threshold modes (LTMs), which are also zeros of $\mathrm{Im}[k(\beta)]$ when the perturbation involves gain with or without balanced loss. Using local Taylor expansions and Puiseux series, we determine the number, locations, and leading-order scaling of real zeros and extreme points for various types of BICs under different types of structural perturbations. The theory recovers known results and predicts new behavior for super-BICs under $\mathcal{PT}$-symmetric perturbations. Specifically, a propagating super-BIC corresponding to a fourth-order zero of $\mathrm{Im}[k(\beta)]$ splits into two real zeros representing either two BICs or two LTMs, and a symmetric standing wave splits into two BIC-LTM pairs. Our theory provides a general framework for studying BICs and nearby resonant modes in both lossless and non-Hermitian periodic structures.
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Physics and Society
Early warning signals for synchronization transitions from partial observations
Yusuke Kato and Naoki Masuda
Anticipating the onset of collective synchronization is important in many networked systems, yet observing every oscillator is often impractical. We investigate whether synchronization transitions can be detected from a small set of monitored, or sentinel, nodes. Using a
stochastic Kuramoto model on networks, we numerically compare three early warning signals: the local order parameter, its temporal variance, and the variance of individual oscillator phases after removing their mean rotational trends. We also compare sentinel-selection strategies based on node dynamics, degree, and random sampling. We show that, under partial observation, the local order parameter and the variance of detrended phases provide substantially stronger warning signals than the variance of the local order parameter. Selecting nodes according to their dynamical behavior near the transition consistently improves performance over other sentinel-selection methods. With only $\lfloor\ln N\rfloor$ dynamically selected sentinels, two success indicators approach the performance obtained by observing all $N$ nodes. These results demonstrate that synchronization transitions can be anticipated from sparse observations when the warning signal and monitored nodes are chosen appropriately.
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High Energy Physics (Experiment)
Vertex reconstruction for a search for neutron-antineutron conversions with HIBEAM
Alexander Burgman, Sze Chun Yiu, Yamna Shaikh et al. (+13 more)
The HIBEAM/NNBAR programme (incorporated into the FINESSE/NNBAR programme) at the European Spallation Source is proposed to search for
neutrons converting to antineutrons. An important observable is the reconstructed vertex arising from charged particles produced by an antineutron annihilating on a thin target foil and which pass through a time projection chamber. This paper studies track clustering and foil-plane vertex reconstruction for this
topology. Both non-machine-learning methods and graph-neural-network methods are tested and compared with each other, including deterministic clustering, trackless projection and a hybrid clustering/graph-neural-network chain with track classification and vertex refinement. We conclude that, for the geometrically simple events in the HIBEAM TPC, classical reconstruction methods perform on-par with machine-learning based methods in terms of vertex coordinate reconstruction. Custom machine-learning based methods can, however, deliver event-shape information that may be important in downstream analyses.
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All authors Alexander Burgman, Sze Chun Yiu, Yamna Shaikh, David Milstead, Eily Merjy, Lucas Åstrand, Kenneth Österberg, Fredrik Oljemark, Bernhard Meirose, Matthias Holl, Valentina Santoro, Jorge Amaral, Ernesto Kemp, André Nepomuceno, Tiago Quirino, Joshua L. Barrow
High Energy Physics (Theory)
Scattering Equations as the lowest order K-identities in the calculation of Stringy Scaling of Hard String Scattering Amplitudes
Sheng-Hong Lai, Jen-Chi Lee and Yi Yang
We prove explicitly the n-point K-identities we proposed previously in the calculation of one tensor hard string scattering amplitudes (HSSA). These K-identities were the key to obtain the stringy scaling behavior in the saddle point calculation of the n-point HSSA and, on the other hand, to consistently match with the calculation of decoupling of zero norm states. Moreover, we introduce a G function to generate an infinite set of generalized K-identities (GKI). The lowest order set of these GKI is the scattering equations (SE) used in the calculation of field theory amplitudes in the CHY formalism. The next to leading order set of these GKI is the K-identities used previously in the calculation of one tensor HSSA. We expect that the higher order sets of these GKI can find applications in calculating other HSSA.
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Space Physics
Solar Magnetic Configuration Control over Radiation Belt Electrons
Ahmad Lalti, Jonathan Rae, Clare Watt et al. (+2 more)
Earth is surrounded by two highly dynamic concentric belts of particle radiation. The outer radiation belt exhibits coherent variability at
solar-cycle, seasonal, and 27-day (Carrington) timescales. While the
solar-cycle and Carrington variations have been attributed to the recurrence of coronal hole
solar wind, the seasonal variation has long been explained by local
geometric effects that modulate the
solar wind-magnetosphere coupling. Here, we challenge this paradigm by showing that the periodic recurrence of coronal hole
solar wind likewise drives the seasonal variation. We further demonstrate that the Alfvénic nature of this
solar wind is a key driver of the observed electron flux enhancement in the outer radiation belt. These findings provide a unifying framework linking
solar magnetic topology,
solar wind properties, and magnetospheric dynamics across multiple timescales at Earth and beyond.
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All authors Ahmad Lalti, Jonathan Rae, Clare Watt, Stephanie Yardley, Savvas Raptis
Instrumentation and Methods for Astrophysics
Correction of the influence of rolling shutter detectors on determining the velocity of meteors from video recordings
Lukáš Shrbený, Jiří Borovička, Pavel Spurný et al. (+2 more)
Modern
video cameras use either global or rolling shutter to create individual
video frames. In case of global shutter, the whole frames are exposed and read out at the same time. In case of rolling shutter, the exposure and readout proceed sequentially line by line. Such cameras are now commonly used for meteor observations. It is then necessary to perform a correction for this type of image reading in order to correctly and accurately determine the velocity of recorded meteors. We provide here the correct procedure. The correction must include the value of the rolling period of the sensor, which is generally not provided in camera specifications. We discuss four methods of determining the rolling period experimentally. The most accurate method uses the New EXposure Timing Analyser (NEXTA) of [1]. We list rolling periods measured for several cameras.
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All authors Lukáš Shrbený, Jiří Borovička, Pavel Spurný, Jan Mánek, Jan Fuchs
Accelerator Physics
Wakefield-Dressed Relativistic Vortex Electrons in Plasma Accelerators
Zhigang Bu, Lingang Zhang and Liangliang Ji
Plasma wakefield acceleration is usually regarded as a classical mechanism for producing high- energy charged-particle beams. Here we show that an axisymmetric
plasma wakefield can also act as a moving
quantum structure that supports relativistic
vortex electron states. Starting from the Dirac equation, we derive the electron spinor eigenstates with definite total angular momentum in an ideal bubble-regime wakefield. The transverse focusing field confines and quantizes the electron transverse motion into Laguerre-Gaussian
vortex modes, while the longitudinal electric field acceler- ates the electron without destroying the
symmetry-protected angular momenta. We further analyze the localized and off-axis
vortex electron wave-packets, and non-ideal wakefield perturbations, and identify the conditions for preserving electron-
vortex-state purity. These results suggest
plasma wakefield as a route toward high-energy
vortex electrons and extend
plasma-based acceleration from classical beam dynamics to
quantum-state control of relativistic particles.
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Nuclear Theory
Hadronic rescattering effects on net-proton cumulants from functional renormalization group calculations
Qianru Lin, Shi Yin, Jianing Li et al. (+4 more)
Net-
proton cumulants in the Beam Energy Scan region of heavy-ion collisions are widely used to probe critical fluctuations associated with the conjectured critical endpoint of
Quantum Chromodynamics (QCD). Most existing studies, however, concentrate on the initial-state or phase-transition contributions, while the impact of hadronic rescattering on these observables has not been fully quantified. To address this gap, we construct event-by-event
proton and antiproton distributions from functional renormalization group (fRG) cumulants using the maximum
entropy principle, and propagate the resulting particles through the hadronic transport model SMASH in a simplified spherical
evolution setup. We systematically investigate how the hadronic cascade modifies net-
proton cumulants at collision energies $\sqrt{s_{NN}}=3.0$, 3.9, 4.9, 7.2, and 7.7~GeV. In the canonical-ensemble framework, which enforces exact net-
baryon number conservation, the higher-order cumulant signal—in particular the ratio $C_4/C_2$ at $\sqrt{s_{NN}}=4.9$~GeV—is strongly reduced during the early stage of the cascade; the suppression of $C_4/C_2$ reaches approximately $20\%$. The non-monotonic energy dependence inherited from the fRG input survives the hadronic
evolution, but its magnitude is substantially modified. These results demonstrate that hadronic rescattering provides a non-negligible background effect that must be accounted for when extracting QCD critical-point signals from experimental data.
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All authors Qianru Lin, Shi Yin, Jianing Li, Hannah Elfner, Fabian Rennecke, Long-Gang Pang, Jan M. Pawlowski