High Energy Physics (Phenomenology)
Cosmological signals of dark matter semi-annihilation
Boris Betancourt Kamenetskaia, Mathias Garny, Alejandro Ibarra et al. (+2 more)
The growth of
primordial density fluctuations in the early Universe leads to an inhomogeneous dark matter distribution at high
redshift, where semi-annihilation processes of the form $\chi\chi \rightarrow \chi^c \phi$, with $\phi$ being dark radiation, can occur with a sizable rate. Using a state-of-the-art model for the cosmological boost factor, we compute the resulting
redshift-dependent flux of boosted dark matter particles generated by semi-annihilation, and we study the implications of the boosted component for structure formation and direct detection experiments. We find a model independent upper limit on the semi-annihilation cross-section from structure formation, which reads $\langle\sigma_{2\to1} v\rangle\leq4.2\times10^{-19}~\left(m_\chi/1~\rm GeV\right)~\mathrm{cm}^3/{\rm s}$. Further, we find that the cosmological contribution to the boosted dark matter flux can be comparable to the
galactic one, providing an $O(1)$ enhancement to the sensitivity of dark matter searches, thus slightly enhancing the discovery potential in direct detection experiments of semi-annihilation scenarios where the dark matter interacts with the
nucleus.
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All authors Boris Betancourt Kamenetskaia, Mathias Garny, Alejandro Ibarra, Alessia Musumeci, Merlin Reichard
High Energy Astrophysical Phenomena
Pulse profile modelling of accreting millisecond pulsars with disc occultation and its impact on parameter inference
Ying-Han Mao, Bas Dorsman, Anna L. Watts et al. (+3 more)
Pulse profile modelling is a relativistic ray-tracing technique used to infer
neutron star mass, radius, and surface hotspot properties from X-ray pulsations. Pulse profile modelling has been widely applied to rotation-powered millisecond
pulsars, where the local environment is relatively empty. Application to accreting millisecond
pulsars is complicated by the geometry of the local
accretion flow, including disc occultation of surface emission. In this work, we extend an established pulse profile modelling code, X-PSI, to incorporate
accretion disc occultation in accreting millisecond
pulsar pulse profile modelling. We quantify how disc occultation depends on system geometry and evaluate its impact on parameter inference. We find that disc occultation is primarily governed by the viewing inclination and can significantly reshape pulse profiles at moderate to high inclinations. Using synthetic
Neutron Star Interior Composition Explorer
datasets, we investigate parameter recovery for two representative hotspot configurations. For hotspots close to the rotational poles, statistically acceptable fits can yield posteriors that deviate noticeably from the true parameters. In contrast, in a case with hotspots located closer to the equator we find more reliable parameter recovery. We further find that neglecting disc occultation can introduce spurious posterior modes with comparable statistical support, potentially affecting the interpretation of inferred
neutron star parameters, suggesting that this effect should be included in accreting millisecond
pulsar pulse profile modelling.
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All authors Ying-Han Mao, Bas Dorsman, Anna L. Watts, Tuomo Salmi, Juri Poutanen, Xiang-Dong Li
Lattice Field Theory
Electric charge fluctuations from lattice QCD in the continuum limit
Szabolcs Borsányi, Zoltán Fodor, Jana N. Guenther et al. (+5 more)
Electric charge fluctuations $\chi_n^Q$ allow comparisons between theory and experiment, but are elusive on the
lattice due to severe cutoff effects. We use a 4HEX action to obtain $\chi_2^Q$ and, for the first time ever, $\chi_4^Q$ in the continuum limit. We find disagreement with the
hadron resonance gas (HRG) model, which we cannot explain with finite volume effects. We include light
meson interactions in the HRG model via the S-
matrix, reducing the tension for $\chi_4^Q$, but worsening the agreement for $\chi_2^Q$. We propose measuring the ratio $\chi_4^Q/\chi_2^Q$ at the LHC to investigate this tension.
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All authors Szabolcs Borsányi, Zoltán Fodor, Jana N. Guenther, Paolo Parotto, Attila Pásztor, Claudia Ratti, Volodymyr Vovchenko, Chik Him Wong
Earth and Planetary Astrophysics
A population view of transiting hot giant exoplanets: Tracing Fe and Ti chemistry with ESPRESSO and MAROON-X
Bibiana Prinoth, Vivien Parmentier, Stefan Pelletier et al. (+9 more)
Hot and ultra-hot Jupiters offer a unique laboratory to study atmospheric chemistry at the population level using ground-based high-resolution spectroscopy. Fe and Ti are key tracers of thermal and chemical structure, yet they exhibit different observational trends across the population. We present a homogeneous reanalysis of high-resolution transmission spectra of ten hot and ultra-hot Jupiters observed with VLT/ESPRESSO and Gemini-N/MAROON-X. We search for neutral Fe and Ti absorption and perform injection-recovery tests using models spanning a range of Ti-depletion levels and T-p profiles. For direct comparison across observations, we introduce the relative cross-correlation metric, $\Delta$Ti-Fe. We detect Fe in 7 and Ti in 4
planets above 5$\sigma$. Across the population, $\Delta$Ti-Fe decreases sharply towards lower
equilibrium temperatures. Under the assumption of equal Ti depletion across
planets, isothermal models fail to reproduce this trend, instead requiring a temperature-dependent depletion of Ti that increases toward cooler
planets, consistent with cold-trapping processes in cooler atmospheres. Models with inverted T-p profiles naturally reproduce the decline without invoking temperature-dependent depletion. There, Ti is converted into TiO in deeper, cooler layers and then removed from the gas phase through condensation, leading to strong suppression of the observable atomic Ti signal. Nevertheless, even in the gradient models, overall depletion of Ti relative to Fe is required to match the hottest
planets. Our results demonstrate that observable refractory chemistry is governed by the interplay of molecular partitioning, ionisation, condensation, and cold-trapping processes, as well as the vertical structure of ultra-hot Jupiter atmospheres. Additional observations will be necessary to distinguish between temperature-dependent cold-trapping and overall depletion.(abbrev.)
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All authors Bibiana Prinoth, Vivien Parmentier, Stefan Pelletier, Daniel Kitzmann, Julia V. Seidel, Adrien Simonnin, Valentin De Lia, Sydney Vach, Jens Kammerer, Matteo Brogi, Florian Debras, Michael R. Line
Quantum Physics
Physics-Informed Variational Quantum Classifier for Phase Detection in Strongly Correlated Matter
Hugo Catalá, Ezequiel Valero and Germán Rodrigo
The characterisation of
quantum phases in strongly correlated systems is a crucial milestone for the deployment of
quantum sensors. In this work, we present a Physics-Informed Variational
Quantum Classifier (VQC) designed to detect the topological phase transition between the
Fermi polaron quasiparticle and the molecular bound state. Unlike conventional Machine Learning approaches, our
quantum architecture is constructed via the Trotterised time-
evolution of an effective
Hamiltonian, ensuring that the learnable parameters correspond to interpretable physical quantities. We show that the VQC efficiently discovers the optimal interferometric protocol, specifically the
evolution time and effective bath interactions required to maximise the visibility of Ramsey fringes, thereby clearly distinguishing the Bose-Einstein Condensate (BEC) and Bardeen-Cooper-Schrieffer (BCS) regimes. Furthermore, we report the validation of this classifier on the QRed superconducting
quantum processor (BSC-CNS). Despite the intrinsic hardware noise and decoherence, the VQC preserves the relative ordering of the topological phases. We demonstrate that the physics-informed architecture achieves a linear gate complexity $\mathcal{O}(N)$, bypassing the exponential
memory wall of classical simulation and ensuring scalability to many-body regimes.
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Mesoscale and Nanoscale Physics
Spin-orbit coupling by design in quantum state engineering of atomically defined quantum dots
Hermann Osterhage, Julian H. Strik, Ivan Ado et al. (+4 more)
Tuning
spin-orbit coupling is essential in controlling both
spin and charge in confined
semiconductor nanostructures, yet it is rarely a truly controllable parameter. Here, we show control over the
spin-orbit
Hamiltonian in
quantum dots and the resulting
quantum states by tailoring the confinement potential with atomic-scale precision. Using scanning tunnelling microscopy and spectroscopy, we pattern individual Cs ions into designer
quantum dot structures on the surface of indium antimonide, in which electrons from a two-dimensional electron gas are confined with chosen in-plane electric-field gradients. We then quantify the atomic level structure, both spatially resolving the orbital character of the electronic states and their
magnetic-field
evolution. We demonstrate that the level structure, including the induced zero-field splitting, can be tailored by the designed geometry of the local electric fields. These effects can be described using a
Hamiltonian that allows consistent treatment of the confinement-induced
spin-orbit coupling beyond the conventional Bychkov-Rashba description. This
Hamiltonian is derived from a multiband k.p model and takes the energy dependence of the relevant physical parameters into account. Such precise control of
spin-orbit coupling in
semiconductor quantum dots is relevant to
quantum and spintronic technologies.
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All authors Hermann Osterhage, Julian H. Strik, Ivan Ado, Anna M. H. Krieg, Daniel Wegner, Mikhail Titov, Alexander A. Khajetoorians
Applied Physics · Cross-listed from eess.SP
Implications of the Reciprocity Theorem for Reconfigurable Intelligent Surfaces
Uday K Khankhoje and Debidas Kundu
Reciprocity between a transmitter and receiver is a foundational requirement in wireless communications. A few recent works have suggested that reciprocity is broken under reflection by reconfigurable intelligent surfaces (RIS) when the reflection phase becomes incident angle dependent. In this work, we rigorously show that these claims are based on the use of idealized reflection coefficients that ignore mutual coupling between heterogeneous unit
cells, surface-truncation effects, and structural scattering contributions from the RIS. Full-wave electromagnetic simulations of transmit/receive
antennas and a finite-size RIS implemented via a particular unit
cell design are performed to quantitatively demonstrate that reciprocity holds even in the presence of incident-angle dependent reflection phases. To show this, we calculate two-port
antenna scattering parameters and evaluate the electromagnetic reciprocity integral to support our claims.
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Quantum Physics
Quantum Horizon: An evaluation of quantum computing as a threat to Bitcoin and Ethereum
Iosif M. Gershteyn and Jacob A. Alber
Quantum computing poses a real, broad-based, but bounded and substantially mitigable threat to Bitcoin and Ethereum. We separate the two
quantum algorithms that public discussion routinely conflates: Shor's
algorithm breaks the
elliptic-curve signatures (ECDSA over secp256k1, BLS over BLS12-381) that authorize spending, whereas Grover's
algorithm does not meaningfully threaten proof-of-work mining, which is protected by a merely quadratic speedup, fault-tolerant per-operation costs, a square-root parallelization wall, and difficulty adjustment. Folding hardware scaling, the falling resource requirement, a fault-tolerance readiness lag, and expert surveys into a single Monte-Carlo forecast yields a wide, bimodal arrival distribution for a cryptographically relevant
quantum computer: about a one-in-six chance by 2035, near 30% by 2040, and about 60% by 2050. Exposure is concentrated and mostly migratable: of Bitcoin's roughly six million
quantum-exposed coins only about 2.3 million are irreducibly at risk, while 50 to 65% of Ether sits at key-revealed accounts that can adopt post-
quantum signatures. A timely migration beats even an optimistic 2035 machine, so the binding constraint is governance, not technology. A survey of the top twenty cryptocurrencies finds none fully post-
quantum. Reproducible models accompany every quantitative claim.
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Statistical Mechanics
Generic nonlocal statistics of the stationary measure in conserved active systems
Filippo De Luca, Michael E. Cates and Cesare Nardini
The stationary measure of
equilibrium systems with detailed balance follows a Boltzmann distribution, so that for short-ranged interactions the measure is local, meaning that distant spatial domains are statistically independent. In contrast, active systems break detailed balance, and can have nonlocal stationary measure even for fully local dynamics. Here, by expanding in nonlinearity about a Gaussian-model limit, we construct the measure perturbatively deep in the disordered phase for a class of models that includes Active Model A, Active Model B+, Model AB, the Nonreciprocal Cahn–Hilliard model, and the Toner–Tu model. In this regime, nonlocality is linked to a dynamical conservation law. Our results generically preclude construction of a Landau–Ginzburg expansion of the stationary measure (as opposed to the dynamical equations) for conserved active field theories.
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Optics
Statistical Methods for Determining Turbulence in Supercontinuum Generation
Mehmet Müftüoglu and Mario Chemnitz
Distinguishing coherent, turbulent, and chaotic operating regimes in supercontinuum generation is important for understanding nonlinear optical dynamics and optimizing broadband light sources. Experimentally identifying the onset of
turbulence remains challenging because the most common metric, first-order coherence, requires access to the complex optical field and cannot be directly obtained from intensity-only measurements. In this work, we investigate whether experimentally accessible statistical observables can identify
turbulence in supercontinuum generation. We compare wavelength-integrated variance and kurtosis with simulation-based first-order coherence over a chirp-controlled pulse-duration sweep implemented through additional $\beta_2$ dispersion. The study combines generalized nonlinear Schrödinger equation simulations with shot-to-shot dispersive
Fourier transform measurements validated against optical spectrum analyzer spectra. Statistical intensity distributions were analyzed using histograms, complementary cumulative distribution functions, and kurtosis measurements across the generated supercontinuum bandwidth. Simulations and experiments both revealed heavy-tailed intensity statistics in the intermediate pulse-duration regime associated with reduced spectral coherence. The integrated kurtosis reached a maximum near 600 fs in simulations and near 700 fs in experiments, while the integrated variance within the first 20 dB spectral range decreased with increasing pulse duration. The agreement between simulations and experiments demonstrates that variance- and kurtosis-based observables can serve as experimentally accessible indicators of
turbulence in supercontinuum generation. These results show that intensity-only statistical measurements can distinguish coherent and incoherent operating regimes without requiring direct field-resolved coherence measurements.
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Instrumentation and Detectors
Seeding and Matching algorithms for the first GPU-based High Level Trigger of the LHCb experiment
Christina Agapopoulou, Lukas Calefice, Álvaro Fernández Casani et al. (+10 more)
We describe the GPU implementation of the Seeding and Matching
algorithms, developed for the first level trigger of the LHCb experiment and key to reconstruct long and very displaced tracks at 40 MHz. The
algorithms have been participating in the data taking during the full Run 3 of LHCb with a very high throughput, increasing the physics reach of the experiment. The Seeding is a standalone pattern recognition
algorithm aiming at finding charged particle trajectories in the most forward tracker of LHCb. These trajectories are then extrapolated backward by the Matching
algorithm which combines them with stubs formed from hits in the first tracker in order to form what we call Long tracks. Hits in the second tracker are then searched for to better define the trajectory and improve the track momentum resolution. This backward approach, complementary to the approach of extrapolating the stubs in the first detector to the forward tracker through the
magnetic field, improves the Long track efficiency at low transverse momenta, increasing the potential of key physics decay channels.
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All authors Christina Agapopoulou, Lukas Calefice, Álvaro Fernández Casani, Vava Gligorov, Arthur Marius Hennequin, Louis Henry, Valerii Kholoimov, Brij Kishor Jashal, Arantza Oyanguren, Lorenzo Pica, Volodymyr Svintozelskyi, Da Yu Tou, Jiahui Zhuo
Quantum Physics
Sensitivity of polaron-molecule observables to MDR/GUP-like ultraviolet deformations at low energies via quantum computing
Ezequiel Valero, Hugo Catala, Victor Ilisie et al. (+1 more)
We show that
impurity many-body observables can display enhanced sensitivity to ultraviolet deformations of generalized-uncertainty-principle and modified-dispersion-relation type at accessible energy scales. Using a deformed polaron-molecule
Hamiltonian constructed to preserve the infrared sector, we quantify the impact of such deformations on spectral and Ramsey observables and implement the corresponding dynamics in a controlled
quantum computing setting. We identify regimes near the polaron-molecule crossover where small ultraviolet deformations are strongly amplified, leading to experimentally resolvable changes in quasiparticle properties and spectral response. Our results establish a concrete sensitivity-based route to low-energy
quantum-
gravity phenomenology in a well-defined many-body platform and delimit the validity of the effective description. Furthermore, we report experimental validation on the QRed superconducting
quantum processor (BSC-CNS).
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All authors Ezequiel Valero, Hugo Catala, Victor Ilisie, Germán Rodrigo
Astrophysics of Galaxies
GATOS XV: A JWST/MIRI survey of extended circumnuclear dust emission in nearby Seyfert galaxies
David J. Rosario, Houda Haidar, Steph Campbell et al. (+32 more)
The subarcsecond angular resolution and stable background of JWST has given us the first high-fidelity images of the arcsecond-scale environment around Active
Galactic Nuclei (AGNs) in the nearby Universe. With mid-infrared (MIR) surface brightness sensitivities that are much deeper than the best ground-based instruments, the Mid-InfraRed Instrument imager (MIRIM) now allows us to understand the structure and thermal properties of
dust using information over wavelengths of $5$-$25$ $\mu$m, almost all of the MIR range. We present a Cycle 1 JWST MIRIM survey of Seyfert
galaxies with the express aim of characterising AGN-heated
dust in the central few 100 pcs, and searching for signatures of
dust-laden
nuclear outflows. This paper outlines the motivation behind the programme, the data reduction and analysis techniques used to isolate the
nuclear and extended emission, and a comparison of the observed MIR structures with those seen in other phases (
stars, ionised and molecular gas, absorbing
dust). In concert with earlier studies that used these data, we conclude that resolved AGN-heated
dust is widespread in the Seyfert population, extending out to a few hundred pcs from the
nucleus and often displaying a higher surface-brightness compared to the more widespread
star-forming dusty circumnuclear disk. Even after accounting for contamination from emission lines in the MIRI filters, we find strong spatial correlations between MIR
dust emission and the AGN-ionised gas in the narrow-line region (NLR).
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All authors David J. Rosario, Houda Haidar, Steph Campbell, John Schneider, Chris Packham, Nancy A. Levenson, Almudena Alonso-Herrero, Richard I. Davies, Dan Delaney, Santiago García-Burillo, Erin K. S. Hicks, Sebastian F. Hönig, Mason Leist, Enrique Lopez-Rodriguez, Miguel Pereira-Santaella, Anelise Audibert, Enrica Bellocchi, Françoise Combes, Ismael García-Bernete, Peter Boorman, Andrew J. Bunker, Luis Colina, Tanio Diaz Santos, Fergus R. Donnan, Poshak Gandhi, Omaira González-Martín, Laura Hermosa Muñoz, Alvaro Labiano, Cristina Ramos Almeida, Claudio Ricci, Rogemar A. Riffel, Dimitra Rigopoulou, Daniel Rouan, Marko Stalevski, Lulu Zhang
High Energy Astrophysical Phenomena
Detecting classical nova-like explosions with LISA
Ethan McKeever, Shu Yan Lau, Hang Yu et al. (+1 more)
Gravitational waves from close binary white
dwarfs will form the bulk of measurements obtained by the
Laser Interferometer Space
Antenna (LISA). Previous studies have highlighted the importance of including the effects of steady-state mass transfer in waveform models as many individually resolvable white
dwarf binaries will be interacting during the LISA observation window. However, few studies have considered the effect of novae on gravitational wave observations and parameter estimations. We fill in this gap by analyzing the detectability of novae in these systems and the biases in physical parameters when these bursts are not considered. We model a nova burst as a rapid loss of mass from the accretor that suddenly shifts the gravitational wave frequency. We analytically predict the signal-to-noise ratios for direct detection of the nova and where bias from mismodeling becomes greater than the statistical uncertainty. We also consider comparison of two halves of future LISA data to detect bursts in a model agnostic way. Our work has implications for identifying and classifying individual nova events as well as constraining the
galactic nova rate throughout the entire
galaxy, a challenging task for optical surveys.
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All authors Ethan McKeever, Shu Yan Lau, Hang Yu, Neil J. Cornish
High Energy Astrophysical Phenomena
Transitions in the Mass-ratio and Spin Properties of Binary Black Holes in GWTC-5
Elizabeth Flanagan, Fabio Antonini, Thomas Callister et al. (+4 more)
We analyze the mass-ratio and effective-
spin ($\chi_{\rm eff}$) distributions of binary black hole mergers in the latest gravitational-wave catalog, GWTC-5, as a function of primary mass. Using hierarchical
Bayesian inference with flexible Gaussian-process population models, we identify four distinct mass regions separated by sharp transitions in both mass-ratio and
spin properties. Below $\sim15~M_{\odot}$, the population strongly favors equal-mass binaries and exhibits a narrow $\chi_{\rm eff}$ distribution peaked at positive values. In the range $18$-$30\,M_{\odot}$, the mass-ratio distribution becomes substantially flatter, while the $\chi_{\rm eff}$ distribution broadens, shifts to a peak consistent with zero, and shows tentative–but not statistically required–evidence for positive skewness. The region associated with the feature near $\simeq35~M_{\odot}$ returns to a narrow $\chi_{\rm eff}$ distribution consistent with
symmetry at zero and strongly favors equal-mass binaries. Above $\simeq 45~M_{\odot}$, both the mass-ratio and $\chi_{\rm eff}$ distributions broaden significantly. The inferred support of the
spin distribution converges toward the range expected for binaries containing remnants of previous black hole mergers, making the highest-mass region fully consistent with a
star cluster population of hierarchical mergers. The close correspondence between transitions in mass ratio and effective
spin suggests that different primary-mass ranges trace distinct formation channels, with isolated binary or triple
evolution likely dominating the lower-mass population and dynamical assembly becoming increasingly important at higher masses.
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All authors Elizabeth Flanagan, Fabio Antonini, Thomas Callister, Debatri Chattopadhyay, Fani Dosopoulou, Isobel Romero-Shaw, Jakob Stegmann
High Energy Physics (Theory)
On the branes behind scale-separated AdS$_{3}$ flux vacua
Álvaro Arboleya, Adolfo Guarino, Clara Roldán-Domínguez et al. (+1 more)
We investigate the brane origin of supersymmetric and scale-separated AdS$_3$ flux
vacua arising in a class of type IIB orientifold reductions with G$_2$-structure. First, using the effective three-dimensional supergravity together with explicit uplift formulae, we trace back the $F_{(7)}$ and $F_{(3)}$ fluxes responsible for scale separation and identify the type IIB background that is probed by the corresponding D1- and D5-branes. Second, by restoring such D1- and D5-branes, we obtain a type IIB solution that interpolates between the previous background in the asymptotic region and the scale-separated AdS$_3$ flux
vacua in the near-horizon region. Third, by working directly in ten dimensions, we construct a codimension-one D1-D5-KK5 intersection whose near-horizon region realises the scale-separated AdS$_3$ flux
vacua. Our results provide a higher-dimensional interpretation of these flux
vacua in terms of (smeared) brane configurations.
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All authors Álvaro Arboleya, Adolfo Guarino, Clara Roldán-Domínguez, Giuseppe Sudano
Quantum Physics
QCI Connect: A Modular Full-Stack Quantum Computing Platform
Eric Bertok, Hannes Busche, Florian Drinkler et al. (+17 more)
In a world of various competing
quantum computing architectures, hardware-agnostic, full-stack platforms are necessary to bring the full power of
quantum computing hardware to domain experts via the cloud. QCI Connect and its Software Development Kit provide a reference architecture for a full-stack platform with a modular design and open-source interface definitions, built to facilitate a community-driven application ecosystem. Here, we present its overall design and features, central interfaces, and lessons learned, both for users of the platform and as a reference guide for future developments.
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All authors Eric Bertok, Hannes Busche, Florian Drinkler, David Emmanuel-Costa, Daniel Herr, Steffen Hien, Thomas Keitzl, Elisabeth Lobe, Alexandru Paler, Johannes Renkl, Martin Rymarz, Gary Schmiedinghoff, Peter K. Schuhmacher, Thomas Stehle, Benedikt Strobel, Hanna Tschakert, Adrian Vetter, Andre Waschk, Alexander Weinert, Lukas Windgätter
Quantum Physics
Optimal Decoding of Small Codes by Density Matrix Propagation
Anthony Benois, Pierre Cussenot, Grégoire Misguich et al. (+2 more)
Accurate and efficient decoding is a crucial component for achieving fault-tolerant
quantum computing. Realistic
circuit-level noise introduces temporal correlations and degeneracy, making optimal (maximum-likelihood) decoding computationally intractable in general. As a result, practical decoders rely on heuristic approximations, and it is generally difficult to quantify how suboptimal they are, as this strongly depends on the code and noise model considered. In this work, we study the accuracy of practical decoding
algorithms under
circuit-level noise by comparing them against a maximum likelihood decoding
benchmark. Our approach propagates the density
matrix through the full
memory experiment and computes the optimal decoding decision for each syndrome history. We introduce
pruning techniques with rigorous bounds, allowing us to access larger numbers of syndrome-extraction rounds. We apply this framework to small instances of the repetition code and a cellular automaton code, and
benchmark minimum-weight perfect matching (MWPM), belief propagation with ordered statistics decoding (BP+OSD), Tesseract, and Planar decoders against optimal decoding. While standard decoders remain close to optimal for the repetition code, we find significant deviations for the cellular automaton code, with BP+OSD deteriorating already in experimentally relevant noise regimes. Moreover, the
pruning method developed here highlights that, at low physical error rates, only a narrow fraction of syndrome histories contributes significantly to the logical error rate.
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All authors Anthony Benois, Pierre Cussenot, Grégoire Misguich, Nicolas Sangouard, Kiara Hansenne
High Energy Physics (Phenomenology)
Subhashish Banerjee, Heinrich Päs and Erika Rani
We study
entanglement measures for oscillating
neutrinos in the wave-packet formalism and confirm that an oscillating
neutrino exhibits genuine tripartite
entanglement and can be characterized as a member of the W class of states. We also show that this feature survives in the decoherence limit, and discuss the effect of CP phases on the
entanglement. These findings provide new insights into the
quantum nature of
neutrino oscillations and their potential role in
quantum information science, especially for
neutrinos propagating large distances such as the astrophysical
neutrinos observed at
neutrino telescopes.
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Adaptation and Self-Organizing Systems
Multiple hysteresis widths in inertial Kuramoto model
Jayesh C. Jain and Sarika Jalan
Multistability is a well-known feature of the inertial Kuramoto system (KMI). Here, we demonstrate that an interplay of phase lag and triadic interactions in KMI leads to distinct hysteresis widths corresponding to different stable states. This phenomenon becomes more pronounced with increasing inertia. Theoretical calculations for the backward branch based on self-consistent analysis show that these multiple widths arise from saddle-node bifurcation occurring at different coupling strengths. Moreover, the forward branch corresponds to oscillatory state and does not admit steady-state solution. The study of multiple hysteresis widths may be useful in modeling power grid systems, information storage, and
memory selection in real-word systems.
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High Energy Physics (Phenomenology)
Light hybrid baryons in the constituent model of QCD
Joachim Viseur, Claude Semay and Cyrille Chevalier
Hybrid
baryons, in which gluonic degrees of freedom play an explicit dynamical role, provide a key testing ground for nonperturbative
quantum chromodynamics. In this work, we investigate the mass spectrum of light hybrid
baryons composed of identical
quarks within a phenomenological constituent framework, applied to a
quark core-
gluon approximation. In this approach, the hybrid
baryon is described as a bound state of a color-octet three-
quark core and a constituent
gluon, allowing the original four-body problem to be reduced to a three-body calculation followed by an effective two-body treatment. The spectrum of the color-octet
quark core is obtained by solving a semirelativistic three-
quark Hamiltonian with linear confinement, Coulomb, and regularized hyperfine interactions using an oscillator basis expansion. Finite-size effects of the core are incorporated through the convolution of the effective core-
gluon interaction with the spatial
quark density. The resulting two-body problem, whose associated
Hamiltonian has the same shape as the one of the core, is solved applying the helicity formalism and using the Lagrange mesh method. Our results predict the lightest hybrid
baryons to occur at energies above $3~\mathrm{GeV}$, with negative-parity states generally lying below their positive-parity counterparts. The predicted spectra are compared with
lattice QCD and QCD sum-rule calculations, showing qualitative agreement although the lowest-lying
lattice QCD results are significantly lighter than the present ones. Possible extensions of the model and implications for future experimental searches are discussed.
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Biological Physics
Measurement-limited learning of conformational heterogeneity in cryo-electron microscopy
Henry H. Mattingly, Luke Evans and Pilar Cossio
Cryogenic electron microscopy images sample individual biomolecules from their conformational landscapes, offering a route to infer the distributions underlying molecular mechanisms. However, because images are indirect measurements, they limit which features of an underlying landscape are statistically identifiable. In ensemble reweighting, this problem appears as a choice of resolution: conformational space is discretized into representative structures whose population weights are inferred from images. Adding structures increases nominal resolution, but nearby conformations may generate overlapping image distributions and indistinguishable weights. Here, we develop an information-theoretic framework that selects representative conformations by maximizing mutual information between ensemble weights and images under a probabilistic forward model. Analytically, we show in a one-dimensional Gaussian model that measurement noise sets the optimal spacing. Applied to molecular conformations sampled from simulation, the framework constructs near-optimal ensembles that span heterogeneity while avoiding redundancy. Thus, the measurement process induces a maximally learnable coarse graining of conformation space.
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Quantum Physics
Dealing with locality in QAOA
Mithilesh Kumar and Yusuf Tahir
Shallow-depth QAOA on sparse, high-diameter MaxCut instances faces a locality bottleneck: at depth \(p\), local observables can depend only on a bounded neighborhood of the
circuit interaction graph. We propose a transport-augmented QAOA that keeps the MaxCut cost
Hamiltonian unchanged but enriches the mixer with optimized, unweighted shortcut couplings (scheduled \(XX+YY\)) to collapse the effective interaction-graph diameter. Using exact finite-depth support recursions, we relate optimal shortcut placement to bounded-diameter graph augmentation, and show in
benchmarks that (unlike ma-QAOA) performance becomes effectively size-invariant once the diameter is reduced. For bipartite families (base diameter 4), reducing the interaction path to \(d=1\) raises the ensemble-averaged approximation ratio from 0.7378 (ma-QAOA) to 0.9767 at \(p=1\) (\(\sigma=0.0251\), nine system sizes); on random trees (base diameter 10), at \(p=2\) it improves from 0.9226 to 0.9997 (\(\sigma=0.0001\)).
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High Energy Physics (Phenomenology)
Bose-enhanced Neutrino Decays in a Thermal Medium
Yuber F. Perez-Gonzalez, Manibrata Sen and Walter Tangarife
We compute the decay width of
neutrinos in a thermal medium using finite-temperature
quantum field theory, focusing on non-standard decays into lighter
neutrinos and a scalar or light vector
boson. We derive general expressions for the thermal decay rate and show that finite-temperature effects can dramatically enhance
neutrino decays when the parent and daughter states are nearly degenerate in mass. In this regime, the emitted
boson is kinematically soft and undergoes strong Bose enhancement, leading to decay widths that can exceed their
vacuum values by a couple of orders of magnitude. We demonstrate that this effect is largely insensitive to the Lorentz structure of the underlying interaction and arises generically from the interplay of thermal occupation factors and quasi-degenerate kinematics. Our results highlight a previously underappreciated feature of
neutrino decay in thermal environments and provide a general framework applicable to a broad class of fermionic decay processes.
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Solar and Stellar Astrophysics
Realtime forecasting of solar energetic particle event and proton flux using multi-source solar observations and multi-task deep learning
Yian Yu, Yang Chen, Lulu Zhao et al. (+3 more)
Solar energetic particle (SEP) events, defined by
proton flux exceeding 10 pfu in the > 10 MeV channel, pose major risks to spacecraft operations, astronaut safety, and high-latitude aviation. Due to the complexity and rarity of SEP events, reliable operational SEP
forecasting remains an important challenge in space weather. Here we present a novel 24-hour-ahead realtime
forecasting framework, SEPNET-PRISM, based on a multi-task learning structure and a thoroughly constructed list of features from multiple sources spanning multiple
solar cycles, that jointly predicts SEP event occurrence and future
proton and soft X-ray fluxes. SEPNET-PRISM extends the earlier-introduced SEPNET-based models by integrating a broader range of
solar observations, including active-region
magnetic parameters from SHARP and SMARP,
solar-
flare information, coronal mass ejections, soft X-ray flux, and historical > 10 MeV
proton flux. As compared with SEPNET, the inclusion of SMARP data expands the temporal coverage of
magnetic-field predictors to earlier
solar cycles, while flux-based inputs provide additional precursor information. Evaluation on the CLEAR SEP
benchmark dataset shows improved classification performance over the earlier SEPNET-O (operational version of SEPNET) on the newly aligned
dataset. The best operational model is obtained when
magnetic, radiative, and
proton-flux predictors are combined, highlighting the value of expanded historical coverage and complementary precursor information for improving realtime SEP
forecasting.
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All authors Yian Yu, Yang Chen, Lulu Zhao, Kathryn Whitman, Ward Manchester, Tamas Gombosi
Plasma Physics
Plasma Instabilities in Arbitrary Distributions: Comparison between ALPS and BO
Xudong Guo, Huasheng Xie, Kristopher G. Klein et al. (+3 more)
Determining accurate wave dispersion relations is a central problem in
plasma physics. Recent advances have enabled the numerical computation of linear dispersion relation in
plasmas with arbitrary particle velocity distribution functions (VDFs), using two distinct solvers, BO and ALPS. Their reliability and mutual consistency, however, have not been systematically tested for a broad range of VDFs. Here we compare the dispersion relations obtained from BO and ALPS for several representative distributions. We find that the two solvers give consistent unstable modes for kappa distributions with large values of $\kappa$, as well as for ring-beam, shell, and
proton core-beam distributions. BO, however, becomes unreliable for kappa distributions with $\kappa < 4$. For an observationally derived VDF, the two solvers give similar real frequencies for the unstable waves but substantially different growth rates. This difference is mainly caused by the imperfect fitting of the input distribution required by BO. Despite this limitation, BO has a clear computational advantage because it can obtain all roots in a single run. Considering the complementary strengths of the two solvers, their combined use can provide a more reliable and effective framework for investigating instabilities in non-Maxwellian
plasma environments.
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All authors Xudong Guo, Huasheng Xie, Kristopher G. Klein, D. Verscharen, Chen Shi, Jinsong Zhao
Quantum Physics
Spin counting via projection noise measurement of mesoscopic solid-state spin ensemble
Lorenzo Bechelli, Konstantin Herb, Laura Alicia Völker et al. (+1 more)
Quantum projection noise is the fundamental noise source for the population measurement of
spin ensembles. While projection-noise-limited measurements have been extensively studied in atomic systems, corresponding experiments on solid-state
spin ensembles remain challenging due to dominant classical readout noise. Here, we report direct measurement of the
quantum projection noise of mesoscopic ensembles of nitrogen-vacancy (NV)
spin defects at room temperature. Our experiment is enabled by a high optically-detected
magnetic resonance (ODMR) contrast of over 20% for a single crystallographic orientation of the defect
spins, obtained by combining polarization-selective optical excitation with
spin-to-charge conversion. We use our protocol to demonstrate projection noise measurements and
spin counting from nanoscale NV ensembles of up to 43
spins. We further demonstrate that the protocol allows for significant gains in sensitivity for magnetometry applications without need for cryogenic operation or high bias
magnetic fields.
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All authors Lorenzo Bechelli, Konstantin Herb, Laura Alicia Völker, Christian L. Degen
Earth and Planetary Astrophysics · Cross-listed from eess.SY
Orbital Station-Keeping in the Earth-Moon System via Nonlinear Backstepping
António Nunes, Pedro Batista and Sérgio Brás
A nonlinear orbital station-keeping solution for the circular and
elliptic versions of the Earth-Moon Restricted Three-Body Problem (R3BP) is developed via a backstepping technique. Formal guarantees for global asymptotic stability (GAS) are attained, as shown through Lyapunov's stability theory. The adequacy of the proposed control law is evaluated through the means of numerical trials over closed periodic solutions of the circular and
elliptic R3BPs. The ramifications of the control gain choice are carefully studied and simulated.
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Mesoscale and Nanoscale Physics
On-chip superconducting GHz RF reflectometry of the capacitance response in bilayer graphene
Sung Jin An, Minseo Cho, Minjun Park et al. (+12 more)
In dual-gated
bilayer graphene, a perpendicular displacement field opens a band gap that modifies both the channel conductance and the electronic compressibility, motivating measurements that resolve resistive and capacitive responses on the same device. We integrate an hBN-encapsulated
bilayer graphene heterostructure with an on-chip superconducting Nb lumped-element LC resonator and carry out RF reflectometry near 4.25 GHz. DC transport and finite-bias spectroscopy on the same device provide a transport reference. Top and bottom gates independently set the carrier density and displacement field. The DC and RF gate maps share the same gate-dependent features, with finite-bias measurements revealing a region of suppressed conductance whose bias extent grows with the displacement field, consistent with a field-induced gap. The gate-dependent resonance-frequency shift is converted to the effective capacitance seen by the resonator using an equivalent-
circuit model. The capacitance shows a minimum near the conductance-suppressed region, consistent with reduced electronic compressibility in the gapped
bilayer graphene, and exhibits an electron-hole asymmetry. The on-chip configuration probes the gate-dependent admittance of a dual-gated van der Waals
heterostructure, providing capacitance-sensitive information that complements DC transport within a single device.
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All authors Sung Jin An, Minseo Cho, Minjun Park, Dohun Kim, HyeonJeong An, Seung-Bo Shim, Hakseong Kim, Sunghun Lee, Myoung-Jae Lee, Kenji Watanabe, Takashi Taniguchi, Jungpil Seo, Myunglae Jo, Youngwook Kim, Minkyung Jung
Computational Physics
Measuring qualitative change: A variational score for tracking dynamical shifts in partial differential equations
Joseph J. Pollacco, Jonathan Wong, Navonil Neogi et al. (+2 more)
Partial differential equations (PDEs) regulate the behaviour of countless spatiotemporal systems in the physical and life sciences. In many cases, they encode the coupling between the system's degrees of freedom, leading to nonlinear equations whose solution space is challenging to explore exhaustively. Systematic approaches to PDE model exploration are a holy grail of computational science. In this article, we formulate a criterion for increasing the diversity of a search campaign, based on the PDE residual behaviour under solution deformation. We develop a practical formalism to compute this property and illustrate its role in a few cases of interest.
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All authors Joseph J. Pollacco, Jonathan Wong, Navonil Neogi, Callum Simpson, Eloisa Bentivegna