Quantum Gases
Phase-Noise-Induced Heating in Optical Lattices
Jean Paul Nohra, Cyprien Daix, Joris Verstraten et al. (+5 more)
We experimentally and theoretically study the origin of heating in optical
lattices by disentangling the respective roles of intensity and phase noise depending on the
lattice parameters. While intensity noise is widely identified as a major limiting factor, we show that phase noise can become the dominant heating source, especially for light atoms and deep optical
lattices. We provide a simple theoretical framework to predict the phase-noise-induced heating from the power spectral density of the
laser phase noise, which can be measured experimentally. We show that such predictions can accurately reproduce the measured heating rates of lithium-6 atoms in a triangular
lattice. Our approach is readily generalized to other
lattice geometries and atomic species.
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All authors Jean Paul Nohra, Cyprien Daix, Joris Verstraten, Maxime Dixmerias, Tim de Jongh, Bruno Peaudecerf, Fabrice Gerbier, Tarik Yefsah
Optics
Active Control of Extreme Ultraviolet Photon Flux and Resolution with a Plane Ruled Reflection Grating Spectrometer that Measures Diverging High-Harmonics
Caleb H. DeWitt, Nnamdi C. Okey, Griffin W. Hancock et al. (+1 more)
High harmonic generation is a versatile tabletop source for the investigation of ultrafast dynamics with atomic fidelity and few-femtosecond time resolution. However, intensity modulations in the high harmonic spectra due to an alternating peak-and-valley structure in femtosecond extreme ultraviolet (XUV) sources can lead to significant distortions in measured XUV absorption spectra. We report a broadband extreme ultraviolet (XUV) spectrometer with a plane ruled reflection grating that can be spectrally adjusted on the fly using a motorized iris aperture in the entrance slit to control the divergence of the XUV beam prior to its dispersive detection. The effective divergence is tuned between 0.03 to 1.9 milli-radian with concomitant variation in the detected XUV
photon counts of 1.0 $\times$ 10$^6$
photons/s/eV to 1.5 $\times$ 10$^7$ near 40 eV. Metallic samples of Fe (10 nm) and Ti (10 nm) deposited on Si$_3$N$_4$ membranes (100 nm) are measured under these conditions, with a spectral coverage of > 30 eV and a resolution of up to 500 meV. A volcano plot between signal-to-noise ratio (SNR) and spectral resolution determines the trade-off point in measuring elemental near-edge absorption spectra of thin film samples. Consistent with ray tracing simulations, we show that this design parameter offers on-demand high resolution or high SNR configurations for the rapid acquisition of XUV absorption spectra of thin film solid-state samples, especially strongly correlated materials.
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All authors Caleb H. DeWitt, Nnamdi C. Okey, Griffin W. Hancock, Aditi Bhattacherjee
Quantum Physics · Cross-listed from cs.CL
An Exploratory Evaluation of LLM-Assisted Rewriting of Moderate-Complexity Financial Sentences for DisCoCat-Based Sentiment Analysis
Brian Llinas and Nikos Chrisochoides
Quantum natural
language processing (QNLP) provides a grammar-aware framework for text modeling, and Distributional Compositional Categorical (DisCoCat) is one of its theoretically grounded formulations. Prior work on financial sentiment analysis has identified practical limitations of DisCoCat, including parser sensitivity, high simulation cost, and difficulty handling longer sentences. We study an LLM-assisted preprocessing workflow that uses controlled rewriting to compress, simplify, or decompose moderate-complexity financial sentiment sentences into parser-compatible,
circuit-efficient variants while preserving sentiment-bearing meaning. We compare prompting strategies,
language models, and filtering configurations with the low-complexity-only DisCoCat baseline of Stein et al. At the
circuit level, the strongest compression variants reduce average
qubit and gate counts by more than 70 percent relative to the raw moderate-complexity subset. Across repeated training runs, GPT-4.1-mini with
Prompt B achieves the highest observed mean accuracy, $0.550 \pm 0.035$, compared with $0.521 \pm 0.050$ for the baseline. Larger training splits do not necessarily improve downstream performance; across evaluated configurations, training-split size has a moderately negative association with accuracy (Pearson $r=-0.446$). These results provide exploratory evidence that LLM-assisted rewriting can make some moderate-complexity inputs usable within the evaluated DisCoCat configuration, while highlighting
prompt design, filtering, and
circuit-aware preprocessing as considerations for more scalable QNLP-based financial sentiment analysis.
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Quantum Physics
Designer Codes from GALA: Compact, Self-Dual, and Rate-1/2 QEC on Reconfigurable Atom Arrays
Willers Yang, Casey Duckering and Arpit Dua
Achieving useful fault-tolerant applications requires co-designing the
quantum error-correcting code for footprint, logical instruction set, and hardware compatibility simultaneously. Recent breakthroughs in ultra-high-rate codes have the potential to reduce footprint of large scale
quantum applications but their practical utility is limited without an addressable logical instruction set and efficient implementation on near term hardware. Reconfigurable neutral atom arrays, for example, support only hundreds of
qubits with constrained reconfigurability from a few crossed acousto-optic deflectors (AOD). We introduce the GALA codes, or Group-Action Lifts with Active orthogonality, that allows such co-design by construction. GALA lifts over a product group $G = H_k \times C_m$ (or $H_k \ltimes C_m^k$); the small non-abelian factor $H_k$ supplies active orthogonality that improves
qubit overhead, reaching 1/2 encoding rate with above-weight distance, while the large abelian factor $C_m$ supplies
symmetries that give code
automorphisms and explicit, simple AOD move schedules. Logical addressibility and hardware compatibility follow directly from construction, rather than verified post-hoc. The GALA family contains several known rate-1/2 Kasai codes of Ref.[arXiv:2601.08824, arXiv:2604.16209] while exposing simpler parameter bounds, logical operations, and ZX-dual variants with AOD-compatible fold-transversal Clifford gates. In particular, we find a compact self-dual $[[132,30,12]]$ with $1.0^{+0.9}_{-0.6}\times 10^{-9}$ per-round per-
qubit logical error rate at $10^{-3}$ physical error rate, equipped with 3.1 ms syndrome-extraction cycles and an addressable logical instruction set; a ZX-dual, girth-6, rate-1/2 $[[672,336,12]]$ with a 6.76 ms cycles; and barrier-breaking $[[1752,880,14]]$ and $[[2232,1120,16]]$ smaller than previously known hardware-compatible rate-1/2 codes.
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Quantum Physics
QMIMO: Circuit Based Quantum MIMO Design with Variational Receiver
Sayeda Bipanchi Ahmed, Bikash K. Behera, Mandar Thatte et al. (+1 more)
This paper investigates a
quantum extension of classical Multiple-Input Multiple-Output (
MIMO) communication in which the conventional linear channel model is replaced by a parameterized multi-
qubit unitary transformation. Within this framework, interference is represented through coherent
quantum interactions rather than additive signal coupling. To recover transmitted information, a Variational
Quantum Circuit (VQC) receiver is introduced that learns an approximate inverse channel transformation through supervised variational optimization. The proposed system is evaluated under realistic noisy intermediate-scale
quantum (NISQ) conditions incorporating depolarizing noise, thermal relaxation, and measurement imperfections, and its performance is compared with that of standard classical detection methods. The results reveal a trade-off between the two approaches: classical detectors achieve substantially lower bit-error rates across much of the investigated parameter range but exhibit pronounced performance degradation for specific channel configurations, whereas the VQC receiver maintains a more uniform error profile as channel complexity increases, albeit at a higher average BER. These findings suggest that variational
quantum receivers are not a direct replacement for classical detection methods, but rather a complementary approach that may offer increased performance stability in communication scenarios characterized by strong coupling and complex interference patterns.
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All authors Sayeda Bipanchi Ahmed, Bikash K. Behera, Mandar Thatte, Prasanta K. Panigrahi
Optics
Harnessing bound states in the continuum for quantum and nonlinear photonics in silicon nitride microresonators
Eduardo C. Lima, Marco Clementi, Alice Viola et al. (+4 more)
In this work we theoretically and experimentally investigate bound states in the continuum (BICs) in a reconfigurable integrated photonic structure, focusing on spontaneous four-wave mixing. We consider a configuration in which only one mode, the idler, is tuned to the BIC condition, and show that suppressing the radiative loss of this single mode profoundly reshapes the overall nonlinear dynamics. In particularly, we realize electrically tunable Friedrich-Wintgen BICs with Q > 10^6 in an interferometrically coupled silicon-nitride microresonator. Although inaccessible through linear excitation, the BIC is populated by four-wave mixing and read out through its radiative
photon partner. In the low-gain regime, we investigate the spectral, correlation, and coherence properties of the generated
photon pairs, revealing distinctive signatures in the signal-idler correlations and an extracted signal whose coherence time approaches the intrinsic-loss-limited lifetime of the dark idler. In the high-gain regime, making one mode participating in optical parametric amplification a BIC enhances the parametric gain by 12 dB and lowers the oscillation threshold by 1.6 dB. These results establish BICs as a tool for mode-selective lifetime engineering, enabling control over both biphoton wavepackets and the threshold dynamics of integrated parametric devices.
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All authors Eduardo C. Lima, Marco Clementi, Alice Viola, Matteo Galli, Daniele Bajoni, Marco Liscidini, Massimo Borghi
Optics
Optomechanical Levitation and Control of High Aspect Ratio Silicon Nanorods
Zhenan Chen, Sophie Sanghera, Yanhui Hu et al. (+7 more)
Nano- and micro-particles levitated by optical, electrical or
magnetic fields are a new frontier in precision sensing and for tests of fundamental physics. For optically levitated anisotropic particles it is possible to control their translation,
alignment and rotation. We report on the levitation and characterization of nanofabricated, high uniformity, high aspect ratio, high refractive index silicon cylinders, with diameters as low as 50 nm and lengths up to 1500 nm. We are able to tune their oscillation frequencies from 10 kHz to over 1 MHz, and exert huge optical torque to generate high rotation rates. These optically levitated silicon nanorods will enable precision torque sensing, and when pushed to smaller sizes, tests of
quantum physics through the generation of angular momentum superposition states.
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All authors Zhenan Chen, Sophie Sanghera, Yanhui Hu, James Sabin, Maryam Nikkhou, Alex Gee, David Burt, Qiongyuan Wu, Joseph Kelly, James Millen
High Energy Physics (Theory)
Analytic Spread Complexity from Level Statistics: From Chaos to Integrability
Pallab Basu, Suman das and Bigboy Madlala
Spread complexity has emerged as a useful probe of
quantum chaos, yet the microscopic spectral origin of its characteristic finite-time peak remains incompletely understood. We develop an analytic framework that relates spread complexity directly to local spectral statistics. Starting from an energy-space representation of the Krylov kernel, we show that the kernel is approximately banded, leading to a rapidly convergent diagonal expansion dominated by nearby levels in the ordered spectrum. Motivated by this structure, we propose an approximate kernel-universality hypothesis: after unfolding, the Krylov kernel is well approximated by that of a uniform
lattice. Combining this universal kernel with local spectral statistics yields a simple analytic expression for spread complexity in terms of the
Fourier transforms of the $k$-th nearest-neighbour spacing distributions. In particular, at leading order, the finite-time peak is controlled by the
Fourier transform of the nearest-neighbour spacing distribution. The resulting framework describes both chaotic random-
matrix ensembles and the integrable Poisson limit, identifies the spectral origin of the complexity peak and its late-time behaviour, and provides a direct connection between Krylov dynamics and spectral statistics.
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Atmospheric and Oceanic Physics
Explainable AI for Geoscientific Regression: Evaluating Sensitivity and Attribution Methods with the Lorenz-63 System and Applications
Ieuan Higgs, Todd Jones, Kieran Hunt et al. (+1 more)
As artificial intelligence (AI) moves from research prototypes to operational tools in Earth system science, trust in its predictions becomes increasingly important. Explainable AI (XAI) offers insight into how AI models make predictions. However, many influential XAI methods were developed or popularised for classification, and their interpretation for regression, which dominates geoscience, is less well established. A central obstacle is the lack of ground truth for judging explanations. We show that, for a dynamical system with known governing equations, matched references can be built directly from the physics. We extend established sensitivity methods to provide physical references for both sensitivity and attribution, separately for methods with implicit and explicit baselines, all computed from the governing equations independently of the network. Applied to an AI emulator of the Lorenz-63 system, these references show that method families answer distinct questions rather than approximating one “true” explanation. The emulator's sensitivities and attributions can depart most from their physical references where it forecasts best, so predictive skill is not a substitute for the physical realism of what a model has learned. We then review XAI applications to Earth system regression, organised by method family, extending to issues an idealised system cannot address: computational scalability, strongly correlated high-dimensional predictors, and reliance on expert judgement where no physical reference exists. We also discuss how an XAI method can be mathematically valid yet only partially relevant to a given stakeholder group. We close with future directions and practical recommendations for responsible XAI use in geoscientific modelling and
forecasting.
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All authors Ieuan Higgs, Todd Jones, Kieran Hunt, Anna-Louise Ellis
Cosmology and Nongalactic Astrophysics
Simplified treatment of kinematic corrections to the SZ effect using the boost operator approach
Alex Hoey, Jacob Long and Jens Chluba
The Sunyaev-Zeldovich (SZ) effects provide a potent cosmological probe of the large-scale structure in the universe. Here, we present a simplified derivation of the kinematic corrections to the relativistic thermal SZ effect using the boost operator approach. By first performing the thermal average inside the moving electron cloud frame, the thermal and peculiar motion contributions can be naturally separated, leading to a significant simplification of the scattering calculation. The angular dependence of the problem is resummed into the pre-computed Doppler operators avoiding the otherwise cumbersome many-dimensional angular integrals required using conventional approaches. We provide expressions for the relativistic SZ signal, exact to all orders in the electron temperature theta_e and the peculiar velocity beta_p of a given cluster. These reproduce well-known results for the relativistic SZ effects and extend the description to higher orders in the cluster's speed. We also derive a closed-form expression for the thermally-averaged thermal SZ scattering operator by studying the underlying
symmetries of the Doppler operators fundamental to the formalism. Through these results, we also demonstrate how the boost operator approach gives clarity to the physical description of the problem at hand, promising to be useful to a wide range of astrophysical problems.
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Materials Science
DynaCrys: Crystal Generation with Dynamic Space-Group Diffusion
Zhuotao Jin, Xiaoyun Wang, Nicholas Brawand et al. (+5 more)
The search for new crystalline materials spans an enormous compositional and structural space. Generating candidates in this space requires jointly modeling discrete crystallographic
symmetry, elemental composition, and continuous geometry. We introduce DynaCrys, a generative model for
crystals in which the space group co-evolves with Wyckoff occupations and elements through a coupled symbolic
diffusion process. The structured space-group transitions follow crystallographic group-subgroup relations. As the space group changes, a shared, pretrained
symmetry codebook provides both the legality-constrained
stochastic decoder and the
symmetry-constrained
crystal-geometry model with a common representation of the corresponding Wyckoff vocabulary. Across large-scale evaluations using two independent relaxation-and-evaluation engines, DynaCrys achieves best-in-class performance in
symmetry-aware discovery of stable, unique, and novel
crystals, both overall and under the additional requirement of nontrivial post-relaxation
symmetry. It also enables fast sampling while generating structures with consistently low relaxation-induced structural displacements.
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All authors Zhuotao Jin, Xiaoyun Wang, Nicholas Brawand, Roman Zubatyuk, Atul Thakur, Eric Qu, Boris Kozinsky, Justin Smith
High Energy Astrophysical Phenomena
Core-Collapse Supernova detections from Einstein Telescope within the Milky Way
I.F. Giudice, A.L. De Santis, M.T. Botticella et al. (+6 more)
Core-collapse
supernovae are key drivers of
galaxy evolution and promising sources of gravitational waves, which provide a unique probe of the physics driving their explosion mechanism. Third-generation detectors, such as the Einstein
Telescope, will dramatically improve the prospects for detecting these signals. This study assesses the capability of the Einstein
Telescope, alone and in synergy with next-generation detectors such as
Cosmic Explorer, to detect gravitational waves from core-collapse
supernovae. We estimate the detection horizons and expected event rates for sources in the Milky Way and nearby satellite
galaxies. We employed the GWFish simulation framework, customized to include core-collapse
supernovae waveform catalogs from state-of-the-art 3D simulations and
stellar population data generated with TRILEGAL. This approach allows us to model gravitational waves detectability as a function of progenitor mass, source position and detector network configuration. Our analysis shows that the Einstein
Telescope can detect gravitational waves from PNS-driven core-collapse
supernovae up to distances ranging from ~20 to more than 100 kpc with a 90% confidence level, depending on the progenitor mass and waveform, while a combination of this detector in a network can extend the reach up to ~170 kpc in the most favorable cases. For a representative 15 M_sun progenitor, ET (in its 2L configuration) achieves a detection horizon of ~100 kpc, ensuring essentially complete coverage of the Milky Way and partial coverage of the Magellanic Clouds.
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All authors I.F. Giudice, A.L. De Santis, M.T. Botticella, M. Branchesi, G. Pastorelli, L. Girardi, L. Izzo, E. Cappellaro, M. Della Valle
Chemical Physics
The origin of carotenoid triplets in purple photosynthetic bacteria
Juan J. Romero, Andrew Gall, Viola D'mello et al. (+4 more)
Photosynthetic
antenna proteins harvest light energy while at the same time protecting the organism against photodamage. Carotenoid molecules are essential in the latter process, efficiently quenching unwanted (bacterio)chlorophyll excited states created after
photon absorption. (Bacterio)chlorophyll triplets, formed by inter-system crossing, are particularly significant, since in the absence of carotenoid quenching, they sensitise the highly oxidative singlet oxygen. In light-harvesting complex 2 (LH2) from Rhodoblastus acidophilus, the pathways that populate carotenoid dark and triplet states remain controversial, involving bacteriochlorophyll-to-carotenoid triplet-triplet transfer and/or generation of triplets by the carotenoid molecules themselves through singlet fission. Transient absorption has been central to understanding photoprotection in these organisms, but spectral congestion limits the separation of the overlapping species needed to discriminate between these pathways. By applying femtosecond stimulated resonance Raman spectroscopy (FSRRS) in different resonance conditions to this
protein, in combination with an extension of global analysis to four dimensions (wavenumber, time, intensity and resonance condition), we separate each component of the carotenoid dark-state
manifold together with its kinetics. An entangled triplet pair S*/1(TT) is observed, which lives about 60 ps, some eight times longer than in solution. However, this stabilisation does not open a pathway to separated triplets or to carotenoid-BChl a heterofission. Triplet-triplet transfer from bacteriochlorophyll a to carotenoid is also resolved under BChl a excitation, and fits cleanly as a single 2100 ps component. The carotenoid triplet in LH2 is thus produced by photoprotective triplet-triplet transfer from BChl a, and not by singlet fission.
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All authors Juan J. Romero, Andrew Gall, Viola D'mello, Cristian Ilioaia, Andrew A. Pascal, Bruno Robert, Manuel J. Llansola-Portoles
Medical Physics
An Angular Spectrum Method for Nonlinear Propagation in Heterogeneous Tissue with Immersed Sources for Ultrasound
Gianmarco Pinton
A modified angular spectrum method (ASM) is developed for three-dimensional nonlinear acoustic propagation through heterogeneous tissue, targeting transcranial and therapeutic ultrasound. First, a consistent obliquity correction is applied to both the linear and nonlinear operators of the split-step update. The attenuation and dispersion filter carries a per-mode k/kz factor on the full wavenumber-frequency grid, so each component accumulates absorption and phase over its true path length dz/cos(theta), while the Burgers coefficient is scaled by the power-weighted mean beam obliquity. Second, the retarded-time Burgers update is discretized with a second-order Kurganov-Tadmor central-upwind flux using MUSCL reconstruction and SSP-RK2 time integration, composed with diffraction and attenuation through Strang splitting with adaptive CFL sub-cycling, resolving fully developed shocks without the temporal refinement that the CFL coupling imposes on FDTD. Third, a plane-by-plane source-injection scheme decomposes deeply curved bowl transducers into axial slices injected at their correct propagation depths, preserving the aperture-dependent shock-formation distance. Phase-and-amplitude screens derived from skull CT data model transcranial aberration and insertion loss, and three enhanced absorbing-boundary treatments reduce boundary reflections by a factor of 2.4. Analytical validation reproduces the baffled-piston far-field pattern to 0.014 RMS and the focused-piston focal pressure to within 2.3 percent. In a transcranial
benchmark through an ex vivo human skull, the ASM matches the Fullwave 2 focal-plane intensity to 1.1 percent RMS and predicts a 5.4 dB through-skull insertion loss. For a bowl transducer (R = 80 mm, f0 = 1 MHz), the ASM matches the Fullwave 2 focal depth to within 2.3 percent with 9x less
memory and 2.9x less wall time.
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General Relativity and Quantum Cosmology
Inflation with Nieh-Yan-like terms in metric-affine gravity
Ilaria Andrei, Christian Dioguardi, Damianos Iosifidis et al. (+3 more)
We study single-field slow-roll inflation in metric-affine
gravity with a scalar field non-minimally coupled to the non-Riemannian
Ricci scalar and to the divergences of the torsion and nonmetricity vectors, a structure that generalizes the well-known Nieh-Yan term. By imposing projective coherence of the matter sector and solving the connection field equations, we integrate out torsion and nonmetricity and obtain an equivalent Einstein-frame formulation in which the metric-affine couplings are encoded in a modified kinetic function and potential. For the choice of coupling functions $\mathcal{A}(\phi) = M_P^2 + \xi \phi^2$ to the non-Riemannian
Ricci scalar, $\mathcal{C}_i(\phi) = \xi_i \phi$ to the Nieh-Yan-like terms and a monomial Jordan-frame potential $\mathcal{V} \propto \phi^k$, we show that in the limit of a large positive effective Nieh-Yan-like coupling $\bar{\xi}$ the canonical field satisfies $\chi \sim \phi^2$, the Jordan-frame field values during inflation become sub-Planckian, and the Einstein-frame potential reduces to $U \sim \chi^{k/2}$. We compute the slow-roll predictions numerically for quartic and quadratic Jordan-frame potentials and compare them with the current CMB constraints from Planck, BICEP/Keck, ACT, and SPT. We find that intermediate values of $\bar{\xi}$ can restore the compatibility of non-minimally coupled Palatini inflation with observations: in the quartic case, the model predicts a tensor-to-scalar ratio within reach of next-generation CMB experiments for $\bar{\xi}\lesssim10^4$, while in the quadratic case the coupling cures the $\eta$-problem arising for $\xi \gtrsim 10^{-2}$ and yields viable predictions for $10^{-2}\lesssim\bar{\xi}\lesssim 10^2$. In the negative $\bar{\xi}$ regime, the model does not improve upon standard Palatini inflation, though it can still produce distinct, testable predictions.
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All authors Ilaria Andrei, Christian Dioguardi, Damianos Iosifidis, Laur Järv, Antonio Racioppi, Margus Saal
Instrumentation and Methods for Astrophysics
Closing the loop on-sky with a vector-Zernike wavefront sensor using a convolutional neural network as phase reconstructor
Francisco Oyarzún, Mathieu Motte, Cedric-Taissir Heritier et al. (+11 more)
Context: The new
giant segmented mirror
telescopes will use adaptive optics to reach the fundamental limits in resolving power. To accomplish this, new wavefront sensors (WFS) have been designed to fulfill the requirements, but they may require non-linear reconstruction techniques to operate given the nature of the signal of the WFSs Aims: In this article we show that it is possible to use non-linear reconstructors to extend the dynamic range of one of the most sensitive wavefront sensors far beyond the designed limits: the Zernike wavefront sensor (ZWFS). Methods: We trained a convolutional neural network (CNN) completely in simulation to perform the phase reconstruction of a vector-ZWFS (v-ZWFS), a higher dynamic-range variant of the ZWFS. Contrary to the linear method, the CNN uses the information across the full frame to reconstruct the phase at each point, enabling it to resolve the ambiguities introduced by the periodic response of the ZWFS and thereby extend its effective capture range. We developed a two-step training strategy that ensured closed-loop stability and used a physically informed loss function to maximize the performance of the CNN. Results: We successfully closed the loop on-sky with the v-ZWFS using the CNN in observing conditions that the linear reconstructor could not converge to a stable flat wavefront. In cases where both reconstruction methods were working, the CNN outperformed the linear method in almost all cases, and in favorable seeing conditions we were even able to close the loop with the ZWFS acting as a first stage WFS, highlighting the extended dynamic range brought by the use of a non-linear wavefront reconstructor. Conclusions: We conclude that the use of non-linear wavefront reconstructor can extend the use cases of adaptive optics systems, especially when the WFS used shows highly non-linear behaviors.
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All authors Francisco Oyarzún, Mathieu Motte, Cedric-Taissir Heritier, Benjamin González, Rodrigo Muñoz, Vincent Chambouleyron, Marie Angelie Alagao, Arnaud Striffling, Mettoe Pasinetti, Edvardas Vinerskas, Pauline Trouve-Peloux, Frederic Champagnat, Thierry Fusco, Benoit Neichel
Cosmology and Nongalactic Astrophysics
KiDS-1000: Improved constraints on cosmology, intrinsic alignments and baryonic feedback from clipped cosmic shear
Benjamin Giblin, Joachim Harnois-Déraps, Louise Paquereau et al. (+1 more)
We present improved cosmological constraints from the fourth data release of the Kilo-Degree Survey ("KiDS-1000") using "clipped" shear correlation functions. Clipping filters the projected density field inferred from weak
lensing data for the highest-density regions, allowing for two-point functions to extract additional cosmological information. We model, for the first time, the impact of systematics on clipped
lensing statistics, including intrinsic
alignments, baryonic feedback, photometric
redshift uncertainties, and source-lens clustering. We train Gaussian process emulators on dark-matter-only and hydrodynamical $N$-body simulations to predict the cosmological and systematic dependence of both the clipped and conventional, "unclipped" shear correlation functions. We find that the combination of the clipped and unclipped probes improves the constraints on the free parameters of the $w$CDM model relative to the conventional approach, with a 16% tightening of the $S_8$ uncertainty and 24% for $w_0$. Our constraints, $\Omega_{\rm m} = 0.263^{+0.035}_{-0.038}$, $S_8=0.724^{+0.027}_{-0.027}$, and $w_0 = -1.24^{+0.26}_{-0.28}$, are consistent with the $\Lambda$CDM model and with the
cosmic shear analysis of Asgari et al. (2021) via a completely independent simulation- and emulator-based forward-modelling approach. We also find the complimentary information in the clipped statistic provides an upper limit on the
baryon feedback strength, and improves the constraints on intrinsic
alignments by 27%.
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All authors Benjamin Giblin, Joachim Harnois-Déraps, Louise Paquereau, Catherine Heymans
Mesoscale and Nanoscale Physics
Type-II Mirror Chern Insulator in Altermagnets
Amrita Mukherjee, Pritesh Srivastava, Rahul Verma et al. (+1 more)
Altermagnets with momentum-dependent
spin splitting despite zero net magnetization can support unique topological states under broken time-reversal
symmetry. We predict a mirror-
symmetry-protected topological crystalline
insulator with momentum-separated edge modes in a two-dimensional altermagnet. Using a square-octagon
lattice model, we show that altermagnetic order generates
symmetry-related valley-polarized Dirac nodes, which are gapped by
spin-orbit coupling to yield a mirror Chern
insulator with $C_{\mathcal{M}}=2$. In contrast to conventional mirror Chern
insulators, where the two mirror-protected edge modes cross at the same momentum to form a Dirac cone, altermagnetic
spin splitting and valley-selective band inversion separate these edge modes in momentum. We refer to this phase as a type-II mirror Chern
insulator. We further propose a PbSe/$\mathrm{V_2Se_2O}$ heterobilayer as a candidate material for realizing this phase through the altermagnetic proximity effect. Our results establish altermagnetism as a route to mirror-protected topological phases with momentum-separated edge modes.
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All authors Amrita Mukherjee, Pritesh Srivastava, Rahul Verma, Bahadur Singh
Physics Education
A bottom-up taxonomy of student discourse with a Socratic AI physics tutor
Syed Furqan Abbas Hashmi and N. Sanjay Rebello
Large
language model (LLM) tutors are being deployed in introductory physics courses at a scale that produces transcript corpora far larger than traditional qualitative coding can absorb. A central question for physics education research (PER) is empirical and prior to any claim about effectiveness: what do students actually say to these tutors? We address this question for one Socratic AI tutor deployed in an introductory calculus-based mechanics course by building a bottom-up taxonomy of student discourse. Each student turn is assigned an emergent free-text label by an LLM coder using the surrounding conversational context; near-paraphrase labels are then consolidated into a smaller set of discourse categories using a similarity-based grouping procedure. The procedure is validated against a stratified human-coded sample. The resulting taxonomy of 357 categories is strikingly concentrated: the top 25 categories cover roughly half of all student turns, and two thematic bands: equation-handling and meta-procedural requests together dominate the head of the distribution. The substantive contribution is the taxonomy itself: a description of the discourse PER researchers can expect to encounter when students work with an AI tutor of this design, including a striking prevalence of meta-procedural turns in which students cede strategic control to the tutor
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Mesoscale and Nanoscale Physics
Exciton Alchemy: Chern Excitons from Trivial Bands
Yoonseok Hwang, Henry Davenport and Frank Schindler
Exciton topology is commonly inherited from the
topology of the underlying electronic bands. Recent theoretical work, however, has shown that the
exciton Chern number can in general receive an additional contribution from the
topology of the
exciton envelope wave function, allowing, in principle, interaction-induced topological
excitons even when the constituent electronic bands are topologically trivial. Here, we provide an explicit realization of this case by constructing a two-dimensional
exciton model with topologically trivial conduction and valence bands that nevertheless hosts a Chern
exciton diagnosed by inversion
symmetry. Starting from a real-space limit of exponentially localized Wannier states for the conduction and valence bands, we identify the essential ingredients responsible for the emergent
exciton topology and formulate a simple construction recipe. Our work demonstrates that interactions alone can generate nontrivial
exciton topology, independent of the
topology of the underlying electronic bands, and establishes a general framework for designing interaction-induced topological
excitons.
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Medical Physics
Measurements Automatically Extracted from Zero Echo Time MRI Using Deep Learning Image Segmentation and Geometric Modeling Agree with Expert Manual Readings
Jack Consolini, Eric A. Bogner, Meghan Sahr et al. (+3 more)
Computed
tomography (CT) remains the reference for 3D osseous morphometry in femoroacetabular impingement (FAI) but requires ionizing radiation and manual measurement. Zero echo time (ZTE) MRI visualizes cortical bone and yields FAI angles that agree with CT, but automated angle extraction remains limited. We developed and validated automated FAI angle computation from ZTE MRI and assessed agreement with expert manual measurements in a cross-sectional study (level of evidence, 3). Pelvic ZTE MRI was acquired in 73 participants (mean age 36.8 +/- 18.5 years; 51 women, 22 men), yielding 135 hips. nnU-Net was trained on 100 manually curated hips to segment the femur, pelvis, and three osseous landmarks. Custom
geometric algorithms computed alpha, femoral neck-shaft, Tonnis, coronal and sagittal center-edge, and acetabular version angles from inferred
segmentations. Measurements on 35 test hips were compared with the mean of two radiologists' manual measures using intraclass correlation (ICC) and Bland-Altman analysis. Dice exceeded 0.96 for bone and ranged from 0.65 to 0.83 for landmarks. Median landmark error was 0.38 mm (femoral head), 0.82 mm (lateral acetabulum), and <2.5 mm (medial acetabulum, greater trochanter). Interrater ICC was excellent for acetabular version, coronal center-edge, and Tonnis (>=0.82) but poor for alpha and femoral neck-shaft. Model versus rater-mean agreement was excellent for acetabular version, coronal center-edge, and Tonnis (0.92-0.96), good for mid-acetabular sagittal center-edge (0.74), and fair for alpha (0.45) and femoral neck-shaft (0.55). Model Bland-Altman limits of agreement were narrower than interrater limits for most angles. Fully automated morphometric assessment from ZTE MRI is feasible and performs comparably to expert readers for most coverage and version angles.
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All authors Jack Consolini, Eric A. Bogner, Meghan Sahr, Matthew F. Koff, Kevin M. Koch, Hollis G. Potter
Instrumentation and Methods for Astrophysics
Telemetry is a Sensor: Opportunistic Wavefront Estimation for the James Webb Space Telescope
Lahav Buzi, Yoav Y. Schechner, Aviad Levis et al. (+1 more)
Space
telescopes maintain optical
alignment through periodic, resource-intensive wavefront calibration, leaving the optical state unobserved between corrections. We propose treating onboard engineering telemetry as an opportunistic wavefront sensor. Specifically, the high-cadence thermal and pointing signals already recorded by the James Webb Space
Telescope may suffice to recover spatially resolved optical path difference at nanometer precision, without dedicated measurements. Our framework uses a two-stage gradient boosting regressor. It predicts optical path difference residuals for each mirror segment in a low-dimensional principal component basis. The model is trained and evaluated using data captured on-orbit during six months. Based on this limited data, optical path difference inference has high statistical significance in 13 out of 18 mirror segments. In 6 mirror segments, the model achieves explained variance above 50%. These results demonstrate feasibility for telemetry-driven wavefront estimation, as a low-overhead sensing modality. The study suggests a potential to support continuous monitoring and calibration scheduling for large segmented observatories.
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All authors Lahav Buzi, Yoav Y. Schechner, Aviad Levis, Jason J. Wang
Atmospheric and Oceanic Physics
Finite-Response Complementarity in Fluctuation Constraints on Climate Sensitivity
Zaibo Zhao and Yongwen Zhang
Equilibrium climate sensitivity (ECS) is a zero-frequency susceptibility, whereas historical globalmean temperature variability samples a finite, forced projection of the
climate system. We test whether information missed by a scalar fluctuation-
memory coordinate reappears in a finite CO2 response. After conditioning both ECS and the finite response on {\Psi}, CMIP5 residuals are nearly uncoupled (C5 = 0.154), whereas CMIP6 shows strong complementarity (C6 = 0.593, p = 0.00288). A two-mode
stochastic response model attributes this contrast to hidden-response spread that is visible in the finite response but poorly projected onto {\Psi}. The CMIP6 residual direction defines a first-order correction and yields a HadCRUT5 conditional ECS estimate centered at 3.00 K. Thus the weakened CMIP6 fluctuation constraint does not imply that susceptibility information is lost: part of it is recovered through a complementary finite-response projection.
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Chemical Physics
Beyond the Four-Decade DIIS Default:Auxiliary-Curvature Acceleration of Self-Consistent-Field Calculations
Peng Bao and Qiang Shi
Direct inversion in the iterative subspace (DIIS), introduced in 1980, remains the practical default for accelerating Hartree-Fock and Kohn-Sham self-consistent-field (SCF) calculations. Many later methods improve robustness or iteration count, but the near-zero overhead of DIIS makes a broad reduction in total wall time difficult. We introduce AURORA-SCF (auxiliary-
curvature unified Riemannian orbital-response acceleration), which evaluates energy and gradient only with the requested target
Hamiltonian while obtaining most orbital
curvature from an independent valence-STO-3G model. A target-level, transported L-BFGS history corrects the model mismatch; a shifted
matrix-free solve, trust region, and geodesic orbital update control the step. In 16 direct CPU RHF pairs spanning 137-1484 atomic orbitals, AURORA-SCF was faster in every case, reducing mean wall time by 26.2% and target J/K builds by 33.3%. In a separate set of 63 converged, energy-matched density-fitted GPU pairs spanning seven molecules, closed- and open-shell formalisms, and HF, PBE, B3LYP, and M06-2X, it was again faster in every included pair, with mean reductions of 26.5% in wall time and 31.9% in target J/K builds. Focused direct CPU and GPU sweeps show mean wall-time reductions of 30-34%. These results establish a specific advance beyond the four-decade DIIS default: transferred, secant-corrected
curvature can reduce total SCF wall time, not merely iteration count, without changing the target stationary equations. The same optimization pattern also suggests a route to faster orbital optimization elsewhere in
quantum chemistry and to multifidelity optimization across scientific computing.
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Astrophysics of Galaxies
Tracing the early Milky Way thin disc with the Gaia-ESO Survey
Carlos Viscasillas Vázquez, Sofia Randich, Riano Escate Giribaldi et al. (+3 more)
The origin of metal-poor
stars on thin-disc-like orbits remains an open question in
Galactic archaeology and provides important constraints on the earliest phases of Milky Way disc formation. We aim to identify and characterise metal-poor
stars with thin-disc-like kinematics observed in the
Gaia-ESO Survey, using
Gaia DR3 orbital parameters, spectroscopic information, isochrone ages, and detailed chemical abundances. Out of 1784 turn-off
stars, we identify one metal-poor candidate with [Fe/H] = -1.38 on a dynamically cold, prograde orbit, with low eccentricity, high azimuthal velocity ($V_\phi$ approximately 220 km/s), large angular momentum and low vertical action. Chemically, however, it is clearly distinct from the canonical thin disc: it is $\alpha$-enhanced, with [Mg/Fe] = +0.58 and [$\alpha$/Fe] = +0.48, shows a low [Y/Mg] = -0.58 ratio, and lies on the metal-poor sequence in the [Al/Fe]-[Mg/Mn] plane. The
star also has an old age estimate, with a most probable value of about 10.2 Gyr. Its properties suggest that it is not a typical member of the canonical thin disc. Instead, it may be associated with the old thin disc, the metal-weak thick disc, or prograde
halo-related populations. This object provides a useful
benchmark for studying early metal-poor populations on disc-like orbits.
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All authors Carlos Viscasillas Vázquez, Sofia Randich, Riano Escate Giribaldi, Leda Berni, Laura Magrini, Maria Tsantaki
Computational Physics · Cross-listed from math.NA
Mesh-Based Filtering to Alleviate Time-Step Restrictions in Runge–Kutta Discontinuous Galerkin Methods in Spherical-polar Coordinates: Application to the Euler Equations
Joseph Hunter, Eirik Endeve and Yulong Xing
We propose a mesh-based filtering approach to alleviate the severe timestep restrictions arising in explicit Runge–Kutta discontinuous Galerkin (RKDG) methods formulated in spherical-polar coordinates. The filter enables stable
evolution on the original logically Cartesian mesh while using larger time steps associated with an auxiliary merged mesh constructed to eliminate the extreme
cell anisotropies produced by converging coordinate lines near coordinate singularities. The filter is implemented as a sequence of post-processing operations applied within an $s$-stage RK time integrator, making it straightforward to incorporate into existing structured-mesh DG frameworks. We analyze the filter in one spatial dimension and prove that the filtered RKDG method is equivalent to evolving the RKDG discretization on a nonuniform mesh obtained by merging selected elements of the underlying uniform mesh. This equivalence implies that the filtered method inherits the accuracy and stability properties of the corresponding RKDG discretization on the merged mesh. We apply the mesh-based filter to an existing RKDG method for the Euler equations in spherical-polar coordinates and demonstrate, through selected two- and three-dimensional examples, its effectiveness in accelerating simulations through significantly larger stable timesteps.
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Cosmology and Nongalactic Astrophysics
Sample Variance Cancellation for Future Spectroscopic Surveys
James M. Sullivan and Martin White
High-
redshift spectroscopic
galaxy surveys will be the scientific engines of the next generation of large-scale structure cosmology. The clustering signal of high
redshift,
star-forming Lyman-$\alpha$ emitters (LAEs) will be of key importance for obtaining high-
redshift constraints on the growth of structure and
redshift-space distortions. The complex radiative transfer (RT) of Lyman-$\alpha$
photons alters the
symmetry group respected by the overdensity field constructed from these
galaxies, and so the observed large-scale clustering of LAEs may have an angular dependence that differs significantly from that of linear theory, possibly biasing inference of cosmological parameters. While such an effect has been seen in simulations, its amplitude in nature and its detailed form remains unclear. In the restricted context of a linear, Gaussian model, we outline a procedure for pinning down the type and amplitude of such changes in angular dependence on large scales due to unknown RT or a more general unmodeled angular effect in the hypothetical scenario in which an observer is presented with LAE data containing such an effect. We show that if a second tracer without the modified angular dependence is available for cross correlation with the LAEs at the same
redshifts (e.g., Lyman-break
galaxies), then, with a high
redshift survey of modest size, it is possible to rapidly identify: 1) the presence of a nontrivial angular functional form of radiative transfer (by a conditional field-level realization), 2) the functional form itself (with an optimal filter that we derive), and 3) the value of its amplitude with an uncertainty (via an adaptation of the standard quadratic
estimator). Such sample-variance-cancellation strategies therefore provide a statistical solution to unknown astrophysical or systematic angular clustering dependence, including from RT.
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High Energy Physics (Experiment)
Combination of Higgs boson measurements at $\sqrt{s} =$ 13 TeV and their interpretations by the ATLAS experiment
ATLAS Collaboration
This paper presents combined measurements of
Higgs boson production and decay using up to 140 fb$^{-1}$ of
proton–
proton collision data collected by the ATLAS experiment at the LHC at $\sqrt{s} = 13$ TeV. The inclusive
Higgs boson event rate relative to its Standard Model prediction is determined to be $0.990 ^{+0.053}_{-0.051} = 0.990 \pm 0.027 \text{ (stat.) } \pm 0.024 \text{ (exp.) } ^{+0.037}_{-0.035} \text{ (sig. theo.) } ^{+0.016}_{-0.015} \text{ (bkg. theo.)}$, separating statistical, experimental, signal-theory and background-theory uncertainty components. The signal theory uncertainty is the largest contribution, dominated by missing higher-order terms in QCD and the modelling of parton shower effects. Inclusive production cross-sections and decay branching ratios are measured, with sensitivities improved by up to 35% relative to the previous ATLAS publication. Production cross-sections for individual decay channels are also reported. The results are interpreted in terms of modifiers to
Higgs boson couplings. The combination of single
Higgs boson and
Higgs boson pair production measurements yields $\kappa_\lambda = 1.3^{+3.1}_{-1.6}$ for the modifier to the
Higgs boson self-coupling, with an interval of $[-1.5, 6.5]$ at 95% confidence level. The partial width in the $H\to b\bar{b}$ decay channel is used to obtain the first ATLAS determination of the running mass of the $b$-
quark at the
Higgs boson mass scale in the modified minimal subtraction scheme, found to be $m_b(m_H) = 2.73^{+0.27}_{-0.25}$ GeV. The total width of the
Higgs boson is measured to be $\Gamma_H = 3.6^{+2.1}_{-1.6}$ MeV based on its on- and off-shell production rates. The kinematics of
Higgs boson production are probed within the framework of Simplified Template Cross-sections in 44 kinematic regions, and the results are interpreted in the context of Standard Model Effective Field Theory models.
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Solar and Stellar Astrophysics
Host–Non-host Differences in Stellar Chemistry, Activity, and Birth Radius: Hints of Distinct Formation Environments for Earth-like Planets and Sub-Neptunes
Xunzhou Chen, Tiancheng Sun, Yuxi Lu et al. (+2 more)
Host-
star properties provide important clues to
planet formation and
evolution, yet it remains unclear whether the observed differences between
planet-hosting
stars and
stars without detected
planets reflect genuine signatures of
planet formation or underlying differences in
stellar populations. Using a homogeneous sample of 28,383 Kepler-LAMOST-
Gaia dwarf and subgiant
stars, including 629 host
stars with 865
planets, we compare host
stars with age-mass matched non-host
stars after correcting for distribution-induced matching biases. Most host-non-host differences disappear when the full
planet sample is considered. However, separating
planets by radius reveals distinct trends. At the high-abundance end of the [O/Fe], [Mg/Fe], and [Si/Fe] distributions, Earth-like hosts tend to be more O-rich but more Mg-poor and Si-poor than their age-mass matched non-host
stars, whereas sub-Neptune hosts tend to show the opposite behavior. Sub-Neptune hosts also tend to exhibit lower chromospheric activity and smaller birth radii than comparable non-host
stars. These results suggest that host-non-host differences become apparent primarily after separating
planets by size and that Earth-like
planets and sub-Neptunes may be associated with distinct formation environments and evolutionary pathways. We also find that hot-Jupiter hosts are tentatively more metal-rich, chromospherically active, and formed at smaller
Galactic birth radii than hosts of longer-period Jupiters.
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All authors Xunzhou Chen, Tiancheng Sun, Yuxi Lu, Liu Long, Zixuan Lu
Soft Condensed Matter
Segmental Dynamics in the Strain-hardening Regime for Poly(methyl methacrylate) Glasses with and without Melt-stretching
Enran Xing, Trevor Bennin, Masoud Razavi et al. (+1 more)
Strain-hardening is a feature of
polymer glasses during large deformation, which helps to stabilize the glasses against breakage. Experimentally, little is known about the segmental dynamics during strain-hardening, and such data is important for building a molecular-level theory of
polymer glasses deformed in this regime. Here, using a photobleaching technique, we measured the segmental dynamics of lightly-crosslinked poly(methyl methacrylate) (PMMA) glasses with and without melt-stretching, which were deformed into the strain-hardening regime with local engineering strain rates from 10^-4.6 s^-1 to 10^-4 s^-1 at Tg-23K and Tg-33K. We find that melt-stretched PMMA glasses show a more prominent strain-hardening feature and faster segmental dynamics by a factor of about 15% compared to PMMA without melt-stretching. At a given true strain rate, the segmental dynamics of PMMA without melt-stretching are accelerated in the deep strain-hardening regime from the value just beyond yield, by up to 40% at 0.8 true strain. Our observations are in agreement with previously published simulation results.
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All authors Enran Xing, Trevor Bennin, Masoud Razavi, M. D. Ediger