Soft Condensed Matter
Computing stable configurations of confined smectic liquid crystals with a deep variational framework
Yuchen Xie, Baoming Shi, Yucen Han et al. (+1 more)
Smectic
liquid crystals are layered
liquid-crystalline phases characterized by orientational order and periodic density modulation. Although their structures can be modeled using continuum theories, computing stable configurations remains challenging in complex geometries, particularly when the high-frequency density modulations associated with smectic layering should be resolved. We propose a deep variational framework (DVF) for computing these configurations within the modified Landau–de Gennes model, in which the coupled orientational and positional order parameters are represented on a regular reference domain while physical confinement is incorporated through coordinate mappings. A warmup penalty mitigates the spectral bias of neural networks toward smooth, nonlayered fields, enabling robust recovery of oscillatory smectic states. Comparisons with a neural-network baseline and finite-difference relaxation demonstrate the essential role of this penalty and the numerical stability of the resulting layered states. The DVF reproduces experimentally established smectic-A defect structures and layer morphologies across diverse confinement geometries and further predicts a chevron-like smectic-C state in a tangent-anchored sphere. Together, these results demonstrate the applicability of the DVF to computing stable smectic configurations across experimentally relevant confinement geometries and anchoring conditions.
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All authors Yuchen Xie, Baoming Shi, Yucen Han, Lei Zhang
Superconductivity
Doping dependence of local moments in infinite layer nickelates
Martin Gonzalez, Andreas Suter, Michal Kiaba et al. (+5 more)
The infinite layer nickelates are notable for their lack of long-range
antiferromagnetic ordering, in contrast to the parent compounds of the superconducting cuprates. Instead, the nickelates show evidence of short-range glassy behavior in both the undoped and optimally-doped regimes, implying that local electronic moments exist independent of superconductivity. However, the systematic doping-dependent
magnetic behavior is not yet fully resolved, and characterizing it could uncover the relationship between local moments and the superconducting dome. In this work, we use
muon spin rotation ($\mu$SR) on a (La,Sr)NiO$_2$ doping series from the undoped parent compound, through the superconducting dome, to the over-doped normal state (Sr substitution 0% $\leq$ x $\leq$ 25%) to probe the
magnetic ground state and the temperature-dependent static and dynamic behavior. We find that local moments experience
spin freezing into a glassy state at temperatures on the order of a few tens of kelvin regardless of the doping level. We also observe a subtle destabilization of the glassy state with increased hole doping. These observations suggest that magnetism and superconductivity are largely decoupled phenomena with indirect interactions described in a multi-orbital framework.
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All authors Martin Gonzalez, Andreas Suter, Michal Kiaba, Thomas Prokscha, Zaher Salman, Marc Gabay, Harold Y. Hwang, Jennifer Fowlie
Fluid Dynamics
Cascade coalescence dynamically sustains bubble retention near gas-evolving surfaces
Tao Wu, Bo Liu, Haohao Hao et al. (+4 more)
Bubble detachment from solid surfaces governs heat, mass, and charge transport across technologies vital to clean energy, including high-current-density water electrolysis and boiling thermal management. At high gas fluxes, however, bubbles remain trapped at active surfaces despite immense buoyancy, severely restricting mass transfer and increasing energy losses. Here, we show that this unexpected surface retention originates from cascade coalescence between unequal-sized bubbles. High-speed observations around microelectrodes demonstrate that when a rising bubble merges with a smaller surface-attached successor, its trajectory abruptly reverses, accelerating toward the substrate at nearly two orders of magnitude above its rising speed. Direct numerical simulations and scaling analysis reveal that asymmetric interfacial retraction during merging generates non-canceling viscous stresses, producing a net downward impulse toward the smaller bubble. Repeated cascade coalescence events accumulate these transient impulses into a steady, time-averaged retaining force capable of opposing buoyancy three to four orders of magnitude beyond quasistatic limits. Our findings establish bubble coalescence as a previously unrecognized mechanism that dynamically sustains bubble retention under high gas flux.
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All authors Tao Wu, Bo Liu, Haohao Hao, Xuehua Zhang, Fang Yuan, Huanshu Tan, Qiang Yang
High Energy Physics (Phenomenology)
Meson mass spectrum in isospin QCD medium from the $N_f=2+1$ quark-meson model
Yu-Han Gao, Xu-Guang Huang and Daiki Suenaga
We study phase structures,
meson mass spectra, and sound velocities at finite temperature and density in QCD with isospin chemical potential ($\mu_I$). We employ the
quark-
meson model with $N_f=2+1$, incorporating the Kobayashi-Maskawa-'t Hooft type coupling to capture dynamical effects of the $U(1)_A$ axial anomaly. Within the mean-field approximation at
quark one-loop, we analyze the onset of pion condensation, which manifests as a second-order phase transition at low temperatures and may exhibit a first-order behavior at higher temperatures within this approximation. We examine the corresponding mass spectra of scalar and pseudoscalar singlet-octet
mesons, in which the $\pi_+$ mass is exactly massless in the superfluid phase due to its Nambu-Goldstone
boson nature. The neutral pion mass is, meanwhile, found to exhibit a strictly linear growth with $\mu_I$ in the pion condensed phase. We also investigate the isothermal squared sound velocity and identify characteristic structures associated with the phase transitions. Furthermore, we highlight how enhanced $U(1)_A$ anomaly effects facilitate the pion condensate to generate a less-pronounced sound velocity peak in cold medium. Our findings are expected to provide future
lattice simulations with useful information on
meson mass spectra from
symmetry aspects.
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Geophysics
PSDWII: Physical-Structure-Driven Waveform Inversion Imaging
Shengchang Chen
This paper proposes a Physical-Structure-Driven Waveform Inversion Imaging framework (PSDWII), grounded in the recognition that surface-recorded seismic data are directly related to subsurface virtual sources rather than to the model parameters themselves. Based on this recognition, we decompose seismic wave propagation into a three-step physical process: source excitation and incident wave propagation; interaction of the incident wave with heterogeneities, which generates virtual sources with distinct radiation patterns and excites secondary waves; and propagation and reception of the secondary waves. The adjoint of the propagation operator (reverse-time extrapolation) is then used to formulate a linear inversion projection for the virtual sources. By distinguishing different virtual-source expressions and their underlying physical mechanisms, we establish a unified mathematical representation for three inversion tasks: Full Waveform Inversion(FWI), stratigraphic physical properties imaging, and stratigraphic structures imaging. Deconvolution and linear inversion are respectively adopted to achieve multi-parameter decoupling in FWI and in angle-domain common-image gather inversion for stratigraphic physical properties imaging. The PSDWII framework shifts the conventional “mathematical optimization driven” paradigm of waveform inversion to a “physical-structure-driven” one. It neither constructs objective functions nor computes their gradients or Hessian inverses. Within this framework, we develop three specific methods: physical-structure-driven FWI (PSDFWI), physical-structure-driven stratigraphic physical properties imaging with angle-domain common-image gather inversion (PSDSI), and physical-structure-driven stratigraphic structures imaging (PSDMig).
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Instrumentation and Methods for Astrophysics
Night-sky emission correction techniques for high-resolution spectroscopy: Demonstration with NIRPS
Avidaan Srivastava, François Bouchy, Xavier Dumusque et al. (+54 more)
Ground-based spectrographs operating in the near-infrared (NIR) regime are hampered by various absorption and emission features of Earth's atmosphere. While considerable
attention has been paid to mitigating telluric absorption, correcting telluric emission features remains non-trivial and can significantly affect the observation of faint targets. We aim to develop and implement automated
algorithms for sky background emission correction in the context of high-resolution spectroscopy. These empirical-based
algorithms have been officially integrated into both NIRPS data reduction pipelines: NIRPS DRS and APERO DRS. Designed for flexibility, these techniques can be incorporated into the reduction workflow of any high-resolution spectrograph to improve the radial velocity (RV) performance. In our approach, a reference sky spectrum is first created by deep-stacking NIRPS sky calibration frames on a common wavelength grid and calculating the weighted median flux per pixel, separately for both the high-accuracy and high-efficiency instrument modes. This process is repeated for all spectral orders and for both the object and sky-calibration fibres: fibre A and fibre B, respectively. In this reference sky spectrum, the sky emission lines can be identified and used to construct a static library. During the data reduction process, the emission features in the library are individually scaled in terms of flux using two distinct techniques, each specific to the two DRS pipelines. Finally, they are locally subtracted from the science observations to minimise their noise contribution to the final spectrum. We find that the correction
algorithms significantly improve the RV measurements obtained using both the cross-correlation function and line-by-line techniques, enabling NIRPS to achieve submetre-per-second precision in the NIR. The techniques have been successfully validated and demonstrated.
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All authors Avidaan Srivastava, François Bouchy, Xavier Dumusque, Étienne Artigau, René Doyon, Neil J. Cook, Danuta Sosnowska, Flavie Bélanger, David Lafrenière, Frédérique Baron, Lison Malo, Susana C. C. Barros, Björn Benneke, Xavier Bonfils, Marta Bryan, Ryan Cloutier, Nicolas B. Cowan, Elisa Delgado-Mena, Xavier Delfosse, David Ehrenreich, Pedro Figueira, Jonay I. González Hernández, Izan de Castro Leão, Christophe Lovis, Bruno L. Canto Martins, Lucile Mignon, Christoph Mordasini, Francesco Pepe, Rafael Rebolo, Jason Rowe, Nuno C. Santos, Damien Ségransan, Alejandro Suárez Mascareño, Jose Renan De Medeiros, Stéphane Udry, Diana Valencia, Gregg Wade, Romain Allart, Vincent Bourrier, Pedro Branco, Charles Cadieux, Gaspare Lo Curto, Yolanda G. C. Frensch, Jonathan Gagné, Roseane de Lima Gomes, Nicole Gromek, Vigneshwaran Krishnamurthy, Pierrot Lamontagne, Yuri S. Messias, Khaled Al Moulla, Dany Mounzer, Nicola Nari, Léna Parc, Atanas K. Stefanov, Thomas Vandal, Drew Weisserman, Joost P. Wardenier
Instrumentation and Methods for Astrophysics
3.5-meter Segmented-Mirror Robotic Space Telescope Mission White Paper V. Key Scientific Mission: Compact-Object Time-Domain Science
Juhan Kim, Yong-Woo Kang, Sang Hyun Lee et al. (+22 more)
An isolated compact object retains the point-source resolving power of the space-based slitless spectrograph. The baseline wavelength range is 0.2–1.5 $\mu$m. The planning baseline uses $R \simeq 1000$ for broad and faint transient spectra and reserves selectable bands at $R \simeq 5000$ for
accretion-disk profiles, velocity structure, and precision line ratios. Broad features can be measured after binning the native $R \simeq 5000$ data to lower resolution. Rapid-response spectroscopy follows gravitational-wave counterparts and kilonovae from hours to days. Repeated spectra of
dwarf novae and compact binaries trace
accretion state and orbital phase, while uninterrupted imaging of white
dwarfs measures pulsation frequencies. The program combines mission-based monitoring with external alerts, including KGMT transient detections. The instrument study must preserve calibrated throughput to 2.70 $\mu$m and evaluate a 3.0 $\mu$m operational band edge, with 2.5 $\mu$m retained as the formal engineering off-ramp. Mid-infrared imaging is not part of the adopted compact-object baseline.
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All authors Juhan Kim, Yong-Woo Kang, Sang Hyun Lee, Jeong-Yeol Han, Sungwook E. Hong, Bongkon Moon, Donguk Song, Juhyung Kang, Myeong-Gu Park, Sang Chul Kim, Chung-Uk Lee, Sangmo Tony Sohn, Arman Shafieloo, David Parkinson, Hong Soo Park, Dohyeong Kim, Chan Park, Jungjoo Sohn, Young-Beom Jeon, Jong-Hak Woo, Hyung Mok Lee, Hong Bae Ann, Myungkook James Jee, Mansoo Choi, Changbom Park
Instrumentation and Methods for Astrophysics
3.5-meter Segmented-Mirror Robotic Space Telescope Mission White Paper IV. Key Scientific Mission: Solar-System Small Bodies and Planetary Defense
Juhan Kim, Yong-Woo Kang, Sang Hyun Lee et al. (+22 more)
The baseline 0.2–1.5 $\mu$m observatory provides rapid-response astrometry, visible and near-infrared taxonomy, rotation and phase curves, recovery, and long-arc orbit improvement for near-Earth objects and other small bodies. The instrument study also evaluates calibrated throughput to 2.70 $\mu$m with a 3.0 $\mu$m operational band-edge goal. A reduction to 2.5 $\mu$m remains the formal engineering off-ramp if thermal, detector, cooling, mass, power, or cost constraints require it. The 3.5-meter Segmented-Mirror Robotic Space
Telescope does not carry a mid-infrared channel. Coordinated ground-based mid-infrared
telescopes provide the thermal fluxes required to infer diameter and albedo, while the space mission supplies contemporaneous reflected-light measurements and observing geometry. The program combines recovery, physical characterization, orbit refinement, and covariance-based hazard assessment. Its CODES dynamics system and OGFinder-to-OpenOrb processing path connect measured astrometry to reproducible orbit solutions and close-approach predictions.
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All authors Juhan Kim, Yong-Woo Kang, Sang Hyun Lee, Jeong-Yeol Han, Sungwook E. Hong, Bongkon Moon, Donguk Song, Juhyung Kang, Myeong-Gu Park, Sang Chul Kim, Chung-Uk Lee, Sangmo Tony Sohn, Arman Shafieloo, David Parkinson, Hong Soo Park, Dohyeong Kim, Chan Park, Jungjoo Sohn, Young-Beom Jeon, Jong-Hak Woo, Hyung Mok Lee, Hong Bae Ann, Myungkook James Jee, Mansoo Choi, Changbom Park
High Energy Physics (Phenomenology)
Leading-Neutron Electroproduction at HERA and the EIC: Sullivan Process, Target Fragmentation, and Pion PDFs
Wen-Chen Chang, Chia-Yu Hsieh and Satyajit Puhan
Leading-
neutron electroproduction measurements from the H1 and ZEUS experiments at HERA have been used to constrain pion parton distribution functions (PDFs) at small momentum fractions within the Sullivan one-pion-exchange (OPE) framework, complementing large-$x_\pi$ constraints from pion-induced Drell–Yan measurements. Previous analyses have focused primarily on the region of large
neutron longitudinal momentum fraction, $x_L$, where contributions from deep-inelastic scattering (DIS) target fragmentation are suppressed. In this work, we use the Pythia event generator to model the target-fragmentation contribution and show that its combination with the OPE contribution reproduces the main features of the HERA leading-
neutron data over the full measured $x_L$ range without introducing additional ad hoc normalization factors. This result demonstrates the potential of incorporating a broader range of leading-
neutron data into future global analyses, thereby extending sensitivity to smaller pion momentum fractions $x_\pi$. We investigate the model dependence associated with the pion–nucleon vertex form factor and show that the HERA data are sensitive to different target-fragmentation treatments implemented in Pythia. Finally, we present projections for leading-
neutron production at the future U.S. Electron-Ion
Collider (EIC), identifying beam-energy configurations and kinematic regions that provide enhanced sensitivity to pion structure while suppressing DIS target-fragmentation contributions.
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Astrophysics of Galaxies
Evolution of Virial Clouds - II: From the Formation of First Stars up to their Explosion
Noraiz Tahir, Asghar Qadir, Francesco De Paolis et al. (+1 more)
The existence of cold gas and
dust clouds close to the
cosmic microwave background (CMB) temperature was proposed as a potential repository for a significant fraction of the missing
baryons in
galactic halos. While the
evolution of the virial clouds from the last scattering surface (LSS) ($z=1100$) up to the formation of Population III (Pop III)
stars ($z=48$) was studied in [N. Tahir, A. Qadir, M. Sakhi, & F. De Paolis, The Euro. Phys. Jour. C 81, 827 (2021)] (Paper I), the subsequent
evolution during the epoch of the first
stars remained unexplored. In the present work, we investigate the second evolutionary phase of the virial clouds, covering the
redshift range $48 \gtrsim z \gtrsim 10$. We develop a comprehensive model incorporating the coupled thermal, chemical, and dynamical
evolution of the cloud, including CMB heating, adiabatic compression due to gravitational contraction, H$_2$ and metal-line cooling, and feedback from Pop III
supernovae. Solving the coupled ordinary differential equations (ODE) numerically, we find that the cloud cools monotonically from $137$~K to $41.5$~K, contracts from $120$~pc to $89.8$~pc, and becomes enriched in metals and molecular hydrogen, while the cooling rate dominates the heating rate throughout the
evolution.
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All authors Noraiz Tahir, Asghar Qadir, Francesco De Paolis, Noor Fatima
Atmospheric and Oceanic Physics
Added value of dynamical downscaling in sub-seasonal tropical cyclone forecast
Taehyung Kim, Eunji Kim, Haerin Park et al. (+2 more)
Improving the sub-seasonal forecast of tropical cyclones (TCs) remains a significant challenge for
climate models. This study evaluated the characteristics of tropical cyclones (TCs) in sub-seasonal forecasts using the Global Seasonal Forecast System 6 (GloSea6), an operational seasonal-to-sub-seasonal
forecasting model operated by the Korea Meteorological Administration (KMA) during June-September (JJAS) from 1993 to 2016 over the western North Pacific (WNP). GloSea6 was found to underestimate TC frequency, tracks, particularly in mid-latitudes, lifetime, and intensity across all months, with the most significant errors occurring in August. To address these deficiencies, we examined whether applying dynamical downscaling to GloSea6 during August 2016, a period characterized by the lowest TC forecast skill in GloSea6, could improve sub-seasonal TC forecasts. The application of dynamical downscaling demonstrated added value by directly improving the simulation of TCs in terms of frequency, structure, intensity, and lifetime, although slight overestimations were observed. Furthermore, improved reproductions of the Indian monsoon and circumglobal teleconnection (CGT), both of which strongly influence the western North Pacific subtropical high (WNPSH), contributed to more accurate forecasts of WNPSH variability and, consequently, better predictions of TC activity in the mid-latitudes and East Asia. Therefore, dynamical downscaling can significantly advance sub-seasonal TC forecasts by not only directly improving TC characteristics but also indirectly enhancing the environmental fields (e.g., WNPSH, Indian monsoon, and CGT) that are critical to TC activity.
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All authors Taehyung Kim, Eunji Kim, Haerin Park, Dong-Hyun Cha, Johan Lee
Quantum Physics
Nonlinear Dissipation and Hopf Criticality in Driven Dissipative Collective Spins
Shu Yang, Jun Wang, Weidong Li et al. (+3 more)
Self-sustained oscillations combine finite-amplitude stabilization with a neutral phase degree of freedom. We develop this bifurcation-based framework for driven-dissipative collective
spins and show that the microscopic structure of the U(1)-covariant dissipation selects the background attractor, while the explicit U(1)-breaking channel governs its local bifurcation response. In the thermodynamic-limit mean-field dynamics, a single linear U(1)-covariant jump produces only polar fixed-point backgrounds, whereas nonlinear covariant dissipation provides amplitude-dependent saturation and stabilizes a finite-latitude self-sustained-oscillator
manifold through a supercritical
Hopf bifurcation. Under coherent U(1) breaking, exact resonance leads to a reversible double-zero degeneracy with vanishing critical frequency rather than a standard
Hopf onset. Finite detuning unfolds this singularity into a genuine finite-frequency
Hopf boundary, which exists only on the self-sustained-oscillator side and can be either supercritical or subcritical. By contrast, a single linear dissipative U(1)-breaking jump cannot generate a standard
Hopf instability: when its phase-pinning invariant vanishes the azimuthal direction remains neutral, whereas otherwise the phase-locked fixed points have a purely real Jacobian spectrum. These results establish a general design principle: nonlinear covariant dissipation selects the selfsustained background, while the structure of the
symmetry-breaking channel determines whether the resulting local response is double-zero, genuinely
Hopf, or non-
Hopf.
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All authors Shu Yang, Jun Wang, Weidong Li, Cangtao Zhou, Jian-Song Pan, Jianwen Jie
Plasma Physics
Minute-Scale High-Fidelity Gyrokinetic Simulations with Portability from Laptop to Supercomputer
Jian Bao, Huasheng Xie, Ming Yang et al. (+4 more)
Global gyrokinetic particle simulations remain computationally expensive, as they demand both adequate marker statistics and three-dimensional field solvers. In this work, we present a hybrid spectral method within the particle-in-
Fourier (PIF) framework and implement it in the electrostatic model of GTC. Charge scatter and field gather are performed between particles and fields on a two-dimensional poloidal mesh, while the corresponding Poisson solver is discretized using radial finite differences and poloidal $m$-harmonics. Truncated spectral transforms are employed to connect multiple representations for fields, avoiding costly particle-grid operations for each individual $m$-harmonic within the particle loop.
Benchmarks against conventional particle-in-
cell (PIC) simulations successfully reproduce single-$n$ ion temperature gradient (ITG) mode structures and dispersion relations, as well as multi-$n$ nonlinear ITG transport and its regulation by zonal flows. Compared to conventional PIC, the proposed method reduces the effective problem size by more than a factor of 48 and achieves a speedup of over two orders of magnitude for single-$n$ cases. A 2000-step single-$n$ simulation with approximately 2 million markers completes in 78.2 seconds on a laptop GPU, while multi-$n$
turbulence simulation also completes within minutes. Furthermore, the elimination of toroidal particle-shift communication yields promising preliminary scaling performance on multiple NVIDIA A100 GPUs. The numerical scheme is broadly applicable for accelerating particle simulations on platforms ranging from laptops to supercomputers.
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All authors Jian Bao, Huasheng Xie, Ming Yang, Zhixin Lu, Haotian Chen, Zhihong Lin, Feng Zhang
High Energy Physics (Theory)
Conical Defects in JT Gravity from BF Theory: Quantization, Fusion, and Weighted Moduli Spaces
Wei Gu
We construct a gauge-invariant BF representative of a conical defect in Jackiw–Teitelboim
gravity, with its
elliptic direction fixed by the reconstruction of the gravitational variables. In the gravitational sector, the BF observable reproduces the metric defect insertion and its distributional
curvature source, and fixes the holonomy around the defect to an
elliptic conjugacy class. For a single defect on the disk, the position integral combines with the residual \(\mathrm{PSL}(2,\mathbb R)\) quotient, leaving a fixed
elliptic sector. The exact boundary quantization of this sector gives the elementary kernel and one-defect disk amplitude directly, without using a
matrix model. The same local BF operator describes both sharp and blunt defects. Their difference appears only when several defect positions are integrated. BF source composition makes the fractional deficits additive. Requiring a fused source to remain in the gravitational cone sector gives the admissibility condition for defect collisions, while positivity of the
hyperbolic area on each component gives the corresponding stability condition. These conditions coincide with those for Hassett weighted curves. Combining these BF results with the known Hassett compactification and conical Weil–Petersson geometry yields the fixed-order genus-zero contact terms and recovers the cluster expansion of deformed JT
gravity. Thus sharp and blunt defects differ through the compactified geometry of their relative positions, rather than through the elementary BF operator.
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Physics and Society
Large-Language Models as a Cognitive Virus
Ricard Solé, Giulio Ruffini, Francesca Castaldo et al. (+6 more)
Large-
language models (LLMs) are rapidly becoming part of human culture, reshaping how information is produced, transmitted, and used. Here we propose that their
diffusion can be understood through a viral analogy, with LLM use spreading through populations, becoming embedded in cognitive and cultural practices. We model transitions among uncoupled, coupled, and persistently dependent users, and show that the interplay between social transmission, recovery, and collective reinforcement can generate tipping points and technological lock-in. A central consequence is the possibility of runaway dynamics: once a critical threshold is crossed, small increases in adoption can trigger rapid population-level shifts toward persistent dependence, with abrupt losses in cognitive competence. The same framework, however, identifies conditions for cognitive immunization, based on reducing transmission and facilitating reversibility. Our results highlight how LLM adoption may involve nonlinear collective transitions with important consequences for cognitive autonomy.
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All authors Ricard Solé, Giulio Ruffini, Francesca Castaldo, Marco Tuccio, Luis F. Seoane, Manlio de Domenico, Santiago F. Elena, David C. Krakauer, Michael Levin
Materials Science
Polaron Self-Trapping Rates from First Principles
Mark E. Turiansky, Joel B. Varley, Audrius Alkauskas et al. (+1 more)
Polaron formation, also known as self-trapping, is a process akin to nonradiative carrier capture at point defects or
impurities. In this work, we develop the formalism to determine how long it takes to form a small hole or electron polaron from first principles. We employ an accurate, fully first-principles approach based on a Koopmans compliant hybrid functional. The self-trapping rate is the product of two components: the nonradiative capture coefficient, which we evaluate using a one-dimensional approximation, and the maximum density of polaron sites, whose physics we elucidate based on finite-size interactions present in supercells. We apply our methodology to several technologically relevant materials known to host hole polarons, Ga$_2$O$_3$, Al$_2$O$_3$, BeO, KBr, MgO, NaCl, SiO$_2$, SnO$_2$, TiO$_2$, and ZnO, and to an electron polaron in rutile TiO$_2$. We also study an emerging
semiconductor, rutile GeO$_2$, where we find that polaron formation could hamper $p$-type conductivity. The calculated self-trapping lifetimes span 7 orders of magnitude, from $10^{-1}$ to $10^6$~ps, in agreement with experiments where available, and providing detailed insight into the dynamics of carrier localization and relaxation in solids.
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All authors Mark E. Turiansky, Joel B. Varley, Audrius Alkauskas, Chris G. Van de Walle
Quantum Physics
Redesigning quantum theory
Matthew B. Weiss
QBism understands
quantum mechanics to be probability theory supplemented by additional nonclassical coherence conditions. In this dissertation, we develop these nonclassical coherence conditions from first principles, emphasizing the role of a well chosen reference measurement. After treating standard probability on subjective
Bayesian lines, we demonstrate an equivalence between the QBist approach and the existing framework of generalized probabilistic theories. We show that the fundamental nonclassical coherence relation may almost always be taken to be a gentle modification of the law of total probability, and give a coherentist account of when an experimental scenario has a classical explanation. Finally, we show that when the reference measurement is chosen to correspond to a complex projective 3-design, the shape of
quantum state space is implicit in the probabilities which characterize the reference measurement itself. Thus coherence with this single reference measurement, properly understood, implies coherence with all of finite dimensional
quantum mechanics. We then attempt a modest reconstruction of
quantum theory along these lines, one practical consequence of which is a method for self-testing complex projective $t$-designs for $t\ge 3$ in a theory-agnostic way.
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General Relativity and Quantum Cosmology
Introducing SINFONIA: Symplectic, slimplectic and Magnusian (Neural) Flows for Orbital Numerical Integration and Acceleration
Lidia J. Gomes Da Silva
Long-duration gravitational-wave modelling must resolve fast orbital motion together with slow dissipative
evolution while preventing small numerical errors from accumulating into secular phase drift. Here we ask whether the finite-time
evolution map itself can be learned as an explicit, differentiable, structure-preserving object and then repeatedly composed through a complete inspiral. We construct three neural-flow architectures: a
symplectic and slimplectic flow on Galley's doubled phase space, [SINFONIA-J0]; a Taylor-anchored flow, [SINFONIA-J1]; and a Magnusian flow that learns the finite-time dissipative correction in the interaction picture, [SINFONIA-J2]. Applied to a 2.5PN
neutron-
star inspiral, all three expose the same controlling mechanism: long-time accuracy is governed not by pointwise map error alone, but by its signed projection onto a single secular channel fixed by energy–angular-momentum balance. Encoding this structure allows the learned maps to remain accurate through $10^{2}$–$10^{5}$ window compositions to coalescence at timesteps of a full orbital period and beyond, reaching chained phase errors orders of magnitude below a
benchmark slimplectic integrator at lower cost. The same secular structure can also be exploited for physics inference: when the channel is left unconstrained, the accumulated phase retains enough information to recover an un-modelled dynamical-friction-like force, both parametrically and as a learned function of separation. Network-off controls isolate the contribution of learning from the analytic structure already built into each map. These results establish a proof of concept for structure-preserving learned
evolution maps as tools for fast long-duration integration and physics inference in gravitational-wave source modelling.
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Biological Physics
Internal geometries regulate the symmetry of defect configurations in cell populations confined to domains with a negative Euler characteristic
Mina Kamao, Hiroyuki Miyoshi, Takaaki Nara et al. (+1 more)
Nematic order of confined
cell populations plays an important role in determining
cell alignment and stable configurations of topological defects, which are related to various biomechanical phenomena. Topological charges (or winding numbers) of topological defects strictly depend on the Euler characteristic of the confining domain, which has typically been non-negative in studies focused on domains without internal obstacles. However, biological tissues often surround two or more internal obstacles or holes, which inherently generate defects with negative charges. To understand the mechanical interaction between cellular tissue and obstacles, it is necessary to elucidate the geometrical effects of obstacles on
cell alignment and defects with negative charges. Here, we investigate how
cell populations achieve stable defect configurations of two -1/2 defects in a triply connected domain. First, we present experimental observations of C2C12 myoblasts confined by two circular obstacles of varying diameter, demonstrating that two $-1/2$ defects are the most frequent configuration when the obstacles are sufficiently large. Second, to theoretically validate these experimental observations, we perform systematic stability analyses of defect configurations using an explicit expression of
cell alignment and numerical minimization of the Frank elastic energy. Our numerical calculations reveal that the most stable configuration shifts continuously from a horizontal, through off-axis, to a vertical configuration as the obstacle size increases. In addition, the experimentally observed defect positions agreed with these theoretical predictions to within 60 $\mu$m. These findings suggest that obstacle sizes control the
symmetry of
cell alignment, providing insights into how
geometric and topological constraints can generate complex force patterns during morphogenesis or organ movements.
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All authors Mina Kamao, Hiroyuki Miyoshi, Takaaki Nara, Hiroki Miyazako
Quantum Physics
Variable-Cliff Nielsen Geometry and an Exponent -4/3 Lower Bound for the Infinite-Cliff Diameter
Honghuai Fang
Let $D=2^n$ and $M=3n+9\binom n2$. We study the right-invariant one-step-cliff metric $d_Q$ on $\operatorname{PU}(D)$, with unit penalty on Pauli weights one and two and penalty $Q$ on all higher weights. If $M/Q_D\to0$ and $MQ_D^{3/4}/D^2\to0$, then, for every fixed $0<x<\pi/\sqrt3$, \[ \mu_D\bigl(B_{Q_D}([I],x\sqrt{Q_D})\bigr)\le e^{-c_xD^2}. \] Here $\mu_D$ is normalized Haar measure. Thus the Haar-typical distance from the identity and the diameter are both asymptotic to $(\pi/\sqrt3)\sqrt{Q_D}$ throughout the window $M\ll Q_D\ll D^{8/3}M^{-4/3}$. Choosing $Q_D=\kappa D^{8/3}M^{-4/3}$ with sufficiently small fixed $\kappa>0$ yields a Haar-typical lower bound of order $D^{4/3}M^{-2/3}$ for the corresponding infinite-cliff Carnot–Carathéodory distance, outside an $e^{-\Omega(D^2)}$ exceptional set. The infinite-cliff diameter therefore has exponential lower rate at least $4/3$, disproving Brown's exponent-one
conjecture. The same estimate gives a fixed-error no-ancilla two-
qubit circuit lower bound of the same order.
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Quantum Physics
Efficient Estimation of Reduced QAOA Expressibility on Acyclic Graphs
Bao Bach, Boris Tsvelikhovskiy, Jose Falla et al. (+1 more)
Classically equivalent formulations of an optimization problem need not lead to equivalent
quantum algorithms. For MaxCut, fixing the value of a single vertex removes a simple global
symmetry without changing the underlying optimization problem, yet it can substantially alter the
quantum dynamics generated by the
Quantum Approximate Optimization
Algorithm (QAOA). These dynamics are captured by the
circuit's dynamical Lie
algebra (DLA), whose direct construction can become exponentially expensive. Here we show that, for
symmetry-reduced QAOA on trees, substantial information about the reduced DLA can instead be obtained efficiently from the graph alone. We introduce a
polynomial classical
algorithm that recursively distinguishes vertices using shortest path structure and degree parity. When all vertices are resolved individually, the method determines the complete reduced DLA and, under the corresponding graph conditions, certifies maximal expressibility of the reduced QAOA ansatz. Even when full resolution is not achieved, the
algorithm identifies embedded subalgebras, provides rigorous lower bounds on DLA dimension, and certifies controllable subsystems. Our theoretical and experimental results show how classical graph structure can be used to diagnose and potentially guide the
quantum dynamics of variational
algorithms before running them on
quantum hardware.
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All authors Bao Bach, Boris Tsvelikhovskiy, Jose Falla, Ilya Safro
Quantum Physics
Zain Mehdi, Joseph J. Hope and Simon A. Haine
We propose all-optical tests of
photon-
photon interactions in the matter
vacuum using standing-wave
laser interferometers, which do not require external
magnetic fields and use conventional
laser sources. We show that the interferometric detection of
photon-
photon scattering predicted by
quantum electrodynamics is within reach of laboratory-scale experiments with a sensitivity that improves nonlinearly with the circulating power within the cavity. We outline how such an experiment could be adapted to probe properties of
quantum fields beyond the Standard Model of particle physics.
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High Energy Physics (Phenomenology)
Statistical Symmetry Breaking and Emergent Colored Noise in a Stochastic Scalar-Doublet Field Theory
Pei Wang
We investigate a relativistic
stochastic field theory in which a complex scalar doublet is coupled to a complex white-noise source. The action preserves Lorentz and $\mathrm{U(1)}\times\mathrm{SU(2)}$
symmetries at the statistical level, whereas the corresponding Euler-Lagrange equations exhibit
symmetry breaking along individual
stochastic realizations. Within a gauge-field-free sector introduced to obtain analytical solutions, we show that the scalar doublet undergoes a noise-driven random walk in field space, leading to a finite, time-dependent ensemble average of its magnitude. As an illustrative application, we further investigate the coupling of the
stochastic scalar field to
fermions through a Yukawa interaction. The scalar-field solution naturally separates into a tail component, which contributes as an effective mass-like term, and a light-cone component, which acts as a colored-noise source that induces a spatially correlated
stochastic phase in the
fermion wave function. The statistical properties and correlation length of this emergent colored noise are derived analytically within the adopted approximations. The present work provides an exploratory study of statistical
symmetry breaking and emergent colored-noise dynamics in a relativistic
stochastic scalar-doublet field theory.
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Solar and Stellar Astrophysics
NGC 1901: A new benchmark cluster for gyrochronology in the TESS Southern continuous viewing zone
Mara Bernizzoni, Timothy R. Bedding, Prasad Mani et al. (+5 more)
We use
Gaia DR3 astrometry and TESS time-series photometry to study NGC 1901, a sparse open cluster in the TESS Southern continuous viewing zone, that has been neglected due to its proximity on the sky to the Large Magellanic Cloud. We refine its membership list and measure rotation periods for 32 high-confidence rotating
stars. By applying the gyro-interp empirical model, we calculate a gyrochronal age of 830 $\pm$ 50 Myr. Because NGC 1901 possesses a sub-
solar metallicity of [Fe/H]$\approx -0.11$, its excellent agreement with empirical models suggests that temperature-period relations mitigate
metallicity effects for Sun-like
stars. Our results place NGC 1901 in the gap between the
benchmark open clusters Praesepe (670 Myr) and NGC 6811 (1 Gyr). We find that the rotation sequence exhibits significant
spin-down stalling in late K
dwarfs, supporting models of core–envelope recoupling. Furthermore, our findings provide constraints for the cluster's structural
evolution, including its recently identified
tidal tail and corona. This study establishes NGC 1901 as a new
benchmark for calibrating the next generation of gyrochronal models.
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All authors Mara Bernizzoni, Timothy R. Bedding, Prasad Mani, Luke G. Bouma, Courtney L. Crawford, Jason Lee Curtis, Benjamin T. Montet, Samir Nepal
Materials Science
Grain boundary evolution in nanoparticles
Manoj Settem, Pranav Kumar and Ajeet K. Srivastav
Grain boundary
evolution is a key dynamical process that enables structural rearrangements in nanoparticles and drives them towards low energy configurations. Grain boundaries can also enhance catalytic properties, making it important to understand the elementary processes underlying their
evolution for grain boundary engineering in nanoparticles. Compared with bulk materials, nanoparticles have additional rotational and translational degrees of freedom, can accommodate structural changes through shape relaxation, and grain boundaries terminate at free surfaces. However, the atomic-scale mechanisms of GB
evolution under these less constrained conditions remain comparatively less understood than in bulk materials. Here, using atomistic simulations, we focus on low energy $\Sigma3$ (coherent twin boundary) and $\Sigma11$ grain boundaries, which are among the persistent compact GB structures that emerge during nanoparticle structural
evolution. We identify two fundamental atomic displacements, column shift (C) and screw shift (S), that recur during the
evolution of these grain boundaries and their junctions. These displacements occur through different atomic pathways and combine in different ways to generate grain boundary migration, structural transformations, and junction
evolution. In particular, the same initial and final grain boundary configurations can be connected through different atomic pathways, and a column shift can occur either as a full shift or through disconnection kinks. C and S remain identifiable even when the grain boundary character changes, for example during a $\Sigma11$ to $\Sigma3$ transformation. An understanding of these elementary GB processes can help identify strategies to control grain boundary
evolution and thereby engineer GB structures in nanoparticles.
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Instrumentation and Detectors
Multi-Angle Beam Scanning Transmission Electron Microscopy for Diffraction-Contrast-Free Magnetic Imaging
Akira Yasuhara, Zentaro Akase and Takumi Sannomiya
Recent development of the differential phase contrast (DPC) scanning transmission electron microscopy (STEM) technique has significantly advanced materials science supported by high-sensitivity detectors and powerful data processing. Especially the 4D-STEM technique, employing a pixelated camera as a STEM detector, enables extensive information acquisition through post-processing of large
datasets. However,
magnetic or electric field imaging using DPC is often disturbed by diffraction contrasts intrinsic to the crystalline material. In this paper, we demonstrate elimination of the diffraction contrasts for
magnetic field imaging by using angularly distributed multiple electron beams generated by a multi-hole aperture within the 4D-STEM framework. This multi-angle beam configuration suppresses irrelevant crystalline contrast and yields direct
magnetic information with high sensitivity from the specimen. Furthermore, we performed various image analysis to extract and interpret
magnetic domain structures and domain walls.
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Fluid Dynamics
Finite-source filtering and Doppler modulation of infragravity waves generated by breakpoint forcing
Hedi Midouni, Stephanie Contardo, Jaak Monbaliu et al. (+1 more)
Infragravity waves generated in the surf zone contribute substantially to nearshore water-level variability, with group-scale variations in wave breaking generating free long waves through breakpoint forcing. Existing interpretations of this mechanism rely largely on an idealised moving-breakpoint picture in which breaking is tied to a local saturation relation, leaving unresolved how the finite extent and
evolution of a realistic breaking region control the radiated waves. We first derive a local decomposition of the wave-induced forcing into breakpoint and bound wave forcing, separating the two contributions within the same evolving short-wave field. We then describe the breakpoint-forcing field as a finite, evolving source through its integrated strength, centroid, cross-shore width, and shape. This representation shows that finite source extent produces spatial interference, as phase differences between contributions emitted from different positions attenuate the high-frequency part of the infragravity response and shift this attenuation toward lower frequencies as the source widens. Source migration produces a directional Doppler shift by modifying the arrival times of successive emissions, with shoreward motion compressing arrivals at a shoreward observer and stretching them at a seaward observer. Breaking depth controls both the conversion of this forcing into surface elevation and the celerities governing these propagation-time effects. Controlled numerical experiments across a range of plane-beach slopes reproduce the predicted signatures: broader source footprints strengthen upper-band attenuation on both branches. The diagnosed migration history, with breaking strongest during shoreward motion, partly offsets that attenuation shoreward and reinforces it seaward.
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All authors Hedi Midouni, Stephanie Contardo, Jaak Monbaliu, Tomohiro Suzuki
Solar and Stellar Astrophysics
Bifurcations in the Heliosphere: Global-scale Coronal Pseudostreamer Evolution and the Creation of Secondary Heliospheric Current Sheets
Lizet S. Casillas, Benjamin J. Lynch, Victor Réville et al. (+2 more)
The heliospheric current sheet (HCS) is the boundary between open
magnetic fields of opposite polarity in the
solar wind that connect back to their respective open flux regions in the corona. The HCS is often described as a disc-like sheet warped by the combined effects of the inclination of the
magnetic equator on the Sun,
solar rotation, and
solar wind expansion. The HCS is an extension of the helmet streamer belt-the closed-flux region resulting from the global dipole component of the observed photospheric
magnetic field. In the absence of a strong dipole, a dominant quadrupole can result in two separate HCSs. Here we report on a set of idealized, axisymmetric
solar wind simulations designed to study the transition of the single-HCS corona and inner heliosphere into a multiple-HCS configuration, run with the WindPredict-AW PLUTO MHD code. We systematically vary the relative strengths of the dipole/quadrupole contributions to the global field and show this results in the formation of a large-scale, closed-flux pseudostreamer that interacts with the ambient
solar wind. We find that when the dipole and quadrupole magnitudes are approximately equal, our model corona can oscillate between a one- and two-HCS configuration on the timescale of days-to-weeks. We characterize the
plasma dynamics of the transition of a global-scale pseudostreamer into a localized, secondary helmet-streamer belt with its own HCS surrounding a newly-opened, opposite-polarity coronal hole. We discuss the implications of our results for
solar cycle
evolution and the dynamic coupling of the highly structured corona and inner heliosphere.
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All authors Lizet S. Casillas, Benjamin J. Lynch, Victor Réville, Olga A. Panasenco, Marco Velli
Strongly Correlated Electrons
Symmetry-breaking line defects embedded to a 3D $O(N)$ critical bulk
Shuai Yang, Liang-dong Hu, Yan Chen et al. (+1 more)
While spontaneous breaking of a discrete
symmetry in one-dimensional classical systems with short-range interactions is absent, it is expected that a line defect embedded in a bulk criticality exhibits a stable discrete
symmetry spontaneous breaking. Here, we investigate the behavior of a pinning-field line defect immersed in a 3D bulk that remains tuned to the $O(N)$ Wilson-Fisher critical point. Employing the fuzzy sphere technique, we provide convincing evidence of the existence of stable defect conformal fixed points, and we demonstrate their renormalization group stability by showing no relevant operator and less effective degrees of freedom than that at bulk fixed point via $g$-function. Moreover, we investigate the defect domain wall operator for various $N$, and we identify that it becomes irrelevance for $N\gtrsim 3$ but it is relevant for $N<3$.These evidence indicate that a one-dimensional defect coupled to a critical bulk cannot support a stable
symmetry spontaneously broken defect fixed point due to domain wall proliferation for $N<3$ Wilson-Fisher universality, while in the case of $N \gtrsim 3$ a
symmetry broken defect is possible.
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All authors Shuai Yang, Liang-dong Hu, Yan Chen, W. Zhu
Optics
A Silicon-Compatible Uncooled Compact Broadband Infrared Spectrometer
A. Nomezine, G. Daligou, D. Vlassov et al. (+3 more)
Infrared spectroscopy is a widely used technique for molecular identification, yet its widespread deployment remains constrained by bulky instrumentation, cryogenic cooling requirements, and limited portability. Here we demonstrate broadband near- to short-wave infrared spectroscopy enabled by a silicon-compatible GeSn photodetector integrated into a compact digital micromirror device-based single-pixel architecture. By combining detector design with targeted optical reconfiguration and wavelength recalibration, we extend the operational range up to 2.4 micrometers while maintaining room-temperature, zero-bias photovoltaic operation. System-level benchmarking quantifies the intrinsic trade-off between spectral extension and detectivity in narrow-bandgap photodetection, yielding a specific detectivity of $1.12 \times 10^{10}$ cm Hz$^{1/2}$ W$^{-1}$ at 1.55 micrometers with an extended wavelength cut-off. We validate the capabilities of the obtained spectrometer through selective identification of representative commodity plastics, demonstrating a lightweight, low-power, and mechanically robust platform for portable and autonomous deployment. Despite the expected increase in generation-limited noise, access to strong
polymer combination bands beyond 1.7 micrometers allows enhanced material discrimination. This work establishes a pathway toward scalable distributed molecular sensing and broadens access to infrared spectroscopy for environmental monitoring, industrial process control, and community-level chemical detection.
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All authors A. Nomezine, G. Daligou, D. Vlassov, S. Assali, M. R. M. Atalla, O. Moutanabbir