Papers

Fresh from arXiv, typeset properly. Highlighted words trade on the market.

Physics

Tuesday 16 June

Materials Science

Coexistence of Donor and Acceptor Hydrogen States in n-Type InN

Masaki Kobayashi, Yudai Yamashita, Kazuyuki Hirama et al. (+1 more)

Hydrogen often exhibits amphoteric behavior in semiconductors, but its role is in n-type InN remains unresolved. Wurtzite InN is a narrow-gap semiconductor with high electron mobility and is therefore attractive for high-speed electronics and optoelectronic applications. Here we use hard x-ray photoemission spectroscopy (HAXPES) to probe hydrogen-related electronic structure in as-grown and post-annealed InN thin films prepared at different grown temperatures. Post annealing, which reduces the concentration of hydrogen impurities in the films, shifts the core-level spectra toward lower binding energy, consistent with a chemical-potential shift associated with the passivation of electron carriers. In the valence-band spectra, an acceptor-like in-gap feature near the valence-band maximum is suppressed after annealing. Together with the established donor-like behavior of hydrogen in InN, these results suggest that acceptor H- states coexist with donor H+ states in InN. The coexistence of these opposite hydrogen charge states provides a microscopic picture of hydrogen-driven compensation in InN and highlights the amphoteric nature of hydrogen even in a highly n-type semiconductor.

Read the full abstract

All authors Masaki Kobayashi, Yudai Yamashita, Kazuyuki Hirama, Yoshitaka Taniyasu

General Relativity and Quantum Cosmology

Acceleration-induced spectral blind spots in stimulated atomic transitions

Jiawei Hu and Hongwei Yu

Stimulated transitions are among the most fundamental processes in light-matter interaction, underlying resonant absorption and emission in atomic systems. Here we show that uniform acceleration can convert this familiar response into a frequency-selective absence of response. Specifically, when an incident photon has a nonzero momentum component transverse to the acceleration, the stimulated transition probability vanishes at a discrete set of frequencies fixed by the acceleration, the atomic transition frequency, and the photon propagation angle. At these spectral blind spots, both ordinary stimulated absorption and acceleration-induced excitation are simultaneously suppressed, rendering the atom effectively unresponsive to the incident radiation. The effect arises from the nontrivial response of accelerated atoms to quantum vacuum fluctuations and provides a distinctive signature of the Unruh effect through the absence, rather than the enhancement, of stimulated transitions. We further provide an order-of-magnitude estimate showing that an electron-based implementation with spin splitting in combined electric and magnetic fields could access the required parameter regime. These results reveal an unexplored form of acceleration-modified light-matter interaction and identify spectral blind spots as a new manifestation of the Unruh effect.

Read the full abstract

Mesoscale and Nanoscale Physics

Surface-switchable nonreciprocity protected by Fermi arcs in Weyl semimetal TaAs

Dong Li, Yuki M. Itahashi, Ying-Ming Xie et al. (+12 more)

Weyl semimetals host topologically protected surface states, known as Fermi arcs, which connect bulk Weyl nodes in momentum space. Both bulk Weyl nodes and Fermi arcs are anticipated to be chiral. The chirality of bulk bands has been confirmed through observations of the chiral anomaly and Weyl orbits. In contrast, despite their discovery more than a decade ago, the chiral nature of Fermi arcs has remained unresolved. Here we report Fermi-arc-induced nonlinear transport in the archetypal Weyl semimetal TaAs. Using focused ion beam techniques, we fabricated micro-scale devices that enable simultaneous transport measurements on opposing topological surfaces. While linear transport remains dominated by bulk conduction, nonlinear transport uncovers surface-specific contributions, including an exceptionally large third-order nonreciprocal response that exceeds conventional expectations and highlights the crucial role of the singular arc endpoints. Our findings unambiguously demonstrate the chiral nature of Fermi arcs and establish nonlinear transport as a direct probe of these topological surface states. By revealing a surface-switchable, room-temperature nonlinear response that is topologically protected, this work introduces a new functionality in Weyl semimetals. Given the abundance of natural materials predicted to host topological semimetal states, these results open opportunities for exploring nonlinear transport phenomena and device concepts across a broad class of systems.

Read the full abstract

All authors Dong Li, Yuki M. Itahashi, Ying-Ming Xie, Menghu Zhou, Yukako Fujishiro, Kunjie Zheng, Yao Guang, Max T. Birch, Ilya Belopolski, Max Hirschberger, Takahiro Morimoto, Xiao-Xiao Zhang, Zhi-An Ren, Naoto Nagaosa, Yoshihiro Iwasa

Mesoscale and Nanoscale Physics

Dispersive mode coupling in $p$-doped semiconductor nanomechanical resonators

Ankang Liu, Mahmoud T. Elewa and Mark I. Dykman

Dispersive coupling between vibrational modes with different frequencies is a major nonlinear dynamical effect. We show that in $p$-doped semiconductors such coupling is strongly enhanced. Moreover, the coupling parameters increase with the order of the nonlinearity. The doping-induced dispersive coupling becomes much stronger than the intrinsic one already for moderately strong doping. Its dependence on the hole density is nonmonotonic, and the temperature dependence becomes nonmonotonic for higher densities. Relevant mesoscopic frequency fluctuations are briefly discussed. The results are applied to Si resonators, where doping is used to compensate the temperature dependence of a clock mode, whereas another low-frequency mode is used as a thermometer to enable temperature stabilization.

Read the full abstract

High Energy Physics (Theory)

Universal structure in the interactions of massless fields on the lightcone

Jin Kozaki and Yasha Neiman

We consider cubic interactions of massless fields of arbitrary spin in 4 spacetime dimensions, within the lightcone formalism. We extend two key results from flat to (Anti-)de Sitter spacetime. First, we present a simple explicit expression for all the cubic vertices. Second, we prove that the various self-dual/chiral theories, such as Self-Dual Yang-Mills, Self-Dual General Relativity and Chiral Higher-Spin Gravity, are fully consistent with no need for vertices beyond cubic. The key observation behind our results is that all cubic vertices in the lightcone formalism can be expressed as a direct generalization of the "abelian" vertices formed by multiplying linearized curvatures. The simple relationship between flat and (Anti-)de Sitter then follows essentially from the conformal invariance of such linearized curvatures. The price for such simplicity is that our vertex expressions are non-local. It is however easy to bring them into a local form, which we also present.

Read the full abstract

Plasma Physics

First divertor exposure experiments of a renewable boron pebble aggregate in DIII-D

Erick Martinez-Loran, Angelica Ottaviano, Santhosh T. A. Kumar et al. (+21 more)

Boron pebble aggregate was tested for the first time as a high-heat-flux granular plasma-facing material in a tokamak divertor. Exposures of up to $q_{\parallel} = \SI{80}{\MW\per\m\squared}$ incident heat flux were conducted in the DIII-D tokamak. Single protruding rods of pebble aggregate composed of sintered amorphous boron pebbles bound with carbon binder were mounted in the Divertor Material Evaluation System (DiMES) sample holders and exposed to L-mode lower single null (LSN) plasmas. Under these heat loads, significant boron dust emission from the boron spheres was observed, and this dust dominates the divertor boron ionization source. Only about half of the released boron was recovered locally as mm-sized particles; with the rest presumably lost mainly as dust into the plasma and vacuum chamber. Preliminary estimates suggest that the rate of surface recession of $\sim$1 cm/s in the pebble conglomerate within the plasma divertor is consistent with the recession rates observed in laser bench tests subjected to normal-incidence heat loads. Although core performance was not adversely affected by the high boron dust emission, future work will need to improve the boron pebble aggregate design to reduce boron dust emission at high heat loads.

Read the full abstract

All authors Erick Martinez-Loran, Angelica Ottaviano, Santhosh T. A. Kumar, Gabriel Brewster, Renato Perillo, Dmitry Rudakov, Jun Ren, Jonathan D. Coburn, Robert Kolasinski, Ryan Thomas Hood, Cedric K. W. Tsui, Charles Lasnier, Filippo Scotti, Dihn D. Truong, Gilson Ronchi, Igor Bykov, Colin Chrystal, Žana Popović, Shawn Zamperini, Florian Effenberg, Mathias Groth, Dmitri M. Orlov, Jose Boedo, Eric M Hollmann

Astrophysics of Galaxies

Reduced Effective Viscosity from Anisotropic Transport and Plasma Instabilities in the Sloshing Cores of Galaxy Clusters

John A. ZuHone, Stephen Majeski, Annie Heinrich et al. (+3 more)

The $\sim \mu$G magnetic field in the intracluster medium (ICM) introduces a pressure anisotropy with respect to the magnetic field's direction that manifests as an anisotropic viscous stress. Plasma instabilities arising from the pressure anisotropy crossing certain thresholds force it to marginally stable values, reducing viscous transport. Additionally, the feedback of this anisotropic pressure on the velocity field has been predicted to lead to a form of self-organization that also can reduce viscous dissipation without affecting the collisionality. In this work, we present high-resolution Braginskii-MHD simulations of a galaxy cluster core with sloshing gas motions and turbulence, including the effects of anisotropic viscous stress and different simple prescriptions for limiting the pressure anisotropy due to plasma instabilities. Braginskii viscosity has an expected, though modest, effect on suppressing Kelvin-Helmholtz instabilities at sloshing cold front surfaces, dependent on how the pressure anisotropy is limited. Due to the sloshing motions, the magnetic field's strength can become high enough in places that the pressure anisotropy need not be limited. Nevertheless, the combined effect of the limiters and the turbulent structure of the magnetic field in all simulations is that the effective viscosity is much lower than the isotropic Spitzer value in a significant fraction of the core region. However, we find that this reduced viscosity is capable of steepening the velocity-amplitude spectrum and transferring a small fraction of the turbulent kinetic energy into heat. Finally, we present evidence for magneto-immutable dynamics in our simulations.

Read the full abstract

All authors John A. ZuHone, Stephen Majeski, Annie Heinrich, Alexander A. Schekochihin, Francisco Ley, Irina Zhuravleva

Monday 15 June

Materials Science · Cross-listed from cs.AI

Steering topology distributions for unified generative design of architected metamaterials

Haolin Li, Yuyang Miao, Menglei Li et al. (+9 more)

Architected metamaterials derive their functions from structure, creating vast opportunities to program physical responses through topology design. However, existing design methods are often tailored to individual design problems, making limited use of topology knowledge for effective and broadly applicable design as objectives, constraints, and physical functions change. Here we introduce Generative Topology Optimization (GenTO), a unified framework that turns a learned topology prior into a reusable design engine. GenTO trains a diffusion model on a large full-order topology dataset and then iteratively steers the resulting topology distribution toward task-specific high-performing regions using user-defined physical objectives and constraints. This shifts the object of optimization from a single structure to a task-adapted topology distribution. Across topology design problems spanning thermal extremization, multi-objective morphology control, property-targeted auxetic design, and vibration transmission design, GenTO reuses pretrained topology priors for heterogeneous tasks, preserves structural diversity, and reaches high-performing solutions supported by numerical benchmarks and experimental validation. These results establish reusable topology knowledge as a unified principle for effective and scalable architected metamaterial design.

Read the full abstract

All authors Haolin Li, Yuyang Miao, Menglei Li, Jinshuai Bai, Liyuan Wang, Xin Liu, Bo Gao, Jiantao Liu, Danilo Mandic, Zahra Sharif Khodaei, M.H.Aliabadi, Weiqiu Chen

Biological Physics

Action potentials and solitons

Jüri Engelbrecht, Kert Tamm and Tanel Peets

During the last decade, the notion of solitons has been mentioned in neuroscience related to the propagation of action potentials (AP). In this paper, based on many studies in mathematical physics and neuroscience, the clear differences between the APs and solitons are summarised. It is stressed that the physics of the emergence of APs and solitons is fundamentally different. The numerical examples collected from earlier studies demonstrate the differences in the process of generation and interaction of corresponding waves explicitly. It is also noted that although the longitudinal mechanical waves in biomembranes can be described by the Boussinesq-type equation, the time-scale of emerging solitons from an arbitrary initial excitation exceeds the time-scale of the usual AP existence considerably.

Read the full abstract

General Physics

On the Meaning of Localization in Non-Local Quantum Field Theory

E. J. Thompson

In this paper we explore and derive an uncertainty principle for an ultraviolet complete nonlocal quantum field theory where under our hypothesises of an induced equal time detector response kernel, we then prove that the observed localization width obeys an exact variance addition law. Then when we combine this with the ordinary Heisenberg inequality and we obtain a nonlocal uncertainty relation. The bound reduces to the usual local relation in the infrared or local limit when $E_M \to \infty$, while in the ultraviolet it implies a minimal localization length of order $L_M$. We go on to explain what this means for locality, microcausality, the interpretation of spacetime points, and the ultraviolet structure of quantum field theory. In this formulation we note and prove that spacetime will remain a Lorentz covariant continuum at the level of the manifold description but pointlike localization ceases to be a physically realizable observable notion below the nonlocality scale.

Read the full abstract

Quantum Physics

Efficient and SPAM-Robust Ansatz-Free Lindbladian Learning

Savar D. Sinha

Describing the dynamics of open systems is essential for fault-tolerant quantum computation. Under Markovian assumptions, we can characterize dissipative dynamics via the Lindbladian. Using Bell sampling, we provide an efficient, ansatz-free Lindbladian learning algorithm with polynomial-time classical postprocessing. Motivated by the prevalence of state preparation and measurement (SPAM) noise on near-term devices, we also introduce the first efficient SPAM-robust protocol capable of learning the gauge-independent components of sparse Lindbladians to arbitrary precision in the presence of constant-order SPAM error. In doing so, we provide the first rigorous characterization of the gauge degrees of freedom in noisy Lindbladian learning, precisely identifying which components remain learnable under SPAM noise.

Read the full abstract

Classical Physics

A tabletop demonstration of distributed friction: the spinning wine glass

Ruben Canora

When a wine glass is dragged on a table along a circular path, a spontaneous rotation about its vertical axis can develop even if the applied hand force does not directly introduce a yaw torque. This document provides a structured formal derivation of the governing equations that are responsible for this behavior. The analysis shows that the mechanism responsible for this effect is the redistribution of pressure onto the table when applying the force with your hand. This causes an uneven frictional force distribution which exerts a torque on the glass, causing it to spin.

Read the full abstract

Biological Physics

ScopeOne: Flexible and C++-driven Microscope Control Platform

Tianyi Zhao, Staffan Persson and Guillermo Moreno-Pescador

Modern microscopy systems integrate heterogeneous hardware devices that require dedicated software for coordination. However, high-performance C++ implementations of microscopy control software remain scarce. We present ScopeOne, a C++ and Qt-based microscopy control software built on the MicroManager hardware abstraction layer. Through process isolation and shared memory, ScopeOne achieves simultaneous multi-camera preview with real-time image processing, while maintaining full compatibility with the {\mu}Manager device ecosystem.

Read the full abstract

Medical Physics

AI-Driven Lumped-Element Modeling of Human Respiratory System for Studying Voice Mechanics

Maruf Md Ikram, Maryam Naghibolhosseini and Mohsen Zayernouri

A predictive physics-based model of human respiratory, phonatory, and articulatory subsystems is developed to simulate voice production. Representing lungs, compressible airways, and vocal folds as spring-damper-mass controlled piston-cylinder systems, our mathematical model robustly captures the intricate dynamics of airways during phonation. The nonlinear viscoelastic properties of lung tissues and compressible airways were investigated, yielding a responsive and expressive baseline respiratory model with the capability to further extend into a patient-specific model for both respiration and phonation. The resulting framework was subsequently integrated with a mechanical representation of the vocal tract, governed by the glottal area waveform (GAW) capturing the motion of vocal folds during sustained phonation. The GAW is extracted from laryngeal high-speed videoendoscopy data of a normophonic participant using deep learning. Our novel paradigm transcends beyond modeling the respiratory system, enabling AI-driven modeling of vocalization, including vocal fold dynamics, interactions with flow aerodynamics, and flow resistances, induced by the oscillatory behavior of vocal folds. Our investigation leads to the first-ever simulation of respiratory dynamics for vocalization, directly advancing the prediction of subglottal pressure distributions, impossible to measure directly and noninvasively in humans, dynamic resistances, and energy transfer mechanisms during phonation in voice mechanics.

Read the full abstract

Instrumentation and Detectors

Vision AI Agent for Continuous Material Monitoring of LEGEND-1000 LoFi Reentrant Tube

Sonata Simonaitis-Boyd, Soonhong Lee, Lauren N. O'Brien et al. (+5 more)

We report on a vision AI agent pipeline for non-contact material strain and property extraction from video data, demonstrated on video taken during hydrostatic testing of four OFHC copper cylinders conducted as part of the LEGEND-1000 hardware validation campaign. Traditional strain gauge measurements proved unreliable, motivating a fully-automated agentic alternative. The agent was built on the LangChain framework with Claude Haiku 4.5 as its central reasoning engine, integrating a specialized suite of computer vision tools: FFmpeg for video preprocessing and rotation correction via Hough Line Transform, the Segment Anything Model 2 (SAM2) for spatiotemporal segmentation with automated memory-informed dynamic chunking, and a hybrid EasyOCR and LLM-based timestamp validation pipeline. Three specialized sub-agents were developed to process the video data and obtain cylinder diameters and timestamps while autonomously handling obstacles such as corrupted frames and memory limits. From the diameter profiles synchronized to pressure data, hoop stress–strain curves were reconstructed and yield strengths were calculated using the 0.2% offset, 0.5% EUL, and Johnson-Cook methods across two independent tests. Cross-validation against a non-agentic pipeline confirmed agreement for the diameter extraction at the $\pm$5 pixel level. The material properties and testing results were further compared to Ansys mechanical simulations performed as part of the LEGEND-1000 reentrant tube design campaign. This work showcases the power of agentic pipelines to extract materials data from video alone.

Read the full abstract

All authors Sonata Simonaitis-Boyd, Soonhong Lee, Lauren N. O'Brien, Brandon T. Turner, Ralph Massarczyk, Steven R. Elliott, Aobo Li, Alexander F. Leder

Quantum Physics

Time-spectral control of accidental coincidences in daylight entanglement-based free-space QKD

Jiyoung Moon, Yonggi Jo, Zaeill Kim et al. (+2 more)

Daylight entanglement-based free-space quantum key distribution (QKD) is limited by accidental coincidences from receiver-admitted background light. We develop and experimentally validate a receiver-level framework anchored to measured singles rates and reference coincidence components, linking receiver bandwidth, accepted temporal width, and background-noise density to Bob singles, sifted-key rate, error rate, and quantum bit error rate (QBER) in telecom-wavelength BBM92 QKD. Indoor sweeps show that the sifted-key rate saturates near the source-matched bandwidth, whereas broader bandwidth or higher background mainly increases accidental contamination. Increasing the accepted temporal width leaves Bob singles nearly unchanged but directly raises QBER by enlarging the random-overlap probability. A two-dimensional design map calculated from the model shows that the temporal-window margin contracts rapidly with increasing background-to-signal ratio, while the bandwidth margin remains comparatively broad near source-matched filtering. A rooftop experiment demonstrates daylight operation over a 10 m free-space link, yielding a mean sifted-key rate of 2,811 cps and a mean QBER of 4.43%. This framework provides a quantitative basis for choosing receiver bandwidth and temporal acceptance to meet a target QBER under specified background conditions.

Read the full abstract

All authors Jiyoung Moon, Yonggi Jo, Zaeill Kim, Yong Sup Ihn, Nam Hun Park

Solar and Stellar Astrophysics

Extreme Ultraviolet Microflashes at Plume Bases: A Candidate for Powering the Corona and Solar Wind?

Navdeep K. Panesar, Sanjiv K. Tiwari, Meng Jin et al. (+4 more)

Solar plumes - outflows of bright coronal plasma - are a major component of the open-magnetic-field corona and solar wind, but their driving mechanism remains uncertain. Here we report on network microflashes, fine-scale bright bursts captured by Solar Orbiters Extreme Ultraviolet Imager in 174A images encompassing magnetic network at the base of plumes. Because they sit in evidently unipolar magnetic flux, they are evidently a new, previously unidentified, kind of network event. Approximately 20 microflashes are ongoing within a plume base, with a new microflash starting every second. The energy for an average microflash is 1024 erg, in the range of nanoflares. A 3D data-driven global MHD model yields open magnetic field with fast solar wind for the investigated plumes. From our findings, we suggest that network microflashes result from fine-scale bursts of reconnection of crossed legs of unipolar magnetic field, that the bursts are often triggered by 5-minute p-mode oscillations, and that the bursts are candidates for powering the open-field corona and solar wind. That is, unipolar microflashes such as ours are plausibly from unipolar-network-field reconnection bursts that sustain the heliosphere.

Read the full abstract

All authors Navdeep K. Panesar, Sanjiv K. Tiwari, Meng Jin, Ayla Weitz, Ronald L. Moore, V. Aparna, Alphonse Sterling

Quantum Physics

Canonical regularization of the stationary Coulomb problem and an Aufbau-like spectral ordering

Anand Aruna Kumar

The stationary hydrogen atom has Coulomb degeneracy across orbital levels, whereas the Aufbau/Madelung ordering is an empirical, many-electron rule established in atomic physics. We examine the hydrogen atom through a regularized de Broglie–Bohm representation, in which stationary amplitude current constraints generate separable Sturm–Liouville branches. In this formulation, the radial, orbital, and magnetic sectors acquire canonical Langer-like inverse square corrections. The modified boundary value problems allow analytical solutions and produce a hydrogen-like spectrum with regularized radial and angular indices. Consequently, radial Coulomb quantization acquires an orbital dependent shift, lifting the Coulomb degeneracy and producing a spectral ordering that follows the Aufbau/Madelung sequence. On this basis, we construct the ordering of the regularized de Broglie–Bohm states and show that the spectral structure retains the standard degenerate Rydberg sequence in the l=0 sector. The separated amplitudes are represented by generalized special function branches, including the associated Laguerre, Legendre, and Bessel functions with non-integral parameters arising from regularized separation. Therefore, the treatment is intended as an analytical examination of spectral ordering in a regularized one center Coulomb problem rather than as a replacement for the many electron atomic structure theory. Keywords: de Broglie–Bohm representation; Coulomb spectrum; canonical regularization; Langer correction; Sturm–Liouville equations; Aufbau principle; Madelung ordering; associated Legendre functions; associated Laguerre functions; Bessel functions.

Read the full abstract

Quantum Physics

Pulse-optimised circuit elements for scalable and noise-resilient quantum chemistry

Henrik Gothen, Christopher K. Long, Djamila Hiller et al. (+4 more)

Useful chemistry calculations on near-term quantum processors are hindered by current algorithmic runtimes. We develop a methodology to significantly reduce these runtimes. Typically, variational quantum eigensolver (VQE) algorithms are implemented as sequences of primitive gates. Our methodology instead relies on gradient-ascent pulse engineering to construct hardware-tailored pulses for the direct implementation of VQEs. As problem sizes increase, it quickly becomes intractable to optimise a pulse that implements an entire VQE ansatz circuit. However, leading VQEs are constructed in a modular fashion. A problem-tailored VQE is assembled from parameterised circuit elements that simulate hopping between two or four electronic spin orbitals. We show that these circuit elements can be implemented more efficiently using hardware-tailored pulses. We numerically demonstrate our methodology on a silicon spin-qubit quantum processor. We find that common circuit elements, known as single- and double-qubit excitations, can be implemented in less than 289 ns and 927 ns, respectively. Compared with conventional gate-based implementations, our pulse-accelerated qubit excitations provide a scalable approach for faster and therefore more noise-robust quantum chemistry simulations by reducing VQE runtimes by up to a factor of 15.3.

Read the full abstract

All authors Henrik Gothen, Christopher K. Long, Djamila Hiller, Yunming Qian, Crispin H. W. Barnes, Normann Mertig, David R. M. Arvidsson-Shukur

Solar and Stellar Astrophysics

Transformation of solar wind energy and helicity spectra in the frame of magnetohydrodynamics shell modeling

I. Dukanov, E. Yushkov, P. Frick et al. (+1 more)

Based on the data recorded during the Parker Solar Probe mission, it can be suggested that there is no balance between kinetic and magnetic energy in the vicinity of the Sun. The spectra collected at different radial distances show an energy transfer from one component to another, followed by a change in inertial range slope and large-scale break shifted towards lower wavenumbers. Using the shell (cascade) modeling approach, we attempt to explain and understand this observed spectra transformation, considering a free-decay turbulence process and modeling a simple transition to a quasi-stationary equilibrium between the magnetic and kinetic energies. Varying the parameters of turbulence mirror asymmetry (helicity), we numerically simulate changes in spectral indices, large-scale shift position, and inertial range transformations, comparing our model results with spacecraft observations of solar wind turbulence. We present and discuss the chaotic nature of the spectral magnetic helicity distributions, as well as the fact that helicity can accumulate at large scales. The applicability of a simple MHD shell model to repeat the key features of solar wind turbulence dynamics offers wide possibilities for its further use.

Read the full abstract

All authors I. Dukanov, E. Yushkov, P. Frick, D. Sokoloff

Mesoscale and Nanoscale Physics

Operator ordering as an emergent gauge field in twisted bilayer graphene: singular spectral signatures at the magic angle

C. A. S. Almeida

Scanning-tunnelling spectroscopy at the AB and BA stacking points of magic-angle twisted bilayer graphene should reveal two asymmetric Van~Hove peaks separated by $\Delta_{\mathrm{split}}\approx 171$~meV – a splitting absent from the standard Bistritzer–MacDonald spectrum. We show this signature arises naturally from the Hermitian ordering correction of the Dirac Hamiltonian with spatially varying mass, which generates an emergent Aharonov–Bohm flux of $h/(2e)$ at each zero of the effective mass $m_{\mathrm{eff}}(\mathbf{r})=w|f(\mathbf{r})|$. In the chiral limit, the interlayer coupling is locally diagonalised by a spatially dependent unitary transformation; the ordering term $H_{\mathrm{ord}}=-\tfrac{i}{2}\boldsymbol{\sigma}\cdot \nabla\ln m_{\mathrm{eff}}$ then develops a $1/r$ singularity at the AB/BA stacking points, where $m_{\mathrm{eff}}$ vanishes. The splitting scales as $\sqrt{\theta}$ – distinguishing it from correlation-driven gaps ($\propto\theta$ or $\propto 1/\theta$) – is gate-voltage independent, and is spatially localised within $r_c\approx 2.1$~nm of each AB/BA point. Within the local asymptotic theory near the zeros of $\mathrm{eff}$, the ordering-corrected zero mode acquires parabolic-cylinder character $D_{-1/2}$. The spatially resolved AB/BA spectrum reported in recent STM studies of magic-angle TBG has not been analysed for two-peak structure and constitutes an immediate experimental test; the predicted cell-averaged broadening of $\approx 14$~meV is consistent with the $16$~meV discrepancy between existing STM data and the BM tight-binding prediction.

Read the full abstract

Earth and Planetary Astrophysics

Clustering SPH Debris into N-body Fragments: A Collisional Code for Planet Formation

Samuele Crespi, Mohamad Ali-Dib and Ian Dobbs-Dixon

Giant impacts among planetary embryos generate long-lived debris that feeds back on late-stage terrestrial planet growth, yet most N-body models either assume perfect merging or treat fragments in ad hoc ways. We present SHARD, a collision-resolution framework that couples a hybrid integrator (REBOUND/mercurius) to a six-dimensional catalog of smoothed-particle hydrodynamics (SPH) outcomes spanning impact speed, geometry, total mass (up to 2 M_earth), mass ratio, and target/projectile water fractions. For each detected impact we multi-linearly interpolate to return the two largest remnants with self-consistent kinematics and volatile budgets, and we reconstruct the unresolved fragment population by aggregating nearby SPH debris snapshots and compressing them with mass-weighted k-means in velocity space into a tractable number of fragments above a tunable minimum mass. Exact conservation of total mass and water mass is enforced across survivors and debris, with immediate, energy-based reaccretion checks performed within the timestep. Debris interpolation is constrained to the tabulated SPH grid (no extrapolation), and special handling of hit-and-run and catastrophic regimes is included. We benchmark our code against SyMBA in a Mercury-formation experiment and find broad qualitative agreement, though our final embryos distribution is dynamically hotter and more top-heavy in mass. The benchmark outcome suggests that debris clustering is dynamically consequential: fragment resolution controls reaccretion, damping, and volatile retention. This SPH-anchored debris treatment provides a drop-in, compositionally aware alternative to perfect merging, enabling late-stage accretion studies that retains fragment feedback without saturating the integrator.

Read the full abstract

Earth and Planetary Astrophysics

High-Eccentricity Tidal Migration Driven by Secular Chaos in Wide-Binary Systems

Yurou Liu, Hareesh Gautham Bhaskar, Xian-Yu Wang et al. (+1 more)

High-eccentricity tidal migration driven by a distant stellar companion offers a natural pathway for producing some hot Jupiters; yet, most theoretical work has relied on an idealized three-body configuration whose simplicity makes the problem especially tractable. In reality, many cold-Jupiter systems may host additional planets or substellar objects, whose interactions can dramatically alter the pathways to secularly excite extreme eccentricities. We investigate how secular chaos can drive high-eccentricity tidal migration in hierarchical “3+1” systems–stellar binaries hosting a planet and an additional intermediate companion orbiting the primary star. We show that the onset of secular chaos is regulated by the ratio of the von-Zeipel-Lidov-Kozai (ZLK) timescales of the inner and outer orbits $\mathcal{R}$. When $\mathcal{R}\sim 0.5-2$, most systems can undergo migration even when their mutual inclinations remain modest–below the $39.2^\circ$ critical angle for ZLK oscillations–with diffusion timescales spanning a broad range, up to thousands of inner orbit ZLK timescales. For larger mutual inclinations, secular migration operates over a much broader region of parameter space with $\mathcal{R} \sim 0.05-100$, but most evolutionary pathways become non-secular and potentially unstable–behavior recently identified as an alternative pathway to tidal migration. Our model predicts hot Jupiters in nearly polar orbits relative to both the host star's stellar equator (stellar obliquities $\sim 60^\circ-120^\circ$) and the orbits of the outer two companions. Future Gaia releases and long-term radial velocity campaigns are likely to uncover additional “3+1” systems, providing valuable opportunities to test this migration pathway.

Read the full abstract

All authors Yurou Liu, Hareesh Gautham Bhaskar, Xian-Yu Wang, Cristobal Petrovich

Mesoscale and Nanoscale Physics

Vortex-Beam-Driven Dirac Materials: Impurity and Polarization Effects on Light-Induced Vortex and Edge States

Trevor W. Walsh, Eric E. Caldwell, Nancy P. Sandler et al. (+1 more)

We study impurity scattering and polarization detuning in finite-size vortex-light-beam-driven massive Dirac systems. In finite geometries, circularly polarized vortex light opens a dynamical gap where topological edge states coexist with photoinduced multiply quantized vortex states. We analyze how finite-size effects, vorticity, and effective particle-hole symmetry manifest in the quasienergy spectrum, real-space states, and local density of states. We show that angular-momentum mixing due to localized impurities and impurity clusters reshape vortex states, while when produced by circular polarization, it leads to a gradual filling of the dynamical gap with bulk-derived states. Our results indicate that both vortex and edge signatures remain observable in the presence of impurities and realistic polarization deviations, providing guidance for experimental realizations.

Read the full abstract

All authors Trevor W. Walsh, Eric E. Caldwell, Nancy P. Sandler, Mahmoud M. Asmar

Quantum Physics

Effects of Josephson Junction Non-idealities on Adiabatic Quantum Flux Parametron Circuits

Daryoush Shiri, Likai Yang, Mohamed A. Hassan et al. (+2 more)

Adiabatic quantum flux parametron (AQFP) gate is a promising approach to scale up the cryogenic microwave electronics for superconducting qubit multiplexed control. However, the performance of these circuits depends on the quality of the Josephson junctions which are ideally superconductor-insulator-superconductor (SIS) type following the ideal sinusoidal relation between current and quantum phase. We demonstrate how the non-sinusoidal current-phase relation in Superconductor-Normal metal-Superconductor (SNS) and weak link (WL) junctions affects the speed, delay, and margin of the AQFP gates. The JJ models are defined in the Keysight ADS simulator using symbolically defined device (SDD) method.

Read the full abstract

All authors Daryoush Shiri, Likai Yang, Mohamed A. Hassan, Philip Krantz, Eric T. Holland

Materials Science

Characterization of ultrathin nickel films deposited by thermal laser evaporation

David S. Catherall, Yifei Yan, Finley B. Donachie et al. (+2 more)

Thermal laser evaporation is a physical vapor deposition technique of increasing interest because of its ability to evaporate essentially any solid element, even the most refractory such as W. However, many films deposited by this method, especially non-epitaxial films, remain to be characterized; further, key system components such as the laser delivery system have not been described in detail. Here, we present the evaporation and characterization of ultrathin Ni films deposited with a home-built thermal laser evaporation system. The system employs a continuous-wave 1 kW fiber laser (1070 nm) focused to sub-millimeter diameter onto a Ni target rod mounted inside an ultrahigh-vacuum chamber. The laser heats the target to a temperature high enough to produce vapor for film deposition; for Ni, this temperature is around the melting point of 1725 K. We report the characterization of the surface roughness, composition, and room-temperature electrical properties of the films along with the design of the major components of our system. This work advances the growing consensus regarding the potential of thermal laser evaporation for thin film deposition and epitaxy and provides the necessary design information to facilitate broader adoption of the technique.

Read the full abstract

All authors David S. Catherall, Yifei Yan, Finley B. Donachie, Azmain A. Hossain, Austin J. Minnich

Fluid Dynamics

Turbulence Without the Viscous Tilting of Vorticity

Amr Emam, Mostafa Kamal and Perry L. Johnson

Vortex stretching is a fundamental aspect of Navier-Stokes turbulence and is commonly understood in analogy to the stretching of infinitesimal material lines. However, the parallel alignment of material lines and vorticity cannot be maintained due to the role of viscosity in the directional realignment of vorticity. In Navier-Stokes turbulence, the result is relatively modest quantitative differences in the alignment and stretching rates of vorticity compared to material lines. In this study, the qualitative effect of viscous tilting of vorticity is demonstrated directly by surgically removing it from direct numerical simulations of isotropic turbulence. The result is a drastic change to the fundamental structure of the flow, including a substantial deviation from the -5/3 inertial range scaling of the energy spectrum brought about by the infiltration and prevalence of viscous effects beyond the smallest scales. These observations demonstrate that the viscous tilting of vorticity is an essential characteristic of fluid turbulence. By extension, the same may be said of the difference in orientation and stretching rates for vorticity and infinitesimal material lines.

Read the full abstract

Materials Science

Robust Spin Splitting and Strain-Controlled Optical Response in Monolayer CrC2N4 for Valleytronic and Optoelectronic Applications

Md. Samrat, Vivek Chowdhury, Sake Wang et al. (+1 more)

Monolayer CrC2N4 recently emerged as a promising two-dimensional semiconductor, yet its spin-orbit-coupled (SOC) physics and strain-tunable optical response remained largely unexplored. Here, we investigated the electronic, valley, charge-transfer, and optical properties of pristine and biaxially strained monolayer CrC2N4 using first-principles calculations. The monolayer exhibited a direct band gap at the K/K' valleys. SOC produced valley contrasting out-of-plane spin polarization, yielding a moderate valence band spin splitting of 51.9 meV and a small conduction band spin splitting of 1.7 meV. Orbital-resolved analysis showed that the edge states were mainly governed by Cr-d and N-p hybridization, while Bader analysis indicated polar-covalent bonding through charge transfer toward N atoms. Biaxial strain in the range of -4% to +4% tuned the band gap from 1.987 to 1.421 eV and drove an indirect-to-direct gap transition near -1% strain. Tensile strain enhanced the Berry curvature and red-shifted the optical response toward the visible-near-infrared region. These results suggested monolayer CrC2N4 as a promising platform for strain-engineered valleytronic and optoelectronic device applications.

Read the full abstract

All authors Md. Samrat, Vivek Chowdhury, Sake Wang, Ahmed Zubair

Strongly Correlated Electrons

Emergent Antiphase Stacking in a Transient Charge Density Wave

Jade Stanton, Gal Orenstein, Ryan A. Duncan et al. (+14 more)

Photoexcitation can induce novel states in materials that are inaccessible in equilibrium, a recent example being the light-induced charge density wave (CDW) observed in $\text{LaTe}_3$. Here, we investigate this transient CDW using infrared-pump x-ray-probe scattering at a free-electron laser, with high momentum and time resolution. We find that the transient CDW Bragg peak is broad in reciprocal space, indicating a highly disordered state. The ordering wavevector of the transient state is different from the equilibrium orders that develop in this class of materials - the transient peak appears near (2/7, 0, 0) reciprocal lattice units, whereas the equilibrium $a$ order and $c$ order occur at $\approx (5/7, 0, 0)$ and $(0, 0, 2/7)$, respectively. The transient CDW is therefore distinct from the equilibrium $a$ order, differing in the relative phase of the CDW displacement between the two equivalent nearly-square Te-Te nets in the conventional unit cell. Our work highlights how photoexcitation can access states with no equilibrium analog, and how x-ray scattering can provide microscopic insight into such elusive phases.

Read the full abstract

All authors Jade Stanton, Gal Orenstein, Ryan A. Duncan, Gilberto A. de la Peña Muñoz, Yijing Huang, Viktor Krapivin, Quynh Le Nguyen, Samuel Teitelbaum, Anisha G. Singh, Roman Mankowsky, Henrik Lemke, Mathias Sander, Yunpei Deng, Christopher Arrell, Ian R. Fisher, David A. Reis, Mariano Trigo

High Energy Physics (Experiment)

Final Report on the Measurement of the Positive Muon Anomalous Magnetic Moment at Fermilab to 127 ppb

Muon g-2 Collaboration: D. P. Aguillard, T. Albahri, D. Allspach et al. (+191 more)

This report details the final measurement of the muon magnetic anomaly, $a_{\mu}=(g_{\mu}-2)/2$, by the Muon $g-2$ experiment at Fermi National Accelerator Laboratory (FNAL), using positive muons collected from 2021 to 2023. The value of $a_{\mu}$ is determined from the ratio of the anomalous spin precession frequency to the shielded proton precession frequency in the muon storage ring magnetic field, combined with external constants known at the 22 ppb level. The new dataset, containing over $2.5$ times the statistics of our previous results, yields $a_{\mu}=116\,592\,0710(162)\times 10^{-12}$ (139 ppb), or $a_{\mu}=116\,592\,0705(148)\times 10^{-12}$ (127 ppb) when combined with our previous results. The new experimental world average, dominated by the measurements at FNAL, is $a_{\mu}^{\text{Exp}}=116\,592\,0715(145)\times 10^{-12}$ (124 ppb).

Read the full abstract

All authors Muon g-2 Collaboration: D. P. Aguillard, T. Albahri, D. Allspach, J. Annala, K. Badgley, S. Baeßler, L. Bailey, E. Barlas-Yucel, T. Barrett, E. Barzi, F. Bedeschi, M. Berz, M. Bhattacharya, H. P. Binney, P. Bloom, J. Bono, E. Bottalico, T. Bowcock, S. Braun, M. Bressler, G. Cantatore, R. M. Carey, B. C. K. Casey, D. Cauz, R. Chakraborty, A. Chapelain, S. Chappa, S. Charity, C. Chen, M. Cheng, R. Chislett, Z. Chu, T. E. Chupp, C. Claessens, F. Confortini, M. E. Convery, S. Corrodi, L. Cotrozzi, J. D. Crnkovic, S. Dabagov, P. T. Debevec, S. Di Falco, G. Di Sciascio, S. Donati, B. Drendel, A. Driutti, M. Eads, A. Edmonds, J. Esquivel, M. Farooq, R. Fatemi, K. Ferraby, C. Ferrari, M. Fertl, A. T. Fienberg, A. Fioretti, D. Flay, S. B. Foster, H. Friedsam, N. S. Froemming, C. Gabbanini, I. Gaines, S. Ganguly, J. George, L. K. Gibbons, A. Gioiosa, K. L. Giovanetti, P. Girotti, W. Gohn, L. Goodenough, T. Gorringe, J. Grange, S. Grant, F. Gray, S. Haciomeroglu, T. Halewood-Leagas, D. Hampai, F. Han, J. Hempstead, D. W. Hertzog, G. Hesketh, E. Hess, A. Hibbert, Z. Hodge, S. Y. Hoh, K. W. Hong, R. Hong, T. Hu, Y. Hu, M. Iacovacci, M. Incagli, S. Israel, P. Kammel, M. Kargiantoulakis, M. Karuza, J. Kaspar, D. Kawall, L. Kelton, A. Keshavarzi, D. S. Kessler, K. S. Khaw, Z. Khechadoorian, B. Kiburg, M. Kiburg, O. Kim, N. Kinnaird, E. Kraegeloh, J. LaBounty, K. R. Labe, M. Lancaster, S. Lee, B. Li, D. Li, L. Li, I. Logashenko, A. Lorente Campos, Z. Lu, A. Lucà, G. Lukicov, A. Lusiani, A. L. Lyon, B. MacCoy, R. Madrak, K. Makino, S. Mastroianni, R. McCarthy, J. P. Miller, S. Miozzi, B. Mitra, J. P. Morgan, W. M. Morse, J. Mott, A. Nath, J. K. Ng, H. Nguyen, Y. Oksuzian, Z. Omarov, W. Osar, R. Osofsky, S. Park, G. Pauletta, J. Peck, G. M. Piacentino, R. N. Pilato, K. T. Pitts, B. Plaster, N. Pohlman, C. C. Polly, D. Počanić, J. Price, B. Quinn, M. U. H. Qureshi, G. Rakness, S. Ramachandran, E. Ramberg, R. Reimann, B. L. Roberts, D. L. Rubin, M. Sakurai, L. Santi, C. Schlesier, A. Schreckenberger, Y. K. Semertzidis, A. K. Soha, M. Sorbara, J. Stapleton, D. Still, C. Stoughton, D. Stratakis, D. Stöckinger, H. E. Swanson, G. Sweetmore, D. A. Sweigart, M. J. Syphers, Y. Takeuchi, D. A. Tarazona, T. Teubner, A. E. Tewsley-Booth, V. Tishchenko, N. H. Tran, W. Turner, E. Valetov, D. Vasilkova, G. Venanzoni, T. Walton, A. Weisskopf, L. Welty-Rieger, P. Winter, Y. Wu, B. Yu, M. Yucel, E. Zaid, Y. Zeng, C. Zhang