Optics
W.J. Firth and G.K. Harkness
A driven optical cavity containing a nonlinear medium can support stable,
soliton-like objects, bright non-diffracting spots of light on a uniform background. Importantly, the nonlinear medium need not support ordinary (propagating) spatial
solitons, and cavity
solitons have been both predicted and observed in a saturable absorber, and predicted to even exist in self-defocusing media. The history, present status, and physical interpretation of such cavity
solitons is reviewed. Recent research predicts cavity
solitons in
semiconductor cavity models with properties interesting for applications to optical information processing. Cavity
solitons are natural `bits' for spatial information, possessing both robustness and plasticity, and some potential applications of their unique properties are mentioned.
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General Relativity and Quantum Cosmology
Perturbations of black holes with primary hair: time evolutions, quasinormal modes and greybody factors
Georgios Antoniou
In this work we study gravitational perturbations of black holes carrying primary scalar hair in shift-symmetric beyond-Horndeski
gravity. By focusing on the axial sector, we study the
geometric structure of the perturbation equations and perform time-domain evolutions both in the physical and in the effective metric descriptions, in order to quantify differences in the response characteristics of solutions with different hair. In the frequency domain, we then explore the QNM spectrum in the physical-metric formulation, thus verifying and extending existing approximate calculations derived in the effective-metric approach. We also compute the corresponding greybody factors and absorption cross-sections. Finally, we use localized deformations of the effective potential as a diagnostic of the relative stability of quasinormal frequencies and greybody-factor observables.
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Mesoscale and Nanoscale Physics
Hall effect in viscous flows of two-dimensional electrons in samples with edges of arbitrary roughness
A.V. Gert and P.S. Alekseev
In ultra-clean conductors, fast inter-particle collisions can lead to the formation of a viscous electron fluid and realization of the hydrodynamic transport regime. Here we develop a theory of hydrodynamic magnetotransport of two-dimensional (2D) electrons in samples with low densities of defects and edges of arbitrary roughness. Within our model the roughness is described by a single parameter with the dimension of speed in the boundary conditions on sample edges. The electron-fluid flow profiles in long samples, as well as the corresponding longitudinal and
Hall resistances, are calculated. The contribution to the
Hall resistance associated with the relaxation processes exhibits a saturation in the limit of high
magnetic field and a minimum as a function of the
magnetic field for sufficiently rough edges. The minimum disappears as the edge roughness decreases or the sample width and bulk scattering by defects increase. These properties of the
Hall resistance can serve as the signs to identify the hydrodynamic regime of electron transport in experiments and can be used to determine its parameters, in particular, the degree of edge roughness.
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Materials Science
Electronic Structure and Band-Edge Character of Ga-Substituted $\alpha$-Al$_2$O$_3$: A First-Principles Study
Z. S. Machavariani, R. Ya. Kezerashvili and T. Tchelidze
We present a first-principles density functional theory study of substitutional Ga incorporation in an $\alpha$-Al$_2$O$_3$-derived host, isolating chemical
embedding effects without explicit
geometric quantum confinement. Using a 30-atom $\alpha$-Al$_2$O$_3$ supercell with two substituted Ga atoms, we examine three nonequivalent Ga-pair configurations and combine configuration-dependent energetics, local structural analysis, Ga-centered distortion metrics, and electronic-structure calculations.% to establish the relationship between local coordination distortion and band-edge modification. The energetically preferred configuration is governed not solely by Ga–O bond expansion but by the ability of the host
lattice to accommodate bond-length and angular distortions around substituted Ga centers. Ga incorporation narrows the band gap relative to pristine $\alpha$-Al$_2$O$_3$ without generating mid-gap states, primarily modifying the conduction-band
manifold while preserving the oxygen-dominated valence edge. Band-edge charge densities and charge-density-difference maps show that the electronic response remains localized around the Ga-centered coordination environment. These results establish a chemically resolved baseline for understanding Ga incorporation in ultrawide-band-gap
oxides and for future studies of confinement and interface effects in Ga-containing
oxide nanostructures.
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Quantum Physics
Quantum-enhanced ghost imaging recognition via joint optimization of speckle patterns and quantum network parameters
Yirui Mao, Xiangyu Ge, Yuhang Tu et al. (+3 more)
Ghost imaging enables nonlocal image reconstruction and exhibits strong robustness against interference, but achieving high-fidelity recognition at ultra-low sampling rates remains challenging.
Quantum machine learning offers a novel approach for efficient feature extraction on noisy medium-scale
quantum devices; however, existing methods generally suffer from low recognition accuracy and weak noise resistance. This paper proposes a ghost imaging recognition method based on the simultaneous optimization of speckle patterns and
quantum network parameters. By leveraging the mathematical equivalence between classical convolution and speckle-object dot product operations in ghost imaging, a speckle consistency regularization mechanism is introduced to achieve end-to-end joint optimization of optical coding and
quantum feature extractors. A parallel 8-
qubit quantum circuit employing block coding and a
star-shaped
entanglement structure is designed to extract higher-order features from bucket signals. Simulation results on the MNIST and Fashion-MNIST
datasets show that at an ultra-low sampling rate of 1.5625%, the proposed framework achieves recognition accuracies of 90.1% and 81.7%, respectively, representing a 2.6% improvement over classical convolutional neural networks and a maximum improvement of 14.2% over traditional hybrid
quantum machine learning models. This method also exhibits strong robustness to
quantum noise and has been validated on a real optical ghost imaging system, achieving an average recognition accuracy of 84.8%. These results confirm that the joint optimization of speckle patterns and
quantum network parameters provides a reliable and practical solution for low-sampling ghost imaging recognition.
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All authors Yirui Mao, Xiangyu Ge, Yuhang Tu, Anqi Zhang, Le Wang, Shengmei Zhao
Materials Science
Scalable conformal electronics based on roll-to-roll exfoliated van der Waals semiconductors
Yigit Sozen, Esteban Zamora-Amo, Juan J. Riquelme et al. (+1 more)
Integrating electronic devices onto surfaces with complex topography such as skin, textiles, and biological tissues requires fabrication strategies that combine mechanical conformability with high electronic performance and scalable manufacturing. While two-dimensional (2D)
semiconductors are promising materials for such applications, their integration into conformal electronic systems remains challenging because scalable
liquid-phase processing typically yields films with limited electronic performance, whereas high-quality CVD materials require complex synthesis and transfer processes. Here we establish a scalable route toward conformal electronics based on semiconducting van der Waals materials by combining high-throughput roll-to-roll mechanical exfoliation with commercially available temporary tattoo and waterslide decal transfer substrates. This approach enables the fabrication of ultrathin MoS2-based electronic devices that can be transferred onto rough and curved surfaces such as skin, synthetic leather, and plant leaves. The resulting devices operate reliably after transfer and exhibit strong electronic and optoelectronic performance, including photodetectors with responsivities up to approximately 3.5 A W$^{-1}$, thermistors with temperature coefficients of resistance from -2 to -3.5% per degree Celsius, and ionic-gel-gated field-effect transistors with mobilities reaching approximately 18 cm$^2$ V$^{-1}$ s$^{-1}$.
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All authors Yigit Sozen, Esteban Zamora-Amo, Juan J. Riquelme, Andres Castellanos-Gomez
Fluid Dynamics
Turbulent diffusivity and effective rise velocity of buoyant particles in a free-surface boundary layer
Julio E. Chávez-Dorado, Lucia J. Baker, James J. Riley et al. (+1 more)
Predicting the transport of buoyant particles in a free-surface boundary layer is important to the study of many environmental systems, including microplastics in the upper ocean. Current transport models, adapted from sediment transport theory, typically rely on assumptions of a quiescent rise velocity and gradient
diffusion with an uncertain turbulent Schmidt number $Sc_t$. Here, we test this type of model against experiments by studying the vertical mixing of near-neutrally buoyant, finite-size spheres, rods, and disks in a wind-driven, wavy free-surface flow. We measure particle diffusivity directly from Lagrangian trajectories and compare against Eulerian concentration-based estimates. Overall, we find that particle buoyancy is the main control on the diffusivity, and that the diffusivity decreases as particle rise velocity grows relative to the turbulent fluctuations. These observations we find to be consistent with the crossing-trajectories theory, even in the presence of waves. In addition, we find that inferring the diffusivity from concentration profiles with an assumed quiescent rise velocity overestimates the diffusivity by up to a factor of $5$, consistent with effective rise velocities up to $80\%$ lower than the corresponding quiescent values. We also directly measure $Sc_t \approx 1$ for the neutrally-buoyant particles and $Sc_t > 1$ for the buoyant particles. Together, these experimental results demonstrate how standard model closures may be biased in both their diffusivities and rise velocities when applied to buoyant particles at the ocean surface.
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All authors Julio E. Chávez-Dorado, Lucia J. Baker, James J. Riley, Michelle H. DiBenedetto
Quantum Gases
Vortex lattices in coupled one-dimensional Bose-Einstein condensates with a synthetic magnetic field
Holly A. J. Middleton-Spencer, Rose Davies, David G. Reid et al. (+3 more)
We investigate the mean-field ground states of coupled one-dimensional Bose-Einstein condensates subject to a synthetic
magnetic field. The resulting interacting coupled-wire model has one continuous and one discrete spatial direction, providing a controlled way to interpolate between the physics of few-leg ladders and extended
vortex lattices. For two wires, we study the
vortex-like, biased-density, and Meissner-like states, exploring how the finite longitudinal size of the system modifies the transitions between them. Increasing the number of wires, the ground state evolves towards an extended
vortex lattice. We find numerically that periodic boundary conditions in the discrete direction can favour staggered arrays of like-signed
vortices resembling an Abrikosov
lattice, while open boundaries in small finite-size systems confine the
vortices into rows near the centre of the synthetic direction. Our results explore how finite size effects and boundary conditions govern the emergence and spatial organisation of
vortices in continuous-discrete
quantum fluids, with relevance to future experiments in tunnel-coupled atomic wires or with synthetic dimensions.
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All authors Holly A. J. Middleton-Spencer, Rose Davies, David G. Reid, Anna Dalmasso, Theodore Kazanas, Hannah M. Price
Materials Science · Cross-listed from cs.LG
Packora: Systematic Design for Generative Molecular Crystal Structure Prediction
Nayoung Kim, Kiyoung Seong and Sungsoo Ahn
Molecular
crystal structure prediction (CSP) is important in pharmaceuticals, agrochemicals, and organic electronics, where subtle differences in molecular conformation and packing can strongly affect material properties. We present Packora, a flow-based generative model for molecular CSP that jointly predicts atomic coordinates and the
lattice from molecular graphs. Packora supports multi-component and organometallic
crystals and can condition on any subset of molecular conformers, stereochemical labels, and space-group information within a single model. Inspired by the CCDC CSP blind test, we evaluate generation and ranking separately, using generation to isolate generator quality and ranking to measure end-to-end performance under a common relaxation and ranking pipeline. We also systematically study architecture, training, conditioning, inference, and scaling, identifying an effective design based on cacheable pairwise
reasoning, training objective and numerical solver choices, conditioning dropout, and balanced scaling of pairwise and single representations. Packora outperforms the baselines on both structure generation and ranking
benchmarks, achieving the best matched-budget coverage across all six generation
benchmarks, as well as higher experimental-form recovery, lower experimental-form ranks, and faster convergence in ranking.
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Astrophysics of Galaxies
The solitary star cluster of the Andromeda XXV dwarf spheroidal
Chiara Crociati, Annette M. N. Ferguson, Gracie McGill et al. (+6 more)
We present Hubble Space
Telescope Advanced Camera for Surveys observations of Gep I, a globular cluster (GC) candidate in the low-mass ($M_{\star}\sim 6.5 \times 10^5\,M_{\odot}$) M31
dwarf spheroidal (dSph) satellite Andromeda XXV (And XXV). We confirm the nature of this object and provide the first detailed characterisation of its resolved
stellar populations using a colour-magnitude diagram (CMD) that reaches 2 magnitudes below the horizontal branch. We compare Gep I's
metallicity and distance with those of the surrounding And XXV
stellar population, and find them to be strikingly similar, consistent with a physical association between the GC and the dSph. Gep I is very extended ($R_h=24^{+5}_{-4}$ pc) and faint ($M_V = -4.5 \pm 0.2$ mag), similar to the
star clusters residing in other low-mass
dwarf galaxies. It is characterised by a very low
metallicity ($\rm [Fe/H] = -2.4^{+0.3}_{-0.4}\,$dex) and a red horizontal branch morphology, a combination also seen in suspected accreted GCs in the M31
halo and in the Local Group
dwarf irregular
galaxy NGC 6822. While Gep I is most likely a genuine
star cluster, the current data do not exclude the tantalising possibility that it consists of And XXV
stars temporarily captured by a dark subhalo orbiting within the dSph's potential well.
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All authors Chiara Crociati, Annette M. N. Ferguson, Gracie McGill, Raffaele Pascale, Anna Genina, Pete B. Kuzma, Dougal Mackey, Alan W. McConnachie, Rokas Žemaitis
Earth and Planetary Astrophysics
Three-dimensional SPH simulations of the Caloris basin-forming impact: basin scaling, the gravity anomaly, and antipodal effects
Thomas Meier, Christian Reinhardt, Martin Jutzi et al. (+1 more)
The Caloris basin is the largest well-preserved impact structure on Mercury, yet its formation conditions, the origin of its positive
gravity anomaly, and its relation to the antipodal terrain remain poorly constrained. We present global, three-dimensional smoothed particle hydrodynamics simulations of the Caloris basin-forming impact with the pkdgrav3 code, including material strength. We survey 225 combinations of impactor radius, velocity, angle, and target thermal profile, complemented by simulations of up to two billion particles, which resolve the adopted 40 km crust by ten particle layers. At all resolutions, basin sizes are measured directly from the crust particles. The measured basin diameters follow a single power law in impactor radius, velocity, and angle, systematically steeper than idealized point-source crater scaling. The observed Caloris diameter is reproduced by a broad family of impactors favoring oblique incidence; sensitivity to resolution and crust thickness shifts this family toward smaller or slower impactors. All impactor material remaining in the basin region is vaporized, so our crust-like impactors leave no buried remnant. Instead, the impact thins the mantle and raises a local dome on Mercury's core. The dome's isolated
gravity signal is positive and centered on the basin, supporting the mantle-uplift origin proposed for the observed mascon. At the antipode, single seismic pulses cannot loft surface material when strength is included, yet accumulated strain exceeds the elastic limit. A kilometer-scale equivalent thickness of impact-derived material then converges on this weakened surface. Ejecta convergence contributed at least as much as seismic shaking to forming the terrain.
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All authors Thomas Meier, Christian Reinhardt, Martin Jutzi, Joachim Stadel
Materials Science
Decoupled domain-texture switching from magnetic easy axis in kagome ferromagnet EuTi3Bi4
Yunhao Wang, Shiyu Zhu, Guohao Xi et al. (+13 more)
Magnetic anisotropy defines the easy axis of a
magnetic material and governs the spatial arrangement of its domains. To date, anisotropy engineering has focused on reorienting the easy axis or tuning the anisotropy energy, both of which demand substantial energy input. Here, we demonstrate that
magnetic domain textures can be switched without reorienting the easy axis, as observed in a kagome ferromagnet EuTi3Bi4
crystal. Using low-temperature
magnetic force microscopy, we observe that the preferred orientation of
magnetic domains switches from the a-axis to the b-axis upon temperature variation, and that this switching can also be triggered by an out-of-plane
magnetic-field reset. Magnetization measurements and density functional theory calculations confirm a robust c-axis easy magnetization, ruling out a conventional
spin-reorientation transition. Instead, the texture switching is governed by the temperature dependence of the in-plane variation of the
Magnetic anisotropy energy landscape, which arises from two competing interactions with different decay rates: single-ion anisotropy favors a-oriented
spin components, while nearest-neighbor anisotropic exchange favors b-oriented ones. Furthermore, the critical switching temperature is substantially elevated in a mechanically exfoliated EuTi3Bi4 flake. Our findings establish that macroscopic
magnetic textures can be effectively manipulated by tuning the competition between in-plane anisotropic interactions, without the energy cost of reorienting the easy axis.
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All authors Yunhao Wang, Shiyu Zhu, Guohao Xi, Runnong Zhou, Ruwen Wang, Jianfeng Guo, Jiali Liu, Zichao Chen, Kailin Xu, Cong Wang, Chengmin Shen, Jiang Xiao, Haitao Yang, Xiaoli Dong, Wei Ji, Hong-Jun Gao
Disordered Systems and Neural Networks
Low-temperature magnetism and spin dynamics in the disordered triangular-lattice Yb$^{3+}$ compound LiCaYb$_5$(BO$_3$)$_6$
Monika Jawale, Saikat Nandi, Prashanta K. Mukharjee et al. (+2 more)
The interplay between
geometric frustration,
spin–orbit coupling, and structural disorder can give rise to unconventional
magnetic ground states in rare-earth triangular-
lattice magnets. We report low-temperature
magnetic and $^7$Li NMR investigations of the disordered triangular-
lattice compound LiCaYb$_5$(BO$_3$)$_6$ (LCYBO). Rietveld refinement confirms a hexagonal $P6_522$ structure with partial Ca/Yb antisite disorder and fractional Li occupancy.
Magnetic susceptibility and magnetization measurements indicate a well-isolated effective $J_{\mathrm{eff}}=1/2$ Kramers doublet with weak
antiferromagnetic interactions ($\theta_{\mathrm{CW}} \approx -0.54$~K). The specific heat reveals a weak anomaly near 0.43 K, suggesting the development of short-range correlated magnetism rather than conventional long-range order. $^7$Li NMR spectra broaden strongly upon cooling, consistent with increasingly inhomogeneous internal
magnetic fields. The
spin-
lattice relaxation exhibits two relaxation components consistent with disorder-induced distributions of local
magnetic environments arising from antisite disorder and competing exchange pathways. Our results establish LCYBO as a structurally disordered frustrated triangular-
lattice magnet with correlated low-energy
spin dynamics.
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All authors Monika Jawale, Saikat Nandi, Prashanta K. Mukharjee, Philipp Gegenwart, A.V. Mahajan
Quantum Physics
Isotropic Nanoscale Quantum Sensor at Room-Temperature
Daniel T. Möller, Baha Sakar, Ekrem T. Güldeste et al. (+9 more)
Color-center based
quantum sensors provide nanoscale resolution under ambient conditions, yet their applicability remains limited. Because the quantization axes are locked to the host
lattice, conventional color centers suffer severe signal loss in off-axis
magnetic fields. To address this, we report an isotropic magnetometer enabled by the neutrally charged nitrogen-vacancy center (NV0) in diamond. Here,
spin-to-charge dynamics yield an NV0-dark
spin pair whose quantization axis dynamically aligns with the external field. Read out through NV charge-state-selective fluorescence, this system exhibits microsecond room-temperature coherence and nanotesla sensitivity for arbitrary field directions. We demonstrate
alignment-free mapping of steep field gradients and single paramagnetic micro-targets, alongside isotropic readout from randomly oriented nanodiamonds. Resolving longstanding orientation constraints, this platform unlocks unrestricted nanoscale magnetometry across life sciences and
quantum materials.
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All authors Daniel T. Möller, Baha Sakar, Ekrem T. Güldeste, Dhruv Wadhwani, Olt Gashi, Daniel A. García Vaca, Mokessh K. Ciwan, Simone P. Crozier, Christian Laube, Sirswa K. Shree Ram, Matteo Slaviero, Nabeel Aslam
Materials Science
Four-phonon scattering and coherent heat transport in ultrawide-bandgap SrSnO3
Xuejie Li, Xiaoying Wang, Shengying Yue et al. (+4 more)
SrSnO3 is a promising ultrawide-bandgap perovskite
oxide whose thermal transport is governed by structural distortions and anharmonic
lattice dynamics. Here, we investigate the
lattice thermal conductivity (kL) of orthorhombic and cubic SrSnO3 within a unified first-principles framework combining self-consistent
phonon renormalization, three- and four-
phonon scattering, and coherent heat transport. Bonding analysis reveals a rigid Sn-O octahedral framework embedded in a weakly bonded Sr sublattice, giving rise to low-frequency vibrational modes susceptible to strong anharmonic effects. Four-
phonon scattering is identified as a key mechanism limiting particle-like heat conduction, reducing the Peierls thermal conductivity by 19.4% at 300 K in the orthorhombic phase and by 52.1% at 1300 K in the cubic phase, while the coherent contribution provides a finite channel that partially compensates this reduction. We further show that the apparent agreement between three-
phonon calculations and experimental thermal conductivity at room temperature is not indicative of a complete physical description. Instead, it arises from a near cancellation between four-
phonon suppression of the particle-like channel and the neglected coherent contribution. This cancellation breaks down when the full temperature dependence is considered, where only the combined treatment improves agreement with the experimentally observed scaling behavior. A physically consistent description of kL therefore requires
phonon renormalization, four-
phonon scattering, and coherent transport to be treated on equal footing rather than inferred from three-
phonon agreement at a single temperature. These results provide microscopic insight into thermal transport in ultrawide-bandgap stannate perovskites and establish a
benchmark for anharmonic transport in strongly distorted
oxides.
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All authors Xuejie Li, Xiaoying Wang, Shengying Yue, Turab Lookman, Xiangdong Ding, Jun Sun, Zhibin Gao
Quantum Physics
Cavity-assisted homodyne detection with a single photodiode
Jonas Junker
High-frequency squeezed states are important for
quantum metrology and information processing, but quadrature measurements at gigahertz frequencies remain challenging. Balanced homodyne detection (BHD), the standard approach, requires closely matched complex transfer functions in both photodetection channels to suppress local-oscillator (LO) noise and maintain a well-defined readout quadrature. This matching becomes increasingly difficult at high bandwidths. Strongly asymmetric single-photodiode homodyne detection avoids this requirement, but achieving high signal efficiency and shot-noise clearance typically requires hundreds of milliwatts of LO power and does not suppress technical LO sidebands. I propose cavity-assisted homodyne detection, in which the
quantum field and LO enter separate ports of an impedance-matched traveling-wave cavity. The resonant LO carrier is transmitted to the photodetector, where it beats with off-resonant signal sidebands reflected from the cavity. At the same time, technical LO sidebands outside the cavity linewidth are suppressed. I derive the
quantum input-output relations and linearized photocurrent including intracavity loss, and show that near-unity signal-transfer efficiency can be achieved at moderate incident LO power. The cavity linewidth and free spectral range determine the usable detection band.
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High Energy Physics (Experiment)
Search for high-mass resonances in photon-jet final states using 140 fb$^{-1}$ of $pp$ collisions at $\sqrt{s} = 13$ TeV with the ATLAS detector
ATLAS Collaboration
A search for new high-mass phenomena in events with a high-transverse-momentum
photon and a jet is performed using data collected by the ATLAS experiment from
proton-
proton collisions at the LHC, with a centre-of-mass energy of 13 TeV. The analysis is based on a total integrated luminosity of 140 fb$^{-1}$. The $\gamma$$-$jet invariant mass spectrum measured in data is examined for localised excesses above the Standard Model background. No significant deviation from the Standard Model prediction is observed, allowing stringent limits to be set on the production cross sections of specific new physics scenarios. To investigate
quark compositeness, excited
quark models are studied for different couplings ($f$) and flavours: light $q_{\mathrm{L}}^{*}$ $(u^{*}/d^{*})$ and heavy ($b^{*}$, $c^{*}$). For $f=1$, masses up to 6.0 TeV ($q_{\mathrm{L}}^{*}$), 3.5 TeV ($c^{*}$), and 2.6 TeV ($b^{*}$) are excluded. These results provide the first direct constraints on $c^{*}$ production in the $\gamma$$-$ jet final state at the LHC. Additionally, the analysis excludes
quantum black hole mass thresholds up to 5.3 (7.5) TeV in the Randall-Sundrum (Arkani-Hamed-Dimopoulos-Dvali) models at a 95% confidence level, further constraining these theoretical frameworks. Constraints on the visible cross-section are also obtained using generic Gaussian-shaped resonance production.
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High Energy Astrophysical Phenomena
Anisotropy-driven constraints on the transition from Galactic to extragalactic cosmic-ray sources
Teresa Bister, Foteini Oikonomou and Damiano F. G. Fiorillo
The spatial distribution of the
cosmic-ray (CR) flux above $8\,\mathrm{EeV}$ exhibits a significant dipole in agreement with expectations from extragalactic sources following the large-scale structure. At the ankle, the direction changes suddenly and is compatible with the
Galactic center for energies $\lesssim4\,\mathrm{EeV}$. We leverage the direction and strength of the dipole anisotropy as diagnostics of the possible sources of the intermediate-mass
nuclei below the ankle that cannot be associated with the continuation of the Peters cycle of lower-energy
Galactic CRs. Using 3D-simulations of CR propagation in up-to-date
Galactic magnetic field models, we show that the dipole anisotropy of both continuous and transient individual
Galactic sources and source distributions exceeds the measurements by $>3\sigma$. An extragalactic origin of the intermediate
nuclei below the ankle instead agrees with all data, where the observed change in dipole direction is guided by the fading heavy
Galactic component dominant at the second knee.
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Solar and Stellar Astrophysics
Not so typical doubly eclipsing systems
Petr Zasche
Classical doubly eclipsing systems are
stars for which two distinct eclipsing periods that apparently come from one point source are detected. Through thorough analysis, the physical parameters of the component
stars of these systems can be revealed, and sometimes even the mutual motion of the two doubles around a common barycentre can be constrained. This is most typically done via study of the eclipse-timing variations for both pairs, whose behaviour should be opposite in manner to each other, as the two doubles revolve around a common barycentre. In this study, we present rather unusual systems for which such an easy approach does not work. The period changes are clearly detectable, but only for one pair. These unusual systems are V736 And (periods 0.3596 days and 0.3069 days); ASAS J074939-3037.0 (0.4417 d, 0.2648 d); OGLE BLG-ECL-123507 (1.0170 d, 2.9488 d); ASASSN-V J180818.54-684329.4 (0.3392 d, 3.3234 d); and CRTS J191726.4-543540 (0.3129 d, 2.8178 d). Several hypotheses are presented regarding the possible origins of such behaviour. However, a final decisive explanation is still yet to be determined.
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Cosmology and Nongalactic Astrophysics
Bumpy inflation from explosive particle production
Kaloian D. Lozanov, Xavier Pritchard and Misao Sasaki
We present a first-principles derivation of an effective inflaton potential with a bumpy feature. We consider the coupling of a spectator field \chi to the inflaton \phi such that \chi is massive enough for almost all values of \phi, but becomes massless when the inflaton crossed the value \phi_\star. This gives rise to a burst of \chi-particle production at \phi=\phi_\star. By taking the backreaction of the particle production, we obtain a bumpy feature in the effective potential. We discover that for certain choices of the interaction constants and field scale relevant for particle production, the backreaction-induced bumpy effective potential can lead to a sizable enhancement in the
curvature perturbation. In particular, the enhancement can be large enough to generate observationally relevant amounts of
primordial black holes and
stochastic gravitational wave backgrounds.
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Statistical Mechanics
Quenched activity induces nonuniversal scaling in nonreciprocal XY Models and surfaces
Sudip Mukherjee and Abhik Basu
Active XY models and active surfaces are two paradigmatic nonequilibrium systems with distinct microscopic origins. We show that the hydrodynamic theories for a quenched-disordered nonreciprocal random bond two-dimensional XY model and an inversion-symmetric active surface tangentially advected by quenched velocities are identical. This theory predicts sub-logarithmic phase order in the XY model and sub- or super-logarithmic positional order in the surface for short-range disorder with nonuniversal exponents, which vary continuously with the degree of transversality of the disorder variance. We argue that the nonreciprocal random bond XY model can disorder through
vortex proliferation.
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Quantum Physics
Corrections induced by the GUP to the Lamb shift of an accelerated atom interacting with a quantum scalar field
Zhi Wang, Yi Yang and Zhengwen Long
We investigate the effect of the GUP on the Lamb shift of a two-level atom interacting with a real massless scalar
quantum field, within the DDC formalism. For an atom undergoing inertial motion, uniform acceleration, and uniform circular motion, we analyze the separate contributions of
vacuum fluctuations and radiation reaction. We first derive the statistical functions of the field along the atom's trajectories for the three types of motion, expressing them as frequency integrals, and then employ them to calculate the
vacuum fluctuation and radiation reaction contributions to the radiative level shift. We show that the GUP-modified Lamb shift of the two-level atom arises entirely from
vacuum fluctuations and acquires additional corrections proportional to $\beta$. We focus in particular on the acceleration-dependent GUP corrections. For a uniformly accelerated atom, the GUP corrections comprise thermal and nonthermal parts. At low accelerations, the thermal part exhibits nonmonotonic behavior, and is proportional to $a^4$ in the limit $a/\omega_0 \to 0$; the nonthermal part, by contrast, grows nonlinearly and monotonically, exceeding the thermal part by nearly two orders of magnitude at large accelerations. For an atom in uniform circular motion, the GUP corrections are purely nonthermal and also display a nonlinear, monotonic dependence on acceleration, increasing or decreasing steeply according to the sign of $\beta$. For the same $\beta$, the corrections are larger in uniform circular motion than in uniformly accelerated motion, since the former involves terms proportional to both $a^2$ and $a^3$, whereas the latter contains only $a^2$ terms.
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Optics
Ultra-broadband transient absorption down to 200 nm enabled by soliton dynamics in gas-filled hollow capillary fibers
Pieter J. Brongers, Kyle Barlow, Deepjyoti Satpathy et al. (+3 more)
The deep ultraviolet (DUV) window (200-300 nm) is essential for the characterization of (bio)chemical and material systems through the UV signatures of nucleobases, amino acids, peptide bonds, many organic moieties, and wide bandgap transitions. However, extending ultrafast spectroscopy to the DUV to access the associated electronic and structural dynamics has largely remained elusive, due to the limited bandwidth and efficiency of common femtosecond DUV pulse sources. We now close this gap and demonstrate ultra-broadband femtosecond transient absorption (TA) spanning 200-800 nm, achieving unprecedented coverage of the entire DUV window. We generate supercontinuum probe pulses through
soliton self-compression in a helium-filled hollow capillary fiber at a repetition rate of 20 kHz and fully suppress their high intrinsic intensity fluctuations via a correlation
matrix referencing scheme. We thus achieve detector-noise-limited TA measurements with an exceptional resolution of 9 $\mu$OD in one second, and demonstrate these novel capabilities by resolving the ultrafast
spin-crossover dynamics of a Fe(II) complex in the DUV. This work opens the path to unravel previously inaccessible photophysical and photochemical dynamics encoded in the DUV.
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All authors Pieter J. Brongers, Kyle Barlow, Deepjyoti Satpathy, John C. Travers, Christian Brahms, Malte Oppermann
Materials Science
Band offsets and electronic structure at ${\alpha}$/${\beta}$-Ga$_2$O$_3$ and ${\kappa}$/${\beta}$-Ga$_2$O$_3$ phase heterojunctions
D. Q. Fang
Ga$_2$O$_3$ phase heterojunction materials are emerging as promising candidates for deep-ultraviolet optoelectronics. Here, the band offsets at the ${\alpha}$/${\beta}$-Ga$_2$O$_3$ and ${\kappa}$/${\beta}$-Ga$_2$O$_3$ phase heterojunctions are investigated through hybrid functional calculations. Explicit, realistic slab models that satisfy electron counting rules are constructed for the heterojunctions. Our calculations demonstrate that a type-II staggered band
alignment forms at the ${\alpha}$/${\beta}$-Ga$_2$O$_3$ and ${\kappa}$/${\beta}$-Ga$_2$O$_3$ phase heterojunctions, where both the valence and conduction band edges of ${\alpha}$-Ga$_2$O$_3$ and ${\kappa}$-Ga$_2$O$_3$ are higher than those of ${\beta}$-Ga$_2$O$_3$. Strain effects on the band
alignment are also discussed. Spatially resolved local density of states maps are presented, clearly revealing the interfacial electronic structures. These results provide valuable insights into the physical properties of Ga$_2$O$_3$ phase heterojunctions, offering guidance for future device design efforts.
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Materials Science
A novel Grand-Potential Phase-Field Lattice-Boltzmann model for multi-phase solidification with convection
Chirantandip Mahanta, Sanjeev Kumar, Gandham Phanikumar et al. (+1 more)
Melt convection plays a critical role in microstructure
evolution during
alloy solidification, yet accurately capturing its interaction with moving solid-
liquid interfaces remains a significant computational challenge, particularly in multi-phase, multi-component systems. In this work, we develop a computational framework that couples a Grand-Potential phase-field model with the
Lattice Boltzmann method (LBM) to simulate convection-driven solidification within a unified and thermodynamically consistent formulation. The proposed approach rigorously enforces no-slip conditions at evolving solid-
liquid interfaces, while fluid transport is solved using the standard single-relaxation-time Bhatnagar-Gross-Krook collision operator. The framework provides an efficient and robust methodology for resolving the coupled
evolution of interfaces, solute transport, and fluid flow. The versatility of the proposed framework is demonstrated through simulations of dendritic and eutectic solidification under natural convection. The results show that convection significantly modifies solute segregation, destabilizes growth fronts, and induces oscillatory growth modes in both systems. These examples illustrate the capability of the proposed method to capture complex flow-induced morphological instabilities and provide new insights into the mechanisms governing convection-driven microstructure
evolution in
alloy solidification.
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All authors Chirantandip Mahanta, Sanjeev Kumar, Gandham Phanikumar, Abhik N. Choudhury
Mesoscale and Nanoscale Physics
Exceptional point induced by hyperbolicity in an electrostatic spherical shell
Álvaro Buendía, Marcelo S. Barreiro and Nuno M.R. Peres
Exceptional points (EPs) are non–Hermitian degeneracies at which both
eigenvalues and eigenvectors coalesce, usually engineered through balanced gain and loss or non–reciprocity. In this work, we show that the radial electrostatic problem of an anisotropic core–shell nanoparticle realizes an EP without any of the alluded conditons. Written in the logarithmic radial coordinate, the problem is a Cauchy–Euler equation that maps onto a damped oscillator and, equivalently, onto a two-site Hatano–Nelson
Hamiltonian, so that the non-Hermiticity is emulated in space rather than in time and the sole control parameter is the degree of dielectric anisotropy, $\varepsilon_t/\varepsilon_r$. The shell is passive, reciprocal, and lossless, yet it hosts an EP and a non–Hermitian phase transition governed by hyperbolicity alone. Beyond a hyperbolicity threshold the electric field inside the shell turns from monotonic decay into spatial oscillation, producing hotspots at intermediate radii which can be exploited to tailor fluorescence, strong coupling, sensing, or cloaking. More broadly, this establishes
hyperbolic media as a platform to simulate non–Hermitian physics without gain, loss, or non–reciprocity.
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Medical Physics
Dose-PlanNet: Physics Based Radiotherapy Dose Prediction with Deep Learning
Ankit Bhattacharjee, Sougata Maity, Santam Chakraborty et al. (+1 more)
Automating prostate radiotherapy treatment planning is dosimetrically complex, particularly for extreme hypofractionated regimens. In this study, we introduce Dose-PlanNet, a physics-guided 3D deep learning architecture designed to predict dose distributions. This model's performance was evaluated on a cohort of patients treated in a prospective trial where two different dose fractionation regimens were employed. Dose-PlanNet achieved comparable target coverage ($D_{95}$), though statistical analysis revealed a marginal reduction in target homogeneity ($p<0.001$) offset. However the model achieved statistically significant improvements in high-dose organ-at-risk sparing ($p<0.001$). When evaluated against strict Prospective Randomized protocol volumetric constraints, automated plans met prespecified clinical acceptance criteria in $11$ out of $14$ Moderate Hypofraction Arm plans and $9$ out of $12$ Stereotactic Body Radiation Therapy Arm plans. This pipeline demonstrates that physics-informed deep learning can accelerate radiotherapy workflows while safely maintaining the stringent dosimetric quality required for high-precision clinical deployment.
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All authors Ankit Bhattacharjee, Sougata Maity, Santam Chakraborty, Indranil Mallick
Materials Science
The Effect of Geometry on Thermodynamic Response
Bojana Bokic, Sébastien R. Mouchet, Biljana Stankov et al. (+9 more)
At the nano- and microscale, various patterns influence and shape thermal and optical response, making them essential for the survival of various biological species. In addition, controlling thermal radiation is vital for a broad range of applications, such as thermal management, spectroscopy, optoelectronics, and energy conversion technologies. For this reason, there is strong pressure to elucidate the physics of thermal radiation at the nanoscale. In this article, we provide evidence that complex nanoscale geometries affect thermal management, leading to an unusual thermal response in heat-capacity measurements as a function of temperature. Beyond identifying the structural constraints associated with this unusual thermodynamic response, the current study introduces the possibility of shaping the apparent heat-capacity response through geometry without necessarily altering the system's chemistry.
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All authors Bojana Bokic, Sébastien R. Mouchet, Biljana Stankov, Sanja Ostojic, Nicolas Roy, Darko Vasiljevic, Yin Chang, Marija Radmilovic-Radjenovic, Branislav Radjenovic, Thierry Verbiest, Mohamed Hatifi, Branko Kolaric
Quantum Physics
Davide Rinaldi, Mattia Moroder, Dario Gerace et al. (+2 more)
Fast and reliable
qubit reset is essential for the efficient operation of
quantum processors. Among the proposed strategies, Mpemba-effect-based protocols offer a simple route to accelerated relaxation, but provide limited insight into the optimality of the full reset dynamics.
Geometric approaches, by contrast, quantify optimality but do not generally suggest practical acceleration protocols. Here, we bridge these perspectives through a
geometric analysis of
entanglement-assisted
qubit reset. We show that entangling operations can redistribute local coherences across a multi-
qubit register, allowing the reduced state of each
qubit to follow a geodesic path towards the ground state. Remarkably, this locally optimal behaviour can emerge even when the collective
evolution becomes suboptimal in the full state space. We illustrate this interplay for different families of initial multi-
qubit states. Our results provide a
geometric perspective on Mpemba-inspired reset acceleration and clarify when extending two-
qubit protocols to larger registers provides a further advantage in the reset process.
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All authors Davide Rinaldi, Mattia Moroder, Dario Gerace, Giacomo Guarnieri, Steve Campbell
Quantum Physics
Correcting Connectivity in Arc-Based QUBO Models for Fixed-Fleet Vehicle Routing
Omer Gurevich, Maor Matityahu, Tal Mor et al. (+1 more)
We revisit a degree-only arc
Hamiltonian for fixed-fleet, homogeneous, uncapacitated vehicle routing. Its local penalties define only a cycle cover, so ground states may contain customer cycles disconnected from the depot. We construct a
polynomial-size quadratic unconstrained binary optimization (QUBO) repair using capped single-commodity flow and prove connected, cost-optimal ground-state routings under explicit penalty assumptions. For $N-1$ customers and $K$ nonempty routes, the unreduced encoding uses exactly $|E|(1+\lceil\log_2(N-K+1)\rceil)$ logical problem
qubits. A reversible compute-phase-uncompute implementation evaluates the flow penalties in $O(N^2\log N+N\log^2N)$ logical gates on a complete graph, using $O(\log N)$ reusable workspace and no product register. On complete loopless graphs, a position encoding that arranges all routes in one sequence separated by depot occurrences uses fewer problem
qubits and written terms when the number of bits per flow register grows. Under the same reversible accounting model, the flow formulation admits a smaller logical-gate upper bound. Exact
Hamiltonian and
circuit audits and a
benchmark of 1,200 cost
matrices verify the formulation and quantify the connectivity gap. A 32,000-shot Amazon Braket task on IQM Emerald characterizes depth-one termwise Ising
circuits for a diagnostic $N=4$, $K=1$ counterexample. In the degree-only
circuit, 78.05% of selected $p=1$ shots realize the invalid disconnected ground state; the reduced 14-
qubit flow-augmented
circuit yields no fully feasible sample. These device results characterize mapped
Hamiltonians and compilation, not an asymptotic advantage in solving routing problems.
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All authors Omer Gurevich, Maor Matityahu, Tal Mor, Aryeh Lev Zabokritskiy