Earth and Planetary Astrophysics
The Length of Martian Crater Rays and Their Relation to Lunar Cold Spots
Trevor P. Erwin, Brandon C. Johnson, David Minton et al. (+1 more)
Impact-generated crater rays are well-documented on the Moon, with most appearing as high-albedo streaks extending radially from a crater's center. On Mars, however, crater rays are significantly rarer and discernible only through thermal imaging due to their lower thermal inertia compared to surrounding terrain. This study presents the first comparative analysis between the lengths of Martian and lunar crater rays, including lunar albedo rays and cold spots, which are ray-like thermal anomalies associated with many of the youngest lunar craters. Our findings indicate that both Martian crater rays and lunar cold spots extend significantly farther than lunar albedo rays, with lengths an order of magnitude greater for craters of equivalent diameter. Furthermore, we propose a connection between the formation mechanisms of Martian crater rays and lunar cold spots based on their thermal properties. By integrating thermal rays into existing ejecta models, we refine the understanding of crater-ray formation and suggest that Martian crater rays and lunar cold spots may share a similar formation mechanism via secondary cratering processes. Advancing knowledge of these features has implications for impact dynamics and surface
evolution across planetary bodies.
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All authors Trevor P. Erwin, Brandon C. Johnson, David Minton, Alexandria V. Johnson
Quantum Physics
Salini Rajeev and Mayukh Lahiri
The goal of
quantum process
tomography is to fully characterize an operation performed on a
quantum state. By considering high-dimensional
quantum states (qudit), we show that it is possible to fully reconstruct an arbitrary operation without performing any measurement on the transformed qudit. Our method is interferometric and conceptually different from existing techniques of
quantum process
tomography that must perform a measurement on the transformed qudit.
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Optics
Cavity optomechanics with a suspended resonant mirror
Trishala Mitra, Gurprret Singh, Søren Peder Madsen et al. (+1 more)
We investigate optomechanical effects in cavities consisting of a plane-plane arrangement of a broadband reflectivity mirror and an ultrathin, suspended resonant mirror possessing a high-Q internal optical resonance. We first investigate dispersive optomechanics in such cavities on the basis of a generic analytical model as well as finite element method simulations of realistic structures. We then report on experimental optical spring measurements using a suspended silicon nitride membrane patterned with a subwavelength grating. While the observed optical spring variations qualitatively match those expected from the dispersive cavity optomechanics model, their magnitude is more than two orders of magnitude larger than predicted. We surmize that this strong optomechanical interaction is due to photothermal effects and put forward a phenomenological model that plausibly supports the observations.
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All authors Trishala Mitra, Gurprret Singh, Søren Peder Madsen, Aurélien Dantan
Cosmology and Nongalactic Astrophysics
Response to: "Isotropic deceleration and near-zero baseline acceleration in Pantheon+ supernovae: new arguments in the dark energy debate”
Animesh Sah, Mohamed Rameez and Subir Sarkar
Ray et al. [1] have claimed that the acceleration of the Hubble expansion rate inferred from Type Ia
supernovae in the Pantheon+ catalogue "is equally strong in the CMB dipole ($q_m = + 1.45$) and anti-dipole hemispheres ($+ 1.55$), directly contradicting the SRS26 anisotropy argument". Here SRS26 refers to our analysis [2] which showed that "locally $q_0$ has a strong dipole anisotropy aligned approximately with the bulk flow, and only a small monopole component remains at distances exceeding a few hundred Mpc". We find that these authors confused Equatorial with
Galactic coordinates, thereby getting the CMB dipole direction wrong. Hence their conclusion is baseless.
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General Relativity and Quantum Cosmology
A parity selection rule for regular black holes
Farid Thaalba, Julio Arrechea and Stefano Liberati
Regular black hole metrics are usually studied kinematically, but a finite-
curvature static core does not guarantee that the underlying theory can consistently evolve generic matter through a regular center. We derive a necessary local consistency condition within the most general class of action-based, identically conserved, second-order gravitational field equations in spherical
symmetry. Regularity requires that the two functions defining the theory have opposite parities under reversal of the signed radial coordinate, together with additional center-regularity and nondegeneracy conditions. In the integrable sector, this criterion is equivalent to requiring the generalized Misner–Sharp–Hernandez mass to be odd across the center, to vanish cubically there, and to contain no point-mass contribution. For theories reconstructed from static one-parameter
vacuum families, the condition becomes covariance under simultaneous reversal of radius and mass. The theories associated with the Hayward and Dymnikova geometries satisfy this selection rule. In contrast, the Bardeen theory does not, demonstrating that
curvature regularity of a static solution is insufficient for dynamical consistency with generic matter. We also characterize an infinite class of admissible theories containing Hayward-like black holes with de Sitter cores. The selection rule provides a necessary condition for theories intended to describe regular collapse, but does not by itself establish well-posedness or guarantee a nonsingular endpoint.
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High Energy Physics (Phenomenology)
FCC precision requests: challenges for Monte Carlos and phenomenology tools
Z. Was
One can define three levels of ambiguities for the accelerator experiments: worse than 0.3%, around 0.3% and better than 0.3%. I will address issues important, for the last case, when Monte Carlo programs that simultaneously account for theoretical and experimental effects are necessary. To complete efforts, simultaneous effort in many specialities over years was necessary. The monumental projects of Bryan Lynn, Robin Stuart, Dima Bardin, Wolfgang Hollik and contributions of S. Jadach in the domain of precision physics need to be mentioned, they provide theoretical foundations. Incomplete lists of methodology domains and projects, usually left into references, appendices, and private notes include: (i) Phase space–>
symmetries (ii)
matrix element preparation –> factorizations (iii) program and development process design (iv) testing strategies (v) user interaction (vi) software tools (vii) partners and competitors. Usually we were publishing our own projects, let me mention incomplete lists of methodology domains and projects, which were usually left aside into references, appendices, and private notes: The work started on the basis of previous efforts which can be listed following names of the programs: (i) FOWL, (ii) GENRAP, (iii) Mustraal, (iv) Koralb, (v) Lesko, (vi) Tauola, (vii) KoralZ, (viii) Lumlog, (ix) Oldbab, (x) Bhlumi, (xi) Bhwide and (xii) KKMC. I will focus on some of these points. Others, hopefully, are covered in other talks. In particular I do not need to cover exponentiation and some issues of factorization; see contributions to the proceedings by B.F.L. Ward and A. Tapadar. Developments took years and did not follow a straight line; that is why there are simplifications, biases. Also a review of literature could not be completed.
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Strongly Correlated Electrons
Optimized Tensor-Network Renormalization for Quantum Dynamics: Resolving the Spectral Function of $\mathrm{K_2Co(SeO_3)_2}$
Jiahang Hu, Runze Chi, B. Normand et al. (+2 more)
Tensor-network methods have opened a powerful route for the study of dynamical spectral functions in two-dimensional
quantum systems. However, existing approaches within the framework of infinite projected entangled-pair states construct the required renormalization tensors solely from the ground-state environment and can suffer from severe numerical instability. We identify the origin of this instability and introduce an excitation-tailored corner-transfer-
matrix renormalization-group (ET-CTMRG) method to resolve it. By incorporating excitation tensors into the renormalization procedure, the method constructs a substantially more accurate effective
Hamiltonian matrix and thereby yields reliable and well-converged excitation spectra. For Heisenberg antiferromagnets, it reduces truncation errors by orders of magnitude and for the particularly complex case of the supersolid phase in the triangular-
lattice XXZ magnet $\mathrm{K_2Co(SeO_3)_2}$, it achieves excellent quantitative agreement with inelastic
neutron-scattering measurements. ET-CTMRG therefore provides a robust framework for investigating the dynamical properties of strongly correlated
quantum systems.
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All authors Jiahang Hu, Runze Chi, B. Normand, Hai-Jun Liao, T. Xiang
Nuclear Theory
The $g$-mode frequencies in cold neutron stars and nuclear saturation parameters
Hajime Sotani and Hajime Togashi
Oscillation frequencies excited in
neutron stars are crucial for extracting their interior properties. In addition to the fundamental and pressure modes, the
gravity ($g$-) modes can be excited even in zero-temperature
stellar models due to the composition gradient. In this study, we systematically study the $g$-mode frequencies, focusing on the nucleonic equation of state. Then, we can derive an empirical relation for the 1st $g$-mode frequencies as a function of the
stellar compactness and the combination of the
nuclear saturation parameters, $\eta_0 \equiv L/K_0$, where $K_0$ and $L$ denote the incompressibility of symmetric
nuclear matter and the density dependence of the
nuclear symmetry energy, respectively. If an observed 1st $g$-mode frequency significantly deviates from our empirical relation, it may indicate the emergence of additional degrees of freedom or new compositions inside the
star.
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Quantum Physics
Nanohertz Pendulum toward Macroscopic Entanglement under Structural Damping
Azusa Sawada, Hina Nakano, Kanta Watanabe et al. (+3 more)
Pendulums are attractive for macroscopic
quantum control because
gravity dilution reduces mechanical loss, while the $1/f$ force-noise spectrum associated with structural damping allows nearly lossless trapping to suppress the thermal noise sampled at an upward-shifted resonance. The same $1/f$ spectrum, however, produces a low-frequency tail that penalizes
entanglement. With $10\%$ detection loss, we find that this tail raises the required back-action-to-thermal force-noise ratio by about $50\%$, corresponding to a required suspension gain $G_{\rm req}=1.49$. To overcome this structural-noise penalty, we realize a $7$-mg pendulum suspended by a stepped fused-silica fiber, with an energy-decay rate $\Gamma/2\pi=361(39)$ nHz ($Q\equiv\omega_0/\Gamma=7.3(8)\times10^6$) at $\omega_0/2\pi=2.63$ Hz. The reduction in $\omega_0\Gamma$ yields a measured gain $G_q\simeq2.5$ relative to the previous monolithic device, exceeding the requirement.
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All authors Azusa Sawada, Hina Nakano, Kanta Watanabe, Gaku Ohashi, Shota Okumura, Nobuyuki Matsumoto
Mathematical Physics · Cross-listed from math.PR
Response Calculus for Spectral Simplicity and Joint Eigenvalue Densities
Chunhao Cai
We develop a perturbative response calculus for spectral problems obtained by changing the speed measure of a fixed symmetric energy form in a Gaussian environment. If Cameron–Martin translation acts by $\mu_{x+f}=e^{\kappa f}\mu_x$,
unitary transport identifies the varying $L^2$ spaces and produces a common-domain analytic family. For a positive
eigenvalue $\Lambda$, the first-order operator is $-\kappa\Lambda$ times the compression of multiplication by $f$ to the $\Lambda$-eigenspace; its
eigenvalues are the derivatives of the analytic branches issuing from $\Lambda$. A countable separation condition and finite-dimensional Gaussian disintegration then give almost-sure simplicity; a response-transversality condition and the inverse function
theorem give joint densities for all finite vectors of positive ordered
eigenvalues. We verify these hypotheses for every $0<\gamma<2$ in two models: Dirichlet Liouville Brownian motion on an arbitrary bounded connected planar domain, and the Liouville–Cauchy operator on the circle. In the first model the whole spectrum is almost surely simple; in the second the constants form the deterministic zero mode and the positive spectrum is almost surely simple. Transversality follows from a local eigenfunction-square identity in the Brownian case and its nonlocal jump-form analogue in the Cauchy case.
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Cosmology and Nongalactic Astrophysics
Isotropic universes with a preferred direction
Jose Beltrán Jiménez and Shinji Tsujikawa
We present a class of cosmological scenarios in which a preferred spatial direction in the matter sector coexists with an exactly homogeneous and isotropic Friedmann–Lemaître–Robertson–Walker (FLRW) geometry. The Cosmological Principle is realized on shell, with the vector-field equations enforcing a vanishing momentum density and suitable interactions eliminating the anisotropic stress. Consequently, the construction yields an entire FLRW branch without tuning the matter-field initial conditions. The preferred direction reemerges in perturbations, producing direction-dependent propagation and mixing among scalar, vector, and tensor modes already at linear order. In particular, the mixing opens a linear channel through which perturbations in the scalar sector can in principle source gravitational waves. Our construction thus reveals a new route by which preferred-direction physics can leave observable cosmological signatures while remaining hidden in the background geometry.
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Materials Science
Real-time dynamics of the two-step charge-density-wave transition in bulk 1T-TaS$_2$
Daeheon Kim, Jinseok Oh, Kahyeon Koh et al. (+4 more)
The charge-density wave (CDW) of bulk 1T-TaS2 is built from
Star-of-David (SoD) clusters tiling a sqrt{13} x sqrt{13} superlattice, and it melts through a two-step sequence accompanied by order-of-magnitude changes in resistivity. Whether these steps proceed by collapse of the SoD amplitude or by rearrangement of the SoD
lattice has remained unresolved, because the relevant dynamics occur on length and time scales beyond the reach of ab initio molecular dynamics. Here we follow the CDW transitions in real time using a machine-learning force field trained on first-principles data, giving access to 1404-atom supercells over 5 ns. The two steps are mechanistically distinct. Above 200 K, SoD clusters translate coherently by transiently dissolving and re-forming about shifted centers, a deformation-formation process that preserves the local SoD amplitude while randomizing the interlayer stacking order and nucleating domain walls. Only near 350 K does the SoD distortion itself collapse. These results provide microscopic support for the recently proposed two-step model of the CDW transition and offer a framework for interpreting light-induced hidden phases and cavity-modified transition temperatures in 1T-TaS2.
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All authors Daeheon Kim, Jinseok Oh, Kahyeon Koh, Yejun Cho, Angel Rubio, Noejung Park, Dongbin Shin
High Energy Physics (Theory)
Confinement as Decoding: Higher Form Codes and Lattice Yang-Mills Theory
Ning Bao
We study the relationship between
quantum error correction, confinement, and
lattice Yang-Mills theory. We first formulate decoding for finite Abelian homological codes in terms of higher form gauge fields. For positive local noise, the logical classes are topological sectors of a Nishimori ensemble, and the optimal decoding error is determined by the relative weights of the nontrivial sectors. We derive
Fourier relations between logical probabilities, disorder operators, and information in the channel environment, and we give contour and fractional moment criteria for a threshold. We then study a four dimensional $\Z_N$
memory and its possible relation to confining $\PSU(N)$
vacua. Finally, we define a finite
curvature center sheet model coupled to Wilson $\SU(N)$ link variables. In this model the conditional logical probabilities are center twisted Yang-Mills partition functions. A strong coupling expansion gives the leading effective interaction for the syndrome and shows that local syndrome correlations can decay even when the global sheet sectors are mixed. We also show that the likelihood for a separated pair of syndrome worldlines is the center monopole correlator. Its decay determines a transfer
matrix mass. This distinguishes the suppression of global flux sectors from the local spectral information needed to discuss a mass gap.
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Quantum Physics
Spread complexity as a probe in generalized and long-range Aubry-Andre-Harper models
Triyas Sapui, Tanoy Kanti Konar, Subinay Dasgupta et al. (+1 more)
We investigate the spread complexity of
quantum quenches in generalized and long-range Aubry-Andre-Harper (AAH) models, encompassing regimes with and without mobility edges. In particular, in the generalized AAH models supporting energy-dependent mobility edges, we demonstrate that the long-time averaged spread complexity exhibits nonanalytic behavior when the post-quench quasiperiodic potential crosses the mobility edge associated with the energy of the initial eigenstate, thereby accurately identifying the mobility-edge transition. Such a behavior is supported by the spreading of local density of states. We further derive analytical expressions for the moments and the corresponding Lanczos coefficients for quenches between the limits of vanishing and strong quasiperiodic potentials. The Lanczos coefficients display qualitatively distinct behavior depending on the presence of mobility edges - they exhibit an initial plateau followed by a decay with the Krylov basis index, in contrast to the nearly constant behavior of the conventional AAH model without mobility edges. For LR hopping, the coefficients decay with the Krylov basis index for quenches from the localized to the extended phase, while they coincide with the AAH results for quenches in the opposite direction.
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All authors Triyas Sapui, Tanoy Kanti Konar, Subinay Dasgupta, Aditi Sen De
High Energy Physics (Theory)
Local subtractions and renormalization-group monotonicity: exact defect and sphere flows
Francesco Scardino
We ask when local subtractions of the sphere free energy yield a function that decreases monotonically along a renormalization-group flow. The subtractions are
polynomials in $D=R d/dR$ that remove the local counterterms and leave fixed-point values unchanged, in a fixed renormalization prescription. We prove that if the subtracted free energy $C$ approaches its infrared value from below, with ordered endpoints and a power-law approach to both fixed points, no such subtraction is monotone, and that further factors with real zeros cannot remove a nonmonotonicity already present. For a three-dimensional flow to a gapped phase, $C-C_{\rm IR}=4\pi^2(M_2-3M_0)/R+\dots$, where $M_0$ and $M_2$ are spectral moments of the flat-space stress-tensor two-point function, so every subtraction fails when $M_2<3M_0$, as for a free conformally coupled massive scalar. In two dimensions the leading term is always negative, so no
unitary flow to a gapped phase whose subtracted free energy starts at $c_{\rm UV}/3$ admits a monotone subtraction; the massive Dirac
fermion on $S^2$ is an exact example. In the conformally coupled massive $O(N)$ model, $M_2-3M_0$ is negative at leading order in $N$ for every finite nonnegative quartic coupling. At criticality it vanishes at that order and its first correction is negative. At weak positive coupling it is negative for every
curvature coupling and every finite $N$. For the Gross–Neveu flow from an interacting fixed point, it is negative already at leading order. In contrast, we prove monotonicity for Robin boundary flows on every sphere $S^p$ with $p\ge2$ and for massive Dirac fields on every odd sphere $S^d$ with $d\ge3$. For two solvable double-trace families we find exact thresholds: a monotone subtraction exists if and only if $\widehat\Delta\ge1/2$ on a spherical surface defect, and $\Delta\ge(3-\sqrt{37/13})/2$ on $S^3$ at leading large $N$.
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Quantum Physics
Detecting high-dimensional entanglement with simple measurements
Suraj Goel, Alexander Bernal, Gabriele Cobucci et al. (+3 more)
The standard
benchmark for high-dimensional
entanglement is the number of dimensions in which
entanglement must be present in order to generate the state. This is called the Schmidt number and its detection is usually based on implementing an appropriate set of local basis measurements. However, as
quantum technology brings increasingly large physical dimensions within reach, the implementation of such measurements typically becomes more costly. Here, we develop a scheme for detecting Schmidt numbers based only on sequences of single-
qubit observables. These measurements are simpler to implement as they require only low-depth
quantum circuits. Using up to sixteen-dimensional photonic spatial mode
entanglement and multi-plane light conversion technology, we demonstrate how it simplifies setup complexity and successfully detects the maximal (or close-to-maximal) Schmidt number. Our results reveal that simple and more scalable measurements are sufficient to detect high-dimensional
entanglement properties.
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All authors Suraj Goel, Alexander Bernal, Gabriele Cobucci, Will McCutcheon, Mehul Malik, Armin Tavakoli
Superconductivity
Florian Simon, Thomas Bernat and Annica M. Black-Schaffer
The interplay of superconductivity and the
quantum geometry of the normal state has recently been the subject of an array of studies, especially regarding the superfluid weight. In this work, we turn our
attention to the
quantum geometry of the superconducting state itself, set by the Bogoliubov-de Gennes (BdG)
Hamiltonian, which dictates the
geometric and topological properties of superconductivity. We show that under three general conditions, namely superconducting fitness, orbital uniformity of the superconducting pairing, and absence of normal-state
spin-flip terms, the BdG
quantum geometry exactly separates into a sum of the normal-state
quantum geometry and an additional pairing
quantum geometry, thereby displaying a simple composite structure. We show that this separation holds for all
spin-singlet and -triplet pairings, including nonunitary
spin-triplet pairing. We further provide explicit analytical formulas for the pairing
quantum geometry for all these cases. These results establish how superconducting pairing alone easily drives both
topology and a finite
quantum metric, thus being present even in topological trivial or flat band
superconductors, with no normal state
quantum geometry. To complement these results, we also derive the BdG
quantum geometry of a general two-orbital
spin-singlet
superconductor with non-uniform pairing and finite superconducting fitness. Here, our explicit analytical results establish a non-separable composite BdG
quantum geometry, with the normal state and pairing contributions generally intertwining, thereby producing even more possibilities for finite
quantum geometry. Our results provide design rules for creating
superconductors and superconducting hybrid structures with nontrivial
topology and finite
quantum metric and will additionally help in the experimental diagnosis of unconventional superconductivity.
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Mesoscale and Nanoscale Physics
Discrete states and ballistic interference in quantum wires approaching macroscopic lengths
Henok Weldeyesus, Taras Patlatiuk, Christian P. Scheller et al. (+4 more)
Increasing the size of a system showing
quantum effects is a difficult task limited by decoherence, a diminishing
quantum level spacing, and the effects of disorder spoiling the
quantum behavior when growing in size. Systems in 1D offer very strong confinement in the transverse directions, thus generally enhancing
quantum effects, but are notoriously sensitive to disorder. In this work, we present a system of 1D electrons exhibiting discrete
quantum levels and fully ballistic coherent
quantum interference with lengths of up to 18\,$\mu$m. Tunneling spectroscopy between two parallel
quantum wires with a central gated segment shows intricate interference patterns exhibiting several different periods in
magnetic field and density. An analysis over three different wire lengths and a comparison with single particle numerical simulations without any free parameters remarkably explains the full pattern including the observed periods. Therefore, these wires are essentially ideal 1D systems with aspect ratios approaching 1'000. In addition, at low bias, we also observe not only the Coulomb charging energies but can clearly resolve the discrete orbital and
spin states in up to 10\,$\mu$m long wires when filling 100 electrons with the center gate. This is made visible by a state-of-the-art low temperature and low noise measurement system. The
spin filling sequence is completely regular, strictly alternating
spin up and down, avoiding high
spin states, while the peak conductance is modulated in accordance with the previously discussed interference patterns. These striking results show that single particle Schrödinger
quantum mechanics such as ballistic
quantum interference and discrete
quantum states may be observed, under the right conditions, in systems of up to 18\,$\mu$m length, thus approaching macroscopic sizes.
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All authors Henok Weldeyesus, Taras Patlatiuk, Christian P. Scheller, Amir Yacoby, Loren N. Pfeiffer, Ken W. West, Dominik M. Zumbühl
Quantum Physics
Caustics and Superenergy in the Quantum Bouncer
Marko. M. Ćosić and Andrew N. Jordan
We investigate the
quantum interference and energetic phenomena associated with classical caustics in the
quantum bouncing ball problem, we refer to as
quantum caustics. By considering an initial Gaussian wavepacket, we show that caustics associated with the underlying classical trajectory families are exhibited. We connect the associated phase singularity chains in the vicinity of the caustic with the semiclassical Pearcey function built on the cusp catastrophe lines. We also quantify the amount of superenergy exhibited in these solutions - regions of space where the local energy exceeds the largest constituent energy
eigenvalue. We give a complimentary description of the caustic and superenergy behavior using the Madelung/Bohm trajectories, which gives additional insight about the energy of the trajectories and how they traverse the phase singularity chains.
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Superconductivity
Jian-Feng Zhang, Ze-Feng Gao, Xiao-Qi Han et al. (+6 more)
The first-principles search for
superconductors is severely limited by the high cost of electron-
phonon coupling (EPC) calculations. Here we develop a low-cost, physically transparent framework that identifies strong-EPC materials directly from static orbital-based
Hamiltonians without explicit
phonon perturbation calculations. Verification using density functional perturbation theory (DFPT) for representative
superconductors shows that the framework captures semi-quantitatively the EPC scale at substantially lower computational cost. Applied to more than 36,000 compounds in the MattKeyBond database, it identifies 34 dynamically stable superconducting candidates with calculated $T_c > 10$ K after DFPT verification. These candidates reveal two distinct routes to relatively high-$T_c$ superconductivity: a metallized covalent $\sigma$-bond route that is more favorable for achieving high-$T_c$
superconductors, and a
Fermi-level density-of-states accumulation route that can enhance $T_c$ but usually to a more limited extent.
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All authors Jian-Feng Zhang, Ze-Feng Gao, Xiao-Qi Han, Dingshun Lv, Miao Gao, Kai Liu, Xinguo Ren, Zhong-Yi Lu, Tao Xiang
Atomic Physics
Measurement and control of the interaction frequency shift in bosonic optical lattice clocks
J. P. Salvatierra, M. Barbiero, G. Bertaina et al. (+3 more)
We report precise measurements of inter-level interactions in a bosonic optical
lattice clock based on $^{88}$Sr atoms. We observe a nonlinear density dependence of the clock shift, even without reaching
quantum degeneracy. In a 2D
lattice, the Rabi line shape exhibits an interaction sideband consistent with a collective
spin model, while in a 1D
lattice the shift is modified by density-induced dephasing. These findings, combined with a careful choice of interrogation detuning and atomic density, can enable operation at a net-zero systematic density shift in $^{88}$Sr
lattice clocks. We discuss the implications of these findings in many-body physics,
quantum simulation, and precision isotope shift measurements, which provide a powerful probe for new physics beyond the Standard Model.
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All authors J. P. Salvatierra, M. Barbiero, G. Bertaina, D. Calonico, F. Levi, M. G. Tarallo
Plasma Physics
Direct Optimization of Stellarator Omnigenity from the Second Adiabatic Invariant
Hanlin Chen, Zhiyuan Lu, Guosheng Xu et al. (+4 more)
Stellarators offer a steady-state, disruption-free path to fusion energy but suffer from enhanced particle losses due to their three-dimensional geometry. Existing optimization methods rely on
geometric proxies rather than the actual trapped-particle orbit condition. We present a differentiable framework that directly optimizes the fundamental orbit action governing particle confinement. The approach yields compact stellarator designs with excellent fast-ion confinement, finite-pressure stability, and coil compatibility, demonstrating that first-principles orbit optimization can be integrated with engineering constraints in a single computational workflow for fusion reactor design.
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All authors Hanlin Chen, Zhiyuan Lu, Guosheng Xu, Shuai Cao, Yang Han, Dehong Chen, Baonian Wan
Materials Science
Magnetically tunable symmetry-enforced nodal lines producing huge anomalous Hall conductivity in altermagnetic $\alpha$-MnTe
Mathews Benny, Xujia Gong, Amar Fakhredine et al. (+17 more)
Altermagnetic $\alpha$-MnTe exhibits huge anomalous
Hall conductivity (AHC) up to room-temperature together with weak ferromagnetism arising from
spin and orbital polarizations. We clarify the origin of the large value of the AHC by identifying two sets of distinct
symmetry-enforced nodal lines in the valence bands with Mn character, located at $k_z=0$ and $k_z=\frac{\pi}{c}$, protected by mirror
symmetry $M_z$ and glide
symmetry $G_z = \{M_z\,|\,0,0,\tfrac{c}{2}\}$, respectively. Both nodal lines are energy-dependent with an approximate C$_6$
symmetry, which is reduced to an exact C$_2$
symmetry due to the presence of the Néel vector. The highest valence band exhibits a Mexican-hat dispersion, whereas the second-highest valence band exhibits an inverted Mexican-hat dispersion, with nodal lines at the crossing between the two bands. Within first-principles accuracy, we demonstrate that these nodal lines give rise to the large AHC observed experimentally and exhibit a strong interplay with the weak ferromagnetism. We further show that even a small
spin canting strongly modifies the nodal lines and the AHC, making them both magnetically tunable. By disentangling the altermagnetic and
ferromagnetic contributions to the AHC, the altermagnetic contribution dominates at small canting angles, while the
ferromagnetic contribution becomes sizeable for larger values. Using linear dichroism in angle-resolved photoemission spectroscopy, we show a signature of the nodal line at the border of the Brillouin zone.
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All authors Mathews Benny, Xujia Gong, Amar Fakhredine, Raphaël Salazar, Ashutosh S. Wadge, Juraj Krempaský, Gunther Springholz, Sarath Sasi, Mahdi Hajloui, Martin Heinrich, Dawid Wutke, Rafał Kurleto, Natalia Olszowska, Sahar Izadi Vishkayi, Asiyeh Shokri, Ján Minár, Carmine Ortix, Jeroen van den Brink, Jakub Schusser, Carmine Autieri
Solar and Stellar Astrophysics
A catalogue of high angular resolution and contrast polarimetric maps of 45 nearby AGB stars with SPHERE/ZIMPOL
Nekolgne Aymard Badolo, Eric Lagadec, Mamadou N'Diaye et al. (+7 more)
We present the largest catalogue of asymptotic
giant branch (AGB)
stars, 45 targets in total, observed in polarized light at high angular resolution (~ 20 milliarcsec). The main goal of the study is to detect and characterize
dust shells in the close environment of nearby AGB
stars. This work also aims to systematically classify the AGB
star circumstellar morphologies obtained with the SPHERE instrument installed at the Very Large
Telescope (VLT), thanks to its Zurich Imaging Polarimeter (ZIMPOL). We extracted and analyzed polarized intensity maps for 45 AGB
stars, constructed from polarimetric observation data obtained with the SPHERE/ZIMPOL instrument. An ellipse fitting method was applied to characterize the circumstellar envelopes.
Stellar parameters (luminosity, effective temperature, surface
gravity, extinction,
metallicity) were compiled and recalculated when necessary from spectral energy distribution (SED) fitting using the Python SED fitting tool (PySSED) software. These data were then used to train a random forest machine learning model to determine the most discriminating variables for a resolved envelope around a given
star. We constructed polarization maps for all
stars in the sample, revealing a wide diversity of circumstellar morphologies. We detected 16 dusty circumstellar envelopes, including three never observed before. They display a wide range of morphologies, all of them showing a clear departure from spherical
symmetry, indicating interaction with a companion or asymmetric mass ejections. The random forest model identified optimal thresholds for several physical parameters, thus providing robust criteria to anticipate SPHERE's ability to resolve
dust envelopes around AGB
stars. These results facilitate the selection of targets for future observations and contribute to a better understanding of the
evolution mechanisms of circumstellar envelopes.
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All authors Nekolgne Aymard Badolo, Eric Lagadec, Mamadou N'Diaye, Sie Zacharie Kam, Iain McDonald, Alexis Matter, Jean Koulidiati, Lyu Abe, Marcel Carbillet, Thierry Fusco
Quantum Physics
Entanglement Generation Beyond Quantum Theory: From Product States to Popescu-Rohrlich Boxes
Shun Umekawa, Akihiro Hokkyo, Hayato Arai et al. (+1 more)
Entanglement generation is a fundamental dynamical capability in
quantum information science and underpins many
quantum advantages. While
quantum theory enables it through
unitary dynamics, boxworld, a generalized probabilistic theory admitting Popescu–Rohrlich boxes with supraquantum correlations, has no reversible transformation capable of generating
entanglement. We show that this no-go picture changes fundamentally once reversibility is relaxed to pure-state preservation. We construct a pure-state-preserving transformation that maps every uncorrelated pure state to a Popescu–Rohrlich box and completely classify all pure-state-preserving entangling transformations in the simplest bipartite boxworld. Our results provide the first explicit mechanism for generating beyond-
quantum entanglement without introducing mixing and demonstrate a physical distinction between reversibility and pure-state preservation that is obscured by the structure of
quantum theory.
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All authors Shun Umekawa, Akihiro Hokkyo, Hayato Arai, Kazuaki Takasan
Materials Science
GRADAR: orientation-map-driven detection and ranking of grains for targeted two-beam electron channeling contrast imaging
Johan Ewald Westraadt
Electron channeling contrast imaging (ECCI) resolves individual dislocations in bulk samples, but only when the imaged grain is held in a two-beam diffraction condition to well under half a degree. In a polycrystal it must be re-established grain by grain, and every published workflow we are aware of chooses the grain first and solves the stage for that orientation. This paper treats the inverse problem: nominate one reflection family and a stage envelope, and determine which grains of an EBSD-mapped polycrystal can reach that family's two-beam condition, a question posed in 2019 and open since. At fixed tilt $t$, stage rotation sweeps the incident beam around a cone of half-angle $t$ in each grain's
crystal frame, and a family with Bragg angle $\theta_B$ is reachable exactly when one of its plane normals lies within $(t + \theta_B)$ of the specimen surface. On a measured 163-grain austenitic stainless steel map at 20 kV, {111} reachability rises from 38.7% at 7 deg tilt to 77.3% at 15 deg; {220} and {311} already reach 79.8% and 91.4% at 7 deg. Ranking survivors by predicted darkness alone is wrong: same-family candidates are equivalent with respect to their own band at exact Bragg incidence, and the darkest tend to lie closest to rival-band Bragg conditions. GRADAR therefore ranks darkest-clean, gating every candidate on a minimum clearance from all rivals, and returns a dial-ready stage move per selected grain. Because the beam moves only ~0.12 deg per degree of stage rotation at 7 deg tilt, an ordinary rotation stage sets the selected condition to better than 0.1 deg. The predicted sweep is checked against the AstroECP
dataset's published silicon precession series: simulated and measured traces agree at r = 0.84, and the measured intensity is dark at all 16 predicted two-beam edges. Per-grain polycrystal validation is deferred to a companion study.
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Physics and Society · Cross-listed from cs.SI
Network Information Enhances Unreliable News Domain Detection
Raphaela Keßler, Roman David Ventzke, Viola Priesemann et al. (+1 more)
Content-based detection of unreliable news is increasingly difficult, as low-reliability sources mimic credible journalism and generative AI makes fabricated content harder to flag. We ask whether network structure can improve news reliability classification, taking a domain-level approach that shifts the focus from individual articles to source reliability. From URL-sharing patterns in Telegram chats, we build a statistically validated domain co-sharing network and find assortative mixing by reliability: low-reliability domains group together, as do reliable ones. Exploiting this structure, we compare Graph Neural Networks against network-unaware baselines using both content-aware features (
multilingual text
embeddings) and content-agnostic features (spreading dynamics). GNNs consistently outperform Multi-Layer Perceptrons on identical features, with GraphSAGE best in both settings (accuracy 0.63 with content, 0.53 without), a 13-14% relative gain over the network-unaware baseline. Network
topology thus systematically improves domain reliability assessment, and remains effective even when content analysis is infeasible.
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All authors Raphaela Keßler, Roman David Ventzke, Viola Priesemann, Giordano De Marzo
Superconductivity
Emergence of Double-Dome Superconductivity in the Pressurized Dirac Semimetal BaMg2Bi2
Qi Wang, Juefei Wu, Cuiying Pei et al. (+3 more)
Dirac semimetal BaMg2Bi2 is reported to be a unique topological material that manifests surface superconductivity that coexistswith bulk band
topology at ambient pressure. Here, we present a comprehensive investigation of high-pressure superconductingproperties in BaMg2Bi2 single
crystal. Significantly, a pressure-driven double-dome superconducting behavior was revealed, withthe superconducting transition temperature Tc approaching the maximum values of 6.67 K at 4.5 GPa and 7.22 K at 10.4 GPafor the first and second superconducting domes, respectively. The combination of high-pressure X-ray diffraction,
Hall resistivitymeasurements, and theoretical calculations demonstrates that, the first superconducting regime is closely related to the pressure-modulated Lifshitz transition, whereas the second superconducting phase emerges concurrently with a structural transition fromthe ambient-pressure P3m1 phase to a high-pressure Pnma phase.
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All authors Qi Wang, Juefei Wu, Cuiying Pei, Yi Zhao, Yiyan Wang, Yanpeng Qi
Mesoscale and Nanoscale Physics
Floquet spin-group theory for light-tailored spin splitting in collinear magnets
Tongshuai Zhu, Zixuan Li, Huaiqiang Wang et al. (+2 more)
Spin groups have emerged as a fundamental
symmetry framework for
spin-splitting antiferromagnets, including altermagnets. For periodically driven magnets, where new
spin-splitting electronic structures can emerge beyond
equilibrium, an analogous
symmetry theory is still lacking. Here, we develop a Floquet
spin-group theory for optically driven collinear magnets by combining the static
spin group of the
magnetic crystal with the dynamical
symmetry group of the light field. This theory determines the
symmetry-allowed parity, momentum dependence, and nodal structure of light-induced
spin splitting under general periodic driving. We show that odd-, even-, and mixed-parity
spin splittings can be selectively switched within the same material by tailoring the drive
symmetry, accompanied by distinct
symmetry-allowed transport responses. We further uncover higher-order $h$- and $k$-wave Floquet
spin splittings unique to three-dimensional systems. Our work extends
spin-group theory from static magnets to periodically driven systems, providing a general
symmetry principle for engineering light-controlled nonequilibrium
spin-resolved electronic structures.
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All authors Tongshuai Zhu, Zixuan Li, Huaiqiang Wang, Su-Huai Wei, Jiawei Ruan
Chemical Physics
Degradation of Proton Exchange Membrane Water Electrolyzers in Accelerated Stress Tests of Dynamic Load Cycling
Yunyi Zhang, Qingbo Gao, Jiawei Yang et al. (+4 more)
Proton exchange membrane water electrolysis (PEMWE) is a promising technology for harnessing intermittent renewable energy. This study experimentally investigates the degradation of PEMWE under fluctuating power supply, characterized by dynamic load cycling under accelerated stress test (AST). We focus on the effects of key parameters of dynamic loading, including the peak voltage and cycling frequency, in a set of simplified AST protocols designed to represent selected features of dynamic load fluctuations associated with variable renewable-energy operation. The results unveil the intricate relationship between the structural characteristics of the catalyst layer and the electrochemical performance. An elevated peak voltage accelerates the degradation in the initial phase of the AST. However, a low cycling frequency can mitigate the degradation by limiting the rise in various resistance forms, whereas a higher cycling frequency exacerbates the degradation primarily by increasing mass transport resistance, suggesting a frequency-sensitive deterioration of the system's components.
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All authors Yunyi Zhang, Qingbo Gao, Jiawei Yang, Zhen Zeng, Rui Chen, Tianyou Wang, Zhizhao Che