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Wednesday 16 September

Quantum Physics

Exact logical error rates for magic state cultivation

We compute exactly the acceptance and logical error rates for the distance $d=3$ and $d=5$ magic state cultivation circuits from Clifft [arXiv:2604.27058] and SOFT [arXiv:2512.23037] using Pauli propagation and binary tensor contraction. Actual $T$-gates are studied, not the $S$-gate proxy used for sampling. The calculation includes every fault order at several circuit-level noise strengths ($p$). We provide a series expansion form to the logical error rates, through order $(p/(1-p))^{10}$. The analytical results recover the numerical values from Clifft and SOFT at both $d=3$ and $d=5$ to within their sampling uncertainty. Then, we show that the $d=3$ and $d=5$ circuits actually have fault distances of $d_{\text{fault}}=2$ and $d_{\text{fault}}=3$ respectively, explaining the similar distance degrading effects from the companion code of [Quantum 10, 2134 (2026)].
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Mathematical Physics

Wehrl-type entropy problem for compact connected semisimple Lie groups

Let $G$ be a compact connected semisimple Lie group, and let $\pi:G\to U(V_\lambda)$ be a finite-dimensional irreducible unitary representation associated with the highest weight $\lambda$. We prove that coherent projectors are the unique minimizers of the Wehrl entropy over all density matrices on $V_\lambda$. Similar extremal properties hold for power functions in place of the entropy function. The proof uses a second variation at the extremizer by perturbation in directions associated with Killing fields, similar to the strategy of Frank and Lieb used in \cite{FrankLieb}. Then the problem reduces to the uncertainty principle characterizing coherent states. This solves the Wehrl-type entropy problem for arbitrary compact connected semisimple Lie groups.
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Strongly Correlated Electrons · Cross-listed from math.NA

Graph lattice sums and graph zeta functions for long-range interacting quantum lattice models

Taming the exponential increase of the Hilbert space dimension with system size in the simulation of gapped quantum lattice models is of the highest relevance for understanding and designing exotic quantum materials, where nonlocal interactions are of particular interest. High-order linked-cluster expansions provide access the solution of the eigenvalue problem for the infinite system, yet rely on the computation of high-dimensional oscillatory lattice sums with a graph structure, only approachable with Monte Carlo methods so far. This work resolves this issue, rendering all required graph lattice sums, referred to as graph zeta functions for kernels involving power-laws, computable. The resulting method reduces the evaluation time for state-of-the art series expansions from tenthousands of core-hours to minutes. After factorizing the lattice sum over blocks, each block is evaluated by the cheapest available strategy depending on its treewidth $\mathrm{tw}$. Basic blocks admit analytic forms in terms of generalized zeta functions. Series-parallel blocks with $\mathrm{tw}\le 2$ can be computed at linear cost in the number of graph nodes and in the size of the momentum grid using a semi-analytical algebra based on Epstein zeta functions and rapidly decaying Fourier series. Finally, for $\mathrm{tw}>2$, the method is combined with tensor-network bucket elimination yielding polynomial scaling of numerical work and memory in momentum grid size with exponents only growing with $\mathrm{tw}$ rather than with the number of vertices. Through use of FFT, the full momentum grid is recovered at the cost of a single momentum evaluation. We provide a detailed analysis of the precision and runtime of our method against analytic and numerical benchmarks. We further reproduce published Monte Carlo data for the transverse-field Ising model on different 1D, 2D, and 3D lattices, obtaining full agreement.
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Fluid Dynamics

Influence of fluidizing medium on hydrodynamics and particle mixing in a binary fluidized bed: a CFD-DEM study

Three-dimensional CFD-DEM simulations were used to investigate the influence of fluidizing medium on the hydrodynamics and mixing of a binary fluidized bed containing equal-density 3 and 4 mm particles. Water and air were compared using identical geometry, particle properties, and initial conditions over matched normalized superficial velocities of 0.5-3.0 times the minimum fluidization velocity. The numerical framework was validated against published liquid-solid bed-expansion data and benchmarked against an established gas-solid CFD-DEM case. At matched normalized superficial velocities, water fluidization produced a comparatively dense and homogeneous bed with stable bed height and pressure drop and weak velocity fluctuations. Air fluidization resulted in greater expansion, persistent oscillations, void- and bubble-like structures, stronger circulation, and greater spatial heterogeneity. Mixing, quantified using the Lacey mixing index, increased with superficial velocity in both media but developed more rapidly and reached higher levels in air. Particle trajectories and mean-square displacement further showed greater particle mobility and transport in air. The results demonstrate that normalization by the minimum fluidization velocity does not collapse the hydrodynamic or mixing behavior across fluidizing media because fluid properties strongly influence the underlying particle-transport mechanisms.
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Cosmology and Nongalactic Astrophysics

Follow-up of SN 2025wny VI: The Rate and Detectable Population of Strongly Lensed SLSNe-I in ZTF

The Type I superluminous supernova (SLSN-I) SN 2025wny, multiply imaged by two foreground galaxies at $z_l = 0.375$, is the first confirmed strongly lensed SLSN and the highest-redshift ($z_s = 2.015$) multiply imaged supernova in a galaxy-scale configuration. We ask whether one discovery in seven years of Zwicky Transient Facility (ZTF) operations is consistent with expectations, and whether SN 2025wny is typical of the detectable population. We develop a forward simulation of strongly lensed SLSNe-I in ZTF, combining an empirically calibrated volumetric rate and luminosity function with a galaxy-scale deflector population, unresolved lensed light curves, and the actual ZTF observing history. We predict $0.037^{+0.022}_{-0.020}\,{\rm yr}^{-1}$, consistent with the rate of $0.14^{+0.31}_{-0.11}\,{\rm yr}^{-1}$ inferred from a single discovery in seven years of ZTF operations. Conditioning the simulation on discovery by ZTF corrects the magnifications and intrinsic luminosity of SN 2025wny for Malmquist- and magnification biases: the debiased peak bolometric luminosity, $\log_{10}(L_{\rm bol,int}/{\rm erg\,s^{-1}}) = 44.60^{+0.05}_{-0.10}$, places it at the $\sim$97th percentile of the assumed SLSNe-I luminosity function. SN 2025wny is typical of the detectable population in redshift, luminosity, and magnification, but its $4.9''$ image separation exceeds single-galaxy deflector expectations, implying our rates are conservative for wide-separation systems.
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All authors Jacob O. Hjortlund, Edvard Mörtsell, Ariel Goobar, Joel Johansson, Avinash Singh, Alice Townsend, Erin E. Hayes, Maggie L. Li, Steve Schulze, Suhail Dhawan, Jakob Nordin, Aleksandra Bochenek, Chiara Ventura, Conor M. B. Omand, Jacob L. Wise, Jesper Sollerman

Quantum Physics

Hamiltonian engineering via pulses: beyond group averaging

We develop a geometric framework for Hamiltonian engineering in finite-dimensional quantum systems using ideal control pulses. Starting from a bilinear Schrödinger equation with unbounded control amplitudes, we construct the closed pulse group and use extensions of control systems and Filippov's relaxation theorem to obtain a family of effective Hamiltonians given by the convex hull of the drift's adjoint orbit plus the Lie algebra of the pulse group. The geometry of this orbitope describes possibilities beyond group averaging. Using the isotypic decomposition of the adjoint representation, we characterize its affine hull and show that the group average lies in its interior. This yields locally accessible families of effective Hamiltonians around the invariant part of the drift. We apply the framework to recover the necessary and sufficient condition for dynamical decoupling from arbitrary interactions with a finite-dimensional bath. For connected abelian pulse groups, we describe the relevant representation decomposition through restricted roots. Finally, for qubit networks with identical pairwise couplings, we give a qualitative characterization and quantitative estimation of effective Hamiltonians that can be generated using our framework.
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Quantum Physics

Logarithmic-depth quantum simulation of boson sampling

We show that boson sampling with an arbitrary $m$-mode interferometer and $n\le m$ single-photon inputs can be simulated to inverse-polynomial total-variation error by a logarithmic-depth qubit circuit with polynomially many qubits. The circuit uses Clifford+$T$ gates, arbitrary qubit connectivity, and a single final measurement, and its family is logspace uniform. The key idea is to enlarge the optical system, decompose the resulting transformation into six quadratic shears, and distribute each mode over many submodes. This redistribution permits a fixed local occupation cutoff, after which local basis changes and parallel phase gates give the qubit circuit. Consequently, our result places boson sampling within shallow quantum computation.
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High Energy Physics (Phenomenology)

New Dynamics (?) of $J/\psi J/\psi$ and $\Upsilon\Upsilon$ families from QCD Laplace sum rules at NLO

Motivated by the recent CMS data on a family of $2^{++}$ states from $J/\psi J/\psi$ mass spectrum, we determine the masses of the $2^{++}$ $J/\psi J/\psi$ molecule and $cc\bar c\bar c$ states, by using (for the first time) the two lowest QCD Laplace Sum Rules (LSR) moment-ratios within the standard optimization criteria with respect to the LSR variable $\tau$ and to the QCD continuum threshold $t_c$ implemented by the $R_{P/C}$ requirement that the lowest ground state (Pole) contribution to the LSR is larger than the QCD continuum one. Including factorized NLO perturbative and LO $G^4$ gluon condensates in the OPE, we obtain the the lowest ground state masses: $M^{2^{++}}_{J/\psi J/\psi}=6521(69)$ MeV and $M^{2^{++}}_{cc\bar c \bar c}=6347(99)$ MeV with the couplings\,: $f^{2^{++}}_{J/\psi J/\psi}=96(14)$ keV and $f^{2^{++}}_{cc\bar c \bar c}= 151(29)$ keV normalized as $f_\pi=93$ MeV. The masses of the first radial excitations are :$M^{2^{++}{rad}}_{J/\psi J/\psi}=7987(251 )$ MeV and $M^{2^{++}{rad}}_{cc\bar c \bar c}=7739(221)$ MeV indicating a mass-splitting about $2.5 (M_{\psi(2S)}-M_{J/\psi})$. The decay constants are $f^{2^{++}{rad}}_{J/\psi J/\psi}=248(70)$ keV and: $f^{2^{++}{\rm rad}}_{cc\bar c\bar c}=453(96) $ keV which are (unexpectedly) larger than the lowest ground state ones. These features may indicate some new dynamics compared to ordinary $\bar cc$ states. We extend the analysis to the $0^{++}$ states and to the $\Upsilon\Upsilon$ family where the results are compiled in Tables 2 and 3. We critically review some other QCD spectral sum rules (QSSR) results. We suggest that the X(6600) might be a molecule ground state. Using a two-component mass mixing scheme, the X(6900) and X(7100) might be interpreted as a mixture of the $cc\bar c\bar c$ lowest ground state with its 1st radial excitation via an angle $\theta=5^0$.
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Quantum Physics

Entanglement swapping across a five-node relay in a multiplexed quantum-classical network

Quantum networks are resources for scaling quantum computers and distributed sensing technologies while offering post-quantum security benefits. Teleporting non-classical resources like entanglement, via so called entanglement swapping, is essential for networks in particular overcoming rate-loss limits via quantum repeaters. Deploying these systems on real infrastructure will likely require multiplexing photonic qubits into fibers carrying 'classical' light encoding standard Internet communications and control plane signals for multi-node quantum protocols. Here, we report the first demonstration of entanglement swapping and conventional communications operating over the same fibers. Entanglement is swapped across a five-node quantum relay topology connected by four long-distance fibers, each populated with classical data signals. Time-bin entangled photons in the C-band are multiplexed alongside C-band classical signals using dense-wavelength division multiplexing, introducing noise photons generated by high-power classical light. We experimentally and theoretically characterize the trade-off between quantum fidelity and Raman noise photons. Entanglement swapping is demonstrated over a maximum fiber length of 40 km (four 10-km fibers) while simultaneously transmitting 10-Gbps classical data through all fibers. These results represent a significant advancement in the demonstrated complexity of coexisting quantum and classical networks and provide a roadmap for achieving the widespread deployment of advanced quantum technologies.
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All authors Andrew R. Cameron, Jordan M. Thomas, Alexandru Macridin, Si Xie, Raju Valivarthi, Soumya S. Ghosh, Yerko Muñoz Barros, Neil Sinclair, Panagiotis Spentzouris, Maria Spiropulu, Prem Kumar, Cristián Peña

Astrophysics of Galaxies

Rotational spectroscopy and astronomical search of propane-1-thiol (CH3CH2CH2SH) and propane-2-thiol ((CH3)2CHSH)

This study focuses on propanethiol (or propyl mercaptan, C3H7SH), a sulfur analogue of propanol and a key target for investigating interstellar sulfur chemistry. We report the laboratory rotational spectroscopic characterization of its two structural isomers, propane-1-thiol (1PT) and propane-2-thiol (2PT). For 1PT, experimental analysis led to the observation of three almost isoenergetic conformers, Aa,Ag and Gg, marking the first-time report of the latter. For 2PT, both the anti and gauche conformers were identified. We also assigned, for the first time, several monosubstituted isotopologues in natural abundance: the 34S, 13C1, and 13C2 species for the anti-2PT conformer, as well as the 34S species for the gauche-2PT conformer.Resolvable tunneling splitting, caused by the large-amplitude motion of the sulfhydryl (SH) group, was observed for both the Ag-1PT and gauche-2PT conformers. Global fittings, integrating previous measurements, allowed for the accurate determination of rotational constants, quartic centrifugal distortion constants, and vibrational coupling parameters. The newly derived spectroscopic parameters were utilized to conduct an astronomical search toward the chemically rich Galactic Center molecular cloud G+0.693-0.027. While no evidence for propanethiol was found, we established rigorous upper limits for their column densities. These results indicate that 1PT and 2PT are approximately 13 and 5 times less abundant than ethanethiol in this source, respectively. Furthermore, the derived lower limit for the O/S ratio (29) for the 1-propanol/1-propanethiol pair is consistent with the solar value (37), proviiding a valuable benchmark for understanding the depletion of sulfur in the ISM.
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All authors Wentao Song, Assimo Maris, Victor M. Rivilla, Miguel Sanz-Novo, Izaskun Jimenez-Serra, Luca Evangelisti, Sonia Melandri

Solar and Stellar Astrophysics

A large shell around the hypergiant VY Canis Majoris

We report the detection of a remarkable shell around the red hypergiant VY CMa using data from the Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer (SPHEREx). The shell, which in projection on the plane of the sky appears as a ring, is almost circular in appearance. It has an external diameter of $\sim14'$ to $15'$, and is seen most clearly in the SPHEREx 7827A spectro-photometric image. Filaments, radially aligned with VY CMa, are seen to cut across the shell in several places. We discuss the possibility that the shell is matter swept out from the neighboring star forming region Sh 2-310, by the wind from VY CMa. Resonant atomic scattering, a light echo, or Extended Red Emission are explored as the source of the observed SPHEREx emission. However, no interpretation is without difficulty and further observations are most desirable.
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All authors D. P. K. Banerjee, V. Joshi, A. Evans A. A. Djupvik, Ken Hall, F.-J. Hambsch S. Sharma, G. Rangwal, A. Devaraj, T. R. Geballe, L. Izzo, T. Liimets, T. Schaeffer, S. Starrfield, C. E. Woodward

2609.18895 · 16 Sep · This paper is being withdrawn as we have been informed by Dr Viraj Karambelkar (Columbia University) and colleagues that the ring we have reported around VY CMa is an artifact. The results reported in our paper are therefore invalid. We are very grateful to Dr Karambelkar for drawing our attention to this matter in a timely fashion

High Energy Physics (Phenomenology)

Transverse Tau Spin Correlations and the Weak Electric Dipole Moment at Future $Z$ Factories

Tau spin correlations at the $Z$ pole probe CP violation with a sensitivity that depends strongly on the spin projection. For a fixed $Z$ sample, transverse moments avoid the chirality suppression of longitudinal and triple-product observables, enhancing the response by a factor $m_Z/2m_\tau=26$. Two transverse moments also select the axial tau charge, gaining $|a_\tau/v_\tau|=13.5$; the sign-weighted normal moment has a response $521$ times that of the triple product. These two transverse moments give single-parameter uncertainties no more than $14\%$ above our calculated Cramer-Rao bound for independent single-pion measurements, approaching the best precision within this analysis. A five-moment fit with $5\%$ off-peak luminosity yields statistical uncertainties of $4.5 (5.5)\times10^{-7}$ and $2.7 (3.2)\times10^{-6}$ on $\operatorname{Re}\widetilde{d}_\tau^W$ and $\operatorname{Im}\widetilde{d}_\tau^W$, respectively, at FCC-ee (CEPC), improving on ALEPH by three orders of magnitude. The electromagnetic-dipole uncertainty is $9.6 (12)\times10^{-6}$ on $\operatorname{Re}\widetilde{d}_\tau^\gamma$, two orders beyond Belle. These projections assume ideal angular reconstruction and constant form factors across the scan.
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All authors Xin-Yu Du, Zi-Yue Zou, Xiao-Gang He, Keping Xie

High Energy Physics (Phenomenology)

Addressing the $S$-wave scalar $f_0(1500)$-resonance in quasi-four-body FCNC rare $B_s \to f_0(1500) (\to \pi^+ \pi^- ) \ell^+ \ell^- / \nu \bar \nu$ decays

The $f_0(1500)$ is a quite special resonance in the light scalar spectrum. Compared with other nearby resonance, it has an unexpectedly narrow decay width. Since its mass region overlaps strongly with $f_0(1370)$ and $f_0(980)$, physicists have long debated its internal structure. To explore this issue, this work adopted the conventional quark-antiquark $q\bar{q}$ picture and investigated the behavior of the $f_0(1500)$-resonance in quasi-four-body decay channels. Based on this, we constructed a twist-2 light-cone distribution amplitude(LCDA) schemes based on the light-cone harmonic oscillator model, and presented their moments $\langle \xi ^n _{2;f_0(1500)} \rangle |_\mu$ and Gegenbauer moments $a_{n;f_0(1500)}(\mu)$ at $\mu_0=1~\mathrm{GeV}$ and $\mu_k= 3~\mathrm{GeV}$ for $n=1,3,5$. Meanwhile, the $B_s\to f_0(1500)$ transition form factors (TFFs) are calculated by using the QCD light-cone sum rule. Then, we obtained the three TFFs at large recoil point, i.e., $f_ + ^{B_s f_0(1500)}(0)= 0.390_{-0.046}^{ + 0.047}$, $f_-^{B_s f_0(1500)}(0)= -0.460_{-0.055}^{ + 0.051}$, and $f_{\rm T}^{B_s f_0(1500)}(0)= 0.568^{ + 0.069}_{-0.065}$. In addition, we extrapolated TFFs to the whole physical $q^2$-region by using the simplified $z(q^2)$-series expansion. Then we computed the branching fractions of the quasi-four-body rare decays $B_s \to f_0(1500)(\to \pi^ + \pi^-)\ell^ + \ell^-$ and $B_s \to f_0(1500)(\to \pi^ + \pi^-)\nu\bar{\nu}$. For comparison, we also present the results of the corresponding three-body decays obtained under the narrow-width approximation. Finally, we show the distribution of the double-differential decay width $d^2\Gamma/ds dq^2$ for the quasi-four-body decay $B_s\to f_0(1500)(\to\pi^ + \pi^-)\mu^ + \mu^-$. We hope that our predictions can provide a useful theoretical reference for future experimental measurements and phenomenological research.
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All authors Xue Zheng, Hai-Bing Fu, Dan-Dan Hu, Jing-Kai Yang, Jian-Qi Chen, Wan-Bing Luo

Quantum Physics

Zero bias field selective transition adressing of the NV center via pulse shaping

Nitrogen-vacancy (NV) centers in diamond are a leading platform for vector magnetometry, offering intrinsic sensitivity to both the magnitude and direction of magnetic fields. NV magnetometers typically rely on an external bias field to lift the degeneracy of the ground-state spin sublevels, enabling spectral discrimination of different NV orientations and spin transitions. At high accuracy, however, such a bias field systematically introduces errors through thermal, mechanical, and hysteretic drifts, thus hindering the accurate measurement of the magnetic field of interest. Several strategies have been proposed to address this limitation, including optical polarization-based orientation labeling, optical anisotropy, strong coupling to nearby nuclear spins, circular microwave polarization, and tailored pulse sequences. In this work, we introduce an optimization-based pulse-shaping control framework that enables selective and robust manipulation of NV ensembles without relying on a static bias field. Our method achieves both orientation-selective and subspace-selective control through optimal temporal modulation of the driving fields, providing a route to resolving spectral overlaps in degenerate NV systems.
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Mathematical Physics · Cross-listed from math.PR

Facilitated Exclusion Process in Higher Dimensions: Recurrent Structure and Transient Dynamics

In this article, we study the facilitated exclusion process (FEP) on the $d$-dimensional discrete torus of side length $N$, with $d\ge2$. For Bernoulli initial data with a fixed density $\rho\in(0,1)$, we first prove that, with high probability, the particle-number sector selected by the initial configuration has a unique active recurrent class if $\rho>1-2^{-d}$ and multiple recurrent classes if $\rho<1-2^{-d}$. We then show that, for sufficiently small $\rho$, the process reaches an absorbing state (a singleton recurrent class) within a poly-logarithmic time in $N$ with high probability. In contrast, for $\rho\in(1/2,3/4)$ and even $N$, we establish a polynomial lower bound on the time required to reach the recurrent set. These results provide strong evidence for a double phase transition, analogous to absorbing-state phase transitions in the contact process, activated random walks, and stochastic sandpiles. To our knowledge, these are the first rigorous estimates for absorption and transient times for the FEP in dimensions two and higher.
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High Energy Physics (Theory)

The Geometry of the CKM matrix, the Standard Model and RG fixed points

We investigate the geometry of the Fermion mixing matrix in the Standard Model. The principal structure studied is the CKM matrix, $V$, viewed as an element of the double coset space $M$, where $M=T\backslash SU(3)/T$, and $T=U(1)\times U(1)$. The space $M$ is given a Riemannian metric, and has both point singularities, which it is shown correspond to the known renormalization group fixed points, and line singularities connecting the fixed points. A key discrete object inducing many of these properties is the Weyl group, $W$, of $SU(3)$, $W$ being the symmetric group $S_3$, which appears in the guise of the vertices of a hexagon in $V$.
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Plasma Physics

Helicon wave propagation, plasma generation and interaction with low-frequency waves in toroidal magnetic configurations

Helicon waves are widely used for efficient plasma production in low-temperature devices and have recently attracted attention as a candidate for current drive in fusion plasmas. Yet experimental investigations of helicon waves in toroidal geometries, and of their interaction with plasma dynamics, remain extremely limited. In this work, we present, to our knowledge, the first detailed experimental characterization of helicon waves in a toroidal configuration. A birdcage resonant antenna operating at 13.56 MHz is used to launch helicon waves in the toroidal basic plasma physics device TORPEX, either into a pre-existing magnetron-generated plasma, or as the plasma source. Measurements are performed in pure toroidal and simple magnetized torus magnetic configurations, for both argon and hydrogen plasmas. Three-axis magnetic probe measurements enable clear identification of a dominant m=+1 helicon mode over our parameter space. The helicon amplitude is found to scale linearly with the antenna power, and decreases with the confining magnetic field amplitude. As the antenna power is increased the helicon amplitude exhibits a saturation, correlated with enhanced low-frequency fluctuations and turbulent transport. In addition, a strong interaction between helicon waves and low-frequency density fluctuations is observed, revealing a non-linear coupling between RF waves and plasma turbulence. These results provide the first detailed experimental characterization of helicon waves in a toroidal low-temperature plasma device and establish TORPEX as a unique testbed for studying toroidal helicon wave physics under controlled and well-diagnosed conditions.
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All authors Simon P. H. Vincent, Mounir Alfazzaa, Patrick Quigley, Cyrille Sepulchre, Philippe Guittienne, Rémy Jacquier, Marcelo Baquero-Ruiz, Ivo Furno

Statistical Mechanics

Hierarchy of time scales in kinetically constrained models via stochastic-generator expansion

We revisit the hierarchy of relaxation time scales in stochastic kinetically constrained models (KCMs) obeying detailed balance, using an expansion method developed recently for their quantum counterparts. In the classical setting, we expand the stochastic generator in the low-temperature equilibrium concentration of excitations. As in quantum KCMs, successive truncations of the expansion reveal a nested hierarchy of metastable configurations that remain frozen on progressively longer time scales. Applying the method to the high-to-low temperature quench in the classical one-dimensional East and Fredrickson-Andersen models, we recover the known hierarchy of metastable plateaus and the associated perturbative time scales. We find that the hierarchical time scales are related to the smallest domain lengths. Our results show that the method developed for quantum kinetically constrained models can be used to provide a systematic description of slow relaxation in their classical counterparts as well.
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Solar and Stellar Astrophysics

Interferometric Survey of Stellar Parameters: Limb darkening study with the "Pipeline for Interferometric Measurements of Stars"

Accurate and unbiased determination of stellar parameters is of importance in many astrophysical domains. We therefore present an improved method to estimate stellar parameters, based on interferometric observations and stellar atmosphere models, as well as spectroscopic and photometric data. The fundamental stellar parameters were estimated by fitting a model of intensity profiles to interferometric data over a large spectral window and combining them with spectroscopic and photometric observations as an additional constraint on the fitting. Based on stellar atmosphere models, we have developed an algorithm that trains artificial neural networks (ANNs) to estimate the spectrum and intensity profile of a star over three bands: R, H, and K. The ANNs cover effective temperatures (Teff) ranging from 4500-7000 K for dwarf stars and 2500-8000 K for giant stars, with surface gravities (log g) ranging from 3.0-5.0 dex and -0.5-3.5 dex, respectively, and 12 viewing angles. As a result, consistent and precise stellar parameters, such as Teff, log g, and angular diameter ($\theta$), can be estimated. We fitted $\iota$ Psc (F7V) and $\delta$ Ari (G9.5IIIb) observed with SPICA, MIRC-X, and MYSTIC at the CHARA Array, and archival data of $\alpha$ Cen A and B (G2V and K1V) from VLTI/PIONIER with PIMS. For angular diameter estimations, when fitting with a one-dimensional stellar atmosphere model, we reached a precision of 0.5%. For Teff and radius, we obtained a precision of approximately 1%, while we obtained a precision of 5% for log g. Through evolutionary models, we further show how these constraints can improve the mass and age determination, as they attain a precision of approximately 2% for mass and 5-10% for age.
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All authors N. Ebrahimkutty, D. Mourard, P. Berio, O. Creevey, A. Domiciano de Souza, K. Lee, T. Morel, B. Plez, D. Salabert, N. Anugu, R. V. Ibañez Bustos, J. Jonák, H. Nowacki, M. Vrard, J. Dejonghe, F. Morand, N. Nardetto, A. Meilland, K. Perraut, M. Wittkowski, J. Monnier, S. Kraus, M. Gutierrez, N. Ibrahim

Quantum Physics

Liouvillian exceptional points in the emergence of quantum synchronization

The coupling between self-sustained oscillators, such as lasers or polariton condensates, leads to different steady-states in different regimes. Weak coupling allows the oscillators to behave independently, with different frequencies and uncorrelated phases, while stronger coupling can produce synchronization. In classical or semiclassical theories transitions between these steady-states correspond to changes in the topology of the phase space attractors and occur at generalized exceptional points. We investigate the corresponding changes in a quantum theory of coupled lasers or condensates. We show how the different steady-state regimes of the classical limit give rise to distinct forms for the spectra and eigenmatrices of the slow modes of the Liouvillian. By following the spectral flow between the different regimes we show that the synchronization transition is controlled by cascades of exceptional points in these slow modes, protected by a generalized PT symmetry. Our results show how singularities of the quantum Liouvillian control the different dynamical regimes, and give rise to experimental signatures of the synchronization transition which remain well-defined in the few-particle regime dominated by quantum effects.
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Quantum Physics

Quantum Behaviors Are Not Semialgebraic

The conditional probabilities achievable by local measurements on a shared quantum state in a Bell scenario form the set of quantum behaviors, whose structure was studied by Tsirelson. In 1993, Tsirelson asked whether this set is semialgebraic, that is, describable by finite Boolean combinations of polynomial equations and inequalities. This question has remained open. We answer it in the negative: with four binary measurements per party, the set of finite-dimensional quantum behaviors, its closure, and the commuting-operator set are all nonsemialgebraic. More strongly, none admits a finite real-analytic description even locally near a particular classical behavior. These results rule out exact finite semidefinite representations and show that no finite level of the Navascués-Pironio-Acín hierarchy characterizes these sets exactly.
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Materials Science · Cross-listed from cs.LG

Physics-based prediction, uncertainty quantification and decision-making for IN718 crystallographic texture intensity across LPBF defocus regimes

Reliable prediction of crystallographic texture in laser powder bed fusion is critical for linking process conditions with anisotropic response and for qualification. However, black-box models may fail under shift and cannot distinguish weak data support from loss of physical validity. This study develops a two-stage physics-based model for <001> || BD (build direction) texture in Inconel 718. Stage 1 maps process variables to melting mode and melt pool geometry. Stage 2 predicts texture by combining an empirical physics model with a random-forest residual model. A k-nearest-neighbor weight attenuates residual corrections for poorly supported queries, while a study-specific areal beam-power-density criterion withholds predictions outside the adopted conduction envelope. Conformal intervals are evaluated on the retained physics-valid set, and SHAP and Sobol analyses assess residual sensitivity. Under a controlled leave-one-defocus-out evaluation, the physics anchor achieved R^2 = 0.778, against -0.001 for the black-box model and 0.750 for the gated hybrid. Under leave-one-group-out cross-validation, the gated hybrid reached R^2 = 0.592 against 0.538 for the black-box model. Retained-set coverage was 92.9% at a mean full width of 3.65 multiples of a uniform distribution (MUD) under grouped cross-validation and 100% at a width of 3.21 MUD under transfer to a withheld +80 mm defocus regime. An illustrative mapping produced a retained BD elastic-modulus span of 127-187 GPa. On nine conditions from a separately built sample set, the framework withheld three, attenuated three, and matched the measured ordering for the rest. Separating data applicability, physics validity, and predictive uncertainty into distinct decisions lets the framework transfer where an unconstrained model does not, and withhold predictions where no model class performs adequately.
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All authors Yisheng Lu, John Riris, Jie Song, Yao Fu, Jie Chen

Atmospheric and Oceanic Physics

"La Ola-MJO": a public-friendly nickname for the Madden-Julian Oscillation

The Madden-Julian Oscillation (MJO) is the leading intraseasonal driver of tropical weather, comparable to the interannual ”El Niño/La Niña”, yet remains largely unfamiliar outside the scientific community. The MJO is atmospherically like a ”La Niña” going around the earth, and metaphorically as ”La Ola”, Spanish for ”The Wave”, evoking a stadium wave. Thus a pedagogical nickname such as ”La Ola-MJO” could enhance forecast uptake, especially among climate-vulnerable communities.
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All authors Takeshi Izumo, Bastien Pagli, Claire Rocuet, Mayalen Zubia, Marania Hopuare, Vateanui Sansine, Maxime Colin

Fluid Dynamics · Cross-listed from math.NA

A numerical benchmark for fluid–structure–contact interaction

We propose a two-dimensional benchmark for fluid-structure-contact interaction consisting of a deformable elastic disk falling under gravity within a viscous incompressible fluid and rebounding in the vicinity of the bottom wall. Solid deformability is essential, as rigid solids do not rebound in this framework. Besides this, the setting is deliberately kept simple to facilitate reproduction. The configuration is particularly challenging due to the well-known no-contact paradox, which can lead to a contactless rebound and forces numerical methods to resolve a vanishingly thin fluid layer in the near-contact region, making the dynamics highly sensitive to the spatial and temporal discretizations. In addition to no-slip boundary and interface conditions, a reduced porous modeling of surface roughness, either on the disk boundary or on the bottom wall, is also considered; this circumvents the no-contact paradox and enables genuine contact. An energy balance law is derived theoretically for all three cases. Eight numerical methodologies, developed by five research groups and spanning different model formulations, numerical methods, and codes (including both fitted and unfitted discretizations), are applied to the benchmark at several levels of spatial and temporal refinement. Quantities of interest of varying complexity are collected and compared, showing close agreement during the falling phase and increased sensitivity in the near-contact and rebound regimes. The setting and the results provide a suitable reference for the systematic assessment of fluid-structure-contact interaction solvers. The time histories of all quantities of interest for every approach and refinement level are provided as supplementary material.
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All authors Daniele Corti, Jakub Fara, Miguel Angel Fernández, Stefan Frei, Tobias Knoke, Sebastian Schwarzacher, Karel Tůma, Thomas Wick

Statistical Mechanics

Current fluctuations of diffusive systems with a battery

For a diffusive system on a ring, with a battery at the origin, we use the macroscopic fluctuation theory (MFT) to obtain the large deviation function of the current. In the case of non-interacting particles, the predictions of the MFT agree with the result of a direct exact microscopic calculation. To our surprise, the large deviation function of non-interacting particles with a battery has the same form as for the Symmetric Simple Exclusion Process (SSEP) with open boundary conditions. For the SSEP on a ring with a battery, the predictions of the MFT seem to agree with the results of long Monte Carlo simulations, although much longer simulations would be needed to better test the validity of these predictions.
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Materials Science

Epitaxial inversion of spontaneous polarization in {\epsilon}-Ga2O3

Polar wide bandgap semiconductors offer the unique capability to manipulate internal electric fields and induce two-dimensional electron gases (2DEG). The emerging orthorhombic {\epsilon}-Ga2O3 is a promising candidate owing to its large spontaneous polarization (Psp). However, exploiting this material is hindered by fundamental ambiguities surrounding its absolute Psp vectors and the inability to govern its epitaxial direction. Here we show the resolution of the absolute Psp vectors in {\epsilon}-Ga2O3 and control of its macroscopic polarity via substrate engineering. By correlating interferometric piezoresponse with atomic configurations, we establish an identification criterion where opposing polarities are assigned through the geometric elevation within an asymmetric four-atom sequence. Guided by this signature, we demonstrate that epitaxy on Al-polar AlN and sapphire yields uniformly Ga-polar (upward Psp) and O-polar (downward Psp) architectures, respectively, whereas deteriorated crystallinity disrupts this registry and triggers mixed-polarity. This atomic-to-macroscopic correlation eliminates long-standing ambiguities regarding absolute polar orientations in non-centrosymmetric oxides. Analogous to mature III-Nitride architectures, this blueprint provides the foundational platform for designing macroscopic polarization discontinuities at heterointerfaces, unlocking {\epsilon}-Ga2O3 for advanced polarization electronics.
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All authors Yan Wang, Zhigao Xie, Weihua Tang, Chee Keong Tan

Statistical Mechanics

A first introduction to Matrix Product State algorithms for the integration of Lindblad equation

In this introductory review, we present and compare four algorithms for the numerical integration of the Lindblad equation for one-dimensional quantum lattice systems. All four methods are based on Matrix Product State representations and can be viewed as extensions of the Time-Evolving Block Decimation (TEBD) algorithm to open quantum systems. Two approaches directly integrate the vectorized Lindblad equation, one of them explicitly enforcing the positivity of the density matrix. The other two rely on stochastic unravelings of the Lindblad equation, namely the quantum trajectory and quantum state diffusion approaches. We discuss the principles, numerical implementation, accuracy, and computational efficiency of the different methods, and benchmark them against an exactly solvable free fermion model.
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Classical Physics · Cross-listed from eess.SP

From Multimode Near-Field Coupling to Friis

Near-field propagation between finite apertures can support multiple spatial channels, while far-field transmission is effectively single mode and follows the Friis transmission formula. This letter establishes a direct connection between these two regimes through the mutual shadow area between the transmitting and receiving apertures. The mutual shadow determines the asymptotic number of spatial degrees of freedom and, in the paraxial regime, leads to a simple beamforming distance that provides a characteristic scale for the transition from multimode to effectively single-mode propagation. The channel singular-value sum rule further shows that, below this distance, increasing separation primarily reduces the number of supported spatial channels while their average normalized strength remains approximately constant. Beyond the transition, the remaining channel strength decreases according to the conventional free-space quadratic power law, recovering the Friis transmission formula. Numerical results for circular apertures demonstrate the transition, the scaling with aperture size, and the dependence on the transmitter and receiver apertures. The mutual-shadow formulation also extends the description beyond the paraxial regime.
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High Energy Physics (Theory)

Auxiliary Field Deformations of the Lambda Model

Many examples of integrable sigma models admit families of integrable deformations that involve coupling the undeformed “seed” theory to auxiliary fields with algebraic equations of motion. In this work, we apply this paradigm to the case where the seed theory is the lambda model, which interpolates between the Wess-Zumino-Witten model and the non-Abelian T-dual of the principal chiral model. We present an auxiliary field deformation of the lambda model and exhibit a Lax connection whose flatness is equivalent to the remaining equations of motion after imposing the algebraic field equations. We also carry out a Hamiltonian analysis of the deformed theory, verifying that it obeys the assumptions of theorems in arXiv:2605.18213 which guarantee both (i) that the model enjoys the Maillet structure that ensures involution of its conserved charges, and (ii) that the theory possesses a classical Yangian. Thus, as in other cases, the auxiliary field deformation of the lambda model changes its classical dynamics while leaving the integrable structure essentially unchanged.
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Lattice Field Theory

The soft-gluon limit of the Landau gauge ghost-gluon vertex: results for pure Yang-Mills SU(3) theory from lattice simulations

This work reports on the computation of the ghost-gluon vertex for the pure Yang-Mills SU(3) gauge group, using lattice simulations and the Landau gauge. The simulations access only one of the form factors that describes the vertex. The form factor is estimated using large statistical ensembles of gauge configurations, with two different lattice spacings and two different volumes to check for finite size effects. Moreover, the calculation shows the importance of using lattice perturbation theory, instead of its continuum version, to correct for the breaking of rotational symmetry. The measured bare lattice form factors are compatible, within errors, for all the ensembles. The form factor has a maximum at momentum $\sim 1$ GeV, is suppressed in the infrared and is compatible with a constant behaviour at high momenta, in good agreement with the corresponding lattice estimations for the SU(2) gauge group.
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