Strongly Correlated Electrons
Hidden Magnetic Complexity Within a Simple van der Waals Ferromagnet Ce$_2$Te$_5$
Rajesh Tripathi, D. T. Adroja, C. Ritter et al. (+10 more)
Ce$_2$Te$_5$ is a layered $f$-electron van der Waals magnet in which reduced dimensionality and inequivalent Ce sites give rise to competing
magnetic interactions. We investigate its
magnetic ground state using
muon spin relaxation ($\mu$SR),
neutron powder diffraction (NPD), and inelastic
neutron scattering (INS). Zero-field $\mu$SR reveals an onset of static magnetism below $T_{\mathrm{C}} = 5.0(1)$~K, followed by an additional anomaly in the internal field at $T_{\mathrm{2}} = 2.3(2)$~K, consistent with features observed in bulk thermodynamic and transport measurements. In contrast, NPD data collected between $0.05-8$~K reveal a single long-range ordered
magnetic phase below $T_{\mathrm C}$, with the
magnetic Bragg intensities vanishing at $T_{\mathrm C}$ with no evidence for additional structural or
magnetic phase transitions down to base temperature. The ordered state is characterized by a commensurate propagation vector $\mathbf{k}=(0,0,0)$ and
ferromagnetic alignment of Ce moments along the crystallographic $b$ axis. Remarkably, only one of the two crystallographically distinct Ce sites carries an ordered moment of $\sim 0.85(3)~\mu_{\mathrm B}$ per Ce at 0.05~K. INS measurements establish the
crystal electric field (CEF) energy scale of Ce$^{3+}$, revealing low-lying excitations at 7.94 and 21.46~meV and a Kramers doublet ground state with strong single-ion anisotropy. These results demonstrate that Ce$_2$Te$_5$ undergoes a single
symmetry-breaking
magnetic transition, while additional low-temperature anomalies reflect subtle modifications of the ordered state driven by competing interactions and CEF effects.
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All authors Rajesh Tripathi, D. T. Adroja, C. Ritter, Leandro Liborio, Manuel dos Santos Dias, Leon Petit, D. Khalyavin, Yu Liu, T. Shiroka, M. Aouane, S. Langridge, S. Patil, Eric D. Bauer
Mathematical Physics
The Robust Ten Martini Problem
Lingrui Ge, Svetlana Jitomirskaya and Jiangong You
We solve the robust ten martini problem: Cantor spectrum with no arithmetic restriction on the irrational frequency for Type I analytic one-frequency quasiperiodic Schrodinger operators. We introduce Type I through a new acceleration-type quantity with stability under analytic perturbations. This yields a global open class of analytic potentials whose associated operators have Cantor spectrum for every irrational frequency.
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High Energy Physics (Phenomenology)
Existence of a second phase transition in A-A collisions at energies available at the CERN Large Hadron Collider: A physical interpretation
C. Pajares, R. P. Scharenberg and B. K. Srivastava
The observed fluid behavior of the matter produced in heavy ion and $pp$ collisions implies that the strings stretched between the constituents of the projectile and target should have a hard core giving rise to a repulsion between them. It is shown that in these collisions there are two critical string densities, one corresponding to the well studied percolation of strings and another to the percolation of the hard core of the strings. These two critical densities are related to two critical temperatures, one T $\sim $ 160 MeV would correspond to the restoration of
chiral symmetry and partial deconfinement and a second transition T $\sim $ 220 MeV form the fluid behavior of QCD matter strongly interacting to a quasi free gas of
quarks and
gluons. This argument is supported by the recently published results on the sudden increase in the degrees of freedom above the deconfinement temperature in pp and A-A collisions.
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Solar and Stellar Astrophysics
Multi-chromatic observations of classical Cepheids using the CHARA Array interferometer: Surface brightness-colour relation, projection factor, and limb-darkening
M. C. Bailleul, N. Nardetto, D. Mourard et al. (+28 more)
The Baade-Wesselink (BW) method compares the linear and angular variations of Cepheids to derive their distance. This method is limited, however, by the projection factor, which relates the observed radial velocity to the true pulsation velocity of the
star. Using simultaneous observations from the CHARA Array interferometer in the K, H, and R bands with the MYSTIC, MIRC-X, and SPICA combiners, respectively, we aim to understand the physics of Cepheid atmospheres better. Applying a specific method to multi-chromatic simultaneous interferometric observations of Cepheids, we derived robust limb-darkened angular diameters that were then used to calibrate the SBCR and study the projection factor. We also developed a strategy to measure the limb-darkening of Cepheids in R, H, and K bands. These measurements were then used to constrain the geometrical component of the projection factor. From the limb-darkened angular diameter curves of three Cepheids, we decreased the scatter of the SBCR in $V-K$ colour to 0.0011 magnitude and to 0.0040 for the SBCR in $G_{BP}-G_{RP}$. These SBCRs are particularly robust because they are based on multi-chromatic diameters and are homogeneous, which previous calibrations for Cepheids were not. For the very first time, we derived the limb-darkening of Cepheids in R, H, and K bands. For $\delta$ Cep, we derived an R-based projection factor of $1.275 \pm 0.051$, and the geometrical part obtained from the measured limb-darkening coefficient in R band was estimated to $1.420 \pm 0.016$ (on average), as expected from
stellar static and hydrodynamical atmosphere models. The limb-darkening coefficients obtained in H and K band are consistent with models. These results demonstrate that multi-chromatic interferometry can improve the accuracy of the BW method. It is therefore essential to continue the CHARA survey of Cepheids in the coming years.
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All authors M. C. Bailleul, N. Nardetto, D. Mourard, A. Mérand, P. Kervella, A. Gallenne, G. Bras, J. Monnier, K. Sivkova, B. Apostolova, L. Breuval, W. Kiviaho, W. Gieren, V. Hocdé, R. S. Rathour, G. Pietrzyński, P. Bério, F. Morand, D. Salabert, J. Jones, C. Lanthermann, N. Ebrahimkutty, J. Jonàk, H. Nowacki, R. V. Ibañez Bustos, M. Vrard, S. Kraus, N. Anugu, M. Gutierrez, N. Ibrahim, T. Gardner
Physics and Society
Penalized Maximum Likelihood Inference of Core-Periphery Networks
Antonio Mosca and Piero Mazzarisi
Likelihood-based network models are often fitted under links' independence and low-order constraints, while empirical networks frequently exhibit systematic higher-order structures such as triangles and wedges, characterizing the observed clustering patterns. Real-world core-periphery networks such as the interbank
market or the air transportation system represent key examples, with cores displaying complex and nonlinear features. We formalize Penalized Likelihood with Structural Discrepancies (PLSD) as an inference-level correction that trades likelihood fit for agreement with targeted motifs. PLSD augments the negative log-likelihood with a penalty on standardized wedge and triangle discrepancies, yielding a controlled distortion of the likelihood surface that can be interpreted through a linear response analysis. A calibration approach for the unique tuning hyperparameter is introduced to turn off the penalization term when the model is correctly specified, thereby recovering maximum-likelihood estimation in that case. We then introduce a mixed-constraint maximum-
entropy core-periphery Exponential Random Graph Model (ERGM), derive unconditional semi-closed motif formulas under Pareto-distributed core fitness, and interpret sparse-regime scaling through a big-jump mechanism for heavy-tailed distributions. We finally corroborate the PLSD inference methodology both with Monte Carlo simulations of a toy
stochastic block model and by applying the novel core-periphery ERGM to weekly eMID interbank networks (2009-2015) and monthly US air traffic networks (1991-2000). We show that PLSD describes cores that are not only dense but also higher-order-rich and captures the observed heterogeneous degree distributions and the overexpression of wedges and triangles, at a link-level cost proportional to the model misspecification.
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Quantum Physics
Security framework for practical quantum key distribution with imperfect devices
Jerome Wiesemann, John Burniston, Devashish Tupkary et al. (+1 more)
Practical
quantum key distribution (QKD) systems inevitably exhibit imperfections in both the source and detector. At the same time, the behavior of these imperfect devices is never exactly known due to characterization uncertainty, parameter fluctuations, and potential influence by an adversary. In this work, we present a security proof for generic prepare-and-measure QKD protocols, including decoy-state BB84, with imperfect and imperfectly characterized sources and detectors using the marginal-constrained
entropy accumulation
theorem (MEAT). Our approach uses a sequence of proof technique independent source maps and squashing maps, yielding a very modular framework. We show that practical key rates can be achieved even when multiple imperfections are combined. More broadly, our work provides a unified foundation that avoids the need for dedicated protocol-specific arguments and can be readily extended to other protocols and device imperfections.
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All authors Jerome Wiesemann, John Burniston, Devashish Tupkary, Norbert Lütkenhaus
Optics
Fourier modal method for perturbation analysis of bound states in the continuum
Nan Zhang and Ya Yan Lu
Bound states in the continuum (BICs) supported by periodic photonic structures are surrounded by high-$Q$ resonances and serve as centers of polarization
vortices in momentum space, making them attractive for a wide range of applications. Recently, a perturbation theory has been formulated for resonant states near BICs, yielding a hierarchy of equations whose solutions directly approximate the resonant states and determine the asymptotic behavior of their $Q$ factors and polarizations. Efficiently solving these equations is therefore essential. Since many studies of BICs concern layered structures, we develop an approach based on the
Fourier modal method. Numerical examples confirm the effectiveness of the proposed method and demonstrate its ability to capture higher-order asymptotic scaling. Our work provides a practical tool for the theoretical analysis of BICs and may also facilitate the design of BIC-based photonic devices.
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Materials Science
Microstructure-Resolved Impedance Modeling of Solid-State Batteries
Kaniza Islam, Chengyin Wu, Noriko Katsube et al. (+1 more)
Solid-state batteries (SSBs) with solid electrolytes (SEs) are attracting substantial investment from the automotive industry to enable fast-charging and safer next-generation electric vehicles. The microstructure of the SE critically affects the battery performance. Electrochemical impedance spectroscopy (EIS) is a powerful, non-destructive probe of charge-transfer and transport processes within SEs and across electrode/SE interfaces but quantitatively connecting measured impedance spectra to the underlying microstructural features remains an open modeling challenge. Here we present a modeling framework that predicts the microstructure-resolved impedance response of a Li/Li6PS5Cl/Li symmetric
cell. Taking the Li6PS5Cl SE microstructures from phase-field sintering simulations, we find that increasing porosity shifts the Nyquist semicircle to higher impedance while improved inter-particle contact reduces it, and that impedance decreases monotonically as sintering proceeds. We also isolate the effect of solid electrolyte interphase (SEI) formation: grain boundaries raise impedance only slightly, but SEI volume fraction, and the conductivity of each SEI phase (Li2S, Li3P, LiCl), both strongly affect it. A realistic multi-phase SEI increases interfacial impedance by about two orders of magnitude compared with a grain boundary only network. We further demonstrate that the same pipeline can operate directly on experimental micrographs by extracting pixel-level phase information with AI-assisted image
segmentation and using it to predict an impedance spectrum, illustrating a path toward quantitative microstructure-impedance correlations grounded in real, imaged SE microstructures.
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All authors Kaniza Islam, Chengyin Wu, Noriko Katsube, Yanzhou Ji
High Energy Physics (Phenomenology)
Argon as the test of two interpretations of the LZ 248 keV recoil
Howard Baer and Vernon Barger
Argon decides what the LZ 248 keV
recoil is. Read as an excited pseudo-Dirac state dropping to its ground state, the event predicts a
nuclear-
recoil line in argon at |\delta|\,m_\chi/(m_\chi+m_Ar), 336 keV at 200 GeV, at ten times the xenon rate, and the two line positions fix the mass. Read as a ground-state Higgsino lifted by the fastest
halo particles, it predicts no argon events, since the argon threshold exceeds the
halo maximum. The ratio depends only on kinematics and form factors, and the DEAP-3600 data already recorded hold tens of expected events.
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Mesoscale and Nanoscale Physics
Induced superconductivity in selective-area grown SnTe devices
Maarten J.G. Kamphuis, Yoran F.S. Starmans, Pim J.H. Lueb et al. (+9 more)
Topological
superconductors are of high interest for applications in topological
quantum computation. The required topologically superconducting state can be engineered by proximityinducing superconductivity in a topological
insulator. Here, we explore the induced superconductivity in selective-area grown nanowires of the topological crystalline
insulator SnTe on a InP substrate, through TEM/EDX and low-temperature electronic transport studies. The observed superconducting behavior likely originates from indium in the substrate diffusing upwards into the SnTe nanowire, forming a thin layer of InxSn1-xTe at the interface between the nanowire and the substrate. InxSn1-xTe is intrinsically superconducting for indium concentrations above 2%, resulting in superconductivity within the
heterostructure. Little-Parks oscillations are observed in loop-shaped nanowire networks in an out-of-plane
magnetic field. The half-period shift indicative of a topological superconducting state is absent, which is explained by dominant trivial transport channels obscuring any topological signatures.
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All authors Maarten J.G. Kamphuis, Yoran F.S. Starmans, Pim J.H. Lueb, Femke J. Witmans, Marvin M. Jansen-Zilles, Marcel A. Verheijen, Reinoud Lavrijsen, Joost Ridderbos, Fabrizio Nichele, Floris A. Zwanenburg, Erik P.A.M. Bakkers, Alexander Brinkman
Materials Science
How Accurately Can We Describe Spin Crossover?
Angel Albavera-Mata, Daniel Mejía-Rodríguez, Niranjan Govind et al. (+3 more)
The complicated physicochemical properties of metal complexes that exhibit thermal
spin crossover make it difficult for routine electronic structure calculations to yield an accurate transition temperature prediction, $T_{1/2}$. The difficulty lies in the intricate connection between the
spin-crossover energy, which is a molecular spectroscopic property, and $T_{1/2}$, a condensed phase property. Here we show how to obtain
spin-crossover energies systematically by reverse engineering of experimental $T_{1/2}$ data. The protocol is based upon fitting the range separation parameter, $\omega$, in the hybrid LC-$\omega$PBE density functional to reproduce the experimental $T_{1/2}$ values for a series of metal complexes. We provide insights into the sources of variations of at least $\pm 15$ kJ mol$^{-1}$ found from common exchange and correlation functionals by comparing their performance against our reference data. By analysis of the sensitivity of transition temperatures to $\pm 1$ % shifts in the range separation parameter, we determined a typical uncertainty of $\pm 50$ K for them, and a $\pm 2$ kJ mol$^{-1}$ uncertainty in the extracted
spin-crossover energies due to $\pm 1$ % variations of $T_{1/2}$. Lastly, we present results from the high-level, all-electron coupled cluster method for eight of the smaller molecules in the reference data set, and discuss the influence of the truncation of the excitation series upon the
spin state energies.
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All authors Angel Albavera-Mata, Daniel Mejía-Rodríguez, Niranjan Govind, Ajay Panyala, Richard G. Hennig, S.B. Trickey
Materials Science
Proximity-induced charge density waves in a moiré heterobilayer
Christopher T. S. Cheung, Arash A. Mostofi and Johannes Lischner
Twisted heterobilayers of two-dimensional materials have emerged as a platform for studying emergent phases of matter. In this work, we investigate charge density waves (CDW) in a twisted NbSe$_2$/MoSe$_2$
bilayer using first-principles calculations. We observe CDW formation in both layers, even though MoSe$_2$ does not feature a CDW in its monolayer form. Moreover, we find that the CDW is highly non-uniform with filled-center, hollow-center and hexagonal CDWs coexisting in the moiré unit
cells of both layers. We assess different mechanisms of CDW formation in the MoSe$_2$ layer and conclude that the dominant one is the steric repulsion between Se atoms across the van der Waals gap. The strength of this effect is highly sensitive to the interlayer separation, which explains why the CDW amplitude in the MoSe$_2$ layer depends strongly on the local stacking arrangement. Our work demonstrates that novel broken-
symmetry phases can be induced in twisted heterobilayers through proximity effects.
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Nuclear Theory
Ab Initio Emergence and Collapse of Nuclear Collectivity near N = Z = 40
X. C. Cao, C. F. Jiao and R. Z. Hu
We present an ab initio description of the emergence and collapse of enhanced quadrupole collectivity in
nuclei near $N=Z=40$ using multi-shell valence-space
Hamiltonians derived from
chiral two- and three-nucleon forces with the in-medium similarity renormalization group. Projected generator-coordinate calculations with consistently evolved $E2$ operators capture the strong collectivity in $^{80}$Zr and its decrease toward $^{86}$Mo and $^{88}$Ru without empirical effective charges. While the $N,Z=40$ effective single-particle energy gaps remain open, the $1g_{9/2}$–$2d_{5/2}$ spacing is smallest near $^{76}$Sr and $^{80}$Zr, with its variation governed mainly by the
proton-
neutron monopole contribution. The associated occupancies are consistent with quadrupole correlations involving pseudo-SU(3) $pf$ holes and quasi-SU(3) particles. Excluding the occupation of the
proton and
neutron $2d_{5/2}$ from the variational space strongly suppresses the deformation and $B(E2;2_1^+\rightarrow0_1^+)$ in $^{80}$Zr. These results mark a steady step toward ab initio computations of heavy open-shell
nuclei.
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Mesoscale and Nanoscale Physics
Spatiotemporal programming via asymmetric dielectric engineering for nonvolatile 2D optoelectronics
Xiaoguang Luo, Xiaolong Zhang, Honglei Chen et al. (+11 more)
Ambipolar two dimensional (2D)
semiconductors integrated with floating-gate architectures offer a promising platform for nonvolatile, reconfigurable electronics. However, the switching between p-n and n-p junction polarities has conventionally required complex multi-gate designs, hindering the scalability and integration density. Here, we demonstrate a spatiotemporal programming strategy using a dual-floating-gate architecture with a
symmetry broken tunneling dielectric. An asymmetric dielectric stack creates distinct tunneling thresholds for two floating gates, enabling a single input gate to encode spatial doping profiles in the 2D channel via defined voltage pulse sequences. We achieve on demand, nonvolatile, and reversible switching between p-n and n-p configurations with excellent retention and endurance. The reconfigurable homojunction serves as a multifunctional platform for logic encoding, rectification, photodetection, and in sensor computing. This work establishes a design paradigm that replaces spatial input complexity with spatiotemporal programming, paving the way for high-density, multifunctional intelligent hardware.
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All authors Xiaoguang Luo, Xiaolong Zhang, Honglei Chen, Jiaming Wang, Fan Liu, Jiongtao Zhang, Junqiang Zhang, Yihan Yin, Jinpeng Xu, Lei Ying, Renjing Xu, Yingchun Cheng, Xuetao Gan, Wei Huang
Fluid Dynamics
Assessment of wind energy potential of buildings by CFD simulation in dense urban environments - From Case Studies to a Dendrogram-Based Design Framework
David Serero, Loïc Couton, Jean-Denis Parisse et al. (+1 more)
Building-integrated wind turbines (BIWT) remain under-deployed in dense European urban contexts despite their potential contribution to net-zero energy targets. This paper presents a measurement-validated computational fluid dynamics (CFD) framework to identify optimal locations for micro-wind turbines on the envelopes of dense Parisian Haussmannian blocks. The methodology couples a multi-month on-site anemometry campaign on two case-study buildings, a calibrated steady RANS digital twin using the realisable k-$\epsilon$
turbulence model, and the introduction of an architecturally integrated accelerator wing -termed aerofoil -placed at the envelope edge to amplify and stabilise the local flow. Quantitative validation against year-long anemometer records yields a mean absolute percentage error (MAPE) of approximately 18 % and a hit-rate FAC2 above 0.85, meeting the COST 732 acceptance criteria for urban CFD models. On the École Nationale Supérieure d'Architecture Paris-Val-de-Seine (ENSAPVS) case study, the inter-tower configuration produces a directional speed-up factor of 3.4 (95 % CI 3.18-3.62) for the prevailing north-westerly sector at +70 m above ground; the addition of the aerofoil yields a further +13 % local speed-up, equivalent to +44 % in extractable power. A capacity-factor analysis based on the measured Weibull distribution and the Savonius rotor power curve estimates an annual yield of approximately 69 MWh, offsetting around 6 % of the building's annual electricity consumption -a substantially lower but more realistic figure than the cube-of-mean estimate. The findings are synthesised in a decision dendrogram that maps wind-rose typology, building plan, height and implantation onto recommended device families, providing architects and engineers with a transferable design-stage tool.
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All authors David Serero, Loïc Couton, Jean-Denis Parisse, Robert Le Roy
Materials Science
Freestanding Antiferromagnetic Oxide Membranes: Synthesis and Characterization of Cr$_2$O$_3$
Ella Blake, Tiffany C. Wang, Yi Cui et al. (+9 more)
Antiferromagnetic (AFM)
insulators stand out as a promising class of materials for fast switching, energy-efficient
magnon-based technology, but our understanding of how to tune these properties with the
lattice remains limited. As an AFM
insulator with strong magnetoelectric response, Cr$_2$O$_3$ membranes stand out as a promising platform to explore multi-modal tunability via strain. However, fabricating these membranes is challenging due to the scarcity of etchable sacrificial layers with compatible
lattice constants and sufficient surface quality. We address this issue by utilizing La$_{0.7}$Sr$_{0.3}$MnO$_3$ (LSMO) as a sacrificial layer, enabling successful fabrication of millimeter-scale Cr$_2$O$_3$ membranes. Substrate-free characterization reveals that strain due to the
lattice mismatch during growth is released by the formation of small polycrystalline domains, preserving single-crystalline order over ~90% of the membrane area. Bulk-like structural properties are confirmed by transmission electron microscopy, X-ray diffraction, Raman spectroscopy, and second-harmonic generation spectroscopy. Platinum
Hall measurements reveal an above-room-temperature N$\'e$el transition. These results establish Cr$_2$O$_3$ membranes as a viable platform for strain-tuning antiferromagnetism and magnetoelectricity.
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All authors Ella Blake, Tiffany C. Wang, Yi Cui, Minyong Han, Yinchuan Lv, Christopher T. Parzyck, Octave Duros, Yan Che, Matthias C. Hoffmann, Wei-Sheng Lee, Yi Cui, Harold Y. Hwang
Quantum Physics
Low-Depth Initial-State Preparation for Ground-State Energy Estimation of Two-Dimensional Strongly Correlated Systems
Ryo Watanabe and Keisuke Fujii
Quantum algorithms for ground-state energy estimation require initial states with non-negligible fidelity to the ground state. Guided by classical simulations, we design shallow
circuits for the two-dimensional half-filled Hubbard model by first preparing an approximate Heisenberg ground state and then applying charge-fluctuation gates derived directly from the Schrieffer-Wolff (SW) generator. For the Heisenberg model, we demonstrate effective parameter transfer from a $4\times4$
lattice to
lattices up to $10\times10$ without further optimization. We obtain promising lower bounds on the ground-state fidelity using tensor-network simulations, variational Monte Carlo reference states, and estimates of the ground-state energy and singlet gap. Exact $4\times4$ calculations show that the SW gates substantially improve the Hubbard ground-state fidelity of the embedded Heisenberg state. The successful Heisenberg parameter transfer supports the use of these small-
lattice results to design shallow Hubbard
circuits on larger
lattices beyond the reach of classical simulations. For a $10\times10$
lattice, the estimated preparation cost is on the order of $10^5$ $T$ gates, including Clifford+$T$ synthesis, which is well within the megaquop regime. These results offer a route to low-cost initial-state preparation for ground-starongly correlated systems.
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Fluid Dynamics
Deep Koopman Sensing
Nithin Somasekharan, Yadi Cao and Shaowu Pan
Real-time reconstruction of fluid flows from sparse sensor measurements is important for both physical understanding and flow control. When first-principles models are too expensive for online data assimilation (DA), learned reduced-order models provide an efficient alternative, but are commonly optimized for forward prediction rather than state estimation. We propose Deep Koopman Sensing, a data-driven reduced-order DA framework that combines a nonlinear autoencoder with parameter-conditioned linear latent dynamics approximating the Koopman operator. We compare the proposed model with parametric dynamic mode decomposition (pDMD), a multilayer perceptron (MLP), and xLSTM across four
benchmarks: 1D viscous Burgers, 2D flow past a cylinder, 2D dambreak, and 3D flow past a sphere. Our results reveal a marked distinction between
forecasting and sensing: open-loop accuracy does not reliably predict assimilation performance, while Deep Koopman Sensing achieves the lowest assimilation error across all four
benchmarks. More importantly, with an extended Kalman filter, incorporating sensor measurements improves the estimates of both linear latent models across all four
benchmarks, whereas it degrades the nonlinear models, despite their strong open-loop performance. With ensemble filtering, the nonlinear models are no longer degraded by assimilation, while the Koopman model still attains the lowest assimilation error. These results show that latent dynamics should be designed for the downstream estimation task rather than selected solely for forecast accuracy, and demonstrate Koopman-based reduced-order modeling as an effective approach for real-time flow reconstruction from sparse, streaming measurements.
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High Energy Astrophysical Phenomena
Modeling Gamma-Ray Bursts Using CRISP
Leonel Morejon, Therese Paulsen and Karl-Heinz Kampert
Astrophysical
neutrinos are a clear identifier of photohadronic interactions in sources of Ultra-High-Energy
Cosmic Rays (UHECRs). As the Pierre Auger Observatory has shown that UHECRs exhibit a composition heavier than
protons at Earth, we expect that these heavy primaries undergo
nuclear cascades due to photodisintegration in the dense source environments from which they originate. In this contribution, we will derive the
neutrino spectra including those originating from
nuclei undergoing photohadronic interactions. This will be explored in the context of modeling the emission region of a gamma-ray burst. Photohadronic interactions will be modeled using the new framework for
Cosmic Ray
Stochastic Interactions for Propagation (CRISP), which employs an analytic approach to compute the underlying probabilistic description of UHECR interactions.
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Quantum Physics
Optimal entanglement-assisted source coding under a balanced-difference promise
Julius A. Zeiss
Entanglement can reduce the communication required for coding tasks, but establishing the minimum achievable cost is essential to understanding its limits. We address this question in a zero-error source-coding task where Alice receives a word and Bob knows an unordered pair of candidates containing it. Alice does not know the pair and must enable Bob to identify her word without error using shared
entanglement and one classical message. The candidates satisfy a balanced-difference promise: for words in $\mathbb{Z}_q^n$ with $n=q\ell$, each residue modulo $q$ occurs exactly $\ell$ times in their coordinatewise difference. For all integers $q\geq2$ and $\ell\geq1$, we prove that the task requires exactly $n$ messages when $(q-1)\ell$ is even and two messages when it is odd. These minima allow arbitrary finite-dimensional shared states independent of the inputs and arbitrary local measurements. In even parity, this establishes optimality of an existing
entanglement-assisted protocol. In odd parity, an explicit deterministic protocol achieves the optimum of one bit without
entanglement. Our proof combines
Fourier analysis with a combinatorial counting argument to determine the smallest
eigenvalue of the associated graphs. In even parity, this resolves the spectral assertion of Cao et al.'s
Conjecture 6.3 for balanced cyclic generalized Hadamard graphs. Together with an explicit odd-parity bipartition, this determines the
quantum chromatic number as $n$ in even parity and $2$ in odd parity, where the classical chromatic number is also $2$. All lemmas,
theorems, and corollaries are formalized and verified in Lean.
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Earth and Planetary Astrophysics
Thermophysical characterization of the potentially hazardous near-Earth object 2024 YR4
T. G. Müller, E. M. MacLennan, A. Y. Burdanov et al. (+7 more)
The asteroid 2024 YR4 is a potentially hazardous Apollo-type near-Earth object. Its highly eccentric orbit produces close Earth-Moon encounters roughly every 4 years. A collection of light curves, including JWST-NIRCam data, allowed us to constrain the rotation period,
spin pole, and convex shape solutions for the object. We analyzed two sets of JWST-MIRI observations obtained in three filters on 26 March 2025. The extracted photometry reveals rotationally driven thermal flux variations. The combination of a
spin-shape model from light-curve inversion and the absolutely calibrated 3-band MIR light curves is well reproduced by a convex
spin-shape solution with a
spin pole at (l,b) = (232, -11), a sidereal period of 19.4633 min, and axis ratios of a/b ~1.28 and b/c ~1.45. The corresponding equivalent-volume diameter is 60.8 +1.8/-3.6 m (pV= 0.11 +0.05/-0.03, assuming HV = 24.14+/-0.25 mag). A high thermal inertia and low surface roughness are required to explain the observed MIRI data. The near-Earth asteroid thermal model has limited reliability for this object, requiring an extreme beaming parameter >3, whereas the fast-rotating model and a full thermophysical model provide consistent and reliable estimates of the size and albedo. The combination of high eccentricity and high thermal inertia implies seasonal skin depths of up to ~3 m and radiative timescales of weeks to months. Although seasonal heating is negligible for the March 2025 observations because of the near-equator-on viewing geometry, the seasonal Yarkovsky drift is expected to be dominant over the diurnal component and might become measurable during future encounters. Although JWST astrometry from February 2026 rules out any possible impact on the Earth or the Moon for at least 100 years, the
spin, shape, and radiometric constraints presented here provide an important
benchmark for future potentially hazardous objects.
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All authors T. G. Müller, E. M. MacLennan, A. Y. Burdanov, B. J. Holler, A. S. Rivkin, J. de Wit, P. Pravec, M. Micheli, K. Muinonen, D. Farnocchia
Optics
Tailoring complex coupling for efficient synchronization of semiconductor lasers
Nathan Vigne, Amit Pando, Li-Li Ye et al. (+6 more)
A grand challenge for
laser synchronization is the intrinsic frequency disorder. We build an experimental platform for programming the complex coupling coefficients of
semiconductor lasers to promote frequency and phase locking. The coupling amplitude between every pair of
lasers in an array is tuned to scale with their frequency difference. Coupling phases are scanned to meet the phase matching conditions for constructive interference of coupled fields. The minimum coupling budget for global synchronization is significantly reduced, as shown experimentally for three vertical-cavity surface-emitting
lasers with intrinsic frequency detuning. The customized coupling offers an efficient approach to stable synchronization of
semiconductor laser arrays for coherent beam combining.
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All authors Nathan Vigne, Amit Pando, Li-Li Ye, Mehmet Bütün, KyeoReh Lee, Ying-Cheng Lai, Nir Davidson, Fan-Yi Lin, Hui Cao
Mesoscale and Nanoscale Physics
Effects of residual exchange coupling on simultaneously driven spin qubits
Heun Mo Yoo, Tanner M. Janda, Victor Yu et al. (+3 more)
Exchange coupling and microwave drives are widely used control mechanisms for
spin qubits. However, the influence of exchange coupling on microwave-driven
spin dynamics is not fully understood. We report simultaneous drive measurements of two
spin qubits as a function of exchange coupling and drive power. When the Rabi frequency exceeds exchange, we observe a beating pattern in the Rabi oscillations. In the opposite limit, two exchange-split patterns emerge in the Rabi chevrons. We find that these exchange-induced effects are suppressed when the difference in the Rabi frequencies exceeds the exchange coupling. A theoretical model is developed that reproduces the main features in our data.
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All authors Heun Mo Yoo, Tanner M. Janda, Victor Yu, Michael J. Gullans, Adam R. Mills, Jason R. Petta
Cosmology and Nongalactic Astrophysics
Toward Precision Kinetic Sunyaev-Zel'dovich Cosmology—1. The Matter - Momentum Bispectrum at One-Loop Order
Ryan Raikman, James M. Sullivan and Mikhail M. Ivanov
The kinetic Sunyaev-Zeldovich (kSZ) effect is a sensitive probe of the free-electron momentum field, tapping into spatial correlations relevant for both large-scale cosmology and smaller-scale astrophysics. Precision kSZ measurements will provide a robust channel for constraining inflationary physics and equivalence principle violation, while simultaneously characterizing the small-scale gas distribution and associated baryonic feedback. However, robust kSZ measurement for cosmological applications is challenging, as the primary source of large-scale information is convolved with unknown small-scale dynamics in a degenerate combination. In this paper we address this challenge using the Effective Field Theory (EFT) framework that provides a principled way of treating the effects of small-scale dynamics on large scale-structure. Extracting the kSZ signal can be reformulated as a measurement of the one-loop
galaxy-
galaxy-electron momentum bispectrum. We compute here a pure dark matter version of this bispectrum in EFT and compare it to simulations. We derive the EFT counterterms that capture small-scale backreaction and find that two of them acquire a transverse direction. One transverse counterterm gets generated entirely by the vorticity of the velocity field. Our computation of the bispectrum dipole agrees with simulation data to 5% up to k_max = 0.23 h/Mpc, which is significantly larger than the reach of tree level theory, which breaks down beyond k_max = 0.07 h/Mpc (at
redshift z = 0.5). For the bispectrum computed with the projected momentum field, relevant to measuring the kSZ field, we find a similar k_max, and make the first detection of the transverse counterterms from simulations. Our results suggest that one-loop bispectrum computations can play an important role in advancing kSZ cosmology.
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Cosmology and Nongalactic Astrophysics
Using the Circumgalactic Medium of Dwarf Galaxies as a Calorimetric Dark Matter Detector
Abby Mintz, Digvijay Wadekar and Romain Teyssier
Many well-motivated dark matter (DM) scenarios, including dark
photon DM,
axion-like particles, sterile
neutrinos, and
primordial black holes, can deposit energy into ordinary matter and significantly raise the thermal energy of astrophysical gas. We present a simple, model-independent implementation of DM-induced heating in the RAMSES hydrodynamic simulation code, parameterized by an effective local heat-transfer rate $\Gamma_{\rm heat}$. Using simulations of an isolated gas-rich
dwarf galaxy with properties similar to WLM, we find that DM heating substantially alters the thermal structure of the circumgalactic medium (CGM) while leaving the
star formation rate and the dense ISM nearly unchanged. For $\Gamma_{\rm heat} = 10^{-27}$ to $10^{-25}\ {\rm s}^{-1}$, the neutral hydrogen column at 10 kpc is suppressed by 0.6 to 3.9 dex relative to the control simulation. Similarly, the C II and Si II column densities decrease by 4.1 and 5.5 dex, and by 2.2 and 3.0 dex for C IV and Si IV. These signatures are accessible to
quasar absorption-line spectroscopy, so CGM observations of nearby field
dwarf galaxies provide a promising avenue for constraining dark matter models that inject heat into ordinary matter.
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High Energy Physics (Phenomenology)
Explaining the LZ High-Energy Recoil Event with Inelastic Sneutrino Dark Matter in Supersymmetry
Jingwei Lian and Jin Min Yang
We study an inelastic sneutrino dark matter origin of the LZ high-energy event in the inverse-seesaw next-to-minimal supersymmetric standard model. Approximate
lepton-number conservation protects the small mass splitting, while singlet interactions separate freeze-out from
solar-
neutrino production. The LZ
recoil and
solar constraints overlap even for a fully cooled population in
equilibrium. Three thermal mechanisms reproduce the relic abundance and satisfy all relevant constraints.
Photon-dominated annihilation produces gamma-ray boxes, offering a complementary test of this interpretation.
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Quantum Physics
Pauli spectrum and nonstabilizerness of random fermionic Gaussian states
Xhek Turkeshi, Piotr Sierant and Poetri Sonya Tarabunga
We characterize the magic of random fermionic Gaussian states through their Pauli spectrum and their stabilizer
entropies. For the Haar ensemble of Majorana Gaussian states we derive closed finite-$N$ expressions for the average stabilizer purities and reconstruct the Pauli spectrum exactly, as a mixture of products of beta-distributed variables resolved by Majorana weight. The stabilizer
entropies, and their filtered versions, freeze at Rényi index $q_c=2$: for $q>2$ the magic density is $1/(q-1)$, controlled by rare weight-two Majorana strings. Resolving these contributions requires exponentially many characteristic samples, making direct sampling estimates of the stabilizer
entropies inefficient in this frozen regime. For Haar-random Gaussian states at fixed filling, we express the averaged stabilizer purities at positive integer $q$ as coefficient integrals over $\mathrm{SU}(2q)$, with dimension independent of $N$, and evaluate the $q=2$ case exactly. We establish that the frozen density describes typical states in the Majorana and half-filled number-conserving ensembles and relate these ensembles to the corresponding $\mathrm{SYK}_2$ ground states. Finally, we show that typical fermionic Gaussian states retain certified magic after discarding any fixed fraction $\kappa<\kappa_\star^{\rm G}\simeq0.7613$ of their modes in the thermodynamic limit, remaining magical even beyond the $2/3$ threshold for Haar-random states in the full
Hilbert space.
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Quantum Physics
Disentangling QAOA: From Weakly Entangled Circuits to a Classical QUBO Solver
Boris I. Bantysh, Andrey Yu. Chernyavskiy, Denis A. Kulikov et al. (+2 more)
The role of
entanglement in
quantum optimization remains actively debated. To address this question, we focus on the fixed-parameter expanding-depth regime of the
quantum approximate optimization
algorithm (QAOA), where a compact two-parameter schedule is trained once on small instances and then applied as the problem size and
circuit depth increase. To probe this regime beyond full state-vector simulation, we perform approximate
matrix product state simulations for up to 50
qubits and 100 layers and quantify
entanglement by the bond dimension. We observe an entangle–disentangle profile, with the peak bond dimension decreasing with depth and eventually saturating. This observation motivates an extreme approximation: projecting the state onto the product-state
manifold (bond dimension one) after every two-
qubit interaction. Based on this approximation, we introduce BOND-1, a
quantum-inspired classical solver. Despite the drastic simplification, BOND-1 achieves cut ratios above 0.95 relative to the best known values on standard GSet MaxCut
benchmarks with up to 20000 variables, and in some cases it matches those values. It achieves these results without per-instance optimization and has linear
memory cost, while per-instance tuning can provide further improvement. These results show that, in this regime, a substantial fraction of the optimization power of QAOA survives even in the complete absence of
entanglement. Our conclusions, however, are specific to this setting and do not imply that
entanglement is unnecessary for
quantum optimization in general.
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All authors Boris I. Bantysh, Andrey Yu. Chernyavskiy, Denis A. Kulikov, Maksim A. Gavreev, Evgeniy O. Kiktenko
High Energy Physics (Theory)
Black holes and phase transitions in Conformal Gravity
Luis Guajardo, Luis Gutiérrez Frez, Seyed Naseh Sajadi et al. (+1 more)
We explore the thermodynamic properties of static black holes in conformal gravities in arbitrary, even dimensions. In the spherically symmetric case, up to local Weyl rescalings, these spacetimes are static and unique, due to a Birkhoff's
theorem that applies for all conformal gravities whose Lagrangians are complete contractions of $k$ Weyl tensors in dimension $D=2k$. The solutions can be chosen to be asymptotically locally (A)dS or flat, and the horizon can be extended to be a surface of arbitrary constant
curvature, $\gamma$. We focus on the asymptotically AdS case, for which the cosmological constant at infinity is an integration constant, and compute the mass of the spacetime in terms of the diverse hair parameters which have a purely gravitational origin. We show that the first law of thermodynamics is satisfied, and study phase transitions in the canonical ensemble, showing the existence of zeroth-order black-hole/black-hole phase transitions for arbitrary dimension.
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All authors Luis Guajardo, Luis Gutiérrez Frez, Seyed Naseh Sajadi, Julio Oliva
Materials Science
Twin Domains in Van der Waals Quaternary Oxides
Dorothée S. Mader, Niels Brumby, Xiaosheng Yang et al. (+10 more)
Optical anisotropy is the basis for many intriguing phenomena in van der Waals materials, including
hyperbolic polaritons and extreme birefringence. Stacking and twisting van der Waals materials along the out-of-plane direction emerged as a powerful route to tailor this anisotropy, but designing lateral interfaces remains a challenge. Here, twin domains are reported in the van der Waals quaternary
oxides MgTeMoO$_6$, MnTeMoO$_6$, ZnTeMoO$_6$, and CoTeMoO$_6$ - materials that possess strong in-plane optical anisotropy and second-order nonlinearity. The domains naturally form in their orthorhombic
crystal structure and extend over hundreds of micrometers. It is proposed that this stability is achieved by the domain wall acting as a diagonal mirror plane in the
crystal structure, parallel to the (1-10) or (110)
crystal planes, resulting in nearly opposite birefringence between domains. This hypothesis is experimentally confirmed by determining the angle between the
crystal axes of neighboring domains using polarization-resolved optical microscopy, infrared-visible sum-frequency generation microscopy, and transmission electron microscopy. The latter further allowed an estimate of the domain wall thickness. Overall, the observation of twin domains with orthogonal optical anisotropy opens new routes to use van der Waals quaternary
oxides for birefringent waveguiding, polariton steering, and frequency conversion applications.
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All authors Dorothée S. Mader, Niels Brumby, Xiaosheng Yang, Nele Stetzuhn, Eduardo Ortega, Christian Carbogno, Katayoun Gharagozloo-Hubmann, Sebastian F. Maehrlein, Martin Wolf, Kirill Bolotin, Peining Li, Niclas S. Mueller, Alexander Paarmann