Materials Science
3D Imaging of Complex Skyrmion and Hopf Topologies in an Extended Sample
I. Binnie, H. Fang, B. Shearer et al. (+16 more)
Spin textures are key for emergent
magnetic phenomena such as topological protection and underpin novel spintronic device paradigms based on racetrack
memory, logic gates, and neuromorphic computing. Using a coherent diffractive imaging technique called vector ptycho-
tomography, in combination with
algorithms that are robust to noise, we image the 3D
magnetic texture of skyrmion and
Hopf topologies with no prior assumptions about the sample. This directly reveals experimentally for the first time an extended 3D skyrmion
lattice, including the domain wall shape, topological charge, helicity, and
Hopf index. Our findings demonstrate experimentally that dipole stabilized skyrmions in Fe/Gd multilayers exhibit barrel-shaped skyrmion tubes with a twisted helicity, transitioning from N$\'e$el-type winding at the surfaces to both clockwise and counterclockwise Bloch-type winding in the bulk, that can also be described as fractional hopfions. We image a
lattice of 24 skyrmions with topological charge 1, average depth-dependent domain wall width of 23 to 40 nm, depth-dependent twisted helicity from $\pm$155$\deg$ to $\pm$30$\deg$, and fractional
Hopf index of $\pm$0.3. Over 10 TB of data were analyzed to yield a fully-resolved 3D reconstruction over a >0.4 $\mu$m$^3$ volume, with high fidelity down to the Nyquist limit of 8 nm. This method fills a key gap in the current landscape of
magnetic imaging by enabling high-resolution, element-specific 3D reconstructions of full-field extended
spin textures - offering a new route for exploring the topological complexity of
magnetic materials in three dimensions.
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All authors I. Binnie, H. Fang, B. Shearer, A. Grafov, N. Jenkins, Y. Shao, C. O'Leary, Y. Liao, T. Feggeler, A. Oh, S. Yazdi, J. Zou, B. Wang, E-E. Cating, S. A. Montoya, D. Shapiro, J. Miao, H. C. Kapteyn, M. M. Murnane
High Energy Physics (Phenomenology)
The Effect of Topological Defects and Magnetic Flux on Tetraquarks Using the Analytical Exact Iteration Method
N. H. Gerish, M. Abu-Shady and E. M. Khokha
Investigating the non-perturbative behavior of QCD and the dynamics of strong interaction is crucial for the study of heavy quarkonia and the understanding of exotic fully-heavy tetraquarks. In this work, using the analytical exact iteration method (AEIM), the analytical
eigenvalue solutions of the non-relativistic Schrödinger equation are obtained in the presence of topological defects and external
magnetic flux. The interactions are modelled using a modified Cornell potential supplemented by harmonic and inverse quadratic terms. We demonstrate that the energy levels are distinctly shifted by the topological defect parameter ($\alpha$). The mass spectra of heavy quarkonia ($c\bar{c}$ and $b\bar{b}$) and fully-heavy tetraquarks ($cc\bar{c}\bar{c}$ and $bb\bar{b}\bar{b}$) across several radial and orbital excitation states are successfully calculated using this approach. The computed masses of bottomonium and charmonium accord well with current theoretical predictions and experimental findings. Our findings for the heavy tetraquarks are in line with previous theoretical investigations that consider tetraquarks as configurations of diquarks and antidiquarks. The numerical results demonstrate that a nontrivial interaction between the confining potential and the background space-time geometry governs the mass hierarchy of these exotic hadronic states, providing high-precision data with excellent agreement with established theoretical models and experimental
benchmarks.
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High Energy Physics (Theory)
Probing Probability Geometry with Schwinger–Dyson Identities: Score Mismatch, Fisher Information, and Configurational Temperature
Anosh Joseph
We develop a
geometric interpretation of Schwinger–Dyson identities by showing that their violations are controlled by a single score-mismatch field $\delta s$. For an arbitrary sampled probability distribution $Q$ and
equilibrium measure $P_{\rm eq}$, every Schwinger–Dyson violation is determined by $\delta s = \nabla \log (Q / P_{\rm eq})$, which characterizes the departure from
equilibrium. Each Schwinger–Dyson identity measures a projection of this field onto a probe direction in configuration space. The relative Fisher information is its squared norm. This gives a universal bound relating Fisher information to the complete Schwinger–Dyson hierarchy, thus implying that convergence in Fisher information restores all Schwinger–Dyson identities. We further obtain a variational characterization of the relative Fisher information in terms of Schwinger–Dyson violations, leading to a natural tomographic interpretation in which increasingly rich families of probe fields encode progressively more information about the underlying probability distortion. The configurational temperature, within this framework, emerges as a distinguished Schwinger–Dyson probe. The Stein operators and score-function methods arise naturally from the same probability-
geometric structure. The score-mismatch field, therefore, provides a unified
geometric language for understanding Schwinger–Dyson identities, configurational temperature, Fisher information, and non-
equilibrium sampling in
stochastic processes.
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Quantum Physics
Cultivating logical catalysts for fault-tolerant dyadic phase rotations
Yichen Xu and Xiao Wang
We introduce a surface-code cultivation protocol for reusable logical catalyst states that implement exact fine dyadic phase gates $Z^{2^{-b}}$ by phase kickback. The catalyst is an eigenstate of a high-period Clifford
circuit $U$, with a direct construction supported on $O(2^b)$ logical
qubits. Once cultivated, each invocation implements the target phase through a controlled-$U$ gadget, removing Clifford+$T$ synthesis approximation error from the online gate and making the online non-Clifford depth independent of the target logical accuracy. As a concrete demonstration, we construct a catalyst for $\sqrt{T}=Z^{1/8}$, where $U$ is a nine-
qubit brickwork Clifford
circuit and controlled-$U$ consists of eight controlled-CNOTs. Starting from nine distance-three rotated-surface-code blocks, we cultivate the catalyst through logical-$U$ checks, syndrome extraction and postselection, code growth, and complementary-gap decoding. Due to the intrinsic fault tolerance of the phase read-out, a single verification round already reaches the leading error-corrected scaling, in contrast to the repeated logical checks required when cultivating single-
qubit magic states. A hybrid tensor-network and stabilizer simulation shows that, at physical error rate $p=10^{-3}$, the postselected catalyst can be grown to distance-seven rotated-surface-code blocks with logical leakage rate $\sim 10^{-6}$ using around seven expected attempts, and can be suppressed further with stronger postselection. Compared with existing protocols, our approach trades offline, phase-specific catalyst cultivation for exactness, reusability, and constant-depth online implementation of fixed fine dyadic phases in codes with restricted transversal gate sets.
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General Relativity and Quantum Cosmology
Beyond the equation of state: a second-order diagnostic for dynamical dark energy
Bob Osano
The first-order continuity equations determine the
evolution of the energy densities but depend only on the instantaneous value of the dark-energy equation-of-state parameter. Differentiating these equations with respect to e-fold time introduces the term $\omega'_{\rm DE}$ explicitly, providing a second-order probe of dark-energy dynamics. Consequently, while information about the
evolution of the equation of state is encoded in the full dynamical solution, it is not explicit in the first-order continuity equations evaluated at a given epoch. The second-order formulation, therefore, provides a complementary description in which the local
evolution of the equation of state appears directly through the
curvature of the density trajectory. For a two-fluid interacting dark-sector model with linear coupling $Q_{AB}=\alpha\rho_AH$, the resulting second-order equation defines a
curvature diagnostic, $\mathcal{C}=\rho_{DE}''/\rho_{DE}$, whose leading contribution, in the cosmological-constant limit, is $\alpha^2$, while departures from $\omega_{DE}=-1$ generate corrections through both $\delta\omega=1+\omega_{DE}$ and the distinctive term $-3\omega_{DE}'$. Unlike first-order analyses, this contribution is independent of the interaction strength and directly identifies dynamical dark energy. Applying the diagnostic to a CPL model with parameters consistent with DESI constraints, we recover $\omega_{DE}'$ across the full
redshift range for both weak and strong interactions. Noise propagation shows that the diagnostic is detectable with signal-to-noise ratio exceeding three for $\sigma_H/H\lesssim1.5\%$, while the degeneracy between $\alpha$ and $\omega_{DE}'$ remains negligible for $\alpha\lesssim0.1$. In the non-interacting limit, the formalism naturally recovers the Caldwell–Linder thawing/freezing classification and extends it to interacting dark-energy models.
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Mesoscale and Nanoscale Physics
Specific absorption rate of uniaxial single-domain nanomagnets: stochastic spin dynamics versus linear response theory
H. Kachkachi
We compute the specific absorption rate of a uniaxial single-domain nanomagnet driven by an alternating
magnetic field by two methods: i) direct numerical integration of the
stochastic (Langevin) Landau–Lifshitz–Gilbert equation (the LLL approach), and ii) linear response theory (LRT) based on the Debye susceptibility with the Néel relaxation time $\ta$. We first analytically show that both methods are equivalent for small
magnetic field amplitude, and then compute their deviation $\Lambda\equiv\SAR_{\LLL}/\SAR_{\LRT}-1$ as a function of the
magnetic field amplitude for two temperatures chosen on opposite sides of the Debye resonance. One of the main results is that the sign and magnitude of $\Lambda$ are governed by the dimensionless product $\om\ta$, in addition to the linearity parameter $\xi=\mu_{s}B_{0}/k_{B}T$ for the easy-axis geometry considered here. Indeed, below resonance ($\om\ta<1$), linear response theory overestimates the specific absorption rate, whereas above resonance ($\om\ta>1$, the regime typical of blocked nanoparticles) linear response theory can underestimate the specific absorption rate by up to $\sim70\%$ at $\xi\sim2$. We expect this work to provide a quantitative guidance for the use of linear response theory in
magnetic hyperthermia and related nanoscale heat-transport problems, and to serve as a single-particle
benchmark for extensions to many-
spin and interacting systems.
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Astrophysics of Galaxies
3D Magnetic Field Vectors in Space: Bubbles, Clouds, and Filaments
Mehrnoosh Tahani, Anna Ordog, Jennifer West et al. (+3 more)
Magnetic fields play important roles in the
star-formation process across different spatial scales. The interplay between
magnetic field strength (a key component of the interstellar medium's energy budget) and field orientation relative to density structures impacts how interstellar material evolves toward
star formation. To understand
galactic evolution toward
stars,
planets, and ultimately life, we need to map three-dimensional (3D)
magnetic field vectors in 3D space. However, determining full vector information remains challenging due to projection effects and the complex relationship between observable tracers and field geometry. We outline the observational techniques that can be used to probe the 3D
magnetic field structures of objects such as
supernova remnants (SNR), superbubbles, HII regions, and HI filaments in the diffuse interstellar medium (ISM), and objects in the dense ISM such as molecular clouds, filaments, and cores. The main SKA-specific observational techniques include synchrotron emission and Faraday rotation of both compact sources and the diffuse emission. We discuss how SKA AA4 will allow implementation of the techniques we describe, leveraging the vastly improved sensitivity, resolution and uv-coverage compared to existing
datasets. This will enhance our ability to reconstruct 3D
magnetic field vectors, advancing our understanding of
magnetic fields in
Galactic evolution and
star formation.
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All authors Mehrnoosh Tahani, Anna Ordog, Jennifer West, Georgia V. Panopoulou, Hiroko Shinnaga, Marijke Haverkorn
High Energy Physics (Theory) · Cross-listed from math.QA
On the deformation theory of chiral quantizations
Dylan Butson and Sujay Nair
We give an operadic approach to deformation quantization of vertex Poisson
algebras, a
chiral analogue of the traditional problem of deformation quantization of Poisson
algebras. Our main result is an order-by-order deformation-obstruction theory for such quantizations, controlled by the
chiral analogue of Poisson
cohomology. In the special case of
chiral quantizations of affine
symplectic varieties, quantizations of the vertex Poisson
algebras of functions on their arc spaces, we prove that this deformation-obstruction theory is controlled by their de Rham
cohomology. As another application, we prove that the boundary Virasoro minimal models are rigid under deformations.
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Statistical Mechanics
Exact subsystem dynamics in the deterministic Floquet-PXP model
Katja Klobas
The dynamics of local subsystems in a thermodynamically large
quantum many-body system can be understood as effectively open as the system produces its own effective bath. The action of this bath can be characterised in terms of the so-called influence
matrices. In generic situations, the complexity of these objects grows unfavourably with time, however, there exist solvable cases where influence
matrices can be characterised exactly even in the presence of non-trivial interactions. Here we show that Rule 201, a deterministic version of the Floquet-PXP model, is one of these solvable instances. Indeed, it admits influence
matrices given by a finite-dimensional
matrix-product operator (MPO) that solves a finite set of algebraic conditions. We provide the solution, and characterise multi-time autocorrelation functions.
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High Energy Physics (Theory)
The IKKT renormalization group flow is IIB: toward zero-d holography
Xiangwen Guan, Joel Karlsson, Sébastien Reymond et al. (+1 more)
Supergravity solutions describing stacks of D$p$-branes with $p\neq 3$ feature a non-constant dilaton profile, which is holographically mapped to the running of the SYM coupling in $(p+1)$ dimensions. For D-instantons ($p=-1$), the lack of space and time in the IKKT
matrix model makes such an interpretation difficult at first. In this letter, we propose a method to achieve this based on two closely related concepts: the IKKT method of integrating out heavy strings in a Coulomb branch
vacuum and the
matrix RG flow of Brézin and Zinn-Justin (BZJ). The notable difference between the two is that the BZJ RG flow also integrates over the Coulomb branch position. We first apply the Coulomb branch method and by relating the coefficient of the leading correction to the IKKT action with the string coupling, we can compute its dependence on the Coulomb branch position, finding a match between
matrix theory and supergravity. Next, we apply the BZJ-flow to the IKKT partition function, which leads to a running of the coupling constant $g$ with the rank $N$ of the
matrix model, reproducing the $N$-dependence of the axio-dilaton field in supergravity.
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All authors Xiangwen Guan, Joel Karlsson, Sébastien Reymond, Thomas Van Riet
Fluid Dynamics
Unpinning of trapped oil droplets via non-resonant acoustic streaming in capillary tubes
D. Tsiklauri
We establish self-consistent analytical model demonstrating that trapped non-wetting
liquid phases in narrow capillary channels can be successfully unpinned via non-resonant, second-order acoustic streaming coupled with background static drive gradients. Moving away from boundary-guided or resonant mechanisms, our approach exploits the bulk acoustic-wind force density generated by the steady-state momentum flux of attenuated first-order linear wave interactions. By expanding the hydrodynamic equations up to second order, we determine the critical assisted acoustic wave amplitude required to break capillary pinning thresholds and derive an explicit formulation for steady transport velocity under viscous wall constraints. Furthermore, incorporating both boundary-layer wall effects and bulk core thermo-viscous dissipation reveals a natural mathematical optimum condition where the spatial absorption coefficient matches half the inverse distance to the target droplet ($\alpha = 1/(2x_0)$). This condition is then numerically validated and cross-correlated against legacy industrial frequency baselines, providing a fundamental theoretical framework for minimizing transducer power requirements while maximizing localized mobilization velocities in geological pore networks. Finally, we demonstrate that this optimal operational frequency scales inversely with the transmission distance, providing an analytical framework to optimize downhole acoustic tools according to spatial damping constraints of the specific formation rather than relying on rigid hardware parameters.
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Mathematical Physics
Geometric bulk-edge correspondence for $\mathbb{Z}_2$-topological insulators
Alexis Drouot, Jacob Shapiro and Xiaowen Zhu
Fermionic time-reversal-invariant
insulators in two dimensions–class AII in the Kitaev table–come in two topological phases. These phases are characterized by a $\mathbb{Z}_2$-valued invariant, the Fu-Kane-Mele index. We prove a
geometric bulk-edge correspondence for curved interfaces: if two such
insulators occupy complementary regions separated by a curved boundary, then the $\mathbb{Z}_2$ edge index of the interface system is the product, modulo two, of the difference of the two bulk $\mathbb{Z}_2$ indices and a
geometric intersection number associated with the boundary and the measurement region. The argument is a $\mathbb{Z}_2$ analogue of the curved-interface connection formula proved for
Hall insulators in \cite{DZ24}.
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High Energy Physics (Theory)
Massive Cosmological Correlators from Flat Space: a Laplace-Space Approach
Nathan Belrhali, Arthur Poisson and Sébastien Renaux-Petel
We develop a new approach to cosmological correlators, built on a simple physical fact: deep inside the Hubble radius every mode oscillates as a flat-space plane wave, the
curvature of spacetime making itself felt only as the mode is stretched towards the horizon. A Laplace transform turns this observation into a computational tool, resolving each curved-space mode function into a continuous superposition of plane waves labelled by a dual variable and dressed by a kernel that encodes the spacetime geometry, field content and dynamics. Every time integral then reduces to an elementary flat-space one, yielding simple diagrammatic rules for cosmological correlators. We illustrate the construction on the massive single-exchange correlator. The Laplace representation makes its total- and partial-energy singularities transparent ”from flat space”, and yields a single closed-form, rapidly convergent series valid throughout the entire kinematic domain. Although developed for conformally coupled fields exchanging massive scalars in de Sitter, the approach carries over essentially unchanged to virtually all situations of interest in
primordial cosmology.
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Statistical Mechanics
Proactivity and pinning in the non-reciprocal XY model with vision anisotropy
Gabriele Bandini, Asja Jelic and Andrea Gambassi
We study a non-reciprocal XY model on a square
lattice, in which
spins interact with their nearest neighbors through
vision-induced anisotropic interaction. Such anisotropy breaks rotational
symmetry and leads to the pinning of the
spin orientation along preferred
lattice directions. We systematically characterize this phenomenon for different interaction kernels, including modulated, sinusoidal, von Mises, and hard
vision-cone couplings, and for two classes of microscopic update rules: Glauber and Langevin dynamics. A central result of this work is the identification and detailed analysis of two distinct contributions that naturally arise in the Langevin formulation, which we refer to as the reactive and the proactive term. We derive the corresponding equations governing both local fluctuations and the global orientation, and use them to characterize the mechanisms responsible for directional pinning. We show that both reactive and proactive contributions can generate global pinning, whereas their role in determining local pinning depends on the specific interaction kernel and may differ qualitatively. Our analysis clarifies the distinction between local and global pinning, explains the emergence of preferred
lattice directions in the different models considered, and reconciles apparent discrepancies reported in previous studies. More generally, it provides a microscopic framework for understanding
lattice-induced orientational selection in non-reciprocal XY models.
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High Energy Physics (Theory)
Laplace Space for Cosmological Correlators
Nathan Belrhali, Arthur Poisson and Sébastien Renaux-Petel
Deep inside the horizon, every cosmological mode oscillates as a flat-space plane wave. A Laplace transform turns this fact into a general method: it resolves each curved-space mode into a superposition of plane waves dressed by a kernel that encodes the spacetime geometry, field content and dynamics, collapsing the time integrals onto flat-space ones. This provides simple diagrammatic rules that turn cosmological correlator diagrams into their flat-space counterparts integrated against Laplace-space kernels. On the paradigmatic massive single exchange, this integral representation makes the energy singularities manifest and evaluates in closed form as a single, rapidly convergent series valid throughout the kinematic domain, with no patching of separate expansions. The Laplace approach sheds conceptual and computational light on cosmological correlators in virtually any theory of the early universe.
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High Energy Physics (Theory)
Universal Lichnerowicz Lifting of Near-Horizon Soft Modes
Peng Cheng and Yu-Qi Liu
A recurring universality appears in the low-temperature
quantum thermodynamics of near-extremal black holes, where distinct parent geometries often lead to the same logarithmic temperature dependence at one loop. In this work, we study the Lichnerowicz spectral origin of this infrared universality and understand why the relevant spectral data become insensitive to the details of the parent geometry. For extremal near-horizon geometries containing a two-dimensional maximally symmetric throat, we construct the normalizable transverse-traceless tensor zero modes associated with near-horizon reparametrizations. Turning on a small temperature lifts these zero modes through the first-order deformation of the Lichnerowicz operator. Although the local
matrix element depends on detailed parent-geometry data, these data cancel after projection onto normalized tensor modes, leaving the universal result. For static spherically symmetric backgrounds, the resulting
eigenvalue shift is proportional to the
Fourier mode number and temperature. For rotating backgrounds, the same structure persists in the near-horizon reparametrization tensor sector, while angular warp factors only modify the overall projection factor. We fix the normalized coefficient explicitly, showing how radial integration and bulk normalization remove the near-horizon Taylor coefficients. We further show that this lifted bulk spectrum is the Lichnerowicz realization of the Schwarzian soft sector. Thus, the universal one-loop temperature dependence in the tensor sector is traced to an infrared bulk-boundary matching between near-horizon tensor zero modes and boundary reparametrization dynamics.
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Quantum Physics
Self-Sifting quantum key distribution
Saman Sarshar and Mostafa Annabestani
In this paper, we introduce a novel two-way
quantum key distribution (QKD) protocol in which the sender (Alice) and receiver (Bob) employ one
qubit of a maximally entangled Bell state as the
quantum channel for key exchange. The protocol incorporates a new security mechanism based on a scrambling operator. Unlike conventional two-way QKD protocols, all sifting operations and eavesdropper detection procedures are postponed until the completion of the
quantum communication stage and are performed exclusively by Bob. Since the control mode is never publicly announced, attacks that rely on mode-dependent adaptations or attempt to remain hidden within the control mode are inherently prevented. Furthermore, the traveling
qubit does not directly encode key information, substantially limiting the information that can be extracted from attacks targeting the
quantum channel alone. An additional distinctive feature of the protocol is that rounds that would ordinarily be discarded can instead be utilized to detect the presence of an eavesdropper. We analyze a broad class of ancilla-based attacks, in which an eavesdropper couples an ancillary system to the transmitted
qubit in an attempt to gain information about the key, and show that such attacks are detectable in their most general form.
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Quantum Physics
Exploring dynamics of individual vortices in a superconductor via a levitated magnetic transducer
Yiqi Wang, Trisha Madhavan, J. DaLi Schaefer et al. (+3 more)
Trapped
vortices determine fundamental properties of
superconductors and play an important role in many practical applications such as
magnetic levitation, however their complex dynamics remain poorly understood. Here, we use the mechanical motion of micron-scale levitated
magnetic particles to probe the dynamics of individual
vortices. Specifically, we show that the dynamics of levitated magnets are strongly influenced by
vortices trapped in the YBCO superconducting film. We observe random telegraph signals in the mechanical frequency, dissipation rate, and energy of levitated particles, which we attribute to random tunneling of individual
vortices. The nonlinearity of
vortex-defect interaction manifests as non-exponential decay in ringdown measurements, revealing a complex underlying potential landscape. Our results provide insights into elusive dissipation mechanisms in superconducting levitated systems, open new avenues for using levitated magnets as sensitive probes of static and dynamic properties of individual
vortices in
superconductors and their interactions with material disorder, and point toward novel routes for using
magnetic particles as highly coherent mechanical transducers.
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All authors Yiqi Wang, Trisha Madhavan, J. DaLi Schaefer, Addison NewRingeisen, Frankie Fung, Mikhail D. Lukin
Soft Condensed Matter
Weak-Flow Induced Dielectric Axes Rotation in Dipolar Suspensions
Pramodt Srinivasula
Conventional rheodielectric studies of dipolar suspensions primarily examine flow-induced variations in the principal permittivity components. In contrast, an asymptotic solution of the perturbed Fokker–Planck equation for orientable Brownian dipoles under weak flow predicts the emergence of off-diagonal permittivity components that are linear in the relative flow strength. For planar shear flow, these terms exceed the corresponding higher-order diagonal corrections, leading to a rotation of the principal dielectric axes. This previously unrecognized rheodielectric response suggests new possibilities for flow-controlled dielectric and electro-optical functionalities.
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Cosmology and Nongalactic Astrophysics
A solid unification of the dark sector
Jose Beltrán Jiménez, María Pérez Garrote, Florencia A. Teppa Pannia et al. (+1 more)
We construct a unified description of dark matter and dark energy in terms of a single dark component that behaves as a pressureless fluid in the early Universe and undergoes a transition to a solid phase at late times that can support accelerated expansion. A generalized Chaplygin-type solid provides a simple realization of this scenario. The solid nature of the dark medium prevents the instabilities and strong acoustic oscillations that typically arise in perfect-fluid unifications. It also gives rise to distinctive signatures in cosmological perturbations, such as a suppression of structure growth, a nontrivial gravitational slip, and an effective mass for gravitational waves. Since these effects share a common origin in the solid phase, they become relevant only at low
redshifts, leaving the high-
redshift cosmology essentially unmodified. This demonstrates that a solidly unified dark sector can reproduce the desired background transition from dark matter to dark energy while yielding testable imprints in cosmological perturbations.
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All authors Jose Beltrán Jiménez, María Pérez Garrote, Florencia A. Teppa Pannia, Shinji Tsujikawa
Solar and Stellar Astrophysics
Unveiling Complex Chemistry in Planet-forming Disks with the SKAO
Linda Podio, Lisa Giani, Catherine Walsh et al. (+38 more)
The chemical composition of
planets is inherited from that of the natal protoplanetary disk at the time of
planet formation. In recent years, we have made huge progress in characterizing disk chemistry. (Sub-)millimeter interferometers, such as ALMA, allowed us to detect emission lines from simple to complex organic molecules and to probe their radial and vertical distribution in disks. On the other hand, JWST has started to unveil the composition of disk ices, and line emission from the innermost disk regions. The advent of SKA will open new domains in the field, by observing emission lines from heavier molecules including heavy carbon chains and rings, and prebiotic molecules with peak emission in the cm range. Moreover, SKA will probe molecular emission from regions which are obscured by
dust opacity at mm wavelengths, hence from the disk midplane, and often from the inner 30 au region. These observations will constrain the initial conditions for disk
evolution and
planet formation, allowing us to predict the chemical composition of the forming
planets and their atmospheres. Comparison with forthcoming results on
exoplanet atmospheres and on the chemistry of pristine bodies in the
Solar System will provide new hints on the origin and
evolution of planetary systems including our own.
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All authors Linda Podio, Lisa Giani, Catherine Walsh, Audrey Coutens, Izaskun Jiménez-Serra, Claudio Codella, María José Maureira, Marta De Simone, John D. Ilee, Manuela Lippi, Chin-Fei Lee, Romane Le Gal, Mayank Narang, Giovanni Sabatini, Eleonora Bianchi, Elenia Pacetti, Danai Polychroni, Bihan Banerjee, Paola Caselli, Cecilia Ceccarelli, Amin Farhang, Antonio Garufi, Greta Guidi, Adriano Ingallinera, Stavro L. Ivanovski, Pamela Klaassen, Ana López-Sepulcre, Liton Majumdar, Giulia Perotti, Jaime E. Pineda, Daniel J. Price, Manoj Puravankara, Pablo Rivière-Marichalar, Alvaro Sánchez-Monge, Eugenio Schisano, Paolo M. Simonetti, Leonardo Testi, Claudia Toci, Diego Turrini, Alessio Traficante, Yinhao Wu
Mesoscale and Nanoscale Physics
Strong coupling between propagating spin wave and microwave photons in a superconducting resonator
Yi Li, Jinho Lim, Xingzhi Wang et al. (+12 more)
We demonstrate strong coupling between propagating
spin wave modes and microwave
photons in superconducting resonator-
magnetic thin film hybrid
circuits. By fabricating the resonator directly on yttrium iron garnet thin films grown on rare-earth-free Y$_3$Sc$_2$Ga$_3$O$_{12}$ substrates, we achieve strong coupling of both Damon-Eshbach and backward-volume
spin wave modes to the resonator, with coupling strengths exceeding both the
magnon and
photon damping rates. Furthermore, we observe nonreciprocal
spin wave radiation of the hybrid magnonic mode in the Damon-Eshbach configuration, highlighting the potential for incorporating intrinsic
spin-wave nonreciprocity into hybrid magnonic systems. These results open new avenues for integrating
spin-wave magnonics with cavity magnonics, and for harnessing
spin waves for potential applications in
quantum information science.
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All authors Yi Li, Jinho Lim, Xingzhi Wang, Tomas Polakovic, Carissa Kiehl, Moojune Song, Phuoc Cao Van, Ralu Divan, Ulrich Welp, Charudatta Phatak, Jong-Ryul Jeong, Kab-Jin Kim, Jian-Min Zuo, Axel Hoffmann, Valentine Novosad
Solar and Stellar Astrophysics
Astrochemical Study of Early Embedded Disks
Eleonora Bianchi
The question of how our
planet was formed and, more generally, how a planetary system forms is fundamental and has been addressed in a broad range of research domains. However, we still lack a comprehensive understanding of the basic aspects of the process of
star and
planet formation. In particular, the challenge of measuring the mass and chemical composition of young protostellar disks has, so far, hampered a meaningful comparison with observed
exoplanet populations. This will become critical in the near future to interpret the results of European space missions, such as Ariel, which will yield a comprehensive inventory of exoplanetary masses and chemical compositions. Building on recent developments in astrochemistry and data science, this perspective explores future research avenues for the study of young
planet-forming disks and introduces the project "Astrochemical Study of Early Embedded Disks" (iSEEDs). By integrating machine learning and data mining with astrochemistry, iSEEDs provides a robust framework to systematically extract the physical conditions and molecular abundances hidden within high-resolution
datasets of protostellar environments.
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Quantum Physics
Quantum-Limited Subdiffraction Telescopy Requires Genuine Multi-Telescope Interference
Yujie Zhang, Yunkai Wang, Wilson Wu et al. (+1 more)
Conventional
stellar interferometry reconstructs incoherent sources from pairwise mutual coherences between
telescopes. Are such pairwise measurements sufficient for
quantum-limited subdiffraction imaging with a
telescope array? We show that for generic image-moment estimation, they are not. We consider weak incoherent light from a generic extended source observed by an array of
telescopes, each supporting a single optical mode. For an N-
telescope array, we derive the
quantum Fisher information (QFI) scaling of image moments up to the cutoff 2N-2 and prove that arbitrary measurements restricted to
telescope pairs attain the full-array QFI scaling only up to second order. Thus, estimating higher-order moments at the
quantum limit requires genuinely multi-
telescope interference. Inspired by spatial-mode demultiplexing (SPADE) from single-aperture subdiffraction imaging, we construct array-SPADE measurements that attain the optimal QFI scaling up to the finite-array cutoff. Finally, we show that these measurements can, in principle, be embedded in ancilla- and
memory-assisted
quantum-network architectures for long-baseline telescopy.
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All authors Yujie Zhang, Yunkai Wang, Wilson Wu, Thomas Jennewein
High Energy Astrophysical Phenomena
Origins of Cosmic Rays in the Galactic-extragalactic Transition Energy Range
A. Corstanje, S. Saha, S. Bouma et al. (+28 more)
Cosmic rays arrive at Earth with energies ranging from $10^9$ to over $10^{20}$ eV. One of the open questions in high-energy
cosmic ray science concerns the origin of the highest-energy
cosmic rays that can be accelerated by
Galactic sources, and the transition energy beyond which only extragalactic sources can provide. Measuring the mass composition gives essential information for comparing measurements to source and propagation models, both from the abundances at the source and from the maximum attainable energy which is proportional to the particle charge (and hence its mass). The highest-energy
cosmic rays from the
Galaxy are found in a range of $10^{16}$ to $10^{18}$ eV which is well suited for
radio detection. Building on a decade of experience in measuring
cosmic rays at LOFAR, we show that SKA-Low, augmented with an array of small particle detectors, is well suited to advance the field by measuring the mass composition of
cosmic rays across this energy range.
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All authors A. Corstanje, S. Saha, S. Bouma, J. Bray, S. Buitink, V. de Henau, E. Dickinson, B. Hare, A. Haungs, H. He, J. Hörandel, T. Huege, C. James, P. Laub, X. Li, H-J. Mathes, K. Mulrey, A. Nelles, F. Schlüter, O. Scholten, R. Spencer, C. Sterpka, K. Terveer, S. Thoudam, G. Trinh, P. Turekova, D. Veberic, K. Watanabe, C. Zhang, P. Zhang, Y. Zhang
Atmospheric and Oceanic Physics
Sparse Sensor Placement for Reducing Forecast Errors in Ensemble Kalman Filtering
Takumi Saito and Shunji Kotsuki
Designing efficient observation networks for reducing forecast errors is a fundamental challenge in numerical weather prediction. Data-driven sparse sensor placement (SSP) and ensemble-based data assimilation via the Ensemble Kalman Filter (EnKF) have each addressed this challenge independently, yet their mathematical connections have not been systematically formalized. This study presents a unified theoretical framework integrating SSP and EnKF through optimal experimental design, providing new theoretical and algorithmic results. While conventional SSP methods aim to reduce analysis errors, this study extends the SSP to target forecast error reduction by using a tangent linear model approximated by an ensemble forecast. We derive the Fisher information
matrices in the ensemble and model spaces for the EnKF, and clarify the mathematical interpretations of A-, D-, and E-optimality in terms of forecast error reduction. A-optimality in the model space minimizes the mean forecast error variance; D-optimality is ill-defined in the model space due to rank deficiency and is therefore formulated in the ensemble space, where it maximizes the Shannon information content of assimilated observations; and E-optimality in the model space minimizes the worst-case forecast error variance. We further propose a fast greedy
algorithm for selecting observation locations under A-optimality in the model space, avoiding
matrix inversion at each greedy step and substantially reducing computational cost. Numerical experiments using the Lorenz-96 model support these theoretical findings. Among the three optimality criteria, A-optimality in the model space most consistently reduces forecast spread and root-mean-square error, and yields stable incremental improvements consistent with post-assimilation observation impact diagnostics.
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Quantum Physics
Large-scale multimode entangling-gate synthesis in trapped-ion systems
YingYe Huang, Wentao Chen, Guoyu Zou et al. (+3 more)
Trapped-ion systems have emerged as a leading platform for scalable
quantum information processing owing to their high-fidelity operations and long-range entangling capabilities. As the number of ions in a trap increases, the growing density of collective motional modes makes the synthesis of multimode entangling gates increasingly challenging. Designing large-scale gates requires simultaneously realizing the desired
spin-
spin interactions, suppressing residual
spin-motion
entanglement, and limiting experimental control resources, leading to a high-dimensional non-convex optimization problem. Here we develop a numerical framework for multi-tone gate synthesis that directly searches for control fields satisfying these competing requirements. By employing an alternating-minimization strategy, the framework improves numerical stability and remains effective for large systems with many motional modes and target interactions. As representative demonstrations, we synthesize gates implementing all-to-all and nearest-neighbor interaction patterns in ion chains of up to N = 1000, using only global
laser control. Across the parameter regimes explored here, the control resources required to maintain high-fidelity interactions do not exhibit rapid growth with system size. We extend the framework to individual addressing using a structured qLDPC target at N = 512 as an example. These results identify multimode gate synthesis as a viable route toward programmable interaction engineering in large-scale trapped-ion
quantum processors.
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All authors YingYe Huang, Wentao Chen, Guoyu Zou, Xuan Fan, Jing-Ning Zhang, Kihwan Kim
Solar and Stellar Astrophysics
Revised orbital parameters of the gamma2 Velorum system
Werner Schmutz, Christian A. Hummel, Gloria Koenigsberger et al. (+2 more)
Context. gamma2 Velorum is the closest and visually brightest Wolf-Rayet binary system. Its eccentric orbit modulates the X-rays observed from the wind-wind interaction, and its large separation allows for spatially resolving both components. Aims. We aim to strengthen the constraints on gamma2 Velorum's properties and, in particular, solve the discrepancy between the eccentricity determined from the emission lines and that from the absorption lines. Methods. We obtained VLT/
GRAVITY observations and combined them with earlier spatially-resolved data at different orbital phases. Results. Strong constraints on all orbital parameters were determined and, in particular, we find that e=0.322, close to what was derived from the emission lines. The X-ray light curve declines as s to power -3 after periastron, where s is the separation of the two
stars, but its modulation is likely affected by absorption and occultation of the X-ray emitting region at other orbital phases. We find that previous discrepancies in the reddening value can be traced to a brighter K-band magnitude than that predicted by the WR wind models. We conclude E(B-V)=0.02+-0.02 mag. Our now more precise mass and radius values combined with previously determined effective temperatures provide very strong constraints on evolutionary models. The closest match for the O-
star is provided by an initial mass M=28.7 Mo rotationally mixed model and a M=32 Mo model for the WR
star, with negligible
accretion onto the O-
star during the WR progenitor's Roche Lobe overflow phase. However, the temperature of the O
star is higher and the mass of the WR
star is found to be smaller than predicted by the evolutionary tracks for the current epoch, consistent with the well-known "mass-discrepancy problem" in massive
stars.
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All authors Werner Schmutz, Christian A. Hummel, Gloria Koenigsberger, Florentin Millour, Joel Sanchez-Bermudez
Statistical Mechanics
Field theories for Laplacian Growth
Paolo Pisapia, Assaf Shapira and Kay Joerg Wiese
Loop-erased random walks (LERW), the $O(n)$-model at ${n=-2}$ and
Laplacian random walks (LRW) are three realizations of the same random process. While this equivalence holds on any graph, renormalization is possible only via the $O(-2)$-model. To generalize LRWs to $b$-LRWs or to
Diffusion Limited Aggregation (DLA), a field theory directly on the
Laplacian growth process is necessary. Here we construct an exact
lattice action for LRWs and show that its perturbative expansion equals that of LERWs. We then generalize this approach to $b$-LRWs and DLA.
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Instrumentation and Methods for Astrophysics
The SPOTLIGHT Multibeam Real-Time Transient Detection System
Ujjwal Panda, Jayanta Roy, Kshitij Bane et al. (+17 more)
Fast
Radio Bursts (FRBs) are among the most enigmatic transient phenomena in the Universe. In order to unravel the mystery behind these events, one requires instruments that possess the ability to search, detect, localise, and capture these events in high resolution over large fields-of-view in real-time. The SPOTLIGHT project is one such backend, leveraging the upgraded
Giant Metrewave
Radio Telescope (uGMRT) to conduct a commensal search for FRBs and other
radio transients, using a dedicated high-performance computing facility, comprised of 90 NVIDIA A100 GPUs and 60 compute servers. Here we present the design, implementation, and performance of SPOTLIGHT's real-time transient search pipeline, a GPU-accelerated system capable of processing up to 2000 post-correlation beams in real time. The pipeline combines AstroAccelerate-powered brute-force dedispersion and single pulse search, with a multi-stage and robust candidate optimisation framework, as well as a triggering system for automatic capture of high-resolution visibility and baseband data. To ensure continuous validation of pipeline performance, we have also developed a real-time signal injection framework capable of injecting synthetic bursts directly into SPOTLIGHT's beamformed data stream. The system operates commensally with routine uGMRT observations, processing data streams in real-time while maintaining high sensitivity to ms-duration transients across dispersion measures extending up to 2000 pc cm$^{-3}$. During its initial deployment in uGMRT Cycle 49 and Cycle 50, the pipeline detected 2870 bursts from 42 known sources, and demonstrated sensitivity consistent with the predicted survey threshold of $\sim$ 0.2 Jy ms. The SPOTLIGHT system establishes a scalable framework for wide-field, low-frequency transient discovery and localisation, and provides a key technological foundation for next-generation
radio transient surveys.
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All authors Ujjwal Panda, Jayanta Roy, Kshitij Bane, Chahat Dudeja, Sridhar Gajendran, Param Joshi, Sanjay Kudale, Arpan Pal, Raghav Wani, Karel Adamek, Wes Armour, Kenil Ajudiya, Jayaram Chengalur, Jyotirmoy Das, Nishant Pradeep Deo, Deepak Bhong, Shelton Gnanaraj, Santaji N. Katore, Mekhala Muley, Harshavardhan Reddy