Soft Condensed Matter
Universal scaling of conformations of tangentially driven ring polymers
Antonio Lamura and Marisol Ripoll
The interplay of tangential activity and excluded-volume interactions in ring
polymers adsorbed to a surface, consistently results in the overall swelling of the ring configurations. This is in strong contrast to the case for three dimensional linear and ring
polymers, where activity induces frequently collapsed structures. By means of Brownian Dynamic simulations, we investigate how the scaling properties of such active rings can be universally characterized by an activity-dependent Flory exponent, as a generalization of the
equilibrium behavior. At high activity, an effective persistence length characterizes the conformations of active flexible rings.
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Cosmology and Nongalactic Astrophysics
Dynamics of Biased Domain Walls: The Rocket Effect
R. B. Vilhena, P.P. Avelino and C. dos Santos
We investigate the dynamics of domain walls in scalar field theories with degenerate
vacua (i.e.,
vacua of equal energy density) in which the scalar field mass depends on the
vacuum state. Using analytical arguments and numerical simulations, we show that this
vacuum dependence of the scalar field mass renders the emission of scalar radiation from domain walls anisotropic, preferentially toward regions with smaller scalar field mass. We further show that the resulting
recoil (rocket) effect biases the
evolution of cosmological domain wall networks in favor of the lower-mass
vacuum, thereby promoting network decay. We also demonstrate that the biased
evolution of domain walls in theories with degenerate
vacua, previously attributed to asymmetries of the potential barrier near the local maximum, is instead primarily controlled by the
vacuum dependence of the scalar field mass. More generally, in theories with non-degenerate
vacua, this
recoil mechanism constitutes an additional source of dynamical bias that can either hasten or delay network decay relative to the standard expectation based solely on differences in
vacuum energy density.
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High Energy Physics (Phenomenology)
Analysis of the hidden-charm pentaquark candidates in the $J/\psi \Omega$ mass spectrum via the QCD sum rules
Zhi-Gang Wang
We explore the diquark-diquark-antiquark type $sssc\bar{c}$ pentaquark states with the isospin-
spin-parity $IJ^{P}=0{\frac{1}{2}}^-$, $0{\frac{3}{2}}^-$ and $0{\frac{5}{2}}^-$ via the QCD sum rules in details and obtain the ground state mass spectrum. And we suggest to hunt for these exotic states in the exclusive decay $\Omega_b^- \to P_{csss}^-\phi \to J/\psi \Omega^- \phi $. Observations of the $P_{csss}$ states would shed light on the nature of exotic states and provide an excellent opportunity to distinguish the diquark-diquark-antiquark type pentaquark states from
meson-
baryon type molecular states.
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Strongly Correlated Electrons
Effective theories for many-body systems with nonuniform symmetries
Aleksander Głódkowski
The low-energy dynamics of many-body systems is governed by gapless modes whose properties are dictated by
symmetry. Their existence follows from Goldstone's
theorem, while their effective description at zero temperature is determined by the pattern of
symmetry breaking. At finite temperature, an analogous role is played by hydrodynamics, which describes the universal behavior of many-body systems over long times and large distances. These principles are well understood for uniform
symmetries, which act homogeneously in spacetime and lead to a correspondence between massless Goldstone modes and broken generators, as well as gapless hydrodynamic modes and conserved charges. However, this simple picture changes in the presence of nonuniform
symmetries, whose generators do not commute with spacetime translations. The low-energy implications of these
symmetries remain less understood, as they do not introduce additional gapless modes but instead constrain the dynamics of the existing degrees of freedom. In this thesis, we develop a unified framework for many-body systems with nonuniform
symmetries and show that their effects can be understood in terms of additional fields that are not independent at low energies and can be eliminated, leading to kinematic constraints that reshape the infrared dynamics. In systems with spontaneous
symmetry breaking, this mechanism modifies the effective theory and often softens the dispersion relations of the remaining modes. At finite temperature, it manifests in hydrodynamics as constraints on macroscopic currents. As a result, nonuniform
symmetries give rise to qualitatively new physical phenomena, including modified spectra of collective excitations, exemplified by transverse Tkachenko oscillations in
quantum vortex crystals, and unconventional transport phenomena, such as anomalously slow
diffusion and softened sound modes in dipole-conserving systems.
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Materials Science
Electronic manipulation of polar order in electron crystal
Takashi Kikkawa, Ziyan Chen, Yuto Fujimoto et al. (+8 more)
When interaction among atoms or ions is strong enough, they often arrange periodically, forming a
crystal. The arrangement patterns of atoms or ions can encode information, a concept that has enabled devices such as ferroelectric
memories. It has been found that not only atoms or ions but also electrons in condensed matter can crystallize when Coulomb interaction is strong enough. Typical examples are charge-ordered states in solids, where different valences, or different electron numbers, of an ion spontaneously form a spatial pattern on the
lattice. In such electron
crystals, information is expected to be encoded into the electron-ordering patterns. Here, we demonstrate electronic manipulation and readout of charge-ordering directions in a paramagnetic
semiconductor LuFe$_2$O$_4$. By applying current pulses at room temperature, we observed that the non-reciprocal resistivity of LuFe$_2$O$_4$ is modulated along with a sign reversal, which disappears above the charge-ordering temperature. A numerical calculation incorporating inter-band Berry
curvature affected by the charge ordering is consistent with the experimental results. By applying the observed phenomenon, we also demonstrate a non-reciprocal resistance
memory operation in the charge-ordered LuFe$_2$O$_4$. This result opens the door to realizing charge-ordering electronics.
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All authors Takashi Kikkawa, Ziyan Chen, Yuto Fujimoto, Takahiro Morimoto, Yuya Hirata, Hiroki Arisawa, Alexey A. Kaverzin, Satoshi Okamoto, Yoichi Okimoto, Naoshi Ikeda, Eiji Saitoh
Mesoscale and Nanoscale Physics · Cross-listed from cs.LG
Action-Factored Multi-Agent Reinforcement Learning for Scalable Quantum Device Tuning
Edwin De Nicolo, Rahul Marchand, Cornelius Carlsson et al. (+2 more)
Cooperative multi-
agent reinforcement learning is well suited to problems with large parameter spaces and exploitable local structure, such as the tuning of electrostatically-defined
quantum-dot arrays. However, if parameter cross-talk is strong, a non-stationary environment from the perspective of any individual
agent can destabilize learning - the same effect that plagues manual tuning of such systems. We propose using a factored representation of the action space, learned online, to decouple
agents and minimize their interference. Our framework, QADAPT, uses this factorization to efficiently learn shared policies based on local measurements and rewards. With this modular strategy, we achieve zero-shot generalization to unseen
quantum device sizes and maintain an approximately constant number of convergence steps to reach target regimes. This work provides a scalable route toward the rapid calibration of large-scale
quantum processors.
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All authors Edwin De Nicolo, Rahul Marchand, Cornelius Carlsson, Pranav Vaidhyanathan, Natalia Ares
Strongly Correlated Electrons
Short-range magnetic order and multi-stage phase transitions in the easy-plane van der Waals magnet CrCl$_3$
T. B. Mazitov, M. I. Panin, A. S. Pakhomov et al. (+4 more)
We investigate the
evolution of
spin correlations and the nature of the multi-stage
magnetic transition in the quasi-two-dimensional easy-plane van der Waals magnet $\rm CrCl_3$. By combining broadband
ferromagnetic resonance (FMR) spectroscopy and DC SQUID magnetometry on mechanically exfoliated micro-flakes with non-local dynamical mean-field theory (DFT+DMFT) calculations, we analyze both long- and short range
magnetic order in CrCl$_3$. Experimentally, SQUID and FMR measurements confirm the presence of the crossover to a
spin polarized phase with the subsequent transition into an
antiferromagnetic ground state upon cooling, but show robust short-range correlations at temperatures far above the
magnetic ordering temperatures. Theoretically, we show the existence of highly stable local
magnetic moments at room temperature, with a
giant room temperature lifetime $\tau$ of 130–300 ps due to a wide Mott bandgap. Below room temperature, a rapid growth of the in-plane correlation length $\xi$ signals the formation of strong short range
magnetic order consistent with the experimental observations. We also obtain a temperature-driven crossover of the interlayer exchange interaction, which changes from positive (
ferromagnetic) at high temperatures to negative (
antiferromagnetic) in the low-temperature ordered phase.
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All authors T. B. Mazitov, M. I. Panin, A. S. Pakhomov, M. V. Bakhmetiev, E. O. Chiglintsev, A. I. Chernov, A. A. Katanin
Mesoscale and Nanoscale Physics
Coherent dynamics of individual excitons in a quantum dot embedded in a nanopost
Maxime Gaignard, Karolina Ewa Polczynska, Niels Gregersen et al. (+5 more)
We measured coherent ultrafast dynamics of
exciton complexes in a single strongly-confined InAs
quantum dot embedded in a GaAs nanopost. Such a photonic structure combines a wave guiding with a cavity effect and assures an enhanced light-matter coupling over a broad spectral range of 30 nm. Coherence properties of an
exciton-biexciton system hosted by a
quantum dot are assessed with four-wave mixing microscopy. Our results show that this broad-band photonic structure is an excellent asset to probe coherent couplings in a small set of solid state
quantum systems and to investigate the coherence dynamics within the level structure of their excited states.
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All authors Maxime Gaignard, Karolina Ewa Polczynska, Niels Gregersen, Daniel Wigger, Jean-Philippe Poizat, Jean-Michel Gérard, Julien Claudon, Jacek Kasprzak
Statistical Mechanics
The Statistical physics of unsaturated soil water: kinetic theory and non commutative pore water dynamics
Riccardo Rigon
We develop a statistical-mechanical theory of water in unsaturated soil whose outcome is a continuum field equation for the pore-occupancy g(r,x,t), the fraction of pores of radius r that are water-filled at position x and time t. The theory is built across three scales: microscopic inter-pore transfers set by Hagen-Poiseuille rates and a driving potential (the difference of pore-class chemical potentials, taken in capillary-gravitational form but open to adsorptive, osmotic, or thermal refinement); a mesoscale master equation relaxing the occupancy toward the
equilibrium step g_eq=H(r*-r); and, on contracting the averaging volume to a point, the continuum balance d_t g + div F = C[g] - E - T, of which everything else is a limit, a moment, or a boundary resolution. The kinetic equation is an Onsager gradient flow descending the Gibbs free energy, with an H-
theorem for the isothermal unforced system and mass conservation as its zeroth moment. A single dimensionless group, the pore-resolved Damkohler number Da(r,x), organizes the behavior and unifies phenomenologies long modelled separately. A Chapman-Enskog reduction identifies Richards' equation as the quasi-static (Da->0) limit, with matric potential and hydraulic conductivity K emerging only there and K vanishing below the percolation threshold; capillary-bundle and critical-path models are its diagonal and spectral limits. Hysteresis is the holonomy of a forcing bundle, a
geometric phase rather than per-pore bistability, with a falsifiable loop-area law H ~ I^2. Preferential flow is what the same equation does where Da>1, so the Richards/preferential-flow dichotomy becomes a continuous Da-controlled crossover. Out of the quasi-static limit g(r) is the irreducible state variable. All inputs are
geometric properties of the pore network, measurable from micro-CT and calibrated against no macroscopic data.
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Quantum Physics
Speckle-based feedback control of optical dipole trap axial waist position
D.A. Pershin, D.A. Kumpilov, A.E. Rudnev et al. (+11 more)
Cold neutral atoms is a powerful tool for many experiments ranging from frequency standards and sensing to
quantum simulations. Sensitive experiments often demand transferring cold atoms from one
vacuum chamber to the other with better optical access and
vacuum. In case the transfer is done with a beam waist controlled by a focus-tunable lens, repeatability of the transfer as well as stability of the final position can be below the experimental demands. Here we implement the scheme for stabilization of the axial waist position of the optical dipole trap in the whole range of transfer (38 cm) using speckle patterns, which provides enough stability to achieve Bose-Einstein condensation of around 4*10^4 thulium atoms in the trap formed by the transport beam and the other beam in the target
vacuum volume
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All authors D.A. Pershin, D.A. Kumpilov, A.E. Rudnev, G.E. Subbotin, A.M. Ibrahimov, I.S. Cojocaru, V.A. Khlebnikov, I.A. Pyrkh, P.A. Aksentsev, S.A. Kuzmin, A.D. Raskatov, A.K. Zykova, V.V. Tsyganok, A.V. Akimov
Materials Science
Unlocking ultrafast spin dynamics in a rare-earth magnet
Paul Herrgen, Christian Holzmann, Torben Manzke et al. (+5 more)
The speed of optically driven magnetization dynamics is fundamentally determined by how efficiently angular momentum can be transferred between electronic,
spin and
lattice degrees of freedom. In rare-earth magnets, this process is typically slow because optical excitation primarily addresses itinerant electrons, whereas the
magnetic moment resides in localized 4f states. Here we show that selective optical excitation of localized
magnetic states can overcome this limitation. Using femtosecond pump-probe magneto-optical spectroscopy of ferrimagnetic gadolinium iron garnet, we resonantly excite an intra-4f transition of Gd3+ at 4.65 eV and resolve the ensuing dynamics of the antiferromagnetically coupled Gd and Fe sublattices. Direct excitation of the 4f
manifold induces an ultrafast demagnetization of the Gd sublattice with a characteristic time of 38 fs, more than two orders of magnitude faster than in elemental gadolinium and even faster than the response of the Fe sublattice in the same material. By contrast, off-resonant excitation strongly suppresses the acceleration of the Gd dynamics while leaving the Fe response largely unchanged. These results demonstrate that the ultrafast
magnetic response of rare-earth systems is governed not only by intrinsic material properties but also by the optical excitation pathway. Selective access to localized
magnetic states therefore provides a powerful photonic handle for engineering angular-momentum flow and controlling magnetism far from
equilibrium.
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All authors Paul Herrgen, Christian Holzmann, Torben Manzke, Ulrich Nowak, Peter M. Oppeneer, Manfred Albrecht, Benjamin Stadtmüller, Martin Aeschlimann
Statistical Mechanics
Local-dynamics accessibility of the stripe phase in the triangular-lattice $J_1$-$J_2$ Ising antiferromagnet
Tom Poisblaud
The interplay between energetic relaxation and global stripe-sector selection is investigated by analyzing the finite-rate cooling dynamics of the triangular-
lattice $J_1-J_2$ Ising antiferromagnet under local single-
spin Metropolis updates. A protocol-dependent stripe-accessibility time, $n^*(L,J_2/J_1)$, was established as an operational diagnostic to determine the threshold at which half of the trajectories achieve global stripe order. Real-space morphology diagnostics and fixed-temperature holds were subsequently employed to assess late-stage domain wall elimination and to characterize the finite-time coarsening behavior across varying system sizes and $J_2/J_1$ coupling ratios. The system quickly forms local stripe patterns before aligning them globally. Final
alignment is slowed by domain-wall elimination, taking longer in larger systems but speeding up with a higher $J_2/J_1$ ratio.
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High Energy Physics (Theory)
Circuit and Krylov complexity of primordial perturbations of modified gravity in inflation
Tao Li and Hai-Bing Fu
Taking canonical scalar field inflation as the reference case, we investigate the
circuit and Krylov complexities of
primordial curvature perturbations in an \(f(\phi,R)\) modified
gravity inflation. We derive the
evolution equations for the squeezed strength \(r_k\) and squeezed angle \(\varphi_k\), and calculate the
circuit complexity, Krylov complexity, Krylov
entropy, Lanczos coefficients, and effective dissipative contribution. Compared with the canonical model, the squeezed strength \(r_k\) grows more slowly in the modified
gravity inflation and continues to exhibit oscillations after horizon exit. Consequently, the spreading in Krylov space is suppressed and modulated through the relation \(K=\sinh^2 r_k\). Modified
gravity also changes the squeezed angle, thereby modifying the phase-space correlations and enhancing the oscillatory behavior of the
circuit complexity. In the presence of modified
gravity effects, information loss is suppressed before horizon exit, whereas it barely affects information loss after horizon exit. For the parameters considered, the Lyapunov exponent and Lanczos coefficients indicate that modified
gravity has little effect on the effective degree of
quantum chaoticity. These results show that \(f(\phi,R)\) modified
gravity primarily reorganizes the amplitude, phase, complexity, and information loss dynamics of
primordial quantum fluctuations.
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Solar and Stellar Astrophysics
JWST Edge-on Disk Ice (JEDIce): Vibrationally hot, rotationally cold H$_2$ in the outer disk of Oph 163131 non-thermally excited by UV and cosmic rays
Korash Assani, Zhi-Yun Li, Jennifer B. Bergner et al. (+19 more)
Constraining ionization and excitation processes in protoplanetary disks is essential for understanding the chemical structure and
evolution of disk material, shaping
planet formation pathways. We present JWST/NIRSpec IFU observations of the edge-on disk Oph 163131, which reveal a unusual ro-vibrational H$_2$ spectrum dominated by the 1–0 O(2) line (2.627 $\mu$m), with suppressed higher-$J$ emission despite excitation to $v=2$ and $3$. This vibrationally hot, rotationally cold H$_2$ emission is spatially extended, broadly following the molecular disk traced by CO($J{=}2$–1), with emission increasing above and below a thin midplane dark lane and extending radially beyond $\sim$200 au, where near-IR scattered-light emission is no longer dominant. We interpret the observed H$_2$ emission as arising from non-thermal excitation in cold, dense outer-disk gas, where collisions depopulate higher-$J$ rotational levels within each vibrational
manifold prior to emission, producing the characteristic “$v$-hot, $J$-cold" spectrum. We consider both ultraviolet irradiation and
cosmic-ray excitation as contributors to the H$_2$ emission and find that their combined action, together with collisional de-excitation of high-$J$ level populations, broadly reproduces the observed line ratios and morphology. Within this framework, we infer a rather high effective
cosmic-ray ionization rate of $\sim(1$-$10)\times10^{-15}$ s$^{-1}$ in the presence of a moderate UV field ($\chi_{UV}=100-1000$, in Draine units). These results for disks, together with the recent findings by Bialy et al. 2025 for the lower-density starless core B68, highlight the potential of ro-vibrational H$_2$ emission as a novel probe of
cosmic-ray ionization.
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All authors Korash Assani, Zhi-Yun Li, Jennifer B. Bergner, David A. Neufeld, Daniel Harsono, Maria N. Drozdovskaya, Marco Padovani, Emmanuel Dartois, Jennifer A. Noble, Nicole Arulanantham, Alice S. Booth, Yao-Lun Yang, Mayank Narang, Will E. Thompson, Elizabeth Yunerman, Karin I. Öberg, Julia C. Santos, Charles Mentzer, Jon P. Ramsey, Lukas Welzel, Klaus M. Pontoppidan, Melissa McClure
High Energy Physics (Theory)
Scalar fields, impurities and supersymmetry
D. Bazeia, A.C. Lehum and G.S. Santiago
We develop a rigid $\mathcal{N}=(1,1)$ superspace formulation for multifield scalar models coupled to localized
impurities through spurion superfields in two-dimensional spacetime. The spurionic completion gives a manifestly supersymmetric action and provides a systematic framework for describing interacting scalar fields in the presence of
impurity backgrounds. In this setting, supersymmetry acts as an organizing principle for a controlled bosonic half-BPS sector, with the preserved projector selecting the
impurity-compatible first-order equations. We derive the corresponding coupled BPS equations, energy density, boundary conditions, and Bogomol'nyi bound, showing that localized
impurities deform the BPS profiles and redistribute the local energy density while leaving the total BPS energy fixed by the topological boundary term. We illustrate the formalism through representative one-, two-, and three-field models, analyzing the resulting BPS configurations and their local energy density profiles.
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Medical Physics
Two observables of one wall: how surface relaxivity can bias the diffusion intra-axonal fraction and the myelin water fraction
Rutger H.J. Fick
Surface relaxivity and time-dependent
diffusion are two readouts of the same wall collisions on one substrate: the transverse rate that microstructure imaging fits is a bulk rate plus a surface rate $\rho\,(S/V)$, and intra- and extra-axonal water carry different $S/V$, so their $T_2$ differ and any compartment estimate that normalises by a TE-weighted $b=0$ is biased. We derive closed forms for the interior (Brownstein-Tarr) and exterior (Novikov-Burcaw) surface rates over myelinated cylinders, validate them with wall-counting Monte Carlo, and quantify the resulting bias on the
diffusion intra-axonal signal fraction $f_{\mathrm{intra}}$ and on the myelin water fraction (MWF). The interior/exterior $S/V$ ratio is $(1-\mathrm{VF})/(g\,\mathrm{VF})$, independent of the calibre distribution and crossing unity at fibre volume fraction $\mathrm{VF}^{\ast}=1/(1+g)$. Physiological white matter sits above this crossover, so surface relaxivity over-weights the intra-axonal signal, biasing $f_{\mathrm{intra}}$ by $\approx 12\%$ at clinical PGSE ($\mathrm{TE}=80\,\mathrm{ms}$). That fractions are TE-dependent is known; new here are the surface-relaxivity and packing attribution, a closed-form sign law, and a testable packing-dependent TE drift. The same physics reads through relaxometry as a smaller MWF bias: the thinnest axons' water crosses below the myelin window and is counted as myelin, so fine white matter reads myelin-richer ($\sim 0.33\,\mathrm{pp}$, beneath single-voxel noise but super-linear in the uncertain $\rho$), while in primary lumen-preserving demyelination this bias is nearly constant and cancels in the longitudinal change. One $S/V$ physics thus biases both
diffusion and relaxometry microstructure estimates, the $f_{\mathrm{intra}}$ bias being first-order and packing-dependent, the MWF bias small and structural.
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Chemical Physics
Quantum phases in endofullerene zigzag chains
Tobias Serwatka, Muhammad Shaeer Moeed, Roger G. Melko et al. (+1 more)
We employ large-scale density
matrix renormalization group calculations to study the
quantum phases of dipolar molecules confined in bent (zigzag) endofullerene chains, as a function of the chain angle $\gamma$. For LiF, ferroelectric order persists across the full range $60^\circ < \gamma 180^\circ$, with the critical effective dipole moment increasing as the chain bends and parallel
alignment becomes less favorable. Near the equilateral configuration ($\gamma = 60^\circ$),
geometric frustration drives a transition to an antiferroelectric Néel-ordered phase in which neighboring dipoles anti-align along the chain axis. We show that capturing this reorientation requires including dipolar couplings beyond the nearest-neighbor approximation, since next-nearest-neighbor interactions become equally strong at $\gamma = 60^\circ$. For confined water, o-D$_2$O reproduces both ordered phases, whereas p-H$_2$O – owing to its large rotational constants – develops no order at any chain angle despite the enhanced coordination of the bent geometry. Because a zigzag chain is the narrowest stripe of a two-dimensional
lattice, these results suggest that engineered endofullerene layers could host a rich variety of dipole-ordered
quantum phases beyond the ferroelectric ordering observed in previous work.
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All authors Tobias Serwatka, Muhammad Shaeer Moeed, Roger G. Melko, Pierre-Nicholas Roy
Strongly Correlated Electrons
Sixteenfold Classification of Many-Body Multipoles from Rotation-Compatible Canonical Symmetries
Shingo Kuniyoshi, Rikuto Oiwa and Satoru Hayami
The conventional multipole framework provides a standard
symmetry-based
language for one-body electronic degrees of freedom, but fails to distinguish physically distinct sectors in many-body operator space. We show that canonical
symmetries compatible with rotations provide this structure through two additional 2 labels associated with the particle-number gauge transformation G{\pi}/2 and the particle-hole transformation CA. These labels separate operators with different body numbers and particle-number changes, leading to a sixteenfold classification that organizes selection rules for nonzero expectation values, induced multipoles, and
symmetry-allowed couplings in many-body multipole space.
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Space Physics
Reformation of Supercritical Perpendicular Shock
Yuri V. Khotyaintsev, Domenico Trotta and Daniel B. Graham
Super-critical collisionless shocks are not static structures but evolve continuously as they reflect incoming ions back upstream. The physical process responsible for this non-stationarity – whether it is dominated by wave-like corrugation of the shock surface (rippling) or by a cyclic rebuilding of the shock transition (reformation) – remains debated. We combine Magnetospheric Multiscale (MMS) observations of a nearly perpendicular ($\theta_{Bn}\approx89^\circ$), supercritical ($M_A\approx6$) bow shock with high-resolution two-dimensional hybrid simulations to address this question. MMS reveals repeated ion phase-space holes and intense, localized
Hall electric fields. A virtual-spacecraft analysis of the simulation reproduces these signatures and shows that they arise from a self-regulating feedback cycle: strong
Hall-field ion reflection builds a reflected-ion foot, which weakens the
Hall field and suppresses further reflection until the foot decays and the cycle restarts. This reformation cycle, spatially organized by the two-dimensional shock structure, explains most of the observed non-stationarity.
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Instrumentation and Methods for Astrophysics
Exploration of small footprint stick-slip piezoelectric actuators for use in the FLEX fibre positioner system for the Wide-field Spectroscopic Telescope (WST)
Joseph W. Barrow, Suryansh Saxena, Jon S. Lawrence et al. (+2 more)
This work presents a novel stick-slip piezoelectric actuator for the FLEX fibre positioner, addressing the challenge of reducing footprint while maintaining precision in next-generation multi-object spectroscopic instruments such as the Wide-field Spectroscopic
Telescope (WST). The actuator combines compact geometry (3.2 mm diameter, sub 70 mm length) with high-resolution incremental motion, low power consumption, and high reliability. Three actuators can be integrated into a sub 7 mm diameter circle, enabling a simplified, single-plane assembly. This design offers a promising solution for miniaturized, accurate fibre positioning in wide-field spectroscopic applications.
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All authors Joseph W. Barrow, Suryansh Saxena, Jon S. Lawrence, Aaron Omadutt, Roelof S. de Jong
Soft Condensed Matter
Dispersion Polymerization in an Elastomeric Solvent
Senthilkumar Duraivel, Reagan J Dreiling, Tyler E Ball et al. (+5 more)
Polymerization-induced phase separation (PIPS) provides a powerful route to generate structured polymeric materials by coupling chemical conversion with thermodynamic demixing. PIPS in
liquid-state systems underlies dispersion polymerization, serving as a cornerstone technique for microparticle production, yet is constrained by solvent compatibility and limited range of morphologies. Here, we establish an elastically mediated PIPS regime that bridges these two limits by conducting controlled polymerization within a deformable elastomeric network. This approach, termed Dispersion Polymerization in an Elastomeric Solvent (DiPolES), serves as a solid-state analogue of dispersion polymerization in which an elastomeric network simultaneously serves as solvent and physical stabilizer. Using photoiniferter-mediated polymerization of methyl methacrylate (MMA) within poly(dimethyl siloxane) (PDMS) elastomeric solvent, DiPolES enables robust fabrication of elastomeric composites containing uniform PMMA microparticles with tunable size (0.85 to 3 {\mu}m) and shape (spheroidal and ellipsoidal). The strategy is generalizable beyond the PDMS/MMA system and is applicable to diverse monomers, such as acrylonitrile and 2-vinyl pyridine, which can be extracted from the elastomeric solvent, enabling high-yield production of microparticles. Real-time imaging and compositional analysis reveal that particle formation proceeds through rapid nucleation at low monomer conversion, followed by growth accompanied by cavitation of the surrounding network. Monomer loading governs the particle size, while solvent elasticity modulates the transition from isolated uniform spheroids to heterogeneous clusters. Interestingly, applying uniaxial strain during DiPolES enables production of ellipsoidal particles without any post-processing.
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All authors Senthilkumar Duraivel, Reagan J Dreiling, Tyler E Ball, Harsha Koganti, Jay Fu, Ethan E. O'Banion, Brett P. Fors, Eric R. Dufresne
Quantum Physics
COSMA: Communication-aware Optimization of Fermionic Simulation Kernels for Modular Quantum Architectures
Enrico Russo, Francesco G. Blanco, Elio Vinciguerra et al. (+3 more)
Quantum simulation is a leading application of
quantum computing, but scaling to chemically relevant problems requires modular architectures composed of interconnected
quantum processing units. In such systems, inter-core
quantum communication becomes a major performance bottleneck. In this work, we present COSMA, a communication-aware compilation framework for fermionic simulation kernels targeting modular
quantum architectures. Our approach jointly optimizes
fermion-to-
qubit mapping, Pauli scheduling, and
qubit allocation to minimize inter-core state transfers. Evaluated on molecular
benchmarks, COSMA achieves up to $2.5\times$ reduction in communication cost compared to state-of-the-art baselines, with a median improvement of $1.7\times$. These results demonstrate that cross-layer co-design is essential for efficient and scalable
quantum simulation on multi-core
quantum hardware.
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All authors Enrico Russo, Francesco G. Blanco, Elio Vinciguerra, Davide Patti, Giuseppe Ascia, Maurizio Palesi
Geophysics
Acceleration and Strain-Rate Elastic Wave Equation and its Finite-Difference Solution for Distributed Acoustic Sensing Seismic Simulations
Saeed Izadian
Distributed Acoustic Sensing (DAS) is increasingly being adopted across various seismic disciplines due to its cost-effective acquisition capabilities and its high-resolution spatial and temporal sampling. Fiber-optic cables offer exceptional resistance in high pressure and temperature environments, facilitating both rapid-deployment and long-term continuous monitoring. Unlike traditional sensors, fibre optic cables record seismic vibrations as strain or strain-rate along the cables longitudinal axis. To effectively integrate this data format, the governing equations for seismic wave propagation must be adjusted. This study introduces a formulation based on acceleration and strain-rate, analogous to the conventional velocity-stress framework used for describing elastic waves. The resulting system of first order, coupled partial differential equations closely mirrors existing velocity and stress models, allowing current theoretical frameworks and computational tools to be updated with minimal modification. Numerical validation using finite-difference simulations confirms that the proposed formulation produces strain-rate wavefields in complex media with accuracy equivalent to that of traditional velocity-stress methods, thereby effectively eliminating the requirement for data conversion or extra computations.
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Quantum Physics
When Routes Run Out: Adversarial Co-Learning and Explainable Robustness in Quantum Repeater Networks
Brennan Bell, Inti Gabriel Mendoza Estrada, Andreas Trügler et al. (+1 more)
We study an
adversarial bandit problem for
entanglement-based
quantum-network routing over a modest graph corpus. Alice selects an end-to-end repeater route for an Ekert-91 protocol (E91) representing her move, while Eve selects an attack surface, either edge intercept–resend or repeater
memory degradation. Payoffs are drawn from cached SeQUeNCe-simulated E91 transcripts, and Alice accepts a turn when the finite-sample statistic violates the Clauser-Horne-Shimony-Holt (CHSH) bound. Performing
adversarial co-learning across 50 structured
topologies, we find that learned retention tracks a full-
matrix minimax reference closely (Pearson $r=0.99$): under a one-surface Eve action model, bottleneck families have zero retention, while non-bottleneck families follow a $1-1/N$ coverage principle. We then fit decision-tree explanation models to graph-, attack-, and route-level
topology-corpus targets and report their faithfulness. Finally, we construct
prompt records for local
language models to summarize the tree evidence, resulting in an open-source explanation workflow for
quantum-repeater network games.
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All authors Brennan Bell, Inti Gabriel Mendoza Estrada, Andreas Trügler, Paul Erker
Instrumentation and Methods for Astrophysics
Overview of the Canadian Hydrogen Observatory and Radio Transient Detector (CHORD) Project
The CHORD Collaboration: Kevin Bandura, Leonid Belostotski, Lindsay Berkhout et al. (+48 more)
The Canadian Hydrogen Observatory and
Radio-transient Detector (CHORD) is a next-generation wideband
radio interferometer currently being constructed and commissioned at the Dominion
Radio Astrophysical Observatory in British Columbia, Canada. CHORD is designed for precision 21\,cm cosmology, fast
radio transient discovery, spectral line
galaxy surveys, and
pulsar science using a highly redundant large-N, small-diameter drift-scan array architecture. The
telescope consists of a 512-element core array of 6\,m dishes operating from 300–1500\,MHz in drift-scan mode, together with two 64-dish outrigger stations located at the Hat Creek
Radio Observatory and the Green Bank Observatory for long-baseline transient localization. The instrument supports multiple simultaneous digital backends for interferometric correlation, FRB detection,
pulsar beamforming, and high spectral resolution surveys. CHORD is designed with an emphasis on precision beam control and stable instrumental response, incorporating lessons learned from the Canadian Hydrogen Intensity Mapping Experiment (CHIME) while providing a substantial increase in sensitivity. Initial performance has been evaluated using a three-dish engineering array, and a 64-dish pathfinder array is currently being commissioned. The full array will be commissioned in 2028.
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All authors The CHORD Collaboration: Kevin Bandura, Leonid Belostotski, Lindsay Berkhout, Gianni Bernardi, Akanksha Bij, Duncan Cameron-Steinke, Arnab Chakraborty, Hsin Cynthia Chiang, Jean-Francois Cliche, Sophia Da Costa, Evan Davies-Velie, Matt Dobbs, Emmanuel Fonseca, Simon Foreman, Qwin Goodwin, Ian Hendricksen, Jason Hessels, Alex S. Hill, Mohammad Islam, Michael Jafs, Aditya Krishna Karigiri Madhusudhan, Gordon Lacy, Dustin Lang, Calvin Leung, Jessie Lin, Adrian Liu, Vincent MacKay, Kiyoshi W. Masui, Juan Mena-Parra, James Mertens, Daniele Michilli, Kenzie Nimmo, Robert Pascua, Maura Pilia, Andrea Possenti, Aniket Prasad, Andre Renard, Sophia D'Agostino Rubens, Mawson Sammons, Erik Schnetter, Paul Scholz, Seth Siegel, Jonathan Sievers, Kendrick Smith, Kristine Spekkens, Shronim Tiwari, Martin Topinka, Matteo Trudu, Keith Vanderlinde, Dallas Wulf, Yifan Zhao
Quantum Physics
Deterministic Generation of Linear Photonic Cluster States with Semiconductor Quantum Dots: A Detailed Comparison of Different Schemes
Nikolas Köcher and Stefan Schumacher
Photonic graph states are key resource states for measurement based
quantum information processing. As
semiconductor quantum dots are excellent deterministic
photon emitters, several protocols using them for the generation of linear cluster states have been proposed, either based on constant precession of a hole or electron
spin in a weak
magnetic field, or based on optical
spin control, in a stronger
magnetic field. We theoretically compare four such schemes, using polarization or time-bin encoding, respectively, for a range of cavity environments and
spin coherence times. In particular we study how different error mechanisms affect the different schemes, using a microscopic model of the
spin control, the excitation and emission dynamics, and of the
phonon bath. We find the
spin-precession based schemes to scale well with strong cavity enhancement and to be naturally robust against
phonon-induced decoherence, while the schemes using optical
spin control can perform well for lower
spin coherence times and are strongly dependent on the cooperativity of the cavity induced cycling transition. Our results provide a regime map for choosing between
magnetic-field-driven and optically controlled protocols depending on
spin coherence time, Purcell enhancement, and suppression of unwanted decay channels.
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Nuclear Theory
Bayesian inference of the dense matter equation of state built upon extended Skyrme interactions: A generalization
Mikhail V. Beznogov and Adriana R. Raduta
The nonrelativistic theory of
nuclear matter (NM) based on Brussels-Skyrme interactions is employed to develop models for dense and
neutron-rich matter within a
Bayesian framework. We employ the following set of constraints: the four best-known
nuclear empirical parameters, the density dependence of the energy per particle in pure
neutron matter (PNM), the density dependence of the Landau effective mass ($m_\mathrm{eff}$) of
neutrons in PNM and symmetric NM, and a lower limit on the maximum gravitational mass that
neutron stars (NSs) can support. In addition, a number of “sanity checks” are added: the values of the speed of sound,
neutron and
proton Landau effective masses, and
Fermi velocities are constrained up to the central density of the most massive NS configuration and for isospin asymmetries $\delta=(n_n-n_p)/(n_n+n_p)$ ranging from 0 to 1. Our ensemble of models fully explores the capacity of nonrelativistic Brussels-Skyrme effective interactions to describe NM at densities exceeding several times the
nuclear saturation density. This is a necessary step toward a better understanding of the properties of dense matter and possible correlations between the parameters of NSs and the parameters of NM. Due to the pronounced U-shaped density dependencies of $m_\mathrm{eff}$, which qualitatively agree with the predictions of ab initio calculations featuring three-body forces, all our models exhibit a non-monotonic “rise-and-fall” behavior of the thermal pressure ($p_\mathrm{th}$) as a function of density, which in extreme cases leads to $p_\mathrm{th} < 0$. This work is a generalization of [Beznogov and Raduta, Phys. Rev. C 110, 035805 (2024)].
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Quantum Physics
Quantum Approximate Optimization via Noise-Directed Adaptive Warm-Starting
Filip B. Maciejewski, Stuart Hadfield, Oscar Wallis et al. (+5 more)
Progress towards a
quantum advantage using known heuristic methods for combinatorial optimization is impeded by hardware noise and limited
qubit count. Here, we propose a noise-aware adaptive approach to
quantum approximate optimization, Noise-Directed Adaptive Warm-Starting (ND-AWS), that builds on recent concepts such as Warm-Start QAOA and Noise-Directed Adaptive Remapping. By leveraging bitflip gauge transformations, our
algorithm exploits amplitude-damping-like noise components. We experimentally implement high-performance
quantum optimization ansätze on 100-
qubit Ising
Hamiltonians, showing that ND-AWS generally improves the performance over a non-gauge-transformed iterative Warm-Starting variant, at no additional
circuit cost. This places our results among the highest-quality demonstrations of
quantum optimization with similar ansätze at this scale. Crucially, the simplicity of the framework opens the door for future enhancements such as adaptive bias schedules, and integration with classical solvers.
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All authors Filip B. Maciejewski, Stuart Hadfield, Oscar Wallis, George Pennington, Sebastian Brandhofer, Stefan Woerner, Daniel J. Egger, Davide Venturelli
Astrophysics of Galaxies
Effect of Ice Charging on the Astrochemistry of Interstellar Sulfur Bearing Species on Amorphous Solid Water
T. Vorsselmans, I. Grubova, K. Verhagen et al. (+4 more)
We aim to derive statistically robust and physically interpretable BE distributions for atomic S and the sulfur-bearing molecules H$_2$S, SO$_2$, and OCS on neutral and negatively charged ASW, and assess how excess negative charge alters their retention and potential role in the sulfur reservoir of cold dense molecular clouds. Basis set superposition error (BSSE) and zero-point energy (ZPE) corrected BEs of S, SO$_2$, OCS and H$_2$S, are calculated by density functional theory (DFT), using the ORCA software. Molecule-specific DFT levels of theory were first selected from
benchmark calculations on neutral and charged small water complexes, against coupled-cluster reference energies. The selected protocols were then applied to study adsorption on neutral and charged ASW clusters. A range of adsorption sites were sampled on five independent amorphous ice clusters, yielding BE distributions that account for the site heterogeneity of ASW. Neutral ASW yields broad, site-dependent BE distributions consistent with previous water-ice estimates. On charged ASW, three general cases are identified: the BE will either always increase due to electron transfer (S-atom, SO$_2$), the BE increases slightly without any electron transfer (H$_2$S) or the BE remains the same unless an electron transfer occurs under specific conditions (OCS). These findings are inherently linked to the molecular properties of these molecules.
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All authors T. Vorsselmans, I. Grubova, K. Verhagen, T. Guldentops, R. Buimer, C. King, E. C. Neyts
Quantum Physics
Benchmarking Error Mitigation: Artefactual Improvements in Zero-Noise Extrapolation
Dominik Köster and Wolfgang Mauerer
Reliable benchmarking of
Quantum Error Mitigation (QEM) requires distinguishing genuine improvements from artefacts of the post-processing arithmetic. In this paper, we expose a failure mode in Richardson Zero-Noise Extrapolation (ZNE), a widely used technique routinely (and often implicitly) relied upon in
benchmarks and experiments. When noise amplification operates beyond usable signals - a regime that is quickly reached on current hardware for non-trivial
circuits - we show that the extrapolation no longer reflects the underlying physics, but collapses into a fixed rescaling of a single noisy measurement, producing a bogus apparent improvement that is independent of noise amplification. This poses a rarely considered threat to the validity of many empirical evaluations in
quantum computing. Measurements on real hardware (IQM Euro-Q-Exa) confirm this collapse with ordinary folding alone: as
circuit depth erodes the signal, the reported estimate decouples from the truth and overshoots the ideal by up to 21%. We further introduce a matched-cost "garbage-folding" negative control that carries no usable signal yet reports a larger apparent improvement than genuine folding - showing that the magnitude of an improvement is not evidence of its correctness - alongside a zero-cost check flagging the artefact from data a
benchmark already holds. We distil both into a short reporting checklist for ZNE
benchmarks.
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