Superfluidity in ${}^3\mathrm{He}$ exhibits many unique properties that are of interest to modern condensed matter research, including multiple superfluid phase transitions, topological defects, and exotic classes of excitations like Majorana and Weyl fermions. Many of the most interesting theoretical proposals, which remain underexplored, are realized in highly confined geometries, where surface effects play a dominant role in the thermodynamic and hydrodynamic properties. We have developed nanofluidic resonators capable of exciting a fourth-sound acoustic mode in thin channels with a highly confined dimension ($750\text{–}1800$ nm) that is only $1\text{–}2$ orders of magnitude larger than the superfluid coherence length. When a sufficiently large drive force is applied, we observe a nonlinear softening of the resonance that we interpret as due to the flow suppression of the superfluid gap. We have developed a model of the device that allows the resonance amplitude to be calibrated into a superfluid velocity, which exhibits critical behavior at particular velocities. We identify one of the observed critical velocities as being the velocity at which the gap component parallel to the flow is suppressed to zero. We compare the calibrated velocity to the prediction of a Ginzburg-Landau model, and find reasonable agreement. This measurement represents an ongoing effort to link the hydrodynamic measurements of these nanofluidic devices to theoretical predictions regarding surface gap suppression and surface-bound states.

Bistability, or the coexistence of two stable phases, can be broken by a bias field $h$ destabilizing one of the phases via the nucleation and growth of defects. Strong long-range interactions, $1/r^{\alpha }$ with $\alpha$ less than the system's dimensionality $d$, can suppress the proliferation of defects and restore bistability. The case of weak long-range interactions $d<\alpha <d+1$ remains instead poorly understood. Here, we show that it supports apparent bistability: While the system has in principle a unique stable phase, it appears bistable for all practical purposes for $\alpha <{\alpha }_c$, with ${\alpha }_c>d$ behaving as a genuine critical point. At the core of this is an exponential scaling of the critical droplet size $R_c\sim h^{-1/(\alpha -d)}$ with $\alpha$, which makes nucleating destabilizing droplets extremely unlikely for $\alpha <{\alpha }_c$, and such that ${\alpha }_c$ is mostly independent of system size. In support of these conclusions we provide field-theoretical arguments and numerics on a probabilistic cellular automaton. Overall, our results offer a way to rethink phase stability in systems with long-range interactions as well as another route to achieve practical bistability.

Thermal transport in amorphous materials involves a complex interplay between anharmonicity and atomic-scale dynamics, particularly across the glass transition. To elucidate the underlying mechanisms, we investigate the temperature dependence of thermal transport in amorphous ${\mathrm{Al}}_2{\mathrm{O}}_3$ by combining homogeneous nonequilibrium and equilibrium molecular dynamics (HNEMD and EMD) with the Wigner transport equation (WTE), complemented by structural and dynamical analyses. The thermal conductivity exhibits a significant nonmonotonic temperature dependence, increasing at low temperatures, showing a weak suppression in the glassy regime, and rising again above the glass transition temperature $T_g$. Below $T_g$, heat transport is primarily governed by vibrational excitations and is strongly modulated by anharmonic effects. The WTE framework further reveals that this behavior originates from a competition between two vibrational transport channels: population transport suppressed by anharmonic scattering, and coherence contributions enhanced by intermode coupling. Above $T_g$, strong atomic diffusion renders a purely vibrational description incomplete. EMD decomposition shows that atomic diffusion substantially enhances the kinetic contribution to heat transport. Meanwhile, strong anharmonic interactions give rise to a pronounced negative kinetic-potential cross correlation. This compensating effect, in turn, partially suppresses the rapid increase of the total thermal conductivity with temperature. Element- and coordination-resolved analyses further demonstrate that low-coordination oxygen species exhibit enhanced per-species dynamical activity, which plays a key role in strengthening the kinetic contribution to heat transport at high temperatures.

Although BCS wave functions for superconductors under periodic boundary conditions are well established, obtaining an explicit form of the many-body BCS wave function under open boundary condition is usually a nontrivial problem. In this work, we construct the exact BCS ground-state wave function of a one-dimensional spin-$\frac{1}{2}$ superconductor with $p+is$ pairing symmetry under open boundary conditions for special sets of parameters. The spin magnetization on the edges is calculated explicitly using the obtained wave function. Our work is useful for obtaining deeper understandings of open $p+is$ superconducting chains on a wave-function level.

Moiré superlattices (MSLs) in van der Waals heterostructures have demonstrated their incredible power in driving emergent electronic phenomena, some of which are reminiscent of those usually only observed in bulk strongly correlated quantum materials. With the recent discovery of van der Waals $f$-electron materials, the design of novel MSLs of intrinsic strong correlation is now within the reach. Here we study the novel electron phases of two-dimensional heavy-fermion MSL with increasingly diluted $f$-electron local moments. By applying dynamical mean-field theory with numerical renormalization group as an impurity solver, we demonstrate the appearance of a different energy scale and a reentrant Kondo breakdown in connection with the emergence of a flat band in the system. We further compare our numerical findings with predictions derived from the Lieb-Mattis theorem and show the necessity of this energy scale to consistently reconcile the predictions with the conventional single-impurity limit for exceedingly large unit cells.

We demonstrate that nontrivial multiband topological invariants of electronic wave functions can be revealed through orbital magnetization responses to external magnetic fields. We find that decomposing orbital magnetization into energetic and quantum-geometric contributions allows one to deduce nontrivial multiband topology, provided knowledge of the energy spectrum. We showcase our findings in general effective models with multiband Euler topology. We moreover identify such multiband topological invariants in effective models of strontium ruthenate (${\text{Sr}}_2\text{Ru}{\text{O}}_4$), which may in principle be verified in the state-of-the-art doping-dependent magnetization measurements. Our reconstruction scheme for multiband invariants sheds a topological perspective on the multiorbital effects in materials realizing unconventional phenomenologies of orbital currents or multiband superconductivity.

Magnetic kagome materials have emerged as a new platform for exploring exotic topological transport phenomena. The anomalous Hall effect, a phenomenon prevalently observed in various magnetic kagome materials, is commonly explained using Berry-curvature concepts. Here we report that ${\mathrm{MgMn}}_6{\mathrm{Ge}}_6$, a kagome helimagnet exhibiting a spin-flop transition under magnetic field parallel to the kagome plane, displays a large anomalous Hall conductivity (AHC) of 1179 S/cm at 5 K. The intrinsic AHC reaches approximately 377 S/cm, which is consistent with theoretical calculations and ranks among the highest values reported in magnetic R166 systems. We further reveal that the intrinsic AHC originates from the topological nodal rings at the Fermi level, where a large Berry curvature is induced by the spin-flop transition that breaks time-reversal symmetry. In addition, a pronounced topological Hall effect conductivity of up to 900 S/cm is clearly observed under a magnetic field applied along the [001] $c$-axis direction, strongly indicating the existence of topological magnetic textures. Our results suggest that ${\mathrm{MgMn}}_6{\mathrm{Ge}}_6$ serves as a promising platform for investigating large anomalous transport responses and their interplay with magnetic topological textures.

High-harmonic generation (HHG) in strongly correlated Mott insulators is investigated using exact diagonalization and time-dependent density-matrix propagation of a laser-driven one-dimensional Hubbard chain. By projecting onto equilibrium Hubbard bands, we use the doublon population and its dynamics as a diagnostic to analyze intraband (spin-wave-like) and interband (doublon-holon creation) excitation channels. A filling-dependent crossover emerges: Bloch-like intraband response at dilute filling, mixed dynamics at intermediate filling, and interband-dominated HHG with plateau and cutoff near half-filling. In the considered parameter range, increasing interaction strength $U$ strongly suppresses interband contributions through the enlarged Mott gap and correlation-induced localization. Intra- and interband current decomposition reveals opposing flows below the Mott gap (${\mathrm{\Delta }}_{\mathrm{Mott}}$) and selective dephasing suppression of interband coherence, enhancing net doublon accumulation. Time-frequency analysis uncovers the filling-dependent features of quantum trajectories, manifesting in distinct below-${\mathrm{\Delta }}_{\mathrm{Mott}}$ emission. This doublon-based analysis provides a transparent link between equilibrium spin-charge separation and nonequilibrium strong-field response, and clarifies how dephasing modifies interband coherence and doublon accumulation.

Circuits based on superconducting nanostructures are among the most promising platforms for quantum computing. Understanding how device geometry governs nonlinear electrodynamics is crucial for implementing superconducting quantum technologies. However, to date, research has largely been limited to superconducting nanostructures with collinearly aligned static and dynamic applied magnetic fields. Here, we analyze the dynamics of Meissner currents and Abrikosov vortices in a superconducting nanocube exposed to combined static and microwave magnetic fields, extending the analysis to a more general excitation geometry. We demonstrate that, in a noncollinear configuration, the magnetization component parallel to the static field develops a dominant second-harmonic response under the microwave driving. This effect is strongly enhanced when Meissner currents saturate at static fields just below the thresholds for successive vortex nucleation. By numerically solving the time-dependent Ginzburg-Landau equations, we show that the response originates from Meissner-current saturation combined with the nonlinear oscillations of normal-phase indentations, yielding an anisotropic second-harmonic signal that is directionally separated from, and not overshadowed by, the first-harmonic component of the dynamic magnetization. These findings are relevant for superconducting devices that require controllable high-frequency nonlinearity.

Altermagnetism, characterized by pronounced momentum-space spin splitting without net magnetization, provides an emerging platform for spintronics. Yet nonvolatile control of its spin states remains a key challenge for device application. Here, we demonstrate that antiferroelastic lattice distortions offer a universal structural mechanism for controlling altermagnetism by directly locking the momentum-space spin texture to the antiferroelastic structural order parameter $\eta$. In contrast to ferroelastic distortions, which involve uniform strain, antiferroelasticity consists of oppositely staggered lattice distortions with zero macroscopic strain, analogous to antiferroelectricity (zero net polarization) or antiferromagneticity (zero net magnetization), thereby introducing a hidden structural degree of freedom. Reversal of $\eta$ ($+\eta \to -\eta$) enforces inversion of the altermagnetic spin splitting without Néel vector reversal or net magnetization, providing a low-energy pathway for nonvolatile control. Guided by this principle, we identify a family of antiferroelastic altermagnets, spanning from two-dimensional monolayers (e.g., $\mathrm{Cr}{\mathrm{S}}_3$) to three-dimensional compounds (e.g., $\mathrm{N}{\mathrm{a}}_3\mathrm{Mn}{\mathrm{S}}_4$). Both $\mathrm{Cr}{\mathrm{S}}_3$ and $\mathrm{N}{\mathrm{a}}_3\mathrm{Mn}{\mathrm{S}}_4$ exhibit robust lattice-spin coupling, where biaxial strain triggers antiferroelastic phase transitions accompanied by an inversion of spin-splitting energy (about 396 meV for $\mathrm{Fe}{\mathrm{S}}_2$). Our results establish antiferroelasticity as a general materials design paradigm for strain-driven switchable altermagnets and open avenues for nonvolatile-control spintronic devices.

The process of spin-transfer torque in an altermagnet (AM) is theoretically investigated from the perspective of disparate effective exchange fields acting on the two sublattices. The momentum dependent, anisotropic spin splitting in the AM band structure can cause this asymmetry, leading ultimately to a net uncompensated torque to the Néel vector through preferential absorption of injected electron spins by one of the sublattices. A theoretical model based on this skewed electron spin angular momentum transfer to sublattice magnetizations is developed to account for the effect phenomenologically in the Néel vector dynamics. A subsequent analysis clearly illustrates that a spin-polarized current injection can induce the Néel vector motion in an AM closely resembling that of the magnetization in a ferromagnet under spin-transfer torque. Numerical calculations in a magnetic tunnel junction geometry establish the conditions for a range of responses including deterministic ${180}^{\circ }$ switching and self-oscillations in terms of the injected spin-polarized current density and characteristic material properties. Clearly, the order parameter in an AM with sufficiently strong spin-dependent anisotropy can be modulated effectively via electrical control just as in a ferromagnet, while retaining at the same time advantages attributed to antiferromagnetic dynamics.

We study the impact of off-resonant tunneling and coherences on the electron pumping through quantum dots. Thereby, we focus on two electron-pump setups where lowest-order tunneling processes are suppressed and the pump is exclusively driven by modulations of the coupling energy. The first setup is driven by switching on and off the couplings between the quantum dot and the leads, while the second setup employs measurements of the dot occupation. We derive exact solutions for arbitrarily strong tunnel couplings in the absence of Coulomb interaction, identify parameter regimes with optimal pumping currents or optimal energy efficiency, and discuss similarities between both pumping mechanisms.

We present a theoretical analysis of interface states emerging at junctions between armchair graphene nanoribbons of varying widths. By exploring diverse width combinations and junction geometries, we demonstrate that predicting the precise number of interface states requires considerations beyond the topological classification alone; specifically, the width differences and bonding configuration at the interface play crucial roles. For junctions involving ribbons with small gaps, we further examine how an applied strain affects their topological properties and, consequently, the interface states formed. The spin states at these junctions are investigated using the mean-field Hubbard model, revealing how the magnetic behavior at the interface depends on the number of localized states present. These results are summarized in a series of “rules of thumb” to predict the number of localized states and the magnetic moment at the junction. Our findings contribute to understanding and engineering localized states in graphene-based devices, providing guidelines for manipulating electronic and magnetic properties through structural design.

The fate of quantum entanglement at finite-temperature phase transitions remains an open question, particularly for continuous symmetry breaking where zero-temperature Goldstone modes generate long-range correlations. Using large-scale quantum Monte Carlo simulations, we investigate the third Rényi negativity across the $O\left(3\right)$ transition in the three-dimensional Heisenberg antiferromagnet, studying a thermal critical point with continuous symmetry. We uncover two fundamental results. First, the negativity exhibits a pure area law at the critical point, with the subleading constant term vanishing within statistical uncertainty. This demonstrates that thermal fluctuations completely destroy the long-range entanglement present at zero temperature. The divergent classical correlation length leaves no imprint on such quantum entanglement. Second, despite this absence of singular behavior in the negativity, its temperature derivative follows the exact scaling of the specific heat, yielding critical exponents $-\alpha /\nu \approx 0.190$ and $1/\nu \approx 1.350$ in precise agreement with the $O\left(3\right)$ universality class. Our work establishes that while quantum entanglement is blind to thermal criticality its thermodynamic derivatives encode the full universal scaling, revealing an unexpected connection between entanglement and classical phase transitions.

The Hall effect provides a route for unidirectional manipulations of classical and quantum waves. In optics, the spin Hall effect (SHE) induced by the interaction between intrinsic angular momentum (AM) and material inhomogeneity enables AM-dependent control of light at the subwavelength scale. Despite its significance across various bulk and nanostructured geometries, the effect of non-Hermiticity on the optical Hall effect is generally assumed to be trivial except at the exceptional points in parity-time symmetric systems with tailored gain and loss. Here, we demonstrate the nontrivial Hall effect for light carrying both spin and orbital AM in a general non-Hermitian medium by revealing the emergent Hall shifts which rely solely on loss/gain of the systems. We demonstrate that loss or gain at a simple sharp interface introduce a spectral-selective absorption of light through a complex-valued geometrical phase, leading to AM-related corrections to the usual transverse SHE, including the transverse momentum shift, and the spin-orbit and nonlinear orbital Hall shifts along the longitudinal direction. We also propose to engineer and enhance the Hall effect with non-Hermitian gradient metasurfaces. We generalize the analysis to the propagation of light in inhomogeneous continuous media in the framework of geometrodynamics and identify the anomalous velocities due to non-Hermiticity as the counterparts of the interfacial Hall effect. Our work not only deepens our understanding of the Hall effect but also enables subwavelength light manipulations in non-Hermitian optical systems.

The self-energy encodes the fundamental lifetime of quasiparticle excitations. In one dimension, it is known to display anomalous behavior at zero temperature for interacting fermions, reflecting the breakdown of Fermi-liquid theory. Here we show that the self-energy is also anomalous in the infinite-temperature Hubbard chain, where thermal fluctuations are maximal. Focusing on the second-order ring diagram, we find that the imaginary part of the self-energy diverges nonperturbatively: as a power law with exponent $-1/3$ near half filling, and logarithmically away from it. These divergences are captured numerically by the anomalous temporal relaxation of the Green's function and the composite fermion spectral function. Our results demonstrate that anomalous relaxation and the breakdown of perturbation theory survive even at maximal entropy, which can be observed in cold-atom experiments probing the Hubbard chain at high temperatures.

Using crystal structure prediction and first-principles calculations, we show that the Li-Xe system exhibits diverse structural, electronic, and dynamical behaviors under pressure. Lithium-rich phases display electride character, with interstitial electrons dominating the states at the Fermi level, leading to metallicity and phonon-mediated superconductivity with superconducting transition temperatures of approximately 9–14 K. In contrast, xenon-rich phases transition into a superionic state at elevated temperatures, characterized by Li ions becoming increasingly mobile within a rigid Xe lattice before melting at higher temperatures. These results reveal the dual nature of Li-Xe compounds, combining interstitial electron driven superconductivity at low temperatures with ion diffusion mediated superionicity at high temperatures, providing insights into noble-gas chemistry under extreme conditions and potential implications for planetary interiors.

With first-principles theoretical and symmetry analysis, we establish that (${\mathrm{PbMnO}}_3{)}_1$/(${\mathrm{PbVO}}_3{)}_1$ superlattice is a multiferroic with coexisting ferromagnetism, ferroelectricity, and Berry curvature dipole. Transfer of electronic charge from ${\mathrm{V}}^{4+}$ to ${\mathrm{Mn}}^{4+}$ is shown to drive (a) polar (${\mathrm{\Gamma }}_5^{-}$ symmetry) distortion dominated by ${\mathrm{V}}^{5+}$ ($d^0$) displacements, and (b) Jahn-Teller distortion of ${\mathrm{Mn}}^{3+}{\mathrm{O}}_6$ octahedra to open up a gap. Berry curvature and associated spin-polarized Berry curvature dipole are of magnitude comparable to that of Weyl semimetals composed of heavy elements with strong spin-orbit coupling. Integrating Berry curvature dipole with magnetoelectric multiferroic behavior of the heterostructure ${\mathrm{PbMnO}}_3$:${\mathrm{PbVO}}_3$ gives a combination of magnetoelectric coupling and electrically switchable anomalous Hall effects. The sign and spin-polarization of dc nonlinear transverse Hall voltage, generated by a longitudinal ac electric field, encodes nonvolatile four-state memory in a Hall device, making it useful for oxide electronics and spintronics.

We investigate signatures of quantum chaos in the mixed-field quantum Ising model on finite-size Erdős–Rényi graphs using probes scalable on near-term quantum devices. Upon tuning the graph connectivity, the system exhibits a crossover from a localized regime at low connectivity, through a chaotic regime at intermediate connectivity, to a permutation-symmetric integrable limit near all-to-all connectivity. This crossover has possible implications for the performance and trainability of variational algorithms such as QAOA. We characterize this crossover in finite-size systems using complementary probes. First, deep thermalization of a projected ensemble starting from a product state reveals slow (fast) convergence to the Haar ensemble at extremal (intermediate) connectivities. Second, we analyze eigenstate and eigenvalue correlations using the partial spectral form factor, an experimentally scalable proxy for the spectral form factor with reduced resource overhead, and observe characteristic chaos signatures at intermediate connectivities and distinct deviations at extremal connectivities. Finally, we explore the Krylov complexity of operators, a locality-independent diagnostic that, although not directly experimentally accessible, serves as a tool for quantifying scrambling. We show that it is maximized deep in the chaotic regime, corroborating the signatures observed through the experimentally scalable probes. Our results provide finite-size benchmarks demonstrating robust signatures of chaos in scalable probes and suggest that these diagnostics can be implemented in current quantum platforms to access regimes beyond classical simulation.

We demonstrate that the Kibble-Zurek mechanism holds for open systems transitioning from a disordered phase to a discrete time crystal (DTC). Specifically, we observe the characteristic power-law scaling with quench time of the number of spatial defects and the transition delay measured from the time at which the system crosses the critical point. We show analytically that this universal behavior can be traced back to how systems that can be mapped onto a dissipative linear parametric oscillator (DLPO) satisfy the adiabatic-impulse approximation, evinced by the divergence of the relaxation time of the DLPO near a critical point. We verify our predictions in both the classical and quantum regimes by considering two systems: the sine-Gordon model, which is a paradigmatic system for emulating classical DTCs, and the open Dicke lattice model, an array of spin-boson systems subject to quantum fluctuations. We establish a universality class for DTC formation in systems that can be mapped onto a DLPO, and we show that the classical and quantum models considered here belong to this class.