The anomalous Hall conductivity in magnetic Weyl semimetals scales linearly with the momentum separation between Weyl nodes, establishing a geometric paradigm for three-dimensional Hall responses. Here, we discover an analogous phenomenon in the spin Hall effect: a quantized spin Hall conductivity (SHC) in nodal-ring semimetals that scales linearly with the nodal-ring radius $R$. From an ideal model with a single nodal ring, we derive analytically that the SHC inside the spin-orbit-coupled gap obeys ${\sigma }_{\alpha \beta }^{S,3\mathrm{D}}={\sigma }_0^{S,2\mathrm{D}}(\pi R/2\pi )$, where ${\sigma }_0^{S,2\mathrm{D}}=(e^2/h)(\hslash /2e)$ is the two-dimensional quantum spin Hall conductance. Crucially, the symmetry of the spin-orbit coupling acts as an independent switch: Rashba coupling generates purely conventional SHC components, while Weyl coupling additionally activates unconventional ones, providing separate control over response magnitude and tensor symmetry. We validate this principle in yttrium nitride, where strain tunes $R$ and symmetry breaking toggles between response types. Our Letter establishes a new paradigm for engineering quantized geometric responses in three dimensions, opening pathways to tailored spin-orbit functionalities.

The quantum XXZ spin-$1/2$ chain features non-Gaussian spin current fluctuations in the regime of easy-axis anisotropy. Using ballistic macroscopic fluctuation theory, we derive the exact asymptotic probability distribution of typical spin-current fluctuations in thermal equilibrium at zero average magnetization. The obtained nested Gaussian distribution is fully characterized by its variance, which we analytically relate to the spin diffusion constant and static spin susceptibility, comparing our prediction with numerical simulations. By unveiling how the same mechanism which leads to anomalous charge current fluctuations in single-file systems manifests itself in the XXZ chain, our approach establishes the universal hydrodynamic origin of the observed anomalous fluctuations.

Quantized bulk response functions are hallmark signatures of topological phases, but their manifestation in periodically driven (Floquet) systems is not yet fully established. Here, we show that two-dimensional anomalous Floquet systems exhibit a quantized bulk response encoded in a Chern-Simons axion (CSA) coupling angle ${\theta }_{\mathrm{CS}}^F\in 2\pi \mathbb{Z}$, reflecting a topological magnetoelectric effect analogous to that in three-dimensional insulators. The periodic drive introduces an emergent “photon” dimension, allowing the system to be viewed as a three-dimensional Sambe lattice. Within this framework, quantized cross-correlated responses—namely, photon-space polarization and magnetization density—emerge as physical signatures of the CSA coupling. The CSA angle, constructed from the non-Abelian Berry connection of Floquet states, admits a natural interpretation in terms of the geometry of hybrid Wannier states. These results provide a unified framework linking Floquet band topology to quantized bulk observables, demystifying the topology of gapped 2D anomalous Floquet systems by establishing their connection to static 3D topological systems.

Hybrid systems provide a general framework for realizing cooperative effects among multiple topological phases. Unlike the simple coexistence of topological phases in separate band gaps, intrinsic hybridization integrates different topological phases into a single band gap, enabling controlled spatial distributions of topological states, tailored boundary responses, and emergent states inaccessible in single-phase systems. Here, we propose and experimentally demonstrate a higher-order hybrid topological insulator enabled by intrinsic hybridization, implemented through lattice-deformation engineering to integrate higher-order spin and valley topological phases. This mechanism gives rise to three unconventional types of corner states and enables their selective excitation. As the hybridization parameter is continuously tuned, the system transitions across multiple topological regimes, accompanied by a systematic reconstruction of both the number and nature of corner states. These results extend the landscape of higher-order topological phases, provide a general strategy for designing reconfigurable hybrid topological platforms, and demonstrate potential applications in wave manipulation.

We report a comprehensive study on the origin of the enigmatic disordered ground state within the Shastry-Sutherland lattice, ${\mathrm{BaCe}}_2{\mathrm{ZnS}}_5$, at low temperatures. The magnetization and heat capacity data show a lack of magnetic ordering down to 73 mK. We deploy a localized spin dimer model which can accurately reproduce the dynamic structure factor of the neutron data, magnetization, and heat capacity data. Remarkably, the intradimer exchange interaction shows strong XY-type anisotropy and the ground state of ${\mathrm{BaCe}}_2{\mathrm{ZnS}}_5$ is in an entangled state $(|\uparrow \uparrow ⟩-|\downarrow \downarrow ⟩)/\sqrt{2}$. This is in contrast to the singlet dimer state that is obtained for Heisenberg interactions. These results confirm that ${\mathrm{BaCe}}_2{\mathrm{ZnS}}_5$ is in a quantum paramagnet state consisting of entangled spin dimer states.

Living materials such as membranes, cytoskeletal assemblies, cell collectives, and tissues can often be described as active solids—materials that are energized from within, with elastic response about a well-defined reference configuration. These materials often live in complex and curved manifolds, yet most descriptions of active solids are flat. Here, we explore the interplay between curvature and nonreciprocal elasticity via a covariant effective theory on curved manifolds in combination with numerical simulations. We find that curvature spatially patterns activity, gaps the spectrum, modifies exceptional points, and introduces non-Hermitian defect modes. Together, these results establish a foundation for hydrodynamic and rheological models on curved manifolds, with direct implications for living matter and active metamaterials.

While considering non-Hermitian Hamiltonians arising in the presence of dissipation, in most cases, the dissipation is taken to be frequency-independent. However, this idealization may not always be applicable in experimental settings, where dissipation can be frequency-dependent. Such frequency-dependent dissipation leads to non-Markovian behavior. In this Letter, we demonstrate how a quantum non-Markovian Hatano-Nelson model arises microscopically in a quasi-one-dimensional dissipative lattice. This is achieved using nonequilibrium Green’s functions without requiring any approximation like weak system-bath coupling or a timescale separation, which would have been necessary for a Markovian treatment. The resulting effective system exhibits nonreciprocal hopping, the defining characteristic of the Hatano-Nelson model, as well as uniform dissipation, both of which are frequency-dependent. This holds for both bosonic and fermionic settings. We find solely non-Markovian nonreciprocal features like unidirectional frequency blocking in bosonic settings, and a particular type of nonequilibrium dissipative quantum phase transition in fermionic settings, that cannot be captured in a Markovian theory, nor have any analogs in reciprocal systems. Our results lay the groundwork for describing and engineering non-Markovian nonreciprocal quantum lattices.

I propose a physical measurement scheme on multiple independent and identically distributed quantum objects to approach the Holevo-Nagaoka bound for quantum multiparameter estimation. The scheme entails a physical interaction of the objects with bosonic ancillae, followed by a general-dyne measurement of the ancillae. The proposal offers a more concrete description of the experimental setup needed to achieve the ultimate precision limit set by the bound.

Several theoretical proposals describe horizonless compact objects that can mimic black holes in their gravitational wave signatures; however, their spin-induced quadrupole moments (SIQMs) may reveal their distinct nature. Using the tight bounds on the SIQM of GW241011, we place constraints on the nature of its primary. Across exotic compact object models considered in this Letter, we find that rotating boson stars with quartic self-interactions cannot explain the nature of the primary, whereas models of sufficiently large compactness, $C\gtrsim 0.24$, may still be viable contenders.

The first evidence for the decay $B^{+}\to {\pi }^{+}{e}^{+}{e}^{-}$ is reported using proton-proton collision data recorded by the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of $9{\mathrm{fb}}^{-1}$. A signal excess with a significance of $3.2\sigma$ is observed and the branching fraction is measured to be $\mathcal{B}(B^{+}\to {\pi }^{+}{e}^{+}{e}^{-})=({2.4}_{-0.8}^{+0.9}{}_{-0.2}^{+0.4})\times {10}^{-8}$, where the first set of uncertainties is statistical and the second is systematic. The result is consistent with the Standard Model expectation.

We study the canonical problem of a Fermi gas interacting with a weakly repulsive Bose-Einstein condensate at zero temperature. To explore the quantum phases across the full range of boson-fermion interactions, we construct a versatile variational Ansatz that incorporates pair correlations and correctly captures the different polaron limits. Remarkably, we find that self-bound quantum droplets can exist in the strongly interacting regime, preempting the formation of boson-fermion dimers, when the Fermi pressure is balanced by the resonant boson-fermion attraction. This scenario can be achieved in experimentally available Bose-Fermi mixtures for a range of boson-fermion mass ratios in the vicinity of equal masses. We furthermore show that a larger fermion density instead yields phase separation between a Bose-Fermi mixture and excess fermions, as well as behavior reminiscent of a liquid-gas critical point. Our results suggest that first-order quantum phase transitions play a crucial role in the phase diagram of Bose-Fermi mixtures.

The interplay between topology and nonlinearity represents a central challenge in modern physics. Here, we investigate this interplay by considering a synthetic Su-Schrieffer-Heeger lattice with all-to-all nonlocal interactions. We find that the distinctive nonlinearity maintains an effective chiral symmetry and leads to a quantized nonlinear winding and Berry phase, as corroborated by the developed Bogoliubov nonlinear adiabatic theory. Increasing nonlinearity drives a sequence of topological transitions signaled by the appearance of characteristic swallowtail band structures at intermediate interaction strengths and band swapping in the strong nonlinear regime. The band swapping results in quantized fractional windings and double-period Bloch oscillations that are closely related to discrete time crystals. Remarkably, even starting from a topologically trivial linear system, nonlocal nonlinearity can induce an emergent topological phase with fractional windings. Experimentally, our model can be realized using photons in a degenerate optical cavity with Rydberg-mediated interactions. Our results establish a rigorous framework and pave the way for exploring nonlinear topological phenomena and their applications in synthetic quantum platforms.

Quantum spin liquids (QSLs) host exotic fractionalized magnetic and gauge-field excitations whose microscopic origins and experimental verification remain frustratingly elusive. In the absence of static magnetic order, the spin excitation spectrum constitutes the crucial probe of QSL behavior, but its theoretical computation is a serious challenge. Here we employ state-of-the-art tensor-network methods to obtain the full dynamical spectral function of the $J_1\text{−}{J}_2$ kagome Heisenberg model and benchmark our results by tracking their evolution across the magnetically ordered and QSL phases. Reducing $|J_2|/J_1$ causes increasingly strong spin-wave renormalization, flattening these modes then merging them into a continuum characteristic of deconfined spinons at all finite energies in the QSL. The low-energy continuum and the occurrence of gap closure at multiple high-symmetry points identify this gapless QSL as the U(1) Dirac spin liquid. These results establish a unified understanding of spin excitations in highly frustrated quantum magnets and provide clear spectral fingerprints for experimental detection in candidate kagome QSL materials.

We evaluate electromagnetic-response observables in a half-filled Chern band, across a topological phase transition between a composite Fermi liquid (CFL) and a Fermi liquid (FL) phase. While a sharp gapped plasma mode exists deep in the CFL phase, we demonstrate that it is damped near the proposed continuous phase transition between CFL and FL. This plasmon-damping phenomenon originates from emergent gauge fields and a Dirac-fermion-like spectrum. Similar features also occur in other continuous deconfined topological phase transitions, such as the Laughlin to superfluid transition in a bosonic system. In particular, this damping behavior extends over a finite range across the phase boundary, and, hence, we expect it to persist even when the transition is weakly first order. Furthermore, we analyze the characteristic conductivity behavior, such as the Drude weight, the wave-vector-dependent conductivity, the chiral mirror effect, and thermodynamic behavior, including compressibility and magnetic susceptibility across these topological phase transitions.

Magnetic molecules exhibiting pronounced spin-electric coupling have long been sought to elucidate the intricate relationship between spin orders and electric fields, as well as to advance the development of multifunctional, energy-efficient devices. Through first-principles simulations and spin superexchange theory, we predict the emergence of giant spin-electric coupling in heterometallic porphyrin dimers. The spin-electric coupling coefficients can reach 1 to 4 orders of magnitude greater than those of conventional two-dimensional magnetic systems. These pronounced spin-electric coupling effects are attributed to the asymmetric spin superexchange pathways between two distinct transition metal centers and their asymmetric response to an applied electric field. This remarkable enhancement enables the modulation of local magnetic moments with practically reachable electric fields, facilitating transitions between ferromagnetic and antiferromagnetic couplings. The discovery of such giant spin-electric coupling and its underlying mechanisms paves the way for the realization of magnetoelectric applications at the single-molecule level.