Hyperchaos is a qualitatively stronger form of chaos in which several degrees of freedom contribute simultaneously to exponential divergence of small changes. A hyperchaotic dynamical system is, therefore, even more unpredictable than a chaotic one, and it has a higher fractal dimension. While hyperchaos has been studied extensively over the last decades, only a few experimental systems are known to exhibit hyperchaotic dynamics. Here, we introduce hyperchaos in the context of cavity optomechanics, in which light inside an optical resonator interacts with a suspended oscillating mass. We show that hyperchaos can arise in optomechanical systems with quadratic coupling and is well within reach of current experiments. We compute the two positive Lyapunov exponents characteristic of hyperchaos and independently verify the correlation dimension. We also identify a possible mechanism for the emergence of hyperchaos. As systems designed for high-precision measurements, optomechanical systems enable direct measurement of all four dynamical variables and, therefore, the full reconstruction of the hyperchaotic attractor. Our results may contribute to better understanding of nonlinear systems and the chaos-hyperchaos transition.

We suggest a method to compute approximations to temporal correlation functions of few-body observables in chaotic many-body systems in the thermodynamic limit based on the respective Lanczos coefficients. Given the knowledge of these Lanczos coefficients, the method is very cheap. Usually, accuracy increases with more Lanczos coefficients taken into account; however, we numerically find and analytically argue that the convergence is rather quick if the Lanczos coefficients exhibit a smoothly increasing structure. For pertinent examples, we compare with data from dynamical typicality computations for large but finite systems and find good agreement if few Lanczos coefficients are taken into account. From the method, it is evident that in these cases the correlation functions are well described by a low number of damped oscillations.

We present next-to-leading-order QCD corrections for the cross sections for $\ell p^{\uparrow }\to hX$ and $\ell p^{\uparrow }\to \text{jet}X$ with transversely polarized initial protons. These cross sections are known to be power-suppressed in QCD and probe twist-3 parton correlation functions in the proton. Our calculation exhibits the full complexity of a perturbative QCD analysis beyond leading power, involving in particular various derivatives of the parton correlation functions. We demonstrate that collinear factorization for these single-spin observables holds at one loop. We also present exploratory phenomenological results for the NLO single-spin asymmetry in $e{p}^{\uparrow }\to hX$ and compare to data from the HERMES experiment.

Evidence for a (sub)-shell closure at $Z=14$ has been observed from the spectroscopy of ${}^{22}\mathrm{Si}$ and ${}^{21}\mathrm{Al}$. Using a fast ${}^{23}\mathrm{Si}$ beam on a ${}^9\mathrm{Be}$ target, several proton-decaying resonances have been populated in ${}^{21}\mathrm{Al}$ and ${}^{22}\mathrm{Si}$, including the first measurement of the $2_1^{+}$ state in ${}^{22}\mathrm{Si}$ with an excitation energy of 2.352(55) MeV. Relative to the known $N=14$ subshell closure in ${}^{22}\mathrm{O}$, the ${}^{22}\mathrm{Si}$ $2_1^{+}$ excitation energy indicates the existence of a weakened $Z=14$ subshell closure. To reproduce the new spectroscopic information and known ${}^{22}\mathrm{Al}$ levels, the energy of the $1s_{1/2}$ orbit must be substantially decreased, which imparts Thomas-Ehrman shifts to all excited states observed in the present Letter and explains the structure of nuclei in the $sd$ shell for this region of the proton drip line.

Arrays of Rydberg atoms interacting via dipole-dipole interactions offer a powerful platform for probing quantum many-body physics. However, these intrinsic interactions also determine and constrain the models—and parameter regimes thereof—for quantum simulation. Here, we propose a systematic framework to engineer arbitrary desired long-range interactions in Rydberg-atom lattices, enabling the realization of fully tunable $J_1\text{−}{J}_2\text{−}{J}_3$ Heisenberg models. Using site-resolved periodic modulation of Rydberg states, we develop an experimentally feasible protocol to precisely control the interaction ratios $J_2/J_1$ and $J_3/J_1$ in a kagome lattice. This control can increase the effective range of interactions and drive transitions between competing spin-ordered and spin-liquid phases. To generalize this approach beyond the kagome lattice, we reformulate the design of modulation patterns through a graph-theoretic approach, demonstrating the universality of our method across all 11 planar Archimedean lattices. Our strategy overcomes the inherent constraints of power-law-decaying dipolar interactions, providing a versatile toolbox for exploring frustrated magnetism, emergent topological phases, and quantum correlations in systems with long-range interactions.

Engineered dissipation is emerging as an alternative tool for quantum state control, enabling high-fidelity preparation, transfer and stabilization, and access to novel phase transitions. We realize a tunable, state-resolved laser-induced loss channel for individual Rydberg atoms, in both noninteracting and strongly correlated settings. This capability allows us to reveal interaction-driven shifts of the exceptional point separating quantum Zeno and anti-Zeno regimes, and to demonstrate interaction-enhanced decay. By exploiting interaction-dependent energy level shifts, we observe a configuration-selective two-body Zeno effect that freezes target spin states. We theoretically show that when this mechanism is extended to many-body chains it allows for the dissipative distillation of unwanted spin configurations. These experimental studies establish a versatile approach for exploring strongly interacting, open quantum spin systems, and open possible new routines for dissipative preparation of correlated quantum states in Rydberg atom arrays.

Coherent vector light beams with spatially structured polarization exhibit intrinsic nonseparability between the spatial amplitude and polarization-state degrees of freedom, quantified by optical concurrence—a measure formally analogous to quantum concurrence characterizing entanglement in bipartite quantum systems. Here, we introduce a method to measure the optical concurrence of monochromatic vector beams by encoding the nonseparability into the coherence properties of a partially coherent light field. This enables the concurrence to be retrieved from either a single-shot speckle pattern or a single-pixel temporal intensity measurement. Our technique is efficient and alignment-free, eliminating the need for polarization-resolving components and opening new possibilities in optical communication, sensing, and classical analogs of quantum information protocols.

The nonmonotonic temperature dependence and sign reversal of chirality-related anomalous Hall effect in highly conductive metals are studied. Through the analysis of scattering rate, we find that the nonmonotonicity and sign reversal have two major origins: (1) competition between the contribution from short-range and long-range spin correlations and (2) nonmonotonic spin correlation in the high field. The former mechanism gives rise to nonmonotonic temperature dependence in a wide range of electron density and, in some cases, a sign reversal of Hall resistivity as the temperature decreases. On the other hand, the latter mechanism is responsible for the sign reversal of Hall conductivity in the high field, which sign reversal generally occurs in magnets with antiferromagnetic interactions. The results demonstrate how the Hall effect reflects local spin correlation and provide insights into the mechanism of nonmonotonicity and sign reversal of the anomalous Hall effect by spin chirality.

Over the past decade, graphene has emerged as a promising candidate for exploring the viscous nature of electronic flow facilitated by the availability of extremely high-quality devices employing a graphene channel encapsulated within dielectric layers of hexagonal boron nitride (hBN). However, the level of disorder in such systems is mainly determined by the device fabrication protocols, making it impossible to obtain a tunability between the impurity-dominated and viscous transport within the same device. In this work, using a combination of ultraviolet (UV) radiation and gate electric field, we have demonstrated a dynamic modulation of charge hydrodynamics quantified in the thermal and electrical transport by the extent of departure from the Wiedemann-Franz (WF) law in monolayer graphene devices at room temperature. We achieved this by tuning the disorder level continuously and reversibly using UV light to create transient trap states in the encapsulating hBN dielectric. With progressive UV radiation, we observed a dramatic increase in the momentum-relaxing scattering relative to that between the electrons and to the Lorentz number by nearly a factor of ten, with increasing disorder, thereby approaching the restoration of the WF law in highly disordered graphene. Our experiments outline a potent strategy to tune the fundamental mechanism of charge flow in state-of-the-art graphene devices.

Circularly polarized phonons, characterized by nonzero angular momenta and magnetic moments, have attracted extensive attention. However, a long-standing critical issue in this field is the lack of an approach to accurately calculate phonon magnetic moments resulting from electron-phonon coupling (EPC) in realistic materials. Here, based on the linear response framework, we develop an ab initio theory for calculating EPC-induced magnetic properties of phonons, applicable to both insulating and metallic materials. Our method can precisely calculate phonon Zeeman splittings in magnetic metals with significant EPC, as demonstrated by the remarkable agreement with recent experimental observations of phonon Zeeman splitting in the ferromagnetic Weyl semimetal $\mathrm{C}{\mathrm{o}}_3\mathrm{S}{\mathrm{n}}_2{\mathrm{S}}_2$. In addition, the long-sought magnetic phonon spectra across the entire Brillouin zone are obtained, facilitating the study of magnetic phonon transport and topology. Specifically, by constructing an inertially decoupled lattice model, we propose candidate materials exhibiting intrinsic phonon Chern states with robust unidirectional edge phonon currents. Our Letter paves the way for investigating novel phonon phenomena in magnetic quantum materials.

Altermagnets combine antiferromagnetic order with ferromagnetlike spin splitting, a duality that unlocks ultrafast spin-dependent responses. This unique property creates unprecedented opportunities for spin-current generation, overcoming the intrinsic limitations of conventional spin-transfer and spin-orbit torque approaches in magnetic memory technologies. Here, we establish a fundamental relationship between Fermi surface geometry and time-reversal-odd ($\mathcal{T}$-odd) spin currents in altermagnets through combined model analysis and first-principles calculations. We demonstrate that a $d$-wave altermagnet with a flat Fermi surface can achieve a theoretical upper limit of charge-to-spin conversion efficiency (CSE) of 100%. This mechanism is realized in the newly discovered room-temperature altermagnetic metal ${\mathrm{KV}}_2{\mathrm{Se}}_2\mathrm{O}$, which exhibits a CSE of $\sim 78\%$ at the charge neutrality point—nearly double that of ${\mathrm{RuO}}_2$, setting a new record for $\mathcal{T}$-odd CSE. Under electron doping, this efficiency further increases to $\sim 98\%$, approaching the theoretical limit. Our Letter advances the fundamental understanding of $\mathcal{T}$-odd spin currents via Fermi surface geometry engineering and provides key insights for developing next-generation altermagnet-based memory devices.

The XY models with continuous spin orientation play a pivotal role in understanding topological phase transitions and emergent frustration phenomena such as superconducting and superfluid phase transitions. However, the complex energy landscapes arising from frustrated lattice geometries and competing spin interactions make these models computationally intractable. To address this challenge, we designed a programmable photonic spin simulator capable of emulating the XY models with tunable lattice geometries and spin couplings, allowing systematic exploration of their statistical properties. We experimentally observed the Berezinskii-Kosterlitz-Thouless transition in a square-lattice XY model with nearest-neighbor interactions and determined its critical temperature. Expanding to frustrated systems, we implemented the approach in triangular and honeycomb lattices, uncovering sophisticated phase transitions and frustration effects, which were consistent with theoretical predictions. This versatile platform opens avenues for probing unexplored XY model phenomena across diverse geometries and interaction schemes, with potential applications in solving complex optimization and machine learning problems.

Active solids combine internal active driving with elasticity to realize states with nonequilibrium mechanics and autonomous motion. They are often studied in overdamped settings, e.g., in soft materials, and the role of inertia is less explored. We construct a model of a chemically active solid that incorporates mechanochemical feedback and show that, when feedback overwhelms mechanical damping, autonomous inertial dynamics can spontaneously emerge through sustained consumption of chemical fuel. By combining numerical simulations, analysis, and dynamical systems approaches, we show how active feedback drives complex nonlinear dynamics on multiple timescales, including limit cycles and chaos. Our results suggest design principles for creating ultrafast actuators and autonomous machines from soft, chemically powered solids.

Nuclear magnetic resonance spectroscopy with solid-state spin sensors is a promising pathway for the detection of nuclear spins at the micro- and nanoscale. Although many nanoscale experiments rely on a single sensor spin for the detection of the signal, leveraging spin ensembles can enhance sensitivity, particularly in cases in which the signal merely originates from statistically polarized nuclear spins. In this Letter, we introduce multipoint correlation spectroscopy, which combines the advantages of two well-established methods—correlation spectroscopy and quantum heterodyne detection—to enable temporally efficient measurements of statistically polarized samples at the nanoscale with spin ensembles. We present a theoretical framework for this approach and demonstrate an experimental proof of concept with a nitrogen vacancy center in diamond. We achieve single hertz uncertainty in the estimated signal frequency, highlighting the potential applications of the technique for nanoscale nuclear magnetic resonance.

Nuclear magnetic resonance (NMR) spectroscopy is widely used in fields ranging from chemistry and materials science to neuroscience. Nanoscale NMR spectroscopy using nitrogen-vacancy (NV) centers in diamond has emerged as a promising platform due to an unprecedented sensitivity down to the single spin level. At the nanoscale, high nuclear spin polarization through spin fluctuations (statistical polarization) far outweighs thermal polarization. However, until now efficient NMR detection using coherent averaging techniques could not be applied to the detection of statistical polarization, leading to long measurement times. Here we present two protocols to enable coherent averaging of stochastic oscillatory signals through rectification. We demonstrate these protocols on an artificial radio frequency signal detected with a single NV center at 2.7 T. The signal-to-noise scaling with number of measurements $N$ increases from $N^{0.5}$ to $N^1$, improving the measurement time significantly. The relevance of rectification for the detection of statistically polarized nuclear spins using ensembles of NV centers is outlined, paving the way for efficient nanoscale NMR spectroscopy.

We propose a spectroscopic method to detect vortex proliferation in neutral superfluids that does not require spatially resolving individual vortices. Using stochastic classical-field methods, we theoretically show that a quantum impurity repulsively coupled to a weakly interacting Bose gas at finite temperature carries direct spectroscopic signatures of vortex proliferation. In two dimensions, we find that a low-energy (attractive) branch in the excitation spectrum becomes prominent when the temperature is tuned across the Berezinskii-Kosterlitz-Thouless (BKT) transition. We explain this red-shifted resonance as originating from the binding of the impurity to vortices, where the bosons density (and hence, the repulsive Hartree energy) is reduced. This mechanism could be exploited to spectroscopically estimate the BKT transition in excitonic insulators. In contrast, in three dimensions, the impurity spectra reflect the presence of vortex rings well below the condensation temperature, and herald the presence of a thermal gas above the Bose-Einstein transition. Importantly, we expect our results to have impact on the understanding of Bose-polaron formation at finite temperatures.

Controlling electron spin and orbital degrees of freedom has been a major research focus over the past two decades, as it underpins the electrical manipulation of magnetization. Leveraging a recently introduced quantum kinetic theory of multiband systems [T. Valet and R. Raimondi, Phys. Rev. B 111, L041118 (2025)], we outline how the intrinsic angular momenta linear response is partitioned into intra- and interband contributions. Focusing on time reversal and inversion symmetric metals, we show that the spin and orbital Hall currents are purely intraband. We also reveal that the intrinsic edge densities originate partially, and in the orbital case possibly mostly, from a new interband mechanism. We discuss how this profoundly impacts the interpretation of orbital edge accumulation observations and has broader implications for current-induced torques.