Ferroelectrics and ionic conductors are important functional materials, each supporting a plethora of applications in information and energy technology. The underlying physics governing their functional properties is ionic motion, and yet studies of ferroelectrics and ionic conductors are often considered separate fields. Based on first-principles calculations and deep-learning-assisted large-scale molecular dynamics simulations, we report ferroelectric-switching-promoted oxygen ion transport in ${\mathrm{HfO}}_2$, a wide-band-gap insulator with both ferroelectricity and ionic conductivity. Applying a unidirectional bias can activate multiple switching pathways in ferroelectric ${\mathrm{HfO}}_2$, leading to polar-antipolar phase cycling that appears to contradict classical electrodynamics. This apparent conflict is resolved by the geometric-quantum-phase nature of electric polarization that carries no definite direction. Our molecular dynamics simulations demonstrate bias-driven successive ferroelectric transitions facilitate ultrahigh oxygen ion mobility at moderate temperatures, highlighting the potential of combining ferroelectricity and ionic conductivity for the development of advanced materials and technologies.

The Hopfield model is a paradigmatic model of neural networks that has been analyzed for many decades in the statistical physics, neuroscience, and machine learning communities. Inspired by the manifold hypothesis in machine learning, we propose and investigate a generalization of the standard setting that we name random-features Hopfield model. Here, $P$ binary patterns of length $N$ are generated by applying to Gaussian vectors sampled in a latent space of dimension $D$ a random projection followed by a nonlinearity. Using the replica method from statistical physics, we derive the phase diagram of the model in the limit $P,N,D\to \infty$ with fixed ratios $\alpha =P/N$ and ${\alpha }_D=D/N$. Besides the usual retrieval phase, where the patterns can be dynamically recovered from some initial corruption, we uncover a new phase where the features characterizing the projection can be recovered instead. We call this phenomena the learning phase transition, as the features are not explicitly given to the model but rather are inferred from the patterns in an unsupervised fashion.

We propose and analyze a scalable and fully autonomous scheme for preparing spatially distributed multiqubit entangled states in a dual-rail waveguide QED setup. In this approach, arrays of qubits located along two separated waveguides are illuminated by correlated photons from the output of a nondegenerate parametric amplifier. These photons drive the qubits into different classes of pure entangled steady states, for which the degree of multipartite entanglement can be conveniently adjusted by the chosen pattern of local qubit-photon detunings. Numerical simulations for moderate-sized networks show that the preparation time for these complex multiqubit states increases at most linearly with the system size and that one may benefit from an additional speedup in the limit of a large amplifier bandwidth. Therefore, this scheme offers an intriguing new route for distributing ready-to-use multipartite entangled states across large quantum networks, without requiring any precise pulse control and relying on a single Gaussian entanglement source only.

The LHAASO Collaboration detected the gamma ray burst GRB 221009A at energies above 500 GeV with a tail extending up to 18 TeV, whose spectral analysis has presently been performed up to 7 TeV for the lower energy instrument LHAASO-WCDA only, with no indication of a cutoff. Soon thereafter, Carpet-2 at Baksan Neutrino Observatory reported the observation of an air shower consistent with being caused by a photon of energy 251 TeV from the same GRB. Given the source redshift $z=0.151$, the expected attenuation due to the extragalactic background light is very severe so that these detections have proven very hard to explain. In this Letter, we show that the existence of axionlike particles with mass $m_a\simeq ({10}^{-11}–{10}^{-7})\mathrm{eV}$ and two-photon coupling $g_{a\gamma \gamma }\simeq (3-5)\times {10}^{-12}{\mathrm{GeV}}^{-1}$ strongly reduce the optical depth of TeV photons, thus explaining the observations. Our ALPs meet all available constraints, are consistent with two previous hints at their existence, and are good candidates for cold dark matter. Moreover, we show that Lorentz invariance violation can explain the Carpet-2 result but not the LHAASO observations.

A search for events with a dark photon produced in association with a dark Higgs boson via rare decays of the standard model $Z$ boson is presented, using $139{\mathrm{fb}}^{-1}$ of $\sqrt{s}=13\mathrm{TeV}$ proton-proton collision data recorded by the ATLAS detector at the Large Hadron Collider. The dark boson decays into a pair of dark photons, and at least two of the three dark photons must each decay into a pair of electrons or muons, resulting in at least two same-flavor opposite-charge lepton pairs in the final state. The data are found to be consistent with the background prediction, and upper limits are set on the dark photon’s coupling to the dark Higgs boson times the kinetic mixing between the standard model photon and the dark photon, ${\alpha }_{\mathrm{D}}{ϵ}^2$, in the dark photon mass range of [5, 40] GeV except for the $\mathrm{\Upsilon }$ mass window [8.8, 11.1] GeV. This search explores new parameter space not previously excluded by other experiments.

Interatomic Coulombic decay (ICD) is a significant fragmentation mechanism observed in weakly bound systems. It has been widely accepted that ICD-induced molecular fragmentation occurs through a two-step process, involving ICD as the first step and dissociative-electron attachment (DEA) as the second step. In this study, we conducted a fragmentation experiment of ${\mathrm{ArCH}}_4$ by electron impact, utilizing the coincident detection of one electron and two ions. In addition to the well-known decay pathway that induces pure ionization of ${\mathrm{CH}}_4$, we observed a new channel where ICD triggers the ionization dissociation of ${\mathrm{CH}}_4$, resulting in the cleavage of the C-H bond and the formation of the ${\mathrm{CH}}_3^{+}$ and H ion pair. The high efficiency of this channel, as indicated by the relative yield of the ${\mathrm{Ar}}^{+}/{\mathrm{CH}}_3^{+}$ ion pair, agrees with the theoretical prediction [L. S. Cederbaum, J. Phys. Chem. Lett. 11, 8964 (2020).; Y. C. Chiang et al., Phys. Rev. A 100, 052701 (2019).]. These results suggest that ICD can directly break covalent bonds with high efficiency, bypassing the need for DEA. This finding introduces a novel approach to enhance the fragmentation efficiency of molecules containing covalent bonds, such as DNA backbone.

We present the measurements of individual bound electron $g$ factors of ${{}^{20}\mathrm{Ne}}^{9+}$ and ${{}^{22}\mathrm{Ne}}^{9+}$ on the relative level of 0.1 parts per billion. The comparison with theory represents the most stringent test of bound-state QED in strong electric fields. A dedicated mass measurement results in $m({}^{20}\mathrm{Ne})=19.99244016877(9)\mathrm{u}$, which improves the current literature value by a factor of 18, disagrees by 4 standard deviations, and represents the most precisely measured mass value in atomic mass units. Together, these measurements yield an electron mass on the relative level of 0.1 ppb with $m_{\mathrm{e}}=5.48579909099(59)\times {10}^{-4}\mathrm{u}$ as well as a factor of seven improved $m({}^{22}\mathrm{Ne})=21.9913850982(26)\mathrm{u}$.

Data assimilation (DA) of turbulence, which involves reconstructing small-scale turbulent structures based on observational data from large-scale ones, is crucial not only for practical forecasting but also for gaining a deeper understanding of turbulent dynamics. We propose a theoretical framework for DA of turbulence based on the transverse Lyapunov exponents (TLEs) in synchronization theory. Through stability analysis using TLEs, we identify a critical length scale as a key condition for DA; turbulent dynamics smaller than this scale are synchronized with larger-scale turbulent dynamics. Furthermore, considering recent findings for the maximal Lyapunov exponent and its relation with the TLEs, we clarify the Reynolds number dependence of the critical length scale.

Evaporation of cloud droplets accelerates when turbulence mixes dry air into the cloud, affecting droplet-size distributions in atmospheric clouds, combustion sprays, and jets of exhaled droplets. The challenge is to model local correlations between droplet numbers, sizes, and supersaturation, which determine supersaturation fluctuations along droplet paths (Lagrangian fluctuations). We derived a statistical model that accounts for these correlations. Its predictions are in quantitative agreement with results of direct numerical simulations, and explain the key mechanisms at play.

Moiré superlattices have emerged as an exciting condensed-matter quantum simulator for exploring the exotic physics of strong electronic correlations. Notable progress has been witnessed, but such correlated states are achievable usually at low temperatures. Here, we report evidence of possible room-temperature correlated electronic states and layer-hybridized SU(4) model simulator in AB-stacked ${\mathrm{MoS}}_2$ homobilayer moiré superlattices. Correlated insulating states at moiré band filling factors $v=1$, 2, 3 are unambiguously established in twisted bilayer ${\mathrm{MoS}}_2$. Remarkably, the correlated electronic state at $v=1$ shows a giant correlated gap of $\sim 126\mathrm{meV}$ and may persist up to a record-high critical temperature over 285 K. The realization of a possible room-temperature correlated state with a large correlated gap in twisted bilayer ${\mathrm{MoS}}_2$ can be understood as the cooperation effects of the stacking-specific atomic reconstruction and the resonantly enhanced interlayer hybridization, which largely amplify the moiré superlattice effects on electronic correlations. Furthermore, extreme large nonlinear Hall responses up to room temperature are uncovered near correlated electronic states, demonstrating the quantum geometry of moiré flat conduction band.

It is predicted that strongly interacting spins on a frustrated lattice may lead to a quantum disordered ground state or even form a quantum spin liquid with exotic low-energy excitations. However, a controlled tuning of the frustration strength, separating its effects from those of disorder and other factors, is pending. Here, we perform comprehensive ${}^1\mathrm{H}$ NMR measurements on ${\mathrm{Y}}_3{\mathrm{Cu}}_9{(\mathrm{OH})}_{19}{\mathrm{Cl}}_8$ single crystals revealing an unusual $\overrightarrow{Q}=(1/3\times 1/3)$ antiferromagnetic state below $T_N=2.2\mathrm{K}$. By applying in situ uniaxial stress, we break the symmetry of this disorder-free, frustrated kagome system in a controlled manner yielding a linear increase of $T_N$ with strain, in line with theoretical predictions for a distorted kagome lattice. In-plane strain of $\approx 1\%$ triggers a sizable enhancement $\mathrm{\Delta }{T}_N/T_N\approx 10\%$ due to a release of frustration, demonstrating its pivotal role for magnetic order.

One of the most important practical hallmarks of topological matter is the presence of topologically protected, exponentially localized edge states at interfaces of regions characterized by unequal topological invariants. Here, we show that, even when driven far from their equilibrium ground state, Chern insulators can inherit topological edge features from their parent Hamiltonian. In particular, we show that the asymptotic long-time approach of the nonequilibrium steady state, governed by a Lindblad master equation, can exhibit edge-selective extremal damping. This phenomenon derives from edge states of non-Hermitian extensions of the parent Chern insulator Hamiltonian. The combination of (non-Hermitian) topology and dissipation hence allows one to design topologically robust, spatially localized damping patterns.

Quantum spin liquids (QSLs) are novel phases of matter which remain quantum disordered even at the lowest temperature. They are characterized by emergent gauge fields and fractionalized quasiparticles. Here we show that the sub-kelvin thermal transport of the three-dimensional $S=1/2$ hyperhyperkagome quantum magnet ${\mathrm{PbCuTe}}_2{\mathrm{O}}_6$ is governed by a sizeable charge-neutral fermionic contribution which is compatible with the itinerant fractionalized excitations of a spinon Fermi surface. We demonstrate that this hallmark feature of the QSL state is remarkably robust against sample crystallinity, large magnetic field, and field-induced magnetic order, ruling out the imitation of QSL features by extrinsic effects. Our findings thus reveal the characteristic low-energy features of ${\mathrm{PbCuTe}}_2{\mathrm{O}}_6$ which qualify this compound as a true QSL material.

Nonreciprocal interactions are commonplace in continuum-level descriptions of both biological and synthetic active matter, yet studies addressing their implications for time reversibility have so far been limited to microscopic models. Here, we derive a general expression for the average rate of informational entropy production in the most generic mixture of conserved phase fields with nonreciprocal couplings and additive conservative noise. For the particular case of a binary system with Cahn-Hilliard dynamics augmented by nonreciprocal cross-diffusion terms, we observe a nontrivial scaling of the entropy production rate across a parity-time symmetry breaking phase transition. We derive a closed-form analytic expression in the weak-noise regime for the entropy production rate due to the emergence of a macroscopic dynamic phase, showing it can be written in terms of the global polar order parameter, a measure of parity-time symmetry breaking.

We study fluctuating field models with spontaneously emerging dynamical phases. We consider two typical transition scenarios associated with parity-time symmetry breaking: oscillatory instabilities and critical exceptional points. An analytical investigation of the low-noise regime reveals a drastic increase of the mesoscopic entropy production toward the transitions. For an illustrative model of two nonreciprocally coupled Cahn-Hilliard fields, we find physical interpretations in terms of actively propelled interfaces and a coupling of eigenmodes of the linearized dynamics near the critical exceptional point.

Shadow estimation is a recent protocol that allows estimating exponentially many expectation values of a quantum state from “classical shadows,” obtained by applying random quantum circuits and computational basis measurements. In this Letter we study the statistical efficiency of this approach in light of near-term quantum computing. We propose a more practical variant of the protocol, thrifty shadow estimation, in which quantum circuits are reused many times instead of having to be freshly generated for each measurement. We show that reuse is maximally effective when sampling Haar random unitaries, and maximally ineffective when sampling from the Clifford group, i.e., one should not reuse circuits when performing shadow estimation with the Clifford group. We provide an efficiently simulable family of quantum circuits that interpolates between these extremes, which we believe should be used instead of the Clifford group. Finally, we consider tail bounds for shadow estimation and discuss when median-of-means estimation can be replaced with standard mean estimation.

Building an efficient quantum memory in high-dimensional Hilbert spaces is one of the fundamental requirements for establishing high-dimensional quantum repeaters, where it offers many advantages over two-dimensional quantum systems, such as a larger information capacity and enhanced noise resilience. To date, it remains a challenge to develop an efficient high-dimensional quantum memory. Here, we experimentally realize a quantum memory that is operational in Hilbert spaces of up to 25 dimensions with a storage efficiency of close to 60% and a fidelity of $84.2\pm 0.6\%$. The proposed approach exploits the spatial-mode-independent interaction between atoms and photons which are encoded in transverse-size-invariant vortex modes. In particular, our memory features uniform storage efficiency and low crosstalk disturbance for 25 individual spatial modes of photons, thus allowing the storing of qudit states programmed from 25 eigenstates within the high-dimensional Hilbert spaces. These results have great prospects for the implementation of long-distance high-dimensional quantum networks and quantum information processing.

Whenever two irreversible processes occur simultaneously, time-reversal symmetry of microscopic dynamics gives rise, on a macroscopic level, to Onsager’s reciprocal relations, which impose constraints on the number of independent components of any transport coefficient tensor. Here, we show that in the antiferromagnetic ${\mathrm{YbMnBi}}_2$, which displays a strong temperature-dependent anisotropy, Onsager’s reciprocal relations are strictly satisfied for anomalous electric (${\sigma }_{ij}^A$) and anomalous thermoelectric (${\alpha }_{ij}^A$) conductivity tensors. In contradiction with what was recently reported by Pan et al. [Nat. Mater. 21, 203 (2022)], we find that ${\sigma }_{ij}^A(H)={\sigma }_{ji}^A(-H)$ and ${\alpha }_{ij}^A(H)={\alpha }_{ji}^A(-H)$. This equality holds in the whole temperature window irrespective of the relative weights of the intrinsic or extrinsic mechanisms. The ${\alpha }_{ij}^A/{\sigma }_{ij}^A$ ratio is close to $k_B/e$ at room temperature but peaks to an unprecedented magnitude of $2.9k_B/e$ at $\sim 150\mathrm{K}$, which may involve nondegenerate carriers of small Fermi surface pockets.