Symmetries and quantum anomalies serve as powerful tools for constraining complicated quantum many-body systems, offering valuable insights into low-energy characteristics based on their ultraviolet structure. Nevertheless, their applicability has traditionally been confined to closed quantum systems, rendering them largely unexplored for open quantum systems described by density matrices. In this Letter, we introduce a novel and experimentally feasible approach to detect quantum anomalies in open systems. Specifically, we claim that, when coupled with an external environment, the mixed ’t Hooft anomaly between spin rotation symmetry and lattice translation symmetry gives distinctive characteristics for half-integer and integer spin chains in measurements of $\exp (\mathrm{i}\theta S_{\mathrm{tot}}^z)$ as a function of $\theta$. Notably, the half-integer spin chain manifests a topological phenomenon akin to the “level crossing” observed in closed systems. To substantiate our assertion, we develop a lattice-level spacetime rotation to analyze the aforementioned measurements. Based on the matrix product density operator and transfer matrix formalism, we analytically establish and numerically demonstrate the unavoidable singular behavior of $\exp (\mathrm{i}\theta S_{\mathrm{tot}}^z)$ for half-integer spin chains. Conceptually, our work demonstrates a way to discuss notions like “spectral flow” and “flux threading” in open systems not necessarily with a Hamiltonian.

Defects have a significant influence on the polarization and electromechanical properties of ferroelectric materials. Statistically, they can be seen as random pinning centers acting on an elastic manifold, slowing domain-wall propagation and raising the energy required to switch polarization. Here we show that the “dressing” of defects can lead to unprecedented control of domain-wall dynamics. We engineer defects of two different dimensionalities in ferroelectric oxide thin films—point defects externally induced via ${\mathrm{He}}^{2+}$ bombardment, and extended quasi-one-dimensional $a$ domains formed in response to internal strains. The $a$ domains act as extended strong pinning sites (as expected) imposing highly localized directional constraints. Surprisingly, the induced point defects in the ${\mathrm{He}}^{2+}$ bombarded samples orient and align to impose further directional pinning, screening the effect of $a$ domains. This defect interplay produces more uniform and predictable domain-wall dynamics. Such engineered interactions between defects are crucial for advancements in ferroelectric devices.

We consider Markov jump processes on a graph described by a rate matrix that depends on various control parameters. We derive explicit expressions for the static responses of edge currents and steady-state probabilities. We show that they are constrained by the graph topology (i.e., the incidence matrix) by deriving response relations (i.e., linear constraints linking the different responses) and topology-dependent bounds. For unicyclic networks, all scaled current responses are between zero and one and must sum to one. Applying these results to stochastic thermodynamics, we derive explicit expressions for the static response of fundamental currents (which carry the full dissipation) to fundamental thermodynamic forces (which drive the system away from equilibrium).

The $f$-sum rules set general constraints on the response of a quantum many-body system to an external probe and hold significant relevance in the realm of various spectroscopy measurements. In practical conditions, a system unavoidably couples with the environment and acquires effective dissipation. In this Letter, we derive and prove a set of $f$-sum rules for dissipative systems. Within the framework of linear response theory, we obtain the system response in both linear order of probe field and dissipation parameter. We formulate and prove one first-order and two second-order dissipative $f$-sum rules. These rules are validated numerically for some example models, and the realization schemes are proposed. In addition, the potential applications are discussed for two interacting many-body systems.

We study the scaling behavior of the Rényi entanglement entropy with smooth boundaries at the putative deconfined critical point separating the Néel antiferromagnetic and valence-bond-solid states of the two-dimensional $J-Q_3$ model. We observe a subleading logarithmic term with a coefficient indicating the presence of four Goldstone modes, signifying the presence of an $SO(5)$ symmetry at the transition point, which spontaneously breaks into an $O(4)$ symmetry in the thermodynamic limit. This result supports the conjecture that an $SO(5)$ symmetry emerges at the transition point, but reveals the transition to be weakly first-order. We demonstrate, through this Letter, a novel approach to detect emergent continuous symmetry and, more importantly, identify weakly first-order phase transitions efficiently, which have been notoriously challenging for conventional methods.

For many-particle systems with short-range interactions, the local (same point) particle-particle pair correlation function represents a thermodynamic quantity that can be calculated using the Hellmann-Feynman theorem. Here we exploit this property to derive a thermodynamic Maxwell relation between the local pair correlation and the entropy of an ultracold Bose gas in one dimension (1D). To demonstrate the utility of this Maxwell relation, we apply it to the computational formalism of the stochastic projected Gross-Pitaevskii equation (SPGPE) to determine the entropy of a finite-temperature 1D Bose gas from its atom-atom pair correlation function. Such a correlation function is easy to compute numerically within the SPGPE and other formalisms, which is unlike computing the entropy itself. Our calculations can be viewed as a numerical experiment that serves as a proof-of-principle demonstration of an experimental method to deduce the entropy of a quantum gas from the measured atom-atom correlations.

This Letter presents results from a combination of searches for Higgs boson pair production using $126–140{\mathrm{fb}}^{-1}$ of proton-proton collision data at $\sqrt{s}=13\mathrm{TeV}$ recorded with the ATLAS detector. At 95% confidence level (CL), the upper limit on the production rate is 2.9 times the standard model (SM) prediction, with an expected limit of 2.4 assuming no Higgs boson pair production. Constraints on the Higgs boson self-coupling modifier ${\kappa }_{\lambda }={\lambda }_{HHH}/{\lambda }_{HHH}^{\mathrm{SM}}$, and the quartic $HHVV$ coupling modifier ${\kappa }_{2V}=g_{HHVV}/g_{HHVV}^{\mathrm{SM}}$, are derived individually, fixing the other parameter to its SM value. The observed 95% CL intervals are $-1.2<{\kappa }_{\lambda }<7.2$ and $0.6<{\kappa }_{2V}<1.5$, respectively, while the expected intervals are $-1.6<{\kappa }_{\lambda }<7.2$ and $0.4<{\kappa }_{2V}<1.6$ in the SM case. Constraints obtained for several interaction parameters within Higgs effective field theory are the strongest to date, offering insights into potential deviations from SM predictions.

Hadronic resonances emerge from strong interactions encoding the dynamics of quarks and gluons. The structure of these resonances can be probed by virtual photons parametrized in transition form factors. In this study, twelve $N^{*}$ and $\mathrm{\Delta }$ transition form factors at the pole are extracted from data with the center-of-mass energy from $\pi N$ threshold to 1.8 GeV, and the photon virtuality $0\le Q^2/{\mathrm{GeV}}^2\le 8$. For the first time, these results are determined from a simultaneous analysis of more than one state, i.e., $\sim {10}^5\pi N$, $\eta N$, and $K\mathrm{\Lambda }$ electroproduction data. In addition, about $5\times {10}^4$ data in the hadronic sector as well as photoproduction serve as boundary conditions. For the $\mathrm{\Delta }(1232)$ and $N(1440)$ states our results are in qualitative agreement with previous studies, while the transition form factors at the poles of some higher excited states are estimated for the first time. Realistic uncertainties are determined by further exploring the parameter space.

The $J/\psi$, $\psi (3686)\to {\mathrm{\Sigma }}^0{\overline{\mathrm{\Sigma }}}^0$ processes and subsequent decays are studied using the world’s largest $J/\psi$ and $\psi (3686)$ data samples collected with the BESIII detector. The parity-violating decay parameters of the decays ${\mathrm{\Sigma }}^0\to \mathrm{\Lambda }\gamma$ and ${\overline{\mathrm{\Sigma }}}^0\to \overline{\mathrm{\Lambda }}\gamma$, ${\alpha }_{{\mathrm{\Sigma }}^0}=-0.0017\pm 0.0021\pm 0.0018$ and ${\overline{\alpha }}_{{\mathrm{\Sigma }}^0}=0.0021\pm 0.0020\pm 0.0022$, are measured for the first time. The strong $CP$ symmetry is tested in the decays of the ${\mathrm{\Sigma }}^0$ hyperons for the first time by measuring the asymmetry $A_{CP}^{\mathrm{\Sigma }}={\alpha }_{{\mathrm{\Sigma }}^0}+{\overline{\alpha }}_{{\mathrm{\Sigma }}^0}=(0.4\pm 2.9\pm 1.3)\times {10}^{-3}$. The weak $CP$ test is performed in the subsequent decays of their daughter particles $\mathrm{\Lambda }$ and $\overline{\mathrm{\Lambda }}$. Also for the first time, the transverse polarizations of the ${\mathrm{\Sigma }}^0$ hyperons in $J/\psi$ and $\psi (3686)$ decays are observed with opposite directions, and the ratios between the $S$-wave and $D$-wave contributions of the $J/\psi$, $\psi (3686)\to {\mathrm{\Sigma }}^0{\overline{\mathrm{\Sigma }}}^0$ decays are obtained. These results are crucial to understand the decay dynamics of the charmonium states and the production mechanism of the ${\mathrm{\Sigma }}^0-{\overline{\mathrm{\Sigma }}}^0$ pairs.

Coherent manipulation of quantum states of light is key to photonic quantum information processing. In this Letter, we show that a passive two-level nonlinearity suffices to implement non-Gaussian quantum operations on propagating field modes. In particular, the collective light-matter interaction can efficiently extract a single photon from a multiphoton input wave packet to an orthogonal temporal mode. We accurately describe the single-photon subtraction process by elements of an intuitive quantum-trajectory model. By employing this process, quantum information protocols gain orders of magnitude improved efficiency over heralded schemes with linear optics. The reverse process can be used to add photons one by one to a single wave packet mode and compose arbitrarily large Fock states with a finite total success probability $>96.7\%$.

Driven by a sufficiently powerful pump laser, a cavity optomechanical system will stabilize in coupled oscillations of its cavity field and mechanical resonator. It was assumed that the oscillation will be continuously magnified upon enhancing the driving laser further. However, based on the nonlinear dynamics of the system, we find that the dynamical behaviors of the system are much more complex than this intuitive picture, especially when it is operated near the blue detuning point by the mechanical resonator’s intrinsic frequency. There exists an anomalous stabilization: depending on its intrinsic damping rate and the pump power, the mechanical resonator will metastably stay on one orbit of oscillation after another until it completely stabilizes on the final orbit it can reach. These orbits are consistent with the locked ones with almost fixed oscillation amplitudes, which are realized after the pump power becomes still higher. The oscillatory cavity field is seen to adjust its sidebands following the mechanical frequency shift due to optical spring effect, so that it always drives the mechanical resonator to near those locked orbits once the pump power is over a threshold. In the regimes with such correlation between cavity field sidebands and mechanical oscillation, the system’s dynamical attractors are confined on the locked orbits and chaotic motion is also excluded.

In the 2–10 GPa pressure range, ammonia hemihydrate ${\mathrm{H}}_2\mathrm{O}:({\mathrm{NH}}_3{)}_2$ (AHH) is a molecular solid in which intermolecular interactions are ruled by distinct types of hydrogen bonds. Upon heating, the low-temperature ordered $P{2}_1/c$ crystal (AHH-II) transits to a bcc phase (AHH-$p\mathrm{bcc}$) where each site is randomly occupied by water or ammonia. In addition to the site disorder, experiments suggest that AHH-$p\mathrm{bcc}$ is a plastic solid, but the physical origin and mechanisms at play for the rotational and site disordering remain unknown. Using large-scale ($\sim {10}^5\mathrm{atoms}$) and long-time ($>10\mathrm{ns}$) simulations, we show that, as temperature rises above the transition line, orientational disorder sets in, breaking the strongest hydrogen bonds that provide the largest contribution to the cohesion of the ordered AHH-II phase and enabling the molecules to migrate from a crystal site to a neighboring one. This generates a plastic molecular alloy with site disorder while the solid state is overall maintained until melting at a higher temperature. The case of high $(P,T)$ plastic ammonia hemihydrate can be extended to other water-ammonia alloys where a similar interplay between distinct hydrogen bonds occurs.

On the basis of molecular dynamics simulations of water and ethanol in nanopores, we devise a methodology to determine the free-energy landscape (FEL) imposed by an interface on an adjoining liquid directly from the particle trajectories. The methodology merely uses the statistical mechanical relation between occupancy and energy and, hence, is particularly suitable in complex situations, e.g., for disordered or rough atomistic interfaces and molecular liquids, as encountered in many biological, geological, and technological situations. Moreover, we show that the thus-obtained FEL enables a quantitative understanding of interface effects on liquid dynamics. Specifically, by determining the local minima and barriers of the FEL and using an Arrhenius-like relation, we reproduce the very strong spatial variation of the structural relaxation time of water and ethanol across nanopores over a broad temperature range. We anticipate that the proposed FEL approach is transferable to various other liquids and interfaces.

The classical Hertzian contact model establishes a monotonic correlation between contact force and area. Here, we showed that the interplay between local friction and structural instability can deliberately lead to unconventional contact behavior when a soft elastic shell comes into contact with a flat surface. The deviation from Hertzian solution first arises from bending within the contact area, followed by the second transition induced by buckling, resulting in a notable decrease in the contact area despite increased contact force. Additionally, our results invalidated a previous claim of a linear relation between friction and dissipated energy, demonstrating the suppression of both buckling and dissipation at high friction levels. Different contact regimes are discussed in terms of rolling and sliding mechanisms, providing insights for tailoring contact behaviors in soft shells.

Appropriate symmetry breaking generates an anomalous Hall (AH) effect, even in antiferromagnetic (AFM) materials. Itinerant magnets with $d$ electrons are typical examples that show a significant response. By contrast, the process by which a response emerges from $f$-electron AFM structures remains unclear. In this Letter, we show that an AFM material, ${\mathrm{Ce}}_2{\mathrm{CuGe}}_6$, yields a large AH conductivity (AHC) of $550{\mathrm{\Omega }}^{-1}{\mathrm{cm}}^{-1}$, which exceeds the values previously reported in $d$-electron AFM materials. Observed features, including the scaling relation against electrical conductivity, suggest that this AH transport is induced cooperatively by both intrinsic and extrinsic mechanisms derived from the AFM structure.