Using (10087±44)×10^{6} J/ψ events collected with the BESIII detector at the BEPCII collider at the center-of-mass energy of sqrt[s]=3.097 GeV, we report the first search for η→π^{0}S→π^{0}χχ[over ¯] with S denoting an on-shell dark scalar boson and χ an invisible dark matter particle. No significant signals are observed with S mass ranging from 0 to 400 MeV/c^{2}. The upper limits on the branching fractions and the new physics coupling strengths between S and quarks are set to be (1.8-5.5)×10^{-5} and (1.3-3.2)×10^{-5} at the 90% confidence level, respectively. The constraints on the dark-matter-nucleon scattering cross section is improved by approximately five orders of magnitude over previous dark-matter-nucleon scattering experiments, providing unique insights into sub-GeV dark matter.

Excitons in two-dimensional semiconductors are directly exposed to the environment and are sensitive to the dielectric properties of their surrounding. Here, we show that the Rydberg series of excited states of excitons in a monolayer WSe_{2} encapsulated in hexagonal boron nitride (hBN) can be used to probe the pressure-induced modifications of the surrounding dielectric properties. We propose a model based on the pressure induced evolution of the interlayer distances in this van der Waals heterostructure and on the bulk dielectric properties of hBN. This approach allows a direct measurement of the dielectric constant of pressurized hBN and establishes a new methodology for dielectric sensing.

We establish a mapping between one-dimensional run-and-tumble particle dynamics in the presence of thermal noise, and overdamped Brownian motion in a spatially inhomogeneous temperature field. The approach is formulated as an inverse-Clausius thermodynamic framework, where the effective temperature is inferred from the steady-state density. Within this mapping, the local entropy flux and entropy production rate can be extracted directly from steady-state observables, without requiring explicit knowledge of the full position-velocity distribution. The framework introduces a closure that, to leading order, relates entropy flow to spatial variations of effective temperature, yielding a picture of entropy transfer from hotter to colder regions. We apply the approach to two-state and multistate run-and-tumble models in harmonic and nonlinear potentials. For harmonic confinement, the closure is exact in the two-state case and very accurate in multistate models. For nonlinear potentials that are locally confining (positive curvature at the origin), comparable accuracy is observed. In contrast, potentials with vanishing or negative curvature require higher-order corrections and reveal a correspondence between the spatial structure of the entropy production rate and that of the confining potential.

We show that the canonical formulation of the semiclassical Einstein equation, where the matter terms in the constraints are replaced by expectation values of the corresponding operators in quantum states, is inconsistent due to the nonclosure of the resulting constraint algebra.

Although the absorption of light in a bulk homogeneous semiconductor produces photocarriers with nonzero momenta, it generally does not produce a current in the absence of an applied electric field because equal amounts of carriers with opposite momenta are injected. The interference of absorption processes, for example, between one-photon and two-photon absorption can produce a current because constructive interference for carriers with one momentum can correspond to destructive interference for carriers with the opposite momentum. We show that for the interference between two-photon and three-photon absorption, the current has a narrower angular spread, i.e., a "beam" of electrons in a specified direction is produced in the semiconductor.

We have performed hyperfine spectroscopy of two transitions in ground-state deuterium and searched for violations of CPT and Lorentz symmetry that would manifest as sidereal variations of the observed transition frequencies. Several nonrelativistic proton coefficients of the Standard-Model extension framework have been addressed. The spin-independent coefficients with momentum power k=2, 4 are constrained for the first time. Bounds on spin-dependent coefficients are improved by exploiting a sensitivity enhancement originating from the relative momenta of the nucleons in the deuteron. The best previous constraints by hydrogen maser measurements are surpassed by 4 and 14 orders of magnitude for coefficients with k=2 and 4, respectively.

The emergence of the Abrikosov lattice in the normal phase of type-II superconducting films as the magnetic field approaches the critical field H_{c2} from above was predicted in Glatz et al. [Fluctuation spectroscopy of disordered two-dimensional superconductors, Phys. Rev. B 84, 104510 (2011)PRBMDO1098-012110.1103/PhysRevB.84.104510]. In the quantum fluctuation regime [Galitski and Larkin, Superconducting fluctuations at low temperature, Phys. Rev. B 63, 174506 (2001)PRBMDO0163-182910.1103/PhysRevB.63.174506], it is characterized by the formation of relatively large (ξ_{QF}∼ξ_{BCS}/sqrt[h[over ˜]], h[over ˜]=H/H_{c2}-1) and long-lived (τ_{QF}∼τ_{Δ}/h[over ˜], τ_{Δ}=ℏ/Δ) clusters of rotating fluctuation Cooper pairs, representing precursors of Abrikosov vortices. We show that these fluctuation-induced vortex clusters can be detected through their high-frequency electromagnetic response. Specifically, they produce a pronounced enhancement of the imaginary part of the ac conductivity at characteristic frequencies ω_{QF}∼h[over ˜]/τ_{Δ}, arising directly from quantum fluctuations, being well below the superconducting threshold at 2/τ_{Δ}. For niobium, ω_{QF} falls within the experimentally accessible microwave range, making this effect directly testable using modern microwave spectroscopy.

Device-independent (DI) certification allows the verification of quantum systems based solely on observed statistics, without assumptions about their internal structure. While self-testing, the strongest DI certification, of a wide range of quantum states and measurements is done, the self-testing of quantum operations remains underdeveloped. Here, we show in a proof-of-principle way that any quantum unitary can be self-tested within the DI paradigm. For our purpose, we utilize the framework of quantum networks with multiple independent sources. Our Letter provides a fundamental step toward certifying quantum interactions directly from data, without detailed modelling assumptions. Moreover, the result also serves as a crucial ingredient for quantum computation, where verifying that quantum gates perform as intended is essential for building secure and reliable quantum processors.

Under unitary evolution, chaotic quantum systems initialized in simple states rapidly develop high complexity, precluding any efficient classical description. The hardness of classical simulation within the stabilizer formalism, commonly referred to as magic resources, can be quantified by the stabilizer Rényi entropy, while quantum chaos can be characterized by spectral properties of the Hamiltonian, most notably through the spectral form factor. In this Letter, we propose a relation between the dynamics of the stabilizer Rényi entropy for thermofield double states and the spectral form factor, based on general arguments for chaotic systems with all-to-all interactions. This relation implies that the saturation of the stabilizer Rényi entropy is governed by a first-order dynamical transition. We then demonstrate this relation explicitly in the Sachdev-Ye-Kitaev model, using an auxiliary-spin representation of the stabilizer Rényi entropy that exhibits an emergent Z_{2} symmetry. We further find that, in the high-temperature regime of the SYK model, the transition occurs at a finite time, with the long-time phase marked by spontaneous Z_{2} symmetry breaking. By contrast, at low temperatures, the transition is pushed to times exponentially long in the system size. Our results reveal an intriguing interplay between quantum chaos and magic resources.

We introduce a simplified version of Connes-Narnhofer-Thirring's quantum dynamical entropy for quantum systems. It quantifies the amount of information gained about the initial condition from continuously monitoring an observable. A nonzero entropy growth rate can be obtained by monitoring the thermal fluctuation of an extensive observable in a generic many-body system, away from classical or large N limits. We explicitly compute the entropy rate in the thermodynamic and long-time limit in terms of the two-point correlation functions. We conjecture a universal Planckian bound for the entropy rate. Related results on the purification rate are also obtained.

The development of low-noise, high-sensitivity magnetic sensors is essential for applications such as automotive systems, biomedical imaging, and magnetic microscopy. However, sensor performance has long been impeded by a fundamental constraint that noise and sensitivity increase concomitantly, which imposes a performance limit. Here, we show that this limit can be overcome by engineering spin-texture dynamics. While maintaining high sensitivity, the sensor noise is demonstrated to decrease inversely with enhanced spin-texture dynamics. Leveraging this mechanism, using synthetic ferrimagnets with accelerated spin-texture dynamics, low-noise and high-sensitivity anomalous-Hall sensors are constructed. With an active sensing area of 20×20 μm^{2}, the device demonstrates a field detectability of 15.7 nT/√Hz at 1 Hz, nearly an order of magnitude improvement over existing sensors based on ferromagnetic materials. Our results establish active control of spin textures as a general pathway to ultrasensitive, low-noise magnetic sensing platforms.

The framework of superconductivity unveiled the striking concept that electrons form Cooper pairs through the subtle interplay of lattice vibrations, surmounting their Coulombic repulsion in the process. The concept of Cooper pairs has been established beyond the Fermi system, and this pairing mechanism is expected to extend to quasiparticle systems. Here, we report the soliton Cooper pairs in a Mamyshev oscillator. The soliton-phonon coupling yields a long-range attraction between solitons, balancing the Coulomb-like force, i.e., the gain depletion and recovery effect. With this, two solitons can form high-stable bound pair, even in the presence of intervening solitons. We characterize these long-range paired solitons comprehensively both in the time and phase domains. These discoveries herald a new method to manipulate nonlocal response for applications in optical systems and can help to understand particle-phonon coupling in fundamental physics.

Although entanglement can boost metrological precision beyond the standard quantum limit, the advantage often disappears with particle loss. We demonstrate that scrambling safeguards precision by dispersing information about the encoded parameter into many-body correlations. For Haar-random scrambling unitaries, we derive closed-form analytical expressions for the average quantum Fisher information of the reduced state after tracing out lost particles. The result exhibits a sharp threshold: majority subsystems retain essentially the full quantum Fisher information, while minority subsystems contain negligible information in the large-system limit. We link this threshold to the scrambling-induced transition from area-law to volume-law entanglement and the associated growth of the Schmidt rank. We outline two realizations-a brickwork circuit and chaotic XX-chain evolution-and demonstrate the protection of one-axis-twisted probes for loss of fewer than half the particles.

Extending the sensitivity of terrestrial gravitational-wave detectors below 20 Hz is a long-standing challenge, limited by ground motion and inertial sensing noise. In this Letter, we demonstrate ultra-high-vacuum compatible inertial isolation and position sensing technologies that achieve active platform stabilization down to 10 mHz. Our laser position sensors reach a sub-pm/sqrt[Hz] sensitivity above 10 mHz, independent of the input light polarization, representing a 100-fold improvement over the current LIGO position sensors. In addition, our inertial sensors provide at least a factor of 5 improvement in low-frequency sensitivity compared to state-of-the-art commercial seismometers. We integrate these technologies into a LIGO-like interferometer model and predict a low-frequency sensitivity improvement of up to an order of magnitude at 10 Hz, with enhanced linearity and calibration stability. This extension increases the detection horizon for intermediate-mass black hole binaries of mass 10^{3}M_{⊙} by a factor of 3 and increases the SNR for all lower mass binaries. Our results provide the first experimental demonstration of a practical pathway to sub-10 Hz operation of terrestrial gravitational-wave detectors and establish key technologies for next-generation observatories such as Cosmic Explorer and Einstein Telescope.

We investigate how many-electron excited states emerge in twisted MoSe_{2} homobilayers when the lattice reconstructions evolve. Notably, we identify a new trion resonance that arises in the transition regime of lattice reconstruction, where gradual changes in atomic alignment between the layers occur. Magnetic field-dependent measurements, supported by first-principles calculations, indicate that the exciton forms at the K valley while the doped hole resides in the Γ valley. First-principles calculations further indicate that two nearly degenerate exciton resonances can arise, localized at different sites within the moiré supercell. We propose that the new trion resonance is a "charge-transfer" trion, in which the electron-hole pair is spatially separated from the doped hole. The emergence of these complex excited states stems from the distinct moiré potentials acting on holes and excitons, resulting in their different spatial distribution within the superlattice.