The quantum geometric properties of topological materials underpin many exotic physical phenomena and applications. Quantum nonlinearity has emerged as a powerful probe for revealing these properties. The Berry curvature dipole in nonmagnetic materials and the quantum metric dipole in antiferromagnets have been explored by studying the second-order nonlinear Hall effect. Although the quadrupole moment of the quantum geometric tensor is theoretically predicted to induce higher-order quantum nonlinearity, the quantum metric quadrupole remains experimentally unexplored. Here, we report the quantum metric quadrupole induced third-order nonlinear longitudinal electrical response in few-layer ${\mathrm{WTe}}_2$, persisting up to room temperature. Angle-resolved third-harmonic current-voltage characteristics are found consistent with the intrinsic crystal symmetry of ${\mathrm{WTe}}_2$. Through temperature variation and scaling analysis, we identify the quantum metric quadrupole as the physical origin of the observed third-order longitudinal nonlinearity. Additionally, we determine the angle dependence of the quantum metric quadrupole, establishing third-order nonlinearity as an efficient method for revealing the quantum metric structure.

PHENIX presents a simultaneous measurement of the production of direct $\gamma$ and ${\pi }^0$ in $d+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=200\mathrm{GeV}$ over a $p_T$ range of 7.5 to $18\mathrm{GeV}/c$ for different event samples selected by event activity, i.e., charged-particle multiplicity detected at forward rapidity. Direct-photon yields are used to empirically estimate the contribution of hard-scattering processes in the different event samples. Using this estimate, the average nuclear-modification factor, $R_{d\mathrm{Au},\mathrm{EXP}}^{{\pi }^0}$, is $0.925\pm 0.023(\mathrm{stat})\pm 0.15(\mathrm{scale})$, consistent with unity for minimum-bias (MB) $d+\mathrm{Au}$ collisions. For event classes with low and moderate event activity, $R_{d\mathrm{Au},\mathrm{EXP}}^{{\pi }^0}$ is consistent with the MB value within 5% uncertainty. This result confirms that the previously observed enhancement of high-$p_T$ ${\pi }^0$ production found in small-system collisions with low event activity is a result of a bias in interpreting event activity within the Glauber framework. In contrast, for the top 5% of events with the highest event activity, $R_{d\mathrm{Au},\mathrm{EXP}}^{{\pi }^0}$ is suppressed by 20% relative to the MB value with a significance of $4.5\sigma$, which may be due to final-state effects. This suppression corresponds to a $p_T$ shift of $\delta p_T=0.213\pm 0.055\mathrm{Gev}/c$ at $9\mathrm{Gev}/c$.

We investigate experimentally the quantum coherence of an electronic two-level system in a double quantum dot under continuous charge detection. The charge state of the two-level system is monitored by a capacitively coupled single quantum dot detector that imposes a backaction effect on the system. The measured backaction is well described by an additional decoherence rate, approximately linearly proportional to the detector electron tunneling rate. We provide a model for the decoherence rate arising due to level detuning fluctuations induced by detector charge fluctuations. The theory predicts a factor of 2 lower decoherence rates than observed in the experiment, suggesting the need for a more elaborate theory accounting for additional sources of decoherence.

It is a well-established notion that the spin of a magnon should be flipped when it passes through a 180° domain wall (DW) in both ferromagnets and antiferromagnets, while the magnon spin transport through ferrimagnetic DW is still elusive. In this Letter, we report that the magnon preserves its spin after the transmission through an atomically sharp DW in ferrimagnets due to the intriguing interband magnon scattering at the domain interface. This finding may provide significant insight to resolve the puzzling insensitivity of magnon spin diffusion to the 180° ferrimagnetic DWs observed by recent experiments. Our results reveal the unique role of ferrimagnetic DWs in manipulating the magnon spin and may facilitate the design of novel magnonic devices based on ferrimagnets.

The area law of the bipartite information measure characterizes one of the most fundamental aspects of quantum many-body physics. In thermal equilibrium, the area law for the mutual information universally holds at arbitrary temperatures as long as the systems have short-range interactions. In systems with power-law decaying interactions, $r^{-\alpha }$ ($r$: distance), conditions for the thermal area law are elusive. In this Letter, we aim to clarify the optimal condition $\alpha >{\alpha }_c$ such that the thermal area law universally holds. A standard approach to considering the conditions is to focus on the magnitude of the boundary interaction between two subsystems. However, we find here that the thermal area law is more robust than this conventional argument suggests. We show the optimal threshold for the thermal area law by ${\alpha }_c=(D+1)/2$ ($D$: the spatial dimension of the lattice), assuming a power-law decay of the clustering for the bipartite correlations. Remarkably, this condition encompasses even the thermodynamically unstable regimes $\alpha <D$. We verify this condition numerically, finding that it is qualitatively accurate for both integrable and nonintegrable systems. Unconditional proof of the thermal area law is possible by developing the power-law clustering theorem for $\alpha >D$ above a threshold temperature. Furthermore, the numerical calculation for the logarithmic negativity shows that the same criterion $\alpha >(D+1)/2$ applies to the thermal area law for quantum entanglement.

In the $1+1\mathrm{D}$ ultralocal lattice Hamiltonian for staggered fermions with a finite-dimensional Hilbert space, there are two conserved, integer-valued charges that flow in the continuum limit to the vector and axial charges of a massless Dirac fermion with a perturbative anomaly. Each of the two lattice charges generates an ordinary U(1) global symmetry that acts locally on operators and can be gauged individually. Interestingly, they do not commute on a finite lattice and generate the Onsager algebra, but their commutator goes to zero in the continuum limit. The chiral anomaly is matched by this non-Abelian algebra, which is consistent with the Nielsen-Ninomiya theorem. We further prove that the presence of these two conserved lattice charges forces the low-energy phase to be gapless, reminiscent of the consequence from perturbative anomalies of continuous global symmetries in continuum field theory. Upon bosonization, these two charges lead to two exact U(1) symmetries in the XX model that flow to the momentum and winding symmetries in the free boson conformal field theory.

We propose to identify whether a sterile neutrino is Dirac-type or Majorana-type by counting the peak of the rapidity distribution at lepton colliders. Our method requires only one charged-lepton tagging, and the nature of sterile neutrinos can be pinned down once they are confirmed.

We report new results from the neutrino elastic scattering observation with NaI (NEON) experiment in the search for light dark matter (LDM) using $2636\mathrm{kg}·\mathrm{days}$ of NaI(Tl) exposure. The experiment employs an array of NaI(Tl) crystals with a total mass of 16.7 kg, located 23.7 m away from a 2.8 GW thermal power nuclear reactor. We investigated LDM produced by the invisible decay of dark photons, a well-motivated mechanism generated by high-flux photons during reactor operation. The energy spectra collected during reactor-on and reactor-off periods were compared within the LDM signal region of 1–10 keV. No signal consistent with LDM interaction with electrons was observed, allowing us to set 90% confidence level exclusion limits on the dark matter-electron scattering cross section (${\sigma }_e$) across dark matter masses ranging from 1 to $1000\mathrm{keV}/{\mathrm{c}}^2$. Our results set a 90% confidence level upper limit of ${\sigma }_e=3.17\times {10}^{-35}{\mathrm{cm}}^2$ for a dark matter mass of $100\mathrm{keV}/{\mathrm{c}}^2$, marking the best laboratory result in this mass range. Additionally, our search extends the coverage of LDM below $100\mathrm{keV}/{\mathrm{c}}^2$ for the first time, assuming the specific invisible decay of dark photons.

Understanding the properties of hypernuclei is crucial for constraining the nature of hyperon-nucleon ($Y\text{−}N$) interactions, which plays a key role in determining the inner structure of compact stars. The lightest hypernuclei and antihypernuclei are the hypertriton (${}_{\mathrm{\Lambda }}{}^3\mathrm{H}$), which consists of a pair of nucleons and a $\mathrm{\Lambda }$ hyperon, and its antinucleus (${}_{\overline{\mathrm{\Lambda }}}{}^3\overline{\mathrm{H}}$). Significant knowledge has recently been acquired regarding the mass, lifetime, and binding energy of ${}_{\mathrm{\Lambda }}{}^3\mathrm{H}$. However, its exact spin, whether $\frac{1}{2}$ or $\frac{3}{2}$, remains undetermined in both experimental and theoretical studies. Here, we present a novel method of using the hypertriton global polarization in heavy-ion collisions to decipher not only its total spin but also its internal spin structure. This method is based on the finding that its three different spin structures exhibit distinct beam energy dependence of its global polarization when it is produced in these collisions from the coalescence of proton, neutron and $\mathrm{\Lambda }$. Future observations of the hypertriton and antihypertriton global polarizations thus provide the opportunity to unveil the spin structures of hypertriton and antihypertriton and their production mechanisms in heavy-ion collisions.

At a fundamental level, the interactions between protons and protons, protons and neutrons, and neutrons and neutrons are not identical. Such isospin nonconserving interactions emerge when comparing the excitation energy of analog states in $T=1$ triplet nuclei. Here, we extend such an analysis to the $A=78$, $T=1$ triplet system—the heaviest system for which such complete data exists—and find strong disagreement with contemporary theory. This was achieved by pioneering the technique of recoil-$\beta \text{−}\beta$ tagging to identify excited states in ${}^{78}\mathrm{Zr}$. We also established a ${}^{78}\mathrm{Zr}$ half-life of ${25}_{-8}^{+17}\mathrm{ms}$ and extended the $T=1$ band in ${}^{78}\mathrm{Y}$ to $J^{\pi }=({10}^{+})$.

The dynamics of nonequilibrium closed quantum systems and their route to thermalization are of fundamental interest to several fields, from cosmology to particle physics. However, a comprehensive description of nonequilibrium phenomena still presents a significant challenge. In this work, we report the observation of distinct stages during the relaxation of the decaying turbulence in trapped Bose-Einstein condensates. Our findings show a direct particle cascade from low to high momenta, a consequence of the energy injection in the system, exhibiting a characteristic universal scaling. This stage is followed by an inverse particle cascade responsible for repopulating the previously depleted condensate. Both cascades can be explained through self-similar solutions provided by wave turbulence theory. These findings provide important insights into the relaxation stages of out-of-equilibrium quantum many-body systems.

Large-scale fault-tolerant superconducting quantum computation needs rapid quantum communication to network qubits fabricated on different chips and long-range couplers to implement efficient quantum error correction codes. Quantum channels used for these purposes are best modeled by multimode resonators, which lie between single-mode cavities and waveguides with a continuum of modes. In this Letter, we propose a non-Markovian formalism for quantum state transfer using coupling strengths comparable to the channel’s free spectral range ($g\sim {\mathrm{\Delta }}_{\mathrm{FSR}}$). Our scheme merges features of both the stimulated-Raman-adiabatic-passage-based methods for single-mode cavities and the pitch-and-catch protocol for long waveguides, integrating their advantages of low loss and high speed. It is immune to thermal channel occupations if using harmonic resonators for the sender and receiver.

Metasurface polarization optics have attracted considerable attention due to their ability to manipulate independently the wave fronts of different polarization channels with subwavelength scale. Previous methods mainly focused on the condition of complete polarization conversion, restricting the application range of metasurface polarization multiplexing. Here, we proposed a generalized framework of phase manipulation for the metasurface polarization optics, which can realize independent phase control and arbitrary energy distribution of different polarization channels for the arbitrary polarization conversion efficiency. Based on this principle, we experimentally demonstrate tripolarization-channel wave-front control for the arbitrary polarization state (elliptical, circular, and linear). The arbitrary energy distribution of different polarization channels has been achieved via varying the polarization conversion efficiency. The proposed framework significantly improves the performance of metasurface in the polarization multiplexing and energy distribution, and expands the application scope of metasurface in the polarization optics.

We propose a novel method for changing the length of laser wakefield electron acceleration in a gas jet using a cylindrical blast-wave created by a perpendicularly focused nanosecond laser pulse. The shock front modifies the wake significantly and stops interaction between the laser pulse and accelerated electron bunch, allowing one to directly control the interaction length and avoid dephasing. It also improves the electron beam quality through the plasma lensing effect between the two shock fronts. We demonstrated both experimentally and numerically how this approach can be used to form a quasimonoenergetic electron bunch with controlled energy and improved divergence as well as tracking changes in the bunch parameters during acceleration.

Supercurrent flow can induce a nonvanishing spin magnetization in noncentrosymmetric superconductors with spin-orbit interaction. Often known as the nondissipative magnetoelectric effect, these are most commonly found at linear order in supercurrent flow. Here, we propose that a nonlinear superconducting magnetoelectric (NSM) effect can naturally manifest in magnet-superconductor heterostructures. In such platforms, NSM manifests as the spin polarization generated as a second-order response to a driving supercurrent. Strikingly, we find NSM survives centrosymmetry and is the leading-order magnetic response in a variety of magnetic materials that include both collinear magnets (e.g., $d$-wave planar altermagnet thin film-superconductor) as well as noncollinear magnets (e.g., kagome-superconductor systems). This renders NSM a powerful electric and nondissipative means of controlling magnetization in magnet-superconductor heterostructures, a promising platform for superconducting spintronics.

Hydrodynamic description of collective electron motion turns out to be fruitful, since it provides a reliable physical concept that allows engineering the electron-electron interaction. We experimentally study the relation between two fundamental quantities—the electron viscosity and the Fermi quasiparticle lifetime—beyond the applicability limit of the Fermi liquid theory. We use point contact (PC) geometry to study electron transport and observe superballistic PC conductance, which is a signature of the electron viscosity. At high enough temperatures, the viscosity-lifetime relation is shown to diverge from the theoretically predicted one and turns out to be nontrivial. In addition, we study these phenomena in PCs freely suspended over a substrate, i.e., under the unique experimental conditions of enhanced electron-electron interaction. Suspension is found to reduce the electron viscosity in the whole temperature range, which makes the suspended structures a promising test bed for studying hydrodynamic effects in solids.

We generalize isometric tensor network states to fermionic systems, paving the way for efficient adaptations of 1D tensor network algorithms to 2D fermionic systems. As the first application of this formalism, we developed and benchmarked a time-evolving block-decimation (TEBD) algorithm for real-time and imaginary-time evolution. The imaginary-time evolution produces ground-state energies for gapped systems, systems with a Dirac point, and systems with gapless edge modes to good accuracy. The real-time TEBD captures the scattering of two fermions and the chiral edge dynamics on the boundary of a Chern insulator.