The quantum anomalous Hall (QAH) effect holds fundamental importance in topological physics and technological promise for electronics. It is generally believed that the QAH effect can only be realized in insulators. In this Letter, we theoretically demonstrate that the QAH effect can also be realized in metallic systems, representing a phase distinct from the conventional QAH phase in insulators. This phase is characterized by the coexistence of chiral edge channels and isotropic bulk conduction channels without a bulk energy gap. Notably, in a six-terminal Hall bar, our calculations show that, the quantized Hall conductivity and nonzero longitudinal conductivity can emerge due to dephasing, despite the Hall resistivity itself never becoming quantized. Furthermore, the quantized Hall conductivity exhibits remarkable robustness against disorder. Our findings not only extend the range of materials capable of hosting the QAH effect from insulators to metals, but also provide insights that may pave the way for the experimental realization of the QAH effect at elevated temperatures.

We probe the spectrum of elementary excitations in ${\mathrm{SrIrO}}_3$ by using heterostructured [$({\mathrm{SrIrO}}_3{)}_m/({\mathrm{SrTiO}}_3{)}_l$] samples to approach the bulk limit. Our resonant inelastic x-ray scattering (RIXS) measurements at the Ir $L_3$ edge reveal a robust low-lying collective magnetic mode with an antiferromagnetic (AFM) dispersion similar to the insulators ${\mathrm{Sr}}_2{\mathrm{IrO}}_4$ and ${\mathrm{Sr}}_3{\text{Ir}}_2{\mathrm{O}}_7$, albeit with a large gap and much larger linewidth. At higher energies we find the spin-orbit exciton, also strongly broadened, but with an inverted dispersion and doubled periodicity that are controlled by the charge hopping. These results demonstrate that the AFM paramagnon persists, somewhat counterintuitively, far into the metallic regime of the insulator-metal transition driven by the degree of confinement in the heterostructure. We conclude that these two excitations, which are contrasting but coexisting hallmarks of strong AFM pseudospin and charge fluctuations in a spin-orbit-coupled Mott-Slater material, are properties intrinsic to the ground state of semimetallic perovskite ${\mathrm{SrIrO}}_3$.

Assuming the existence of an axionlike particle (ALP), beams of relativistic particles emit fluxes of quasireal ALPs, analogous to the photon fluxes described by Weizsäcker-Williams-type approximations. Consequently, ALP-ALP and ALP-photon collisions can occur at the LHC. We initiate the study of the LHC as an ALP collider, and show that ALP collisions provide competitive probes of certain ALP couplings. We show that ALP fluxes from heavy ions are suppressed relative to those from protons, unlike their photon counterpart. As a result, the most likely processes are ALP-photon collisions occurring in the proton-ion ($p\mathrm{A}$) ultraperipheral collisions. Using our implementation of ALP fluxes in simulation tools, we show that ALP-photon collisions in $p\mathrm{Pb}$ efficiently probe ALP couplings to third generation fermions. LHC data with realistic $p\mathrm{Pb}$ luminosity can constrain the product of ALP couplings to nucleons and top quarks at the level of $O(0.01{\mathrm{TeV}}^{-1})$. Notably, ALP-photon collisions naturally provide the leading probe of ALP flavor-violating couplings to the top quark. We suggest that the 2016 $p\mathrm{Pb}$ dataset collected at CMS, ATLAS, and LHCb should be explored for evidence of such collisions.

Disordered systems generically exhibit aging and a glass transition. Previous studies have long suggested that nonreciprocity tends to destroy glassiness. Here, we show that this is not always the case using a bipartite spherical Sherrington-Kirkpatrick model that describes the antagonistic coupling between two identical complex agents modeled as macroscopic spin glasses. Our dynamical mean-field theory calculations reveal an exceptional-point-mediated transition from a static disorder phase to an oscillating amorphous phase as well as nonreciprocal aging with slow dynamics and oscillations.

Counterdiabatic (CD) driving has the potential to speed up adiabatic quantum state preparation by suppressing unwanted excitations. However, existing approaches either require intractable classical computations or are based on approximations that do not have performance guarantees. We propose and analyze a nonvariational, system-agnostic CD expansion method and analytically show that it converges exponentially quickly in the expansion order. In finite systems, the required resources scale inversely with the spectral gap, which we argue is asymptotically optimal. To extend our method to the thermodynamic limit and suppress errors stemming from high-frequency transitions, we leverage finite-time adiabatic protocols. In particular, we show that a time determined by the quantum speed limit is sufficient to prepare the desired ground state, without the need to optimize the adiabatic trajectory. Numerical tests of our method on the quantum Ising chain show that our method can outperform state-of-the-art variational CD approaches.

We generalize Landauer’s theory of ballistic transport in a one-dimensional (1D) conductor to situations where charge carrier injection and extraction are not any more confined to electrodes at either end of the channel, but may occur along its whole length. This type of distributed injection is expected to occur from the two-dimensional (2D) bulk of, e.g., a quantum spin (or anomalous) Hall insulator to its topologically protected edge states. We apply our conceptual solution to the case of two metal electrodes contacting the 2D bulk, enabling us to derive criteria that discriminate ballistic from resistive edge channels in multiterminal transport experiments.

We show that interacting electrons in a flat Chern band can form, in addition to fractional Chern insulators, a chiral $f$-wave topological superconductor that hosts neutral Majorana fermion edge modes. Superconductivity emerges from an interaction-induced metallic state that exhibits anomalous Hall effect, as observed in rhombohedral graphene and near the $\nu =\frac{2}{3}$ fractional Chern insulator in twisted transition metal dichalcogenides.

In strong magnetic fields beyond 100 T, the significant Zeeman energy competes with the lattice interactions, where a considerable magnetostriction is expected. However, the microscopic observation of the magnetostriction above 100 T has been hindered due to the short pulse duration of microseconds and the coil’s destruction. Here, we report the observation of the giant and anisotropic magnetostriction of $\sim 1\%$ at 110 T in the spin-controlled crystal $\beta \text{−}{\mathrm{O}}_2$ by combining the single-shot diffraction of an x-ray free-electron laser (XFEL) and the newly developed portable 100 T generator (PINK-02). The soft and anisotropic response of $\beta \text{−}{\mathrm{O}}_2$ should originate in the competing van der Waals force and exchange interaction and also the frustration of spin and lattice on the triangular network. The XFEL experiment above 100 T using PINK-02 enables microscopic investigations on materials’ properties at high magnetic fields, providing insights into how spins contribute to the stability of crystal structures.

Acoustic forces occurring in resonant microfluidic chambers allow the handling of micrometer-sized particles. Trapping of nanoparticles has been shown for high particle concentrations and after preseeding the chamber with larger particles. We show that the trapping mechanism is due to synergy between hydrodynamic shielding and acoustic forces. Acoustic interactions are significant only when seed particles are involved and are negligible when trapping monodisperse particles. Density-selective nanoparticle trapping is suggested based on the numerical results.

The GW170817 neutron star merger event and the PREX-2 experiment probing neutron skin thickness provide crucial clues for understanding the nuclear equation of state (EoS). However, an apparent inconsistency exists between the tidal polarizability ${\mathrm{\Lambda }}^{1.4}$ inferred from GW170817 and the neutron skin thickness $R_{\mathrm{np}}^{208}$ of ${}^{208}\mathrm{Pb}$ measured by PREX-2, based on relativistic energy density functionals (EDFs). This Letter employs both relativistic and nonrelativistic EDFs to identify a multipole correlation involving ${\mathrm{\Lambda }}^{1.4}$, $R_{\mathrm{np}}^{208}$, and the symmetry energy curvature $K_{\mathrm{sym}}$ at saturation density. We demonstrate the essential role of $K_{\mathrm{sym}}$ in reconciling the conflicting ${\mathrm{\Lambda }}^{1.4}\text{−}{R}_{\mathrm{np}}^{208}$ correlations derived from nonrelativistic versus relativistic EDFs and in resolving the discrepancy between the GW170817 and PREX-2 data constraints. Furthermore, we obtain a joint constraint on $K_{\mathrm{sym}}$ from these datasets, providing a vital constraint on the symmetry energy of the nuclear EoS.

Integrating quantum key distribution (QKD) with classical data transmission over the same fiber is crucial for scalable quantum-secured communication. However, noise from classical channels limits QKD distance. We demonstrate the longest-distance continuous-variable QKD (CV-QKD) over 120 km (20 dB loss) in the asymptotic regime, and over 100 km (17 dB loss) in the finite-size regime, both coexisting with a fully populated coarse wavelength division multiplexing system. Natural mode filtering of the local oscillator and phase noise mitigation enabled this without additional filtering or wavelength reallocation. Benchmarking against a commercial discrete-variable QKD system and considering finite-size effects confirms the feasibility of CV-QKD as a plug-and-play solution for typical 80–100 km long-haul optical networks. Our results set a record fiber distance for CV-QKD, showing its potential for cost-effective, large-scale deployment in existing network infrastructure.

We show for the first time that warm inflation is feasible with standard model (SM) gauge interactions alone. Our model consists of a minimal extension of the SM by a single scalar inflaton field with an axionlike coupling to gluons and a monomial potential. The effects of light fermions, which were previously argued to render warm inflation with the SM impossible, are alleviated by Hubble dilution of their chiral chemical potentials. Our model features only one adjustable combination of parameters and accommodates all inflationary observables. We briefly discuss implications for axion experiments, dark matter, and the strong $CP$ problem.

Machine-learning interatomic potentials have emerged as a revolutionary class of force-field models in molecular simulations, delivering quantum-mechanical accuracy at a fraction of the computational cost and enabling the simulation of large-scale systems over extended timescales. However, they often focus on modeling local environments, neglecting crucial long-range interactions. We propose a sum-of-Gaussians neural network (SOG-Net), a lightweight and versatile framework for integrating long-range interactions into a machine-learning force field. The SOG-Net employs a latent-variable learning network that seamlessly bridges short-range and long-range components, coupled with an efficient Fourier convolution layer that incorporates long-range effects. By learning sum-of-Gaussians multipliers across different convolution layers, the SOG-Net adaptively captures diverse long-range decay behaviors while maintaining close-to-linear computational complexity during training and simulation via nonuniform fast Fourier transforms. The method is demonstrated effective for a broad range of long-range systems.

We present a classical algorithm based on Pauli propagation for estimating expectation values of arbitrary observables on random unstructured quantum circuits across all circuit architectures and depths, including those with all-to-all connectivity. We prove that, for any architecture where each circuit layer is randomly sampled from a distribution invariant under single-qubit rotations, our algorithm achieves a small error $ϵ$ on all circuits except for a small fraction $\delta$. The computational time is polynomial in qubit count and circuit depth for any small constant $ϵ$, $\delta$ and quasipolynomial for inverse-polynomially small $ϵ$, $\delta$. Our results show that estimating observables of quantum circuits exhibiting chaotic and locally scrambling behavior is classically tractable across all geometries.

We study the exchange of energy between gravitational and electromagnetic waves in an extended Mach-Zehnder or Sagnac type geometry that is analogous to an “optical Weber bar.” In the presence of a gravitational wave (such as the ones measured by the Laser Interferometer Gravitational Wave Observatory), we find that it should be possible to observe (via interference or beating effects after a delay line) signatures of stimulated emission or absorption of gravitons with present-day technology. Apart from marking the transition from passively observing to actively manipulating such a natural phenomenon, this could also be used as a complementary detection scheme. Nonclassical photon states may improve the sensitivity and might even allow us to test certain quantum aspects of the gravitational field.

We introduce tile codes, a simple yet powerful way of constructing quantum codes that are local on a planar 2D lattice. Tile codes generalize the usual surface code by allowing for a bit more flexibility in terms of locality and stabilizer weight. Our construction does not compromise on the fact that the codes are local on a lattice with open boundary conditions. Despite its simplicity, we use our construction to find codes with parameters $[[288,8,12]]$ using weight-6 stabilizers and $[[288,8,14]]$ using weight-8 stabilizers, outperforming all previously known constructions in this direction. Allowing for a slightly higher nonlocality, we find a $[[512,18,19]]$ code using weight-8 stabilizers, which outperforms the rotated surface code by a factor of more than 12. Our approach provides a unified framework for understanding the structure of codes that are local on a 2D planar lattice and offers a systematic way to explore the space of possible code parameters. In particular, due to its simplicity, the construction naturally accommodates various types of boundary conditions and stabilizer configurations, making it a versatile tool for quantum error-correction code design.

Quantum memory, a pivotal hub in quantum information processing, is expected to achieve temporal storage and coherent manipulation of quantum states with memory efficiency exceeding 90% and quantum fidelity surpassing the noncloning limit. However, the current performance falls short of these requirements due to the inherent trade-off between memory efficiency enhancement and noise amplification, which not only imposes significant demands on quantum purification but also fundamentally impedes continuous-variable quantum information processing. In this Letter, we break through these constraints by unveiling a Hankel transform spatiotemporal mapping for light-spin-wave conversion in quantum memory and proposing an intelligently light-manipulated strategy for spin wave compaction, which maximizes memory efficiency while suppressing excess noise. This strategy is experimentally demonstrated for a Raman quantum memory in warm ${}^{87}\mathrm{Rb}$ atomic vapor with an efficiency up to $94.6\pm 1\%$ and a low noise level of only $0.026\pm 0.012$ photon per pulse. The unconditional fidelity reaches $98.91\pm 0.1\%$ with an average of 1.0 photon per pulse for a 17 ns input signal. Our results successfully demonstrate a practical benchmark for broadband quantum memory that may facilitate advancements in high-speed quantum networks, quantum state manipulation, and scalable quantum computation.

By coupling newly developed triparticle charged particle radiography with radiography reconstruction algorithms and novel reconstruction postprocessing techniques, the spatial structure and time evolution of self-generated electric and magnetic fields in laser-driven vacuum hohlraums have been quantitatively revealed. Through high-fidelity data from a series of experiments, it is shown that late in the hohlraum evolution (after the end of laser drive) these fields are strongly correlated in both space and time, providing evidence that their evolution is primarily dominated by advection with the plasma flow. At these late times, plasma flow velocities inferred from both gross radiography analysis and field reconstructions (and corroborated with Thomson scattering measurements) indicate that the plasma is approaching stagnation near the hohlraum axis. These experiments provide not only new physical insight into spontaneously generated hohlraum fields, but also provide important spatially and temporally resolved information for future benchmarking of numerical codes.

Flat bands, characterized by zero group velocity and strong energy localization, enable interaction-enhanced phenomena across both quantum and classical systems. Existing photonic flat-band implementations were limited to evanescent-wave systems, specific lattice symmetries, or complex supercell modulations. A simple, universal, and efficient approach to realizing flat bands without dedicated source excitation is yet to be explored. Here, inspired by geometrically frustrated configurations, we theoretically proposed and experimentally demonstrated threefold-degenerate flat bands by integrating orbital and rotational degrees of freedom in a photonic dipolar kagome lattice. By rotating the dipole orientation, the system exhibits a band flip transition at which point all bands achieve complete flatness and degeneracy across the entire Brillouin zone. In contrast to conventional $s$-orbital kagome lattices with only a single flat band, our approach flattens the entire band structure, eliminating dispersive modes and enabling compatibility with arbitrary excitations. These results establish a new mechanism for flat-band engineering, offering a tunable strategy for enhancing light-matter interactions and may have applications in compact photonic devices and energy-efficient information processing.

The first dedicated $Z$-boson mass measurement at the LHC with $Z\to {\mu }^{+}{\mu }^{-}$ decays is reported. The dataset uses proton-proton collisions at a center-of-mass energy of 13 TeV, recorded in 2016 by the LHCb experiment, and corresponds to an integrated luminosity of $1.7{\mathrm{fb}}^{-1}$. A template fit to the ${\mu }^{+}{\mu }^{-}$ mass distribution yields the following result for the $Z$-boson mass: $m_Z=91,185.7\pm 8.3\pm 3.9\mathrm{MeV}$, where the first uncertainty is statistical and the second systematic. This result is consistent with previous measurements and predictions from global electroweak fits.