We consider systems of fermions evolved by noninteracting unitary circuits with correlated on-site potentials. When these potentials are drawn from the eigenvalue distribution of a circular random matrix ensemble, the single-particle sector exhibits chaotic dynamics. The corresponding many-body spectral form factors (SFFs) can be computed exactly, revealing signatures of single-particle chaos in the many-body spectral statistics. Due to the absence of interactions the SFF grows exponentially in time, a result which we demonstrate through simple arguments, scaling collapses, and closed-form evaluation of the SFF. Upon introducing interactions, the SFF crosses over to a linear growth regime consistent with many-body random matrix universality. Our exact results for the SFF provide a baseline for future studies of the crossover between single-particle and many-body random matrix behavior.

We extend the Carathéodory principle of the second law to quantum thermodynamics, where energy levels depend on macroscopic variables such as volume and magnetic field. This extension introduces the concept of quantum thermodynamic integrability (QTI), providing an alternative foundation for statistical mechanics. QTI is characterized by the path independence of work and heat within the thermodynamic manifold, locally described by energy levels and specific thermodynamic parameters. Within this framework, temperature naturally emerges as an integrating factor, enabling the derivation of both canonical and noncanonical states from the entropy integrable equations based on QTI. Notably, noncanonical states, which become particularly significant outside the thermodynamic limit, reveal the existence of informational correlations in finite-size thermodynamic systems.

Quantum annealing is a heuristic optimization algorithm that exploits quantum evolution to find low-energy states. Quantum annealers have scaled up in recent years to tackle increasingly larger and more highly connected discrete optimization and quantum simulation problems. Nevertheless, a computational quantum advantage in exact optimization using quantum annealing hardware has so far remained elusive. Here, we present evidence for a quantum annealing scaling advantage in approximate optimization. The advantage is relative to the top classical heuristic algorithm: parallel tempering with isoenergetic cluster moves (PT-ICM). The setting is a family of 2D spin-glass problems with high-precision spin-spin interactions. To achieve this advantage, we implement quantum annealing correction (QAC): an embedding of a bit-flip error-correcting code with energy penalties that leverages the properties of the D-Wave Advantage quantum annealer to yield over 1,300 error-suppressed logical qubits on a degree-5 interaction graph. We generate random spin-glass instances on this graph and benchmark their time-to-epsilon, a generalization of the time-to-solution metric for low-energy states. We demonstrate that, with QAC, quantum annealing exhibits a scaling advantage over PT-ICM at sampling low-energy states with an optimality gap of at least 1.0%. This amounts to the first demonstration of an algorithmic quantum speedup in approximate optimization.

Transmitting unknown quantum states to distant locations is crucial for distributed quantum information protocols. The seminal quantum teleportation scheme achieves this feat while requiring prior maximal entanglement between the sender and receiver. In scenarios with noisy entangled states, optimal teleportation fidelity characterizes the efficacy of transmitting the state, demanding the proper selection of local operations at the sender’s and receiver’s ends. The complexity escalates further in long-range communication setups, prompting the consideration of a repeater-based approach, which incorporates arrays of nodes with multiple segments to facilitate the efficient transmission of quantum information. The fidelity of the communication line gets degraded even if a single segment is affected by noise. In such cases, the general wisdom employs the standard entanglement swapping protocol involving maximally entangled states across the noiseless segments and applying maximally entangled basis measurement at the corresponding nodes to achieve optimal fidelity. In this Letter, we propose a more efficient protocol for a certain class of noisy states, achieving the same fidelity as the standard protocol while consuming less amount of entanglement. Our approach ensures optimal teleportation fidelity even when the end-to-end state gets noisier, and thus promises efficient utility of quantum resources in repeater-based distributed quantum protocols.

Recently, Dong et al., [A modified cosmic brane proposal for holographic Renyi entropy, J. High Energy Phys. 06 (2024) 120] proposed a modified cosmic brane prescription for computing the Rényi entropy $S_{\alpha }$ of a holographic system in the presence of multiple extremal surfaces. This prescription was found by assuming a diagonal approximation, where the Rényi entropy is computed after first measuring the areas of all extremal surfaces. We derive this diagonal approximation for the case of two extremal surfaces and show that it accurately computes Rényi entropies up to $O(\log G)$ corrections. For $\alpha <1$, this allows us to derive the modified cosmic brane prescription, which differs from the original cosmic brane prescription at leading order in $G$. For $\alpha >1$, it leads to the original cosmic brane prescription without needing to assume that replica symmetry is unbroken in the bulk.

We systematically compute five-point correlators of chiral primary operators with arbitrary Kaluza-Klein charges at tree level in ${\mathrm{AdS}}_5\times {\mathrm{S}}^3$ and obtain a unified formula. This result serves as the first concrete confirmation for the existence of the hidden eight-dimensional symmetries at the level of five points.

Isospin symmetry is a fundamental concept in nuclear physics. Even though isospin symmetry is partially broken, it holds approximately for most nuclear systems, which makes exceptions very interesting from the nuclear structure perspective. In this framework, it is expected that the spins and parities of the ground states of mirror nuclei should be the same, in particular for the simplest systems where a proton is exchanged with a neutron or vice versa. In this Letter, we present evidence that this assumption is broken in the mirror pair ${}^{71}\mathrm{Br}$ and ${}^{71}\mathrm{Kr}$ system. Our conclusions are based on a high-statistics $\beta$ decay study of ${}^{71}\mathrm{Kr}$ and on state-of-the-art shell model calculations. In our work, we also found evidence of a new state in ${}^{70}\mathrm{Se}$, populated in the $\beta$-delayed proton emission process which can be interpreted as the long sought coexisting $0^{+}$ state.

A novel quantum control protocol utilizing two-photon processes with trigonometric pulse modulation is developed, enabling the intermediate state population’s dynamic elimination (DE). The proposed DE technique excels at single-photon resonance in contrast to the well-known adiabatic elimination (AE) regime, which requires large single-photon detuning and strong pulses. The DE approach outperforms AE in efficiency and exhibits enhanced resilience to one-photon detuning since the key control parameter, the effective two-photon Rabi frequency, inversely proportional to the modulation frequency, does not depend on the one-photon detuning. The comprehensive analysis of population transfer and Ramsey interferometry demonstrates the protocol’s superiority, achieving enhanced signal-to-noise ratios and higher fidelities with respect to existing two-photon methods.

Integrated photonics provides an important platform for simulating physical models with high-performance chip-scale devices, where the lattice size and the time dependence of a model are key ingredients for further enriching the functionality of a photonic chip. Here, we propose and demonstrate the construction of various time-varying Hamiltonian models using a single microresonator on thin-film lithium niobate chip. Such an integrated microresonator holds high-quality factor to ${10}^6$, and supports the construction of the synthetic frequency lattice with effective lattice sites up to 221 under efficient integrated electro-optic modulation. By further applying different bichromatic modulations composed of two radio-frequency signals oppositely detuned from the resonant frequency in the microresonator, we successfully build various time-varying Hamiltonian models, where the temporal features of the dynamic band structures are captured from experimental measurements, highlighting great flexibility and tunability of this integrated chip. Our work presents a photonic chip for simulating versatile time-varying Hamiltonians, which pushes forward quantum simulations and future photonic applications.

We theoretically propose a scheme to synthesize photonic non-Abelian electric field and spin-orbit coupling (SOC) in the synthetic frequency dimension based on a polarization-multiplexed time-modulated ring resonator. Inside the ring resonator, the cascade of polarization-dependent phase modulation, polarization rotation, and phase retardation enables a photonic realization of minimal SOC with Peierls substitution composed of equal Rashba and Dresselhaus coupling. The synthetic bands and associated spin textures can be effectively probed by the continuous-wave polarization- and time-resolved band structure measurements. Meanwhile, the pulse dynamics in the frequency dimension can be manipulated by both synthetic Abelian and non-Abelian electric fields, leading to Bloch oscillation, Zitterbewegung, and their interplay dynamics. Our proposed setup can be realized with free-space optics, fibers, and integrated photonics, and provides pseudospin control knobs for large-scale synthetic lattices based on frequency combs.

We show how nonreciprocal ferromagnetic interactions between neighboring planar spins in two dimensions, affect the behavior of topological defects. Nonreciprocity is introduced by weighting the coupling strength of the two-dimensional XY model by an anisotropic kernel. As a consequence, in addition to the topological charge $q$, the actual shape of the defects becomes crucial to faithfully describe their dynamics. Nonreciprocal coupling twists the spin field, selecting specific defect shapes, dramatically altering the pair annihilation process. Defect annihilation can either be enhanced or hindered, depending on the shape of the defects concerned and the degree of nonreciprocity in the system. We introduce a continuous description—for which the phenomenological coefficients can be explicitly written in terms of the microscopic ones—that captures the behavior of the lattice model.

Persistent revivals recently observed in Rydberg atom simulators have challenged our understanding of thermalization and attracted much interest to the concept of quantum many-body scars (QMBSs). QMBSs are non-thermal highly excited eigenstates that coexist with typical eigenstates in the spectrum of many-body Hamiltonians, and have since been reported in multiple theoretical models, including the so-called PXP model, approximately realized by Rydberg simulators. At the same time, questions of how common QMBSs are and in what models they are physically realized remain open. In this Letter, we demonstrate that QMBSs exist in a broader family of models that includes and generalizes PXP to longer-range constraints and states with different periodicity. We show that in each model, multiple QMBS families can be found. Each of them relies on a different approximate $\mathfrak{su}(2)$ algebra, leading to oscillatory dynamics in all cases. However, in contrast to the PXP model, their observation requires launching dynamics from weakly entangled initial states rather than from a product state. QMBSs reported here may be experimentally probed using Rydberg atom simulator in the regime of longer-range Rydberg blockades.

The resource theory with covariant Gibbs-preserving operations, also called enhanced thermal operations, is investigated. We prove that with the help of a correlated catalyst, the state convertibility for any coherent state is fully characterized by the free energy defined with the quantum relative entropy. We can extend this result to general resource theories in the form that imposing the covariant condition to a general resource theory does not change the state convertibility, as long as the initial state is coherent and distillable and this resource theory admits the phase estimation and the phase shift. This means that adding a constraint from the law of energy conservation is irrelevant in the correlated-catalytic framework.

Quantum networking protocols, including quantum teleportation and entanglement swapping, use linear-optical Bell state measurements for heralding the distribution and transfer of quantum information. However, a linear-optical Bell state measurement requires identical photons and is susceptible to errors caused by multiphoton emission, fundamentally limiting the efficiency and fidelity of quantum networking protocols. Here we show a nonlinear Bell state analyzer for time-bin encoded photons based on a nanophotonic cavity with a sum-frequency generation efficiency of $4\times {10}^{-5}$ to filter multiphoton emissions, and utilize it for faithful quantum teleportation involving spectrally distinct photons with fidelities $\ge 94\%$ down to the single-photon level. Our result demonstrates that nonlinear-optical entangling operations, empowered by our efficient nanophotonics platform, can realize faithful quantum information protocols without requiring identical photons and without the fundamental limit on the fidelity of a Bell state measurement imposed by linear optics, which facilitates the realization of practical quantum networks.

We propose a novel statistical method to measure cosmic birefringence and demonstrate its power in probing parity violation due to axions. Exploiting an empirical correlation between the integrated radio polarization direction of a spiral galaxy and its apparent shape, we devise an unbiased minimum-variance estimator for the rotation angle, which should achieve an uncertainty of 5°–15° per galaxy. Large galaxy samples from the forthcoming SKA continuum surveys, together with optical shape catalogs, promise a comparable or even lower noise power spectrum for the rotation angle than in the CMB Stage-IV (CMB-S4) experiment, with different systematics.

For the first time the neutron-rich hydrogen isotope ${}^6\mathrm{H}$ was produced in an electron scattering experiment in the reaction ${}^7\mathrm{Li}(\mathrm{e},{\mathrm{e}}^{\prime }\mathrm{p}{\pi }^{+}{)}^6\mathrm{H}$ using the spectrometer facility of the A1 Collaboration at the Mainz Microtron accelerator. By measuring the triple coincidence between the scattered electron, the produced proton, and ${\pi }^{+}$, the missing mass spectrum of ${}^6\mathrm{H}$ was obtained. A clear peak above ${}^3\mathrm{H}+\mathrm{n}+\mathrm{n}+\mathrm{n}$ energy threshold was seen resulting in a ground state energy of ${}^6\mathrm{H}$ at $2.3\pm 0.5(\mathrm{stat}.)\pm 0.4(\mathrm{syst}.)\mathrm{MeV}$ with a width of $1.9\pm 1.0(\mathrm{stat}.)\pm 0.4(\mathrm{syst}.)\mathrm{MeV}$. This Letter challenges the understandings of multinucleon interactions and presents a new method to study light neutron-rich nuclei with electron scattering experiments.