We present a native approach for realizing multiqubit parity phase gates in neutral-atom systems through global phase modulation of a Rydberg excitation laser. By shaping the temporal profile of the laser’s phase, we enable high-fidelity, time efficient entangling operations between multiple qubits without requiring individual qubit addressing. To mitigate intrinsic noise sources including spontaneous decay and motional effects, we develop a noise-aware optimal control framework that reduces gate errors under the presence of noise while maintaining smooth pulse profiles suitable for experimental implementation. In addition to equidistant qubit arrangements, we explore the impact of nonequidistant atomic configurations, where interaction inhomogeneity becomes significant. In these cases, the flexibility of our control approach helps to compensate for such variations, supporting reliable gate performance across different spatial layouts. These results facilitate the practical implementation of complex, multiqubit quantum operations in near-term neutral-atom quantum processors.

Compilation optimizes quantum algorithms’ performances on real-world quantum computers. To date, it is performed via classical optimization strategies. We introduce a class of quantum algorithms to perform compilation via quantum computers, paving the way for a quantum advantage in compilation. We demonstrate the effectiveness of this approach via quantum and simulated annealing-based compilation: We successfully compile a Trotterized Hamiltonian simulation with up to 64 qubits and 64 time steps and a quantum Fourier transform with up to 40 qubits and 771 time steps. We show that, for a translationally invariant circuit, the compilation results in a fidelity gain that grows extensively in the size of the input circuit, outperforming any local or quasilocal compilation approach.

Qutrit with highly efficient algorithms and security is imperative in quantum information processing. Here, we demonstrate for the first time the coherent creation, control, and readout of a single photonic qutrit in a cold Rydberg ensemble. In each measurement, an optical photon is stored as a Rydberg polariton through electromagnetically induced transparency. Employing two microwave fields, the polariton is driven into an arbitrary superposition of three collective states, each encoded in a Rydberg state. The collective state is mapped into a photonic time-bin qutrit with the microwave field and read out sequentially. The complete sequence, including preparation, control, and readout, is less than $1.8\mu \mathrm{s}$, which mitigates decoherence significantly. We measure the coherence of the qutrit with nondestructive Ramsey interferometry, which is preferable for quantum information processing, and find good quantitative agreement with the theoretical model. The ability to write, process, and read out the single photonic qutrit on microsecond timescales with microwave-coupled Rydberg states demonstrates the coherent connectivity among the high Hilbert space of the qutrit. Our study is an important step in exploring qutrit-based quantum information processes and quantum simulation of topological physics with microwave-coupled Rydberg atom ensembles.

The classical simulation of quantum dynamics plays an important role in our understanding of quantum complexity and in the development of quantum technologies. Efficient techniques such as those based on the Gottesman-Knill theorem for Clifford circuits, tensor networks for low entanglement-generating circuits, or Wick's theorem for fermionic Gaussian states have become central tools in quantum computing. In this work, we contribute to this body of knowledge by presenting a framework for classical simulations, dubbed “$\mathfrak{g}\text{-sim}$”, which is based on the underlying Lie algebraic structure of the dynamical process. When the dimension of the algebra grows at most polynomially in the system size, there exist observables for which the simulation is efficient. Indeed, we show that $\mathfrak{g}\text{-sim}$ enables new regimes for classical simulations, is able to deal with certain forms of noise in the evolution, as well as can be used to tackle several paradigmatic variational and nonvariational quantum computing tasks. For the former, we perform Lie-algebraic simulations to train and optimize parametrized quantum circuits (thus effectively showing that some variational models can be dequantized), design enhanced parameter initialization strategies, solve tasks of quantum circuit synthesis, and train a quantum-phase classifier. For the latter, we report large-scale noiseless and noisy simulations on benchmark problems. By comparing the limitations of $\mathfrak{g}\text{-sim}$ and certain Wick's theorem-based simulations, we find that the two methods become inefficient for different types of states or observables, hinting at the existence of distinct, nonequivalent resources for classical simulation.

Neutral hydrogen (HI) is fundamental for tracing spiral structure in galaxies, including the Milky Way, through its 21-cm emission line, revealing features otherwise obscured by dust and gas. However, much of the Milky Way remains poorly resolved due to the Solar System’s embedded location within the galactic disk. Here, we present the first direct comparison between zircon oxygen isotope kurtosis, a terrestrial deep time record, and spatial variations in HI density along the Solar System’s galactic orbit. Significant correlations between Earth’s magmatic zircon oxygen isotope kurtosis and HI density in spiral arms suggest astrophysical influences on Earth’s crustal evolution. Peaks in HI density near the Scutum-Centaurus and Perseus spiral arms are consistent with the hypothesis that periodic disruptions of the Oort cloud during galactic arm crossings increased impact rates on Earth. These periods of elevated impact flux may have contributed substantial thermal energy, leading to more variable magmatic petrogenesis. This variability is recorded by zircon oxygen isotopes, a proxy sensitive to the depth of crustal melting and the degree of interaction with surface-derived water. These results provide new insights into the interplay between galactic-scale processes and Earth’s geological history, arguing for consideration of astrophysical drivers of planetary evolution.

In the last decades, multifaceted manifestations of the breakdown of the self-consistent perturbation theory have been identified for the many-electron problem. Yet, the investigations have been so far mostly limited to paramagnetic states, where symmetry breaking is not allowed. Here, we extend the analysis to the spontaneously symmetry-broken antiferromagnetic (AF) phase of the repulsive Hubbard model. To this aim, we calculated two-particle quantities using dynamical mean-field theory for the AF-ordered Hubbard model and studied the possible occurrence of divergences of the irreducible vertex functions in the charge and spin sectors. Our calculations pinpoint the divergences in the AF phase diagram, showing that while the onset of AF order mitigates the breakdown of the perturbation expansion, it does not fully prevent it. Moreover, we have been able to link the changes in the dynamical structure of the corresponding generalized susceptibilities to the physical crossover from a weak-coupling (Slater) to a strong-coupling (Heisenberg) antiferromagnet, which takes place as the interaction strength is gradually increased. Finally, we discuss possible physical consequences of the irreducible vertex divergences in triggering phase-separation instabilities within the AF phase and elaborate on the implications of our findings for two-dimensional systems, where the onset of a long-range AF order is prevented by the Mermin-Wagner theorem.

We propose a viable design of a microwave two-photon threshold detector. In essence, the considered scheme is an extension of the existing single-photon detector—a Josephson photomultiplier (JPM)—an absorbing microwave detector based on a capacitively shunted rf superconducting quantum interference device (SQUID). To implement a two-photon threshold detector, we utilize a dimer of resonators—two lumped-element resonators interacting via an asymmetric dc SQUID, with one of the resonators capacitively coupled to the JPM. By specific tuning of the resonator frequencies and the external flux through the dc SQUID coupler, we engineer a nonperturbative two-photon coupling between the resonators. This coupling results in the coherent conversion of a photon pair from one resonator into a single photon in another resonator, enabling selective response to quantum states with at least two photons. We also consider an extended coupler design that allows on-demand in situ switching of two-photon coupling. In addition, we propose the modified JPM design to improve its performance. Our calculations demonstrate that, for realistic circuit parameters, we can achieve more than $99\%$ fidelity of photon pair detection in less than 50 ns. The considered scheme may serve as a building block for the implementation of efficient photon-number-resolving detectors in circuit QED architecture.

Noise of a quantum processor can be an important resource for simulating open quantum dynamics. However, this requires characterizing the device noise and then transforming it into a target structure. Here, we take the first step toward this goal: We analytically and numerically study reshaping the noise associated with native trapped-ion two-qubit entangling gates via quantum circuits based on repetition codes, and demonstrate our findings on the IonQ Aria-1 quantum hardware. We investigate all the building blocks, including the quantum channels describing noisy two-qubit entangling gates, the compilation of the encoding circuits into native gates, and the propagation of two-qubit errors across ideal single-qubit gates.

The prospect of transforming a Dirac topological semimetal (TSM) into a Weyl TSM phase, following doping by magnetic impurities, is central to TSM applications. The magnetic field from polarized $d$ levels of magnetic impurities produces a field with a sharp local structure. To what extent magnetic impurities act in the same manner as an applied field and what are the effects of such a field on the electronic structure of a Dirac TSM are the subject of this paper. We present electronic structure calculations of bulk ${\mathrm{Cd}}_3{\mathrm{As}}_2$ with substitutional doping of Mn impurities in the dilute alloy range. Quasiparticle $GW$ ($\mathrm{QS}GW$) ab initio electronic structure calculations are used in conjunction with $k·p$ model Hamiltonian calculations. As expected, we observe the splitting of the Dirac points into pairs of Weyl points following the doping with Mn. We also show that the electronic structure of Mn-doped ${\mathrm{Cd}}_3{\mathrm{As}}_2$ can be emulated by the electronic structure of pristine ${\mathrm{Cd}}_3{\mathrm{As}}_2$ with an appropriate external magnetic field. Some properties of the conductivity of bulk ${\mathrm{Cd}}_3{\mathrm{As}}_2$ for different magnetic field orientations are also investigated. Our results inform future opportunities for unique device functionality based on band structure tuning not found in conventional magnetic Weyl TSM.

We present an International System of Units (SI)-traceable temperature calibration apparatus utilizing optical lattice clocks for precision metrology. The system employs a dual-blackbody radiation shield chamber with independent temperature control, enabling synchronous differential measurements of blackbody radiation (BBR)-induced frequency shifts in atomic ensembles. By correlating these shifts with chamber temperature, we propose absolute temperature determination traceable to the SI second through the optical clock frequency. Comprehensive uncertainty analysis demonstrates an absolute temperature uncertainty below 17 mK across the $200-350\mathrm{K}$ range based on ${}^{87}\mathrm{Sr}$ optical lattice clock, representing an improvement of two orders of magnitude over current temperature measurements based on BBR-induced Rydberg state transitions. This advancement in primary thermometry offers significant improvements in precision, reproducibility, and versatility, with potential applications in metrology, fundamental physics, and industrial processes.

Generalized synchronization, in which a nontrivial interdependence is established between the trajectories of two or more coupled units, has been observed in a wide range of simulated and physical systems. Although several numerical methods are available for its detection, visualization techniques have not been reported, and bidirectional coupling remains challenging, especially for experimental data. This paper introduces a simple empirical method for approximating the functional relation, based on expressing the current value of one system variable as a function of the state variable of the other system, reconstructed by time-delay embedding, along with suitable nonlinearities. Two strongly parametrically mismatched Rössler systems with weak bidirectional coupling have been considered. The proposed method allows the computation of a time series, namely, a “proxy signal,” which shows significantly stronger phase synchronization compared to the original system variables. The underlying approximated functional is visualized through regression coefficients, and its relationship with the Lyapunov exponents is demonstrated by simulated parameter sweeps in two dimensions. The results are validated via tunable analog electronic realization of the coupled systems. The effects of nonidealities in the physical apparatus are also investigated, demonstrating the robustness of the proposed method.

The problem of determining whether two states are equivalent by local unitary (LU) operations is important for quantum information processing. In this paper, we propose an alternative perspective to study this problem by comparing the decidabilities of LU equivalence (also known as LU decidabilities for short) between entanglement witnesses and states. We introduce a relation between sets of Hermitian operators in terms of the LU decidability. Then, we compare the LU decidability for the set of entanglement witnesses to the LU decidabilities for several sets of states. By comparison, we establish a hierarchy of these sets in terms of LU decidabilities. Moreover, we realize that the simultaneous LU (SLU) equivalence between tuples of mutually orthogonal projectors is crucial to LU equivalent operators. We reveal by examples that for two tuples of projectors, the partial SLU equivalence cannot ensure the overall SLU equivalence. Generally, we present a necessary and sufficient condition such that two tuples of states are SLU equivalent.

We obtain a closed-form expression for the energy spectrum of $\mathcal{P}\mathcal{T}\text{-symmetric}$ superlattice systems with complex potentials of periodic sets of two $\delta \mathrm{potentials}$ in the elementary cell. In the presence of periodic gain and loss, we analyzed in detail a diatomic crystal model, varying either the scatterer distances or the potential heights. It is shown that at a certain critical value of the imaginary part of the complex amplitude, topological states depending on the lattice size and the configuration of the unit cell can be pushed out from the given region. This may happen at the $\mathcal{PT}\text{-symmetry}$ breaking (exceptional) points.

The dynamics of open quantum systems are often modeled by non-Markovian processes that account for memory effects arising from interactions with the environment. It is well known that the memory provided by the environment can be classical or quantum in nature. Remarkably, the quantumness of the memory can be witnessed locally by measurements on the open system alone, without requiring access to the environment. However, existing witnesses are computationally challenging for systems beyond qubits, which severely limits their practical applicability. In this work, we present a tractable criterion for quantum memory based on the von Neumann entropy, which is easily computable for systems of any dimension. Using this witness, we investigate the nature of memory in a class of physically motivated finite-dimensional qudit dynamics. Moreover, we demonstrate that this criterion is also suitable for detecting quantum memory in continuous-variable systems. As an illustrative example, we analyze non-Markovian Gaussian dynamics of a damped harmonic oscillator.

We investigate the impact of strain and adsorbed H adatoms on the magnetic properties of zigzag graphene nanoribbons (ZGNRs) using a combination of tight-binding and density functional theory methods for both ferromagnetic (FM) and antiferromagnetic (AFM) edge configurations. We focus on the metallic FM edge configuration of the ZGNRs to better exploit the tuning of its properties. We find that the magnetic configuration of H adatoms is strongly influenced by the edges, with an AFM coupling between edges and the H adatom. In fact, the magnetic spatial pattern of the H adatom differs from that found in graphene due to this edge coupling. Importantly, we find robust discrete plateaus of integer magnetic moment as strain is varied in the defected ZGNRs, which we relate to changes in the band structure, namely, a half-metallic character or the opening of a gap. This behavior can be of interest for magnetic applications of carbon-based nanostructures.

Chiral superfluid ${}^3\mathrm{He}\text{−}\mathrm{A}$ contained in narrow-gapped parallel plate cell with in-plane external magnetic field is expected to form uniformly aligned texture of chiral vectors, which denote the direction of Cooper pair angular momentum. In the real experimental situation, we often observe the existence of a few millimeter sized chiral domains and chiral domain walls in between them. A persistent orbital supercurrent is expected to flow along the wall. We have succeeded in tilting chiral domain walls by applying external supercurrent, which interacts with the orbital supercurrent. This observation confirmed the existence of macroscopic orbital supercurrent along the chiral domain wall. The tilting angle depends on the direction and magnitude of the external supercurrent as well as the direction of the chiral vector in adjacent chiral domains. This allowed us to determine the direction of the chiral vector in each chiral domain. The measured tilting angle also suggests that the magnitude of macroscopic angular momentum of each chiral domain is as large as the ground-state angular momentum $\hslash$ times a number of ${}^3\mathrm{He}$ particles divided by 2.

We introduce a systematic procedure based on optimal control theory to address the full counting statistics of particle transport in a stochastic system. Our approach enhances the performance of a Thouless pump in the nonadiabatic regime by simultaneously optimizing the average pumping rate while minimizing noise. We demonstrate our optimization procedure on a paradigmatic model for the electronic transport through a quantum dot, both in the limit of vanishing Coulomb interaction and in the interacting regime. Our method enables independent control of the moments associated with charge and spin transfer, allowing for the enhancement of spin current with minimal charge current or the independent tuning of spin and charge fluctuations. These results underscore the versatility of our approach, which can be applied to a broad class of stochastic systems.