Reservoir engineering enables unidirectional energy and signal flow. We establish squeezing-induced symmetry breaking between two cavities as a guiding principle for exponentially amplifying reservoir-mediated nonreciprocity. Rather than a simple scaling of the coupling, this mechanism strategically redistributes the squeezing resources to relax experimental requirements, as single-cavity squeezing alone demands a much larger squeezing strength. Moreover, reservoir squeezing does not alter the system symmetry but reshapes the noise correlations and thereby changes the system dynamics. The proposed mechanism improves the performance of the quantum battery by several orders of magnitude, including stored energy, charging power, and ergotropy, with the analytical expressions provided. Extending to the optical isolation, we observe a second-order exponential enhancement of the output signal. Our results open a new avenue for nonreciprocal quantum information processing and nonreciprocal quantum device design.

Practical and robust control of the complex phases of qubit superposition states is necessary for high-fidelity quantum gates. Here we experimentally demonstrate such control in a trapped ultracold 40Ca+ ion, where the phase of qubit ground state is modified by optical driving to an excited state. Using a third spectator quantum level as reference, we experimentally measure the phases generated on the ground state amplitude by different driving schemes. While geometric phases exhibit intrinsic robustness to systematic control errors due to their dependence on global geometric properties (e.g., Berry curvature) rather than dynamical details, their resilience to decoherence remains a topic requiring critical clarification. In this work, we show that geometric phases are not in general immune to environment-induced decoherence, and their practical robustness, including to decoherence, depends on active error-suppression strategies. We implement different driving schemes and find that minimizing excited state decay is more decisive for their robustness on decoherence than whether the phase is of a geometric or dynamical character. This work established and demonstrated a new control strategy that mitigates decoherence effects in geometric/complex phase systems, compensating for their susceptibility to decoherence. We experimentally benchmark four phase-imprinting protocols under a tunable engineered dissipation channel and controlled systematic errors in a single trapped-ion qubit. Our central quantitative finding is that the sensitivity to decoherence is governed by the time-integrated excited-state population, rather than by whether the accumulated phase is labeled geometric or dynamical.

A noteworthy discovery is that the minimal evolution time is smaller for parity-time ($${\mathcal{PT}}$$)-symmetric systems compared to Hermitian setups. Moreover, there is a significant acceleration of two-qubit quantum entanglement preparation near an exceptional point (EP), or spectral coalescence, within such a system. Nevertheless, an important problem often overlooked for quantum EP-based devices is their fidelity, greatly affected by the process of dissipation. We identify an inherent trade-off relation between the degree of entanglement and fidelity, and demonstrate that this limitation can be effectively overcome by harnessing an active $${\mathcal{PT}}$$-symmetric system, which possesses balanced gain and loss, enabling maximal entanglement with rapid speed, high fidelity, and greater resilience to non-resonant and coupling strength errors. Two- to six-partite entanglement is prepared as the concrete example to show (i) how to break this inherent fidelity-entanglement trade-off even with non-balanced gain and loss, and its resilience against non-resonant errors, in contrast to passive $${\mathcal{PT}}$$-symmetric dynamics; (ii) achieving speedups of many orders of magnitude, in contrast to conventional Hermitian dynamics. We use this approach to prepare 10-qubit entanglement to show the generality of this method. These findings highlight the potential of truly $${\mathcal{PT}}$$-symmetric devices as a versatile platform for generating and manipulating diverse quantum resources, with implications for advancing quantum information technologies.

We present a method for suppressing transducer leakage errors in spin-superconducting hybrid quantum systems with the theory of optimal invariant-based shortcut. By mediated virtual photons as a transducer to exchange the energy between the spin qubit and a transmon qubit, the fidelity of the population of the final state features a broad range above 99% under the influence of leakage error. The leakage probability from computational subspace to non-computational subspace can be effectively suppressed at a lowest value with 0.01. Based on the optimized pulse control designed by the invariant-based inverse engineering, the high-fidelity quantum iSWAP gate operations and entanglement state preparation within the computational subspace are achieved. Compared to the traditional π pulse, derivative removal by adiabatic gate, counter-diabatic shortcut schemes, and limited-memory Broyden-Fletcher-Goldfarb-Shanno gradient ascent pulse engineering, the optimized shortcut scheme can still achieve a high fidelity with 99% in the presence of decoherence and control error. When taking into account the possibility of leakage errors in actual situations, our solution can still largely resist the influence of control errors. The results provides a feasible path for precisely manipulating the quantum state of hybrid quantum systems.

We present a reinforcement learning-optimized Rydberg electrometer based on the asymmetric blockade effect and achieve high-sensitivity electric field sensing in Rydberg arrays. Microwave dressing induces asymmetric blockade to suppress interactions between target atoms, while keeping the coupling between the central control atom and target atoms field-tunable near Förster resonance. The field-regulated blockade radius affects the detectable atomic population signals, thereby enabling electric field sensing via state-selective readout. In planar atomic arrays, classical Fisher information exhibits near-quadratic scaling with atom number and approaches the Heisenberg limit. Reinforcement learning-designed composite pulses greatly enhance quantum Fisher information by up to one order of magnitude compared with single π pulses. We further establish a compact six-atom spherical configuration for vector electrometry, in which field orientation is extracted from calibrated axial populations, and weak bias fields eliminate dipole-dipole-induced sign and magic-angle ambiguities. Numerical tests against Rabi frequency deviation, positional error, residual inter-target coupling and projection noise demonstrate the reliability of this scheme. This work provides an experimentally viable approach to realize high-precision three-dimensional Rydberg electric field sensing.

A recent experiment demonstrated delayed superradiance from 88Sr atoms, which are coupled to a longitudinal mode of a cavity while being excited by a laser pulse propagating along a transversal direction [Nat. Commun. 15, 1084 (2024)]. A coherent picture of the atomic ensemble dynamics in this experiment requires complementary representations of the external driving dynamics and the superradiant dynamics. To complement previous analyses, we introduce these representations by considering in-phase and out-of-phase superpositions of transverse collective spin components of two atomic subensembles, and analyze the dynamics with the corresponding collective Dicke states and Bloch vectors. This approach also explains Ramsey spectroscopy experiments based on the delayed superradiance, and it may be employed to explore other intriguing phenomena, such as weak- to strong-coupling phase transitions and triggered superradiance.

Superradiant emission from long-lived excited states of an atomic ensemble confined in an optical cavity constitutes a practical source of light with narrow linewidth. In the pulsed regime, however, superradiance implies rapid emission and a broadening of the spectrum. Recent experiments have demonstrated constructive and destructive interference of superradiant emission by different strontium atomic transitions. In this article, we show that by modulating the atomic transition frequencies with a magnetic field, it is possible to control the release of the atomic excitation energy as a prolonged pulse or a train of superradiant pulses. By simulations, we show that heterodyne detection of the prolonged superradiance shows extremely sharp spectral features, which leads to significantly reduced frequency uncertainty and fluctuation.

Time crystals constitute a novel phase of matter defined by the spontaneous breaking of time-translation symmetry. Here, we present a scheme to realize a continuous-time crystal of the vibrational phonon in the normal mode of two coupled ultra-cold ions. By utilizing two addressable standing-wave lasers and the adiabatic elimination method, we generate a controllable nonlinear phonon mode with the well-designed efficient linear gain and nonlinear damping. By controlling these parameters to satisfy the phase transition conditions of Hopf bifurcation and limit cycle phase, it exhibits stable dissipative dynamics over timescales significantly longer than the oscillation period, indicating the emergence of continuous time-translation symmetry breaking in the phonon mode, i.e., a phonon time crystal. We further numerically simulate this phonon time crystal by using accessible experimental parameters and also demonstrate its robustness to the initial thermal state and thermalization of phonon mode, spin dephasing, and the control errors of Rabi frequencies. These results provide a practical scheme for observing a time crystal in a nonlinear phonon mode and will advance the research of time crystals.

The realization of scalable quantum battery architectures requires concern not only with how much energy can be stored, but also with how energy is transported, distributed, and converted into extractable work across connected battery nodes. While previous studies mainly focused on collective charging in multi-cell quantum batteries, the topology-dependent transport law and the corresponding work-oriented performance of quantum battery networks remain largely unexplored. In this work, we investigate quantum battery networks with engineered reciprocal and nonreciprocal couplings and compare different connection topologies, including cascaded and parallel architectures, within a unified transport framework. In the nonreciprocal regime, the optimal coupling follows distinct scaling laws for the two connection topologies, namely J_ op^c∝ N for cascaded transport and J_ op^p∝ N^-1/2 for parallel charging in the large-N limit. In reciprocal cascaded networks, a parity-dependent spectral response produces an odd-even transport effect that is absent in the nonreciprocal and parallel configurations. We further analyze the role of thermal and squeezed reservoirs and show that thermal noise mainly increases passive energy, whereas squeezing enhances ergotropy and thus the useful fraction of stored energy. These results shift the emphasis from charging enhancement to transport engineering and provide architecture-level design principles for quantum battery networks.

Generally, the precision of microwave measurements is limited by the natural linewidth of the employed spectroscopic features. To overcome this constraint, we exploit collective radiative effects in many-body atomic ensembles as a means of linewidth engineering. We introduce a measurement strategy in which superradiance gives rise to an ultranarrow transmission feature that can be directly accessed via spectroscopic readout, with a linewidth scaling as f /P proportional to 1/N. Additionally, we establish that an incoherent pumping scheme can prepare a stable subradiant state. This state offers an alternative pathway for enhancing sensitivity, which originates from its intrinsically narrow linewidth. Our proposal can be readily implemented on various platforms, such as Rydberg atoms, quantum dots, and waveguide materials, offering an approach to achieving quantum-enhanced measurement precision.

The recently observed two-photon Landau-Zener-St & uuml;ckelberg-Majorana (LZSM) effect in superconducting circuits [Phys. Rev. Lett. 134 060602 (2025)] has provided a robust pathway for high-fidelity population transfer in qudit systems, but its adiabatic nature necessitates long operation times, which are vulnerable to decoherence. In this paper, we present a practical acceleration scheme based on a superadiabatic (SUAD) framework that overcomes these fundamental limitations. Our approach is tailored to a multiphoton LZSM process. By constructing modified pulse envelopes for the existing drive field without introducing auxiliary counterdiabatic controls, we achieve accelerated high-fidelity state transfer from the ground state to the target excited state. For the two-photon case, our protocol reduces the operation time by more than four times compared with the adiabatic reference, while maintaining a fidelity of 0.998. We further generalize this to the three-photon regime, demonstrating a speedup factor exceeding three. Our SUAD LZSM scheme exhibits superior resilience to decoherence, offering a ready-to-implement solution for the fast and reliable control of multilevel quantum hardware.

Quantum sensing near exceptional points (EPs) in non-Hermitian systems has shown promising sensitivity enhancements. However, practical applications are often hindered by structural complexity and strict parameter constraints. In this work, we introduce a simplified anti-parity-time (anti-PT) symmetric platform consisting of two independently cavities, which are indirectly coupled to each other by a shared dissipative environment. We demonstrate a significantly enhanced sensing response at the EPs compared to non-EP configurations. This improvement is attributed to the dominant second-order term in the Laurent series expansion of the eigenvalue response to external perturbations-a characteristic feature of higher-order singularities at EPs. This mechanism not only reinforces the foundation for sensitivity enhancement but also offers a structurally compact and robust strategy for quantum sensing. Our results underscore the potential of anti-PT symmetric systems in enabling high-precision sensing technologies and bridging non-Hermitian physics with scalable photonic device platforms.

We propose a cascaded Rydberg antiblockade (RAB) regime via a Floquet modulation in four fully connected interacting atoms, which establishes a new synthetic dimension, Dicke-state lattice (DSL), in the space of collective spin excitations. By applying a global periodic driving, we synthesize an effective Hamiltonian that enables perfect state transfer across the five-site DSL with multiple programmable pathways from stepwise nearest-neighbor jumps to a single-step transition. This DSL platform further allows us to simulate a dynamic Su-Schrieffer-Heeger model, where soft quantum control is employed to achieve topologically inspired full RAB ∣0000〉 → ∣1111〉 with enhanced robustness against disorder. Moreover, by incorporating the shortcut to adiabaticity technique, we generate high-fidelity entangled twin-Fock and Greenberger-Horne-Zeilinger states on the four atoms within sub-microsecond timescales, outperforming the speed limits of conventional adiabatic protocols. Our work demonstrates a flexible and programmable synthetic dimension for quantum simulation and multipartite entanglement engineering in Rydberg atom arrays, paving the way for the future development of quantum information processing.

In quantum networks, robust and efficient frequency conversions of photons between microwave (MW) and optical regimes serve as a critical interface bridging superconducting quantum processors and optical communication channels. Recently, a topologically protected paradigm of state transfers, based on the topological nature of quantized light in Fock-state lattices (FSLs), has been demonstrated by a superconducting quantum circuit. However, its extension to quantum networks remains unexplored. Here we develop a topological single-photon MW–optics interface based on FSLs with a single nitrogen-vacancy (NV) center spin embedded in a photonic crystal cavity (PCC). The NV spin mediates the effective strong coupling between the optical PCC mode and a superconducting MW resonator via the adiabatic elimination of an intermediate acoustic mode. This scheme establishes a hybrid MW-NV-optics two-mode Jaynes-Cummings model, yielding a topological FSL. Under the significant constraint of optical mode decay, numerical simulations reveal that the MW-to-optics conversion efficiency can exceed 26% for an input five-photon MW Fock state. This work establishes a topological paradigm for hybrid quantum transduction, offering an efficient solid-state framework for constructing large-scale quantum networks.

Topological state transfer in Fock-state lattices has been demonstrated with high speed using sinusoidal profiles of coupling, yet the underlying reason has remained unclear. A global adiabatic criterion (GAC) is developed to bound the infidelity by the mean and variance of the nonadiabatic factor. The GAC reveals that the key to fast transfer is not a constant energy gap but the vanishing nonadiabaticity variance. For power-law coupling profiles, the variance vanishes only for the sinusoidal shape, which is thus globally optimal. Incorporating experimental decoherence parameters, it is predicted that the optimal transfer duration for a five-photon state is 161 ns, far shorter than 600 ns used in the experiment, reducing time by over 73

Microwave-to-optical conversion (MTOC) of single photons plays a pivotal role in bridging quantum devices across different frequency domains, but faces challenges in maintaining efficiency and robustness against fluctuations and dissipation in hybrid quantum systems. Here, we propose a topologically protected MTOC scheme mediated by a Rydberg superatom to address these limitations. By constructing cross-linked Fock-state lattices (FSLs) through a dual-mode Jaynes-Cummings (JC) architecture, we map the effective hybrid system onto an extended Su-Schrieffer-Heeger (SSH) model with tunable hopping rates. Photon-number–dependent property of hopping rates triggers a topological phase transition in the extended SSH chain, converting the defect mode into a topological channel that directionally pumps photons between microwave and optical cavities. This mechanism leverages Rydberg blockade-enhanced photon-superatom couplings to establish a robust energy transfer channel, achieving high-efficiency photon conversion under realistic decoherence. Our theoretical framework demonstrates how topological protection synergizes with Rydberg-mediated light-matter interactions to realize a robust quantum transducer, providing a scalable platform for noise-resilient quantum networks and frequency-multiplexed quantum interfaces.

Adiabatic topological pumping offers a robust mechanism for light transport in integrated photonics, enabling the development of efficient on-chip photonic devices. However, its practical implementations face significant challenges in maintaining both high transport efficiency and scalability due to slow adiabatic modulation requirements, and existing acceleration strategies fall short in achieving substantial device miniaturization. Here, we develop a gap-mode strategy for constructing shortcut to topological pumping, and experimentally demonstrate a superadiabatic paradigm through iterative adiabatic transformations in an on-chip photonic platform. Our approach achieves a 20-fold footprint reduction compared to conventional adiabatic pumping and a 50% size reduction relative to optimized Landau-Zener (as well as recently reported quantum metric and adiabatic infimum) implementations. The device operates over a remarkable bandwidth of 650-920 nm while facilitating scalable waveguide integration. This methodology establishes a framework for realizing high-efficiency topological photonic transport with tailored coupling configurations, paving the way for ultra-compact photonic integrated circuits.

Precision measurements play a pivotal role in testing theoretical models and exploring new physics. Linear Ramsey interferometer is widely employed for measuring physical quantities, enhancing quantum metrology even approaching the Heisenberg limit. However, the linear interferometer is notably susceptible to detection noise, which limits their practical applications. In this paper, we propose an extended SU(1, 1) echo method to realize a generalized nonlinear interferometer, which is resilient to the detection noise. We demonstrate the utility of this approach by applying it to two distinct models: the Lipkin-Meshkov-Glick model and spin-mixing dynamics. Numerical simulations confirm the effectiveness of our proposed method. Additionally, we identify a trade-off in selecting the echoing conditions, which can be utilized to further enhance estimation precision. Our proposal may be easily implemented in many platforms, such as Bose-Einstein condensate, Rydberg atoms, and polar molecules, to enhance the metrology of time and field strength.