Temporal cavity solitons (CSs), recognized for their exceptional stability and controllability, hold great promise as information carriers in all-optical storage and processing systems. Pulsed driving serves as an effective strategy to boost the pump-to-soliton conversion efficiency and optimize CS performance. Nevertheless, this approach introduces amplitude inhomogeneities into the cavity, which induce drift of the CSs. Previous studies have revealed that such drift exhibits a nontrivial dependence on both detuning and driving amplitude. Despite these insights, the temporal control and manipulation of CSs under varying driving pulse widths remain largely unexplored. In this work, we investigate the dynamics of temporal CSs in a fiber Kerr resonator subject to pulsed driving with a tunable pulse width. By utilizing the pump pulse width as a degree of freedom, we achieve a significant decoupling between soliton timing and its peak power—a persistent challenge in traditional intensity-based modulation—thereby enabling precise temporal control. Using a dissipative Lagrangian variational framework, we elucidate the mechanism that governs the equilibrium position in the pulse-width modulation regime and theoretically derive an analytical relationship between the driving pulse width and the stabilized soliton position. Numerical simulations using the Ikeda map confirm that, under constant-amplitude driving, the trapping position scales linearly with the pulse width, in excellent agreement with our theoretical predictions. Moreover, we systematically map the existence regime and equilibrium positions of CSs across varying pulse widths and driving amplitudes, and demonstrate temporal tweezing of two independent CSs. This methodology establishes a pathway for multidimensional control and manipulation of temporal CSs in Kerr resonators.

A time-dependent theory for the interactions between spatially separated lossy cavities in a homogeneous background medium using quantized quasinormal modes (QNMs) is presented. The cavities interact via a bath of traveling photons, described by nonbosonic operators that are orthogonal to the open-cavity QNMs. The retarded (i.e., time-delayed) intercavity dynamics are fully described by system-bath correlation functions, in which the emission from one cavity appears as the input field for another. Coupling between quantum emitters (described as two-level systems), placed inside a cavity or embedded in an external medium, and the electromagnetic field (cavity modes and bath photons) is included in the theory, which gives rise to both bath-mediated and QNM-mediated interactions between the emitters.

In this work, we construct a coupled cavity system consisting of three optical modes to obtain an effective Hamiltonian mediated by coherent and dissipative couplings via adiabatic elimination of a large dissipation mode. We investigate the interference of coherent and dissipative photon-photon couplings in this system, which leads to the nonreciprocity of electromagnetic wave propagation under the zero-damping condition (ZDC). We study the influences of the parameters on the nonreciprocal transmission to capture the generic physics of the interference between coherent and dissipative couplings. Moreover, we extend the study of nonreciprocal transmission with the Markovian approximation to the non-Markovian environments consisting of a collection of oscillators (bosonic photonic modes) and develop the adiabatic elimination method with non-Markovian effects. We illustrate that nonreciprocal transmission at ZDCs exhibits a crossover from the non-Markovian to the Markovian regimes by controlling the environmental spectral widths. This indicates a promising way to enhance or steer quantum nonreciprocal devices in optical cavities and provides potential applications for optical communications with non-Markovian effects.

Universal photon blockade, which enables strong antibunching across a broad nonlinear parameter range, is demonstrated in a two-mode Jaynes-Cummings model incorporating third-order Kerr nonlinearity. Realization of this universal photon blockade is attributed to the cooperative effects of field-atom coupling and Kerr nonlinearity. More importantly, this antibunching is found to be robust against the atomic spontaneous emission, driving-field strength, and defect-induced cavity-mode coupling. The strong antibunching effect in this resonance-driven scheme is essentially different from those without Kerr nonlinearity. Moreover, this work expands the platform for achieving universal photon blockade and reveals the cooperative advantages of nonlinearities in enhancing the purity and brightness of single-photon sources, representing a strategy for high-performance single-photon sources in integrated quantum optical devices.

In this work we investigate the effects of heat-bath-induced colored noise on nonreciprocal Landau-Zener tunneling. We perform numerical calculations of the instantaneous energy levels and find that noise induces stochastic fluctuations in these levels. Beyond such fluctuations, sufficiently large nonreciprocity parameters enable noise to further trigger the emergence of multiple exceptional points. The corresponding tunneling probability is significantly modified by colored noise. On the one hand, colored noise generally enhances the tunneling probability at finite sweep rates. On the other hand, it can break the reciprocity of Landau-Zener tunneling in the slow-sweep limit. In particular, for large nonreciprocity parameters, the slow-sweep-limit tunneling probability is insensitive to noise and governed by exceptional points. We plot phase diagrams of tunneling probability as a function of the sweep rate and nonreciprocity parameter, for different amplitudes and correlation times of colored noise. Analytically, we derive the exact expression for the tunneling probability in the absence of noise and an approximate solution in the white-noise limit, employing Weber functions and the Wiener-Hermite expansion. Some implications of our theory are discussed.

We propose a witness of temporal quantum entanglement using the imaginary component of the complex heat capacity—a measurable thermodynamic quantity in temperature-modulated calorimetry. By establishing a direct correspondence between complex heat capacity and the pseudodensity matrix formalism, our approach enables the characterization of both spatial and temporal quantum correlations without demanding additional state-level manipulation beyond initial tomography. We analytically demonstrate this connection for an open quantum system modeled by a qubit coupled to a thermal bath and show how both pseudodensity matrix negativity and violations of a temporal Clauser-Horne-Shimony-Holt inequality emerge as indicators of nonclassical temporal correlations. We further identify bounds on the imaginary heat capacity that guarantee temporal entanglement, providing an experimentally accessible criterion at the macroscopic scale. This framework offers a feasible route for probing temporal quantum effects in condensed-matter systems and opens a viable path toward experimental realization.

Decoders of quantum error correction (QEC) experiments make decisions based on detected errors and the expected rates of error events, which together comprise a detector error model. Here we show that the syndrome history of QEC experiments is sufficient to correct coherent errors, removing the need for prior device benchmarking experiments. Importantly, our method shows that detector error models determined from syndromes work equally well for both stochastic and coherent noise regimes. We model fully-coherent or fully-stochastic noise for repetition and surface codes and for various phenomenological and circuit-level noise scenarios, by employing Majorana and Monte Carlo simulators. We additionally study several mixed stochastic-coherent noise models, and arbitrary single-qubit completely positive trace preserving maps. We capture the interference of coherent errors, which appears as enhanced or suppressed physical error rates compared to the stochastic case, and also observe hyperedges that do not appear in the corresponding Pauli-twirled models. Finally, we decode the detector error models undergoing coherent noise and find different thresholds compared to detector error models built based on the stochastic noise assumption.

Recently, Yamaguchi and Kempf proved that encrypted qubits can be cloned. In this work we generalize the encrypted cloning protocol and prove that it also applies to higher-order quantum systems. Given that a straightforward generalization of the protocol using the exponential of the shift and phase operators fails to satisfy the unitary requirement for a quantum gate, we propose a different approach. We introduce an alternative operator to be used in the encryption process and show that it is unitary. We adapt the decryption operator from the reference paper to fit in the framework of multilevel quantum systems. We analyze the circuit implementation of the proposed operators and show that the encryption could be implemented with a gate complexity that is independent of qudit dimension.

A hybrid quantum system comprising semiconductor spin qubits and superconducting resonators offers a practical route toward scalable quantum information processing. Achieving a high-fidelity entangling gate between spatially separated spin qubits is, however, both crucial and challenging. Here, we investigate an architecture where two multilevel singlet-triplet spin qubits are coupled to a common resonator. By combining virtual-photon-mediated interactions with parametric modulation, we design and theoretically demonstrate an exchange-type entangling gate between the spin qubits. Through numerical simulations, we analyze the detrimental effects of leakage errors on gate performance and propose an optimized pulse-shaping scheme that effectively suppresses leakage errors, achieving gate fidelities up to 96.9% under realistic experimental conditions. Our protocol can be directly applied to remote quantum state transfer and entangled-state preparation. These results highlight the generality of the proposed gate mechanism, establishing it as a powerful tool for quantum information processing in spin-resonator hybrid systems.

Various entanglement percolation protocols provide distinct statistical-physics frameworks for analyzing the capability of quantum networks (QNs) to achieve long-distance entanglement distribution. The percolation efficiencies and critical exponents exhibited by different existing protocols vary considerably, necessitating a classification of these numerous protocols. This raises an urgent question: From the perspectives of both statistical physics and practical guidance for QNs, do these protocols belong to the same or different universality classes? To date, only the classical entanglement percolation protocol [Acín et al., Nat. Phys. 3, 256 (2007)] and the pure-state concurrence percolation protocol [Meng et al., Phys. Rev. Lett. 126, 170501 (2021)] have been confirmed to belong to distinct universality classes, as demonstrated in [Hu et al., Sci. Adv. 11, eadt2404 (2025)]. In this paper we prove that the pure-state and mixed-state concurrence percolation protocols [Wang et al., Commun. Phys. 9, 28 (2026)] fall into different universality classes. We compute critical exponents for several QN topologies, including $(U,V)$ flowers and two-dimensional lattices. Our results show that the two concurrence percolation protocols exhibit different sets of critical exponents. This demonstrates that the two protocols belong to different universality classes, revealing that the macroscopic connectivity of QNs is governed not only by network topologies but also, fundamentally, by the type of underlying resource states. From the perspective of designing QNs, our results exhibit distinct entanglement transmission capabilities for different protocols: The larger the critical exponent, the stronger the entanglement transmission capability, which directly impacts the design of QNs for achieving long-range entanglement distribution.

Recent studies have shown that Bargmann invariants provide effective detectors of set imaginarity. In this paper, we investigate set imaginarity as a quantum resource in qubit systems. By exploiting the structure of Bargmann invariants, we show that the free operations for qubit set imaginarity consist precisely of common unital operations and common planarized operations. Based on this characterization, we introduce an axiomatic framework for set-imaginarity measures (SIMs). In particular, we propose two refined notions, namely unified SIMs and complete SIMs, which allow a more fine-grained quantification of set imaginarity. To make these notions concrete, we construct two qubit SIMs from the Bargmann invariants of three-state subsets. We prove that one of them is a unified SIM, while the other satisfies the stronger requirements of a complete SIM. Furthermore, we revisit the robustness of set imaginarity previously introduced in the literature. We show that, although this robustness is a valid SIM for qubit systems, it is neither a unified SIM nor a complete SIM. To overcome this limitation, we propose an improved robustness-type measure and rigorously prove that it defines a complete qubit SIM.

The space $\mathrm{Inv}(j_1,j_2,j_3,j_4)$ of SU(2)-invariant four-valent tensors, also known as intertwiners, can be understood as the quantum states of a tetrahedron in Euclidean space with fixed areas. In loop quantum gravity, they are states of what could be called the smallest atom of space with nonzero volume. At the same time they correspond to four-party tensor product states invariant under global rotations. We consider the multipartite entanglement of states in $\mathrm{Inv}(j_1,j_2,j_3,j_4)$ using the recently proposed entropic fill. Numerically evaluating the entropic fill in the case of equal spins between $1/2$ and 11, we find that the distributions of entanglement are very different for intertwiners as compared to generic tensors and for coherent intertwiners as compared to generic ones. The peak in the distribution seems to be at the highest entanglement for generic intertwiners and at the lowest for generic tensors, but in terms of average entanglement, the roles are switched: Average entanglement is highest in arbitrary tensors and lower in intertwiners, at least in the regime of large $j$. We also consider the dependence of entanglement on the geometric data of coherent intertwiners. Coherent intertwiners labeled by a symmetric tetrahedron have maximal entanglement, while minimal entanglement implies a coherent state labeled by a degenerate tetrahedron. Away from these cases, entanglement depends on the geometry in an intricate way.

Dark and subradiant states have emerged as promising resources for stabilizing open quantum batteries against dissipation, but existing studies are largely limited to qubit ensembles and symmetry-based constructions. Here, we introduce a systematic, thermodynamically consistent framework for identifying long-lived energy storage states in interacting multilevel quantum batteries, combining the Davies master equation with a Morris-Shore-type decomposition of dissipative coupling blocks. Focusing on a minimal model of two interacting qutrits coupled to a common bath, we analytically construct dark, bright, and funnel states; excited states that decay exclusively into protected manifolds. We also derive quantitative robustness conditions governed by the ratio of interaction strength to anharmonicity. We show that multilevel ladder structure and exchange interactions enable energetic storage states beyond the qubit case. Numerical simulations confirm that these states exhibit long-lived energy storage under typical Markovian dissipation. Finally, we show that high-energy funnel states provide a natural design target for multilevel quantum batteries, as their decay pathways are highly structured and directed toward protected manifolds. The knowledge and understanding of these pathways offer a principled basis for developing future protection and control strategies in superconducting multilevel platforms.

Multiphoton subtraction from a traveling squeezed vacuum is a standard route to non-Gaussian optical-state engineering. High state-generation rates call for ultrashort optical pulses driven by high-repetition-rate lasers, but combining higher-order subtraction with ultrashort pulsed light and full state reconstruction remains challenging. Here we demonstrate up to four-photon subtraction from 10-ps squeezed-vacuum wave packets generated by a broadband waveguide optical parametric amplifier. Using a Ti-Au transition-edge sensor for photon-number-resolved heralding and homodyne tomography on the signal mode, we reconstruct the generated states up to the four-photon-subtracted case. The reconstructed states exhibit clear parity-dependent structure and visible Wigner-function negativity without loss correction. These results extend the experimentally accessible regime of multiphoton subtraction in broadband traveling optical modes and establish a platform for non-Gaussian optical resource-state engineering in continuous-variable quantum optics.

We propose an adiabatic Ramsey interferometry technique for detecting weak nonlinearities with trapped ions. The method relies on using the quantum Rabi model, which is sensitive to nonlinear symmetry-breaking perturbations, as a probe. We show that the couplings which arise either from anharmonic terms of the trapping potential or from higher-order terms in the Coulomb interaction expansion can be efficiently estimated by measuring the spin-state probabilities alone. We show that the spin signal is amplified by the mean-phonon excitations, which results in the estimation precision reaching the super-Heisenberg limit. Notably, achieving such high-precision estimation does not require specific entangled-state preparation and can be reached even for the initial thermal-motion state. Furthermore, we show that the super-Heisenberg scaling can be observed even in the presence of weak spin dephasing.

Charge-transfer processes in collisions of ground ($2s^{2}2p{}^{2}P$) and metastable ($2s2p^2{}^{4}P$) states of ${\text{C}}^{+}$ ions with ${\text{H}}_2$ are investigated using the quantum-mechanical molecular-orbital close-coupling method in the energy range of 10–1000 eV/u. Molecular potential energy curves and nonadiabatic couplings are calculated using the ab initio multireference single- and double-excitation configuration-interaction method. For the ground-state system, the Franck-Condon approximation is adopted due to the large electronic energy defect relative to the ${\text{H}}_2$ vibrational spacing, and total cross sections rise significantly above 100 eV/u, where capture into the $\mathrm{C}2p^2{}^{1}S, 2p^2{}^{3}P$, and $2p^2{}^{1}D$ states dominates, with interference among these channels. For the metastable system, vibrational effects need to be treated with the electronic-vibrational close-coupling method, since the electronic energy defect is comparable to the vibrational spacing. In contrast to the ground-state system, the vibrationally near-resonant exothermic mechanism enhances total cross sections by an order of magnitude, populating high ${\text{H}}_2{}^{+}$ vibrational levels ($v=5,6$) at energies below 100 eV/u, while above 100 eV/u the cross sections remain constant, with Stueckelberg oscillations arising from short-range potential-well interference. Total cross sections for both initial state-resolved ions agree well with the respective experimental data, and mixed-beam cross sections obtained using the known fraction are in good agreement with the available experimental data.

The detection of prebiotic molecules in astrophysical environments, particularly in star-forming regions, is essential for understanding the origins of life and the chemistry of the interstellar medium. Among such species, cyanomethanimine stands out as an intermediate in adenine formation and as a potential precursor of biologically relevant molecules. Its three structural isomers $Z\text{−}C, E\text{−}C$, and $N$, all of which have already been detected in the interstellar medium, exhibit electron-scattering properties that are crucial for modeling radiation-induced processes in astrophysical environments. This article presents a theoretical investigation of low-energy electron scattering by the three isomers of cyanomethanimine. Elastic integral cross sections were computed using the Schwinger multichannel method. The calculations were performed at the static-exchange and static-exchange-plus-polarization approximations, for impact energies up to 10 eV. Three ${\pi }^{*}$ shape resonances were visible in the static-exchange cross sections of each isomer; the low-lying resonance became a bound state when polarization was considered. Additional analyses included collision-Hamiltonian diagonalization to characterize eigenvalues near resonant and bound states and their associated orbitals. The results indicate that the $Z\text{−}C$ isomer is the most stable isomer, while the $E\text{−}C$ and $N$ isomers lie at higher energies, separated by significant isomerization barriers.

We introduce an exact solution for atom-molecule conversion in a heteronuclear triatomic system in terms of inverse engineering. Since the processes of molecular synthesis and decomposition occur simultaneously, the kinetics become more complicated, but our solution captures the detailed evolution of main and side reactions. Additionally, we further analyze the minimal time $T_{min}$ and energy consumption for the system from an initial state to a given target state, and also investigate the dynamics when two conversion pathways coexist, in which the dynamics will deviate from those of the original single-path scheme.