Quantum teleportation is a fundamental protocol in quantum information science, whose performance is conventionally evaluated under the assumption of ideal Bell-state measurements. In realistic implementations, however, joint measurements are often imperfect and can deviate from maximally entangled bases due to coherent errors in entangling operations. In this work, we analytically show how the entanglement of joint measurements determines teleportation performance, and we propose a strategy to overcome the limitations imposed by partially entangled joint measurements to recover the unit teleportation fidelity with a nonzero success probability. This is achieved by optimizing a reversing operation on the teleported state to compensate for the known coherent deformation of the Bell-state measurement. We then derive an exact equation revealing a quantitative relation between measurement entanglement, channel entanglement, and the success probability to realize the unit-fidelity two-qubit teleportation. We illustrate our results using elegant joint measurements and realistic coherent error models arising from imperfect entangling operations in quantum systems. Our work provides fundamental insight into the role of measurement entanglement in quantum teleportation and offers a practical framework for achieving faithful teleportation without requiring substantial modifications to existing hardware.

Accurate characterization of open many-body quantum systems is constrained by information masking due to exponential growth in Hilbert space and environmental noise. Existing deep learning methods often converge to trivial solutions due to the lack of inductive bias for nonlocal entanglement. To address this, we propose an active learning, entanglement-aware multitask network (AEMTN), a framework designed to efficiently reconstruct disordered Hamiltonians from open dynamics. This architecture overcomes learnability barriers by synergistically integrating three core mechanisms: leveraging entanglement-aware routing to assign task-specific subspace mixtures, applying entanglement-guided inductive biases to impose geometric constraints on the solution space, and leveraging uncertainty modulation of physical correlations to balance gradient flow. Consequently, the framework explicitly translates physical constraints into gradient guidance for inverse parameter identification. Extensive numerical simulations on open quantum spin chains demonstrate the model’s exceptional data efficiency, achieving a dynamical prediction error of $3.0\times {10}^{-4}$ and a correlation coefficient of 99.4%. Crucially, AEMTN demonstrates robust performance in complex phases such as many-body localization and strongly entangled critical points, significantly outperforming baseline models that fail to capture deep nonlocal correlations.

Multipartite non-Gaussian entanglement constitutes a core resource for continuous-variable quantum networks. Although three-mode spontaneous parametric down-conversion (SPDC), a process capable of deterministically generating non-Gaussian entanglement, has recently been observed in superconducting circuits, the weak nonlinearity inherent to such systems limits the practical utility of the generated non-Gaussian entanglement. In this work we propose an entanglement-enhancing protocol based on a cascaded nonlinear model, where three-mode SPDC is sequentially followed by two-mode SPDC. We adopt quantum relative entropy and logarithmic negativity as independent quantifiers to characterize how the coupling strength of two-mode SPDC shapes the non-Gaussianity and entanglement of the system, respectively. Our results show that two-mode SPDC does not enhance the overall non-Gaussianity of the full system; nevertheless, it can boost global entanglement and amplify the non-Gaussianity of specific bipartite subsystems. Furthermore, we analyze the correlations among the three output modes and reveal the entanglement of these output modes in high-order moments by employing the positive partial transpose criterion based on the high-order covariance matrix. Our results provide a theoretical foundation for the manipulation of non-Gaussian entanglement via cascaded nonlinearity, which is expected to facilitate the early application of non-Gaussian entanglement in quantum information protocols.

Standard optomechanical sensors operating in the low-temperature regime often face fundamental precision limits imposed by vacuum fluctuations. Here we demonstrate that moving beyond conventional radiation-pressure interactions and exploiting quadratic coupling can surpass these limits, generating intrinsic squeezing and non-Gaussian features in the probe state. We study quantum thermometry and magnetometry in a coupled two-resonator system, focusing on estimating the temperature of a thermal bath and an external magnetic field. The resonators are assumed to be in thermal equilibrium with a common bath, while a weak magnetic field acts on one of the resonators. We perform measurements on a single resonator, which serves as the probe to estimate both parameters. We compute the quantum Fisher information of the probe for two different interaction models between the resonators. Our results show that the counterrotating terms in the quadratic interaction naturally induce squeezing at intermediate coupling and strong non-Gaussian correlations as the coupling increases further. These effects yield orders-of-magnitude enhancement in sensitivity in the low-temperature and weak-field regimes compared to standard radiation-pressure couplings. Finally, we investigate multiparameter estimation and find that, although the optimal measurements remain compatible, statistical correlations between parameters prevent the simultaneous estimation of temperature and magnetic field from attaining single-parameter precision.

Finite-key effects significantly limit the secret key rates achievable in practical quantum key distribution (QKD) implementations. Device imperfections such as detector efficiency mismatch and deviations of the prepared states from the ideal BB84 states change the relationship between the observed bit error rate (BER) and the phase-error rate that determines security. Here, we derive a composable finite-key security bound for BB84-type QKD that explicitly accounts for bounded detector efficiency mismatch $\alpha$ (the maximum relative deviation between the two detector efficiencies) and state-preparation deviation $\beta$ (the maximum fidelity defect of the prepared states relative to the ideal BB84 states). The resulting secret key length obeys a closed-form scaling law, $\ell (n,Q,\alpha ,\beta ,\varepsilon )=\lfloor n{r}_{\infty }-C_1\left(\varepsilon \right)\sqrt{n}-C_2\left(\varepsilon \right)\rfloor ,$ where the asymptotic key rate ${\mathrm{r}}_{\infty }$ and the finite-size constants $C_1\left(\varepsilon \right)$ and $C_2\left(\varepsilon \right)$ are all given explicitly. The derivation combines an imperfection-adjusted entropic uncertainty relation with a Chernoff-Serfling concentration inequality for sampling without replacement, together with an optimized allocation of the global security parameter. Monte Carlo simulation and semidefinite programming cross-checks show that the analytical bound lies within a few percent of the numerically optimal finite-key rate across a broad parameter range. Because all correction terms are available in closed form, the resulting bound provides a transparent and independently verifiable framework for rapid evaluation of practical BB84 QKD performance without hidden numerical optimization.

We calculate the hyperfine-structure properties of the low-lying states in ${}^{69}\mathrm{Ga}$ and ${}^{71}\mathrm{Ga}$ using the relativistic coupled-cluster method at the singles and doubles level. The properties include the first-order hyperfine constants and the second-order corrections arising from off-diagonal hyperfine interactions. Based on our theoretical results, we reanalyze the previous hyperfine-splitting measurements of the $4p_{3/2}$ state in ${}^{69,71}\mathrm{Ga}$ [Daly and Holloway, Phys. Rev. 96, 539 (1954)] and refine the nuclear magnetic octupole moments of these two isotopes. The refined values $\mathrm{\Omega }\left({}^{69}\mathrm{Ga}\right)=0.123\left(9\right){\mu }_N\times b$ and $\mathrm{\Omega }\left({}^{71}\mathrm{Ga}\right)=0.165\left(15\right){\mu }_N\times b$ are about 13% and 12% larger than the earlier results reported by Daly and Holloway. By providing an independent ab initio determination, the present results offer a reliable set of reference values for the magnetic octupole moments of ${}^{69,71}\mathrm{Ga}$, which will benefit both future high-precision measurements and nuclear-structure calculations.

The emerging generation of high brightness quantum light sources opens up new avenues for exploring ultrafast nonlinear optics beyond the classical field regime. Here we study high-harmonic generation (HHG) in ZnO driven by a bright squeezed vacuum (BSV) and show that the photon statistics of the driving field can strongly reshape the harmonic response. In particular, BSV suppresses the harmonic order modulation in the plateau region, washing out the discrete comb-like structure and giving rise to a markedly more continuum-like spectrum. With the carrier dynamics examined in momentum space and in the time-frequency domain, we find that coherent-state components with different field amplitudes generate different excitation and recombination dynamics. Their Husimi Q weighted superposition statistically reweights these microscopic pathways, leading to a more localized averaged emission pattern in time. We further characterize how the driving field statistics are transferred to harmonic yield fluctuations through an effective harmonic intensity fluctuation indicator. These results show that the photon statistics of BSV pulses can noticeably influence solid-state HHG and provide an additional handle for reshaping broadband harmonic spectra and strong field emission in solids under nonclassical laser conditions.

We investigate open-system charging protocols for Rabi and Dicke quantum batteries under direct incoherent pumping. The charging dynamics follows a Lindblad master equation, while effective non-Hermitian generators describe the conditioned no-jump mechanism. For a single Rabi battery, this pumping suppresses coherent energy backflow, broadens the high-energy charging window, and improves robustness against both timing errors and detuning. At the selected Rabi operating points, pumping also increases ergotropy and the extractable fraction of the stored energy. For finite Dicke batteries, direct incoherent pumping likewise stabilizes the charging dynamics. Across the finite-size scan, the strongest pump considered improves the peak stored energy and ergotropy per cell and near-peak timing robustness relative to the Hermitian reference. The maximum average charging power also increases, although this metric includes pump-assisted jump contributions. Equal-input comparisons show that the relative performance of common-cavity Dicke and independent Rabi batteries varies with the pump-input bound. Taken together, these results show that direct incoherent pumping provides a route to stabilized charging in Rabi and finite Dicke quantum batteries.

A well-known model in game theory, the volunteer's dilemma describes a group of $n$ players who decide whether to volunteer for a collective benefit at a personal cost or to abstain and risk forfeiting the benefit altogether. A quantum version of this dilemma, developed within the Eisert-Wilkens-Lewenstein framework, allows each player to manipulate one qubit of a shared entangled state, leading to symmetric Nash equilibria with higher expected payoffs than in the classical game. Existing analyses, however, assume maximal entanglement, which is experimentally demanding for hardware-constrained quantum systems. Within the same framework, we introduce a generalized quantum volunteer's dilemma with a tunable entanglement parameter $\gamma$ and study the extent to which equilibrium behavior depends on the level of entanglement. We derive explicit conditions relating $\gamma$, the number of players, and the players' strategies under which symmetric Nash equilibria exist, focusing on two canonical strategy profiles: one for $2\le n\le 9$ and one for even $n$. We find that maximal entanglement is not required to sustain symmetric equilibria. Instead, equilibrium behavior persists above a threshold value, which we compute analytically in both cases. We also demonstrate that the threshold value directly depends on system size.

The ab initio calculation of photoelectron angular distributions (PADs) for anions remains a theoretical challenge. In this work we report a joint experimental and theoretical investigation of PADs for nonpolar ${\mathrm{O}}_2{}^{-}$, weakly polar $\mathrm{N}{\mathrm{O}}^{-}$, and strongly polar $\mathrm{As}{\mathrm{O}}^{-}$ and $\mathrm{Sb}{\mathrm{O}}^{-}$. We also determine the electron affinities of AsO and SbO to be 10 318(7) and $12426\left(7\right)\mathrm{c}{\mathrm{m}}^{-1}$, respectively. To improve the description of the long-range region of the initial-state wave function, which contributes strongly to the photodetachment transition amplitude, we modified the standard Gaussian-type orbitals by augmenting them with a correct exponential Slater-tail basis set (approximately $e^{-\xi r}$). This simple yet effective approach substantially improves the agreement between experiment and calculation for ${\mathrm{O}}_2{}^{-}$ and for most vibrational channels of $\mathrm{N}{\mathrm{O}}^{-}$. However, notable discrepancies persist for $\mathrm{N}{\mathrm{O}}^{-}$ for transitions to the $v=0$ vibrational level of neutral NO even after this correction. Given that our methodology successfully reproduces PADs for strongly polar anions, e.g., $\mathrm{As}{\mathrm{O}}^{-}$ and $\mathrm{Sb}{\mathrm{O}}^{-}$, these residual discrepancies are unlikely to stem from exit-channel scattering induced by long-range dipole fields. Instead, we tentatively attribute the remaining discrepancy for $\mathrm{N}{\mathrm{O}}^{-}$ to the breakdown of the Born-Oppenheimer approximation or the frozen-orbital approximation, arising from the extremely weak binding of the excess electron.

We theoretically investigate an annularly confined Bose-Einstein Condensate (BEC) coupled to a four-mirror ring cavity supporting traveling-wave optical modes. Under symmetric driving by counterpropagating Laguerre-Gaussian beams carrying equal and opposite orbital angular momenta, the system realizes supersolid phases coexisting with persistent superfluid circulation. Specifically, we obtain a supersolid state if we start with a BEC of winding number $L_p$ as well as supersolid packets with coherent superpositions of two different BEC $L_p$ values. Under asymmetric pumping, realized with Laguerre-Gaussian beams of different orbital angular momenta, chiral symmetry is broken in the system, resulting in asymmetric cavity field amplitudes, directional density modulations, and tunable rotational dynamics of the resulting supersolid lattice. This leads to rotating supersolid density structures for a single winding-number state, and rotating wave packets for an initial superposition of rotational eigenstates. Finally, we probe the presence of Goldstone and Higgs modes, which can be observed using minimally destructive measurements of the cavity output spectrum. Our mean-field theory reveals interference-driven rotation without physical stirring, and distinguishes our work from prior static cavity supersolids. Our results establish the ring cavity annular BEC as a versatile platform for generating chiral quantum matter, implementing rotation-sensing devices, and generating atomtronic circuits with supersolids.

We investigate single-photon band structure and dynamics of atomic lattices. The calculation of these quantities requires the accurate evaluation of slowly convergent lattice sums generated by long-range photon-mediated interactions. We develop a framework that treats infinite lattices directly without introducing an auxiliary short-distance cutoff, thereby connecting their collective spectra to real-space dynamics. In one and two dimensions, complex bands contain superradiant, subradiant, and dark modes, and radiative loss competes with excitation transport. In contrast, in three dimensions, the collective bands are real away from Bragg-resonant conditions, and coherent transport dominates radiative decay. These results reveal a qualitative change from radiative dynamics in lower-dimensional arrays to predominantly coherent propagation in three dimensions.

In this study, a method for quantum state readout and feature extraction is developed using quantum-overlap-based fitting of function expansions. The approach involves the quantum calculation of quantum overlaps between a target quantum state and a linear combination of nonorthogonal basis functions, such as Lorentzian functions, via measurements, and classical optimization of the parameters in the function expansion. This method is particularly effective in scenarios where the quantum state is approximately represented as a combination of predefined basis functions. The proposed method involves a quantum state readout for both the complex amplitudes and their squared magnitudes (probabilities) in the quantum state. Numerical simulations were performed to reconstruct the grid-based wave function and x-ray absorption spectra from a quantum state, and the results show that our proposed method requires fewer measurements compared with conventional quantum state measurement techniques.

We formulate a theory of laser-assisted radiative recombination of electron with diatomic homonuclear ion in a linearly polarized laser field using the $S$-matrix formalism. We investigate how the multicenter molecular structure modifies the differential power spectra and polarization properties of the emitted x-rays. The emitted spectra exhibit characteristic two-center interference minima whose positions depend on the molecular orientation, internuclear distance, symmetry of the molecular orbital, and the incident electron momentum. We show that the visibility of the interference minima is strongly influenced by the molecular orientation and by the component of the incident electron momentum perpendicular to the laser-field polarization vector. The minima remain comparatively robust against imperfect molecular alignment. In addition, the emitted x-rays remain linearly polarized, while their polarization direction depends on the emitted-photon energy and on the geometry of the recombination process. The obtained results demonstrate that laser-assisted radiative recombination provides direct access to structural and symmetry properties of molecular targets.

We present a quasi-phase-matched (QPM) high-order harmonic generation (HHG) scheme based on a segmented gas target array for the generation of keV harmonics. By optimizing the gas density and intersegment spacing, the total phase mismatch arising from plasma dispersion, geometrical phase shift, and dipole phase variation is locally balanced within each gas segment. Compared with a single-segment configuration, this approach yields an eightfold enhancement in harmonic output. Furthermore, the time-dependent phase-matching condition produces subcycle temporal gating of the harmonic emission. For a 15-fs near-infrared driving pulse, a gating window of approximately 0.9 fs is obtained, with the emission dominated by a single HHG burst. The corresponding QPM bandwidth supports an attosecond-scale transform limit, estimated to be approximately 151 as under ideal spectral-phase compensation.

We investigate the finite-temperature phase diagram of polar molecules confined in a quasi-two-dimensional geometry by a harmonic potential along the polarization axis. We employ quantum Monte Carlo simulations to explore the strongly correlated regime accessible with current experimental setups. By tuning temperature and confinement strength, we identify a rich set of phases, including normal fluid, superfluid, supersolid, cluster crystal, and bilayer crystal states. Our results reveal the emergence of crystallization upon increasing temperature, highlighting the nontrivial role of thermal fluctuations in dipolar systems. In particular, we show that a bilayer crystal with one molecule per lattice site can be stabilized by varying the confinement strength at fixed interaction. Moreover, we show evidence of layering of superfluid states with phase coherence between the two layers. These findings provide insight into the interplay between interactions, confinement, and temperature in low-dimensional dipolar systems, and suggest new directions for engineering quantum phases with ultracold polar molecules.

We theoretically investigate strong-coupling properties of an attractively interacting Fermi atomic gas, where the Cooper-pair formation occurs between atoms belonging to different dimensional bands. Including pairing fluctuations within the framework of the self-consistent $T$-matrix approximation, we examine how the Bardeen-Cooper-Schrieffer (BCS)-type superfluid phase transition temperature $T_{\mathrm{c}}$ varies as one moves from the three-dimensional-–three-dimensional (3D-3D) to the two-dimensional (2D)–3D system, in the wide parameter region with respect to the strength of the pairing interaction. In the 2D-3D limit, we find that, while the mean-field BCS theory predicts $T_{\mathrm{c}}>0$ in the strong-coupling regime, $T_{\mathrm{c}}$ is remarkably suppressed down to zero by pairing fluctuations that are strongly enhanced by the mixed-dimensionality of the system. As the origin of this, we clarify that the lower-dimensional (2D) component dominates the superfluid instability, so that the vanishing $T_{\mathrm{c}}$ is the same phenomenon as that in the 2D-2D case. We also point out that this can already be seen in the mean-field level, when one examines the propagation of the Goldstone mode. However, we find that the pseudogap phenomenon, which is known as a precursor of Cooper-pair formation, exhibits a 3D character of the 2D-3D system. Thus, the effective dimensionality of the 2D-3D system depends on what we observe, reflecting the dimensional character of the elementary excitations that govern it.