We investigate the nonequilibrium dynamics induced by a finite-time linear quench in the $XY$ chain. Initially, we examine the dynamical quantum phase transition (DQPT-LE), characterized by the nonanalytic behavior of the Loschmidt amplitude. We find distinct behaviors of DQPT-LEs during and following the ramp. Following the ramp, the ramp crossing the critical point $h_c$ is the sufficient condition for the occurrence of DQPT-LE, but it is not during the ramp. Through adiabatic-impulse-adiabatic (AIA) approximation analysis, we establish that adequate distancing from the critical point is crucial for DQPT-LE manifestation during the ramp, elucidating the absence of DQPT-LE as the ramp gets faster. Additionally, we explore another type of dynamical phase transition (DQPT-OP), describing the long-term relaxation behavior of the order parameter. Our finding indicates that the asymptotic behavior of the time-dependent part induced by the linear quench is equivalent to that following a sudden quench, i.e., the time-dependent part exhibits power-law decays of $\sim t^{-3/2}$ and $\sim t^{-1/2}$ for the ramp to the commensurate and incommensurate phases, respectively. Moreover, we also delve into the steady part, which showcases nonanalytic singularities at the critical point.

Identifying Bell states without destroying them is frequently dealt with in quantum technologies nowadays, such as in quantum communication and quantum computing. In practice, quantum entangled states are often distributed among distant parties, and it might be required to determine them separately at each location, without inline communication between parties. We present a scheme for discriminating an arbitrary Bell state distributed to two distant parties without destroying them. The scheme requires two entangled states that are preshared between the parties and we show that, without these ancillary resources, the probability of nondestructively discriminating the Bell state is bounded by 1/4, which is the same as random guessing. Furthermore, we demonstrate a proof-of-principle experiment through an IonQ quantum computer that our scheme can surpass classical bounds when applied to a practical quantum processor.

Mechanisms for suppressing thermalization in disorder-free many-body systems, such as Hilbert space fragmentation and quantum many-body scars, have recently attracted much interest in foundations of quantum statistical physics and potential quantum information processing applications. However, their sensitivity to realistic effects such as finite temperature remains largely unexplored. Here, we have utilized IBM's Kolkata quantum processor to demonstrate an unexpected robustness of quantum many-body scars at finite temperatures when the system is prepared in a thermal Gibbs ensemble. We identify such robustness in the PXP model, which describes quantum many-body scars in experimental systems of Rydberg atom arrays and ultracold atoms in tilted Bose-Hubbard optical lattices. By contrast, other theoretical models which host exact quantum many-body scars are found to lack such robustness and their scarring properties quickly decay with temperature. Our study sheds light on the important differences between scarred models in terms of their algebraic structures, which impacts their resilience to finite temperature.

The development of classical ergodic theory has had a significant impact on the areas of mathematics, physics, and, in general, applied sciences. The quantum ergodic theory of Hamiltonian dynamics has its motivations in understanding thermodynamics and statistical mechanics. The quantum channel, a completely positive trace-preserving map, represents the most general representation of quantum dynamics and is an essential aspect of quantum information theory and quantum computation. In this work, we study the ergodic theory of quantum channels by characterizing different levels of ergodic hierarchy from integrable to mixing. The quantum channels on single systems are constructed from the unitary operators acting on bipartite states and tracing out the environment. The interaction strength of these unitary operators measured in terms of operator entanglement provides sufficient conditions for the channel to be mixing. By using block-diagonal unitary operators, we construct a set of nonergodic channels. By using the canonical form of the two-qubit unitary operator, we analytically construct channels on a single qubit ranging from integrable to mixing. Moreover, we also study interacting many-body quantum systems that include the famous Sachdev-Ye-Kitaev model and show that they display mixing within the framework of the quantum channel.

Observations of the rotational spectrum of lead monofluoride, PbF, have been extended up to transitions in the $v$ = 7 level for ${}^{208}\mathrm{PbF}$ in the lowest $X_1{}^2\mathrm{\Pi }_{1/2}$ state of the radical and $v$ = 5 for the ${}^{207}\mathrm{Pb}$ and ${}^{206}\mathrm{Pb}$ isotopologs. The data also include a few measurements for ${}^{204}\mathrm{PbF}$ at $v$ = 0. These new measurements have been combined with existing near-IR measurements of the $X_2\text{−}{X}_1$ fine-structure transition and a simultaneous multi-isotope fit of the data to an effective isotope-independent rovibronic Hamiltonian has been carried out. The resulting parameters fully characterize the vibrational, rotational, and hyperfine structure of the combined $X_1/X_2$ state of the radical. A pair of opposite-parity levels with total angular momentum quantum number, $F=1/2$, in the lowest rotational level, $J=1/2$, of ${}^{207}\mathrm{PbF}$ are close in energy and their spacing decreases with vibrational excitation. The experimental results show the spacing decreases to less than 20 MHz at $v=7$ and 8. The experimental work is complemented by new ab initio calculations which support the results and allow predictions outside the experimental data range. The calculated radiative lifetimes of the relevant vibrationally excited states are of the order of 50 ms. This paper was motivated by interest in using ${}^{207}\mathrm{PbF}$ as a vehicle for future probes of the standard model of physics such as placing limits on the electrons electric dipole moment $\left(e\mathrm{EDM}\right)$, $e\mathrm{EDM}$ calibration, molecular charge-parity nonconservation, and Born-Oppenheimer breakdown effects for example.

We present spectroscopic data for four metastable state clear-out transitions between 399 nm and 412 nm for all even long-lived isotopes of ${\mathrm{Yb}}^{+}$ as well as their hyperfine structure in ${}^{171}\mathrm{Yb}^{+}$. The strong ${}^2{D}_{3/2}\to {}^1{[1/2]}_{1/2}$ transition at 412 nm represents an attractive alternative for the standard 935 nm repumper used in cooling and trapping experiments, while the transition to the ${}^3{[3/2]}_{3/2}$ state at 411 nm clears out the ${}^{2}F_{7/2}$ state, for which typically 638 nm or 760 nm is used. These two alternative transitions simplify the experimental setup by removing the need for infrared optics to cool and manipulate ${\mathrm{Yb}}^{+}$ and may be of particular interest when considering integrated photonics solutions. We also present data for the transitions ${}^{2}D_{3/2}\to {}^3{[1/2]}_{3/2}$ at 399 nm and ${}^{2}D_{3/2}\to {}^1{[5/2]}_{5/2}$ at 410 nm including decay branching ratios of the excited states.

This paper presents a study of the passage of dimuonium through the foil of ordinary matter. First, we provide an overview of how dimuonium is planned to be produced for such a type of experiment and how it is expected to interact with the ordinary atoms—predominantly electromagnetically via the screened Coulomb potential of the atomic nuclei. Then, we describe the transport equations that represent the evolution of dimuonium states during the passage and their solution methods. Finally, for three different foils (beryllium, aluminium, and lead), we present the results of this study. To estimate the impact of uncertainties in the potential of a target atom, we study 15 different approximations of the atomic potential and show that the corresponding atomic-potential-model-dependent error in the yields of the low-lying states of dimuonium is quite small within the framework of the applied Born approximation. The convergence of the results after truncation of the infinite system of transport equations to the finite number of quantum states of dimuonium is also studied, and good convergence for the yields of low-lying states is demonstrated.

Atomic interferometers measure phase differences along paths with exceptional precision. Tweezer interferometry represents a novel approach for this measurement by guiding particles along predefined trajectories. This study explores the feasibility of using condensed bosons in tweezer interferometry. Unlike the factor $\sqrt{N}$ enhancement expected with classical ensembles, using NOON state interferometry can yield an enhancement by a factor of $N$. We consider a protocol for a tweezer-based NOON state interferometer that includes adiabatic splitting and merging of condensed bosons followed by adiabatic branching for phase encoding. Our theoretical analysis focuses on the conditions necessary to achieve adiabaticity and avoid spontaneous symmetry breaking. Additionally, we demonstrate the feasibility of the proposed scheme and estimate the time required to perform these sweep processes.

We demonstrate the generation of nonclassical light by destructive interference of identical Kerr-squeezed states. Perfect pairwise cancellation of amplitudes that contribute to odd Fock states results in light with only even Fock states, independent of the strength of the nonlinearity. The observability of this effect is only limited by the quality of the interferometer. In the low nonlinearity limit, the even-only state resembles a squeezed vacuum state, yet the even-odd oscillations persist when the nonlinearity is strong. The effect is also robust against deviations from the optimum relative phase of the input Kerr-squeezed states.

The non-Hermitian skin effect (NHSE), an anomalous localization behavior of bulk states, is an inherently non-Hermitian phenomenon, which cannot find a counterpart in Hermitian systems. However, the fragility of the NHSE has been revealed recently, such as the boundary sensitivity, and it has stimulated many studies discussing the fate of that. Here we present a theorem which shows that the combined spatial reflection symmetry can be considered as a criterion in one-dimensional non-Hermitian systems to determine whether the NHSE can exist in the thermodynamic limit. Distinct from previous studies, our proposed criterion only relies on analyzing the symmetry of the system, omitting other requirements, such as the information of the energy spectrum. Furthermore, by taking the non-Hermitian Kitaev chain as an example, we verify our theorem through both a mathematical proof via the non-Bloch band theory and exact diagonalization numerical studies. Our results reveal a profound connection between the symmetry and the fate of the NHSE.

We propose and analyze an approach for fast syndrome measurements in an array of rubidium and cesium atomic qubits. The scheme works by implementing an interspecies controlled-not (cnot${}_k$) gate, entangling one cesium ancilla qubit with $k\ge 1$ rubidium qubits which are then used for state measurement. Utilizing Rydberg states with different interspecies and intraspecies interaction strengths, the proposal provides a syndrome measurement fidelity of $\mathcal{F}>0.9999$ in less than $5\mu \mathrm{s}$ of integration time.

The qubit scalability imposes a paramount challenge in the field of quantum computing. Photonic interconnects between distinct quantum computing modules provide a solution to deal with this issue. The fundamental part of this approach is entanglement distribution via traveling photons emitted by matter qubits. However, randomness of the spontaneous emission in the matter qubits limits both the entanglement fidelity and the generation rate. In this paper, by numerical and analytical methods, we investigate the relationship between the entanglement affected by the spontaneous emission and the waveform of the pump pulse used in the photon generation. We confirm and analyze a rate-fidelity trade-off in the entanglement swapping with Gaussian pump pulses and show that a simple extension to non-Gaussian pump pulses improves the trade-off in a certain parameter region. Furthermore we extend our analysis to entanglement distribution in the general multipartite setting and show that the analysis of the bipartite entanglement can be straightforwardly applied in this case as well.

We consider the problem of distinguishing between the elements of a bipartite maximally entangled orthonormal basis using local operations and classical communication (LOCC) and a partially entangled state acting as a resource. We derive an exact formula for the optimum success probability and find that it corresponds to the fully entangled fraction of the resource state. The derivation consists of two steps. First, we consider a relaxation of the problem by replacing LOCC with positive-partial-transpose (PPT) measurements and establish an upper bound on the success probability as the solution of a semidefinite program, and then show that this upper bound is achieved by a teleportation-based LOCC protocol. This further implies that separable and PPT measurements provide no advantage over LOCC for this task. We also present lower and upper bounds on the success probability for distinguishing the elements of an incomplete orthonormal maximally entangled basis in the same setup.

In this study, I compute the static dipole polarizability of main-group elements using the finite-field method combined with relativistic coupled-cluster and configuration-interaction simulations. The computational results closely align with the values recommended in the 2018 Table of static dipole polarizabilities of neutral elements [Mol. Phys. 117, 1200 (2019)]. Additionally, I investigate the influence of relativistic effects and electron correlation on atomic dipole polarizabilities. Specifically, three types of relativistic effects impacting dipole polarizabilities are studied: scalar-relativistic, spin-orbit coupling, and fully relativistic Dirac-Coulomb effects. The results indicate that scalar-relativistic effects are predominant for atoms in groups 1 and 2, with minimal influence from spin-orbit coupling effects. Conversely, for elements in groups 13–18, scalar-relativistic effects are less significant, while spin-orbit coupling significantly affects elements starting from the fourth row in groups 13 and 14 and from the fifth row in groups 15–18. In each category of relativistic effects, the impact of electron correlation is evaluated. The results show that electron correlation significantly influences dipole polarizability calculations, particularly for atoms from groups 1, 2, 13, and 14, but is less significant for atoms from groups 15–18. This study provides a comprehensive and consistent data set of dipole polarizabilities and contributes to a systematic understanding of the roles of relativistic and electron-correlation effects in atomic dipole polarizabilities, serving as a valuable reference for future research.

High-precision measurements of symmetry violations in molecules are a promising route to test the standard model of particle physics. In particular, the violation of parity $\left(P\right)$ and time-reversal $\left(T\right)$ symmetry is enhanced in the LaS, LaO, and LuO molecules due to the small energy differences between states of opposite parity (0.2 ${\mathrm{cm}}^{-1}$ or less) in the electronic ground state. We calculate the molecular enhancement for the relevant symmetry-violating interactions in these molecules, i.e., the $P,T$-violating electron electric dipole moment $W_{\mathrm{d}}$, scalar-pseudoscalar nucleon-electron interaction $W_{\mathrm{s}}$, and nuclear magnetic quadrupole moment $W_{\mathrm{M}}$, and for the nuclear-spin-dependent $P$-violating anapole moment $W_{\mathrm{A}}$. We use the relativistic four-component coupled-cluster method and perform a systematic study to estimate the associated uncertainties in our approach. We find that the individual contribution of each computational parameter to the total uncertainty in a system is approximately the same for all the calculated enhancement factors, summing up to a total uncertainty of $\sim 6$%. Furthermore, we use simple nuclear models to estimate the magnitude of the anapole moment and the magnetic quadrupole moment, from which we calculate the matrix elements probed in experiments and the sensitivity to beyond-the -standard-model physics in terms of higher-energy $P,T$-violating coupling constants, respectively.

We propose diatomic molecules built from gold and carbon-group atoms as promising candidates for optical cycling and precision measurements. We show that this class of molecules ($\mathrm{Au}X,X=\mathrm{C},\mathrm{Si},\mathrm{Ge},\mathrm{Sn},\mathrm{Pb}$) features laser-accessible electronic transitions with nearly diagonal Franck-Condon factors. The ${}^2\mathrm{\Pi }_{1/2}$ ground states can be easily polarized in the laboratory frame and have near-zero magnetic moments, valuable features for quantum science and precision measurement applications. The sensitivities of $\mathrm{Au}X$ molecules to the electron electric dipole moment (EDM) are found to be favorable, with effective electric fields of 10–30 GV/cm. Together these features imply that $\mathrm{Au}X$ molecules may enable significantly improved searches for time-reversal symmetry violation.

This paper presents a routine to align an optical tweezer on a single trapped ion and use the ion as a probe to characterize the tweezer. We find a smallest tweezer waist of $2.3\left(2\right)\mu \mathrm{m}$, which is in agreement with the theoretical minimal attainable waist of $2.5\left(2\right)\mu \mathrm{m}$ in our setup. We characterize the spatial dependence of the tweezer pattern in terms of its Rabi frequency on an optical transition in the ion. We find a peak Rabi frequency of $390\left(70\right)\mathrm{MHz}$ in the center of the tweezer and a suppression factor of 19(3) in the immediate surrounding of the ion. We investigate the effects of optical forces and coherent population trapping on the ion. We show that the challenges posed by these forces can be overcome, and that the number of tweezers can be easily scaled up to reach several ions by using a spatial light modulator.

We report the measurement of ultrafast relaxation dynamics of excited states of the carbon dioxide molecule using time-resolved pump-probe photoelectron spectroscopy. Neutral ground-state carbon dioxide is excited to $nd{\sigma }_g$ Henning sharp Rydberg states with an attosecond extreme ultraviolet pulse train. A time-delayed near-infrared probe pulse is used to photoionize these states to their corresponding ionization limit $B{}^2{\mathrm{\Sigma }}_u{}^{+}$. We obtain differential kinetic energy spectrograms and angular distributions for photoionization and autoionization channels. We model the competition between predissociation and autoionization in the Rydberg-state dynamics and analyze the differential photoelectron yield as a function of the time delay to extract autoionization and predissociation lifetimes for three Henning sharp states $n=4,5,6$.

We investigate the characteristics of near resonant Bragg scattering, the underlying process that produces a signal in a grating-echo atom interferometer. We explore how the density modulation produced in an atomic sample by momentum state interference and optical channeling can be optimally read out using a coherently Bragg-scattered traveling-wave electric field. When both the channeling and Bragg scattering processes are optimized, we report a 20-fold increase in scattering efficiency. Our results suggest that a quantitative understanding of the atomic confinement achievable by channeling is possible through an analysis of reflectivity spectra.

We investigate the expansion dynamics of spin-orbit-coupled Bose-Einstein condensates subjected to a synthetic magnetic field, after their release from an external harmonic trap. Our findings reveal that the condensate experiences a spin-dependent rotation and separation due to the rigid-like rotational velocity field, which leads to a spin-density deflection. The deflection angle reaches a peak at an expansion time that is inversely related to the trap frequency. When the detuning gradient is below a critical value for vortex nucleation, our analytical results derived from a spinor hydrodynamic theory align closely with numerical results using the coupled Gross-Pitaevskii equations. Beyond this critical value, we also numerically simulated the expansion dynamics of the condensates containing vortices with negative circulation. Our findings highlight the pivotal role of the rigid-like rotational velocity field on the dynamics of the condensate and may stimulate further experimental investigations into the rich superfluid dynamics induced by synthetic magnetic fields.