We consider a one-dimensional optomechanical lattice where each site is strongly driven by a control laser to enhance the basic optomechanical interaction. We then study the propagation of photons injected by an additional probe laser beam; this is the lattice generalization of the well-known optomechanically induced transparency (OMIT) effect in a single optomechanical cavity. We find an interesting interplay between OMIT-type physics and geometric, Fabry-Perot-type resonances. In particular, phononlike polaritons can give rise to high-amplitude transmission resonances which are much narrower than the scale set by internal photon losses. We also find that the local photon density of states in the lattice exhibits OMIT-style interference features. It is thus far richer than would be expected by just looking at the band structure of the dissipation-free coherent system.

Achieving fast population transfer (FPT) in multiparticle systems based on the cavity quantum electronic dynamics is an outstanding challenge. In this paper, motivated by the quantum Zeno dynamics, a shortcut for performing the FPT of ground states in multiparticle systems with the invariant-based inverse engineering is proposed. Numerical simulation demonstrates that a perfect population transfer of ground states in multiparticle systems can be rapidly achieved in one step, and the FPT is robust to both the cavity decay and atomic spontaneous emission. Additionally, this scheme is not only implemented without requiring extra complex conditions, but also insensitive to variations of the parameters.

We provide insight into the quantum correlations structure present in strongly correlated systems beyond the standard framework of bipartite entanglement. To this aim we first exploit rotationally invariant states as a test bed to detect genuine tripartite entanglement beyond the nearest neighbor in spin-1/2 models. Then we construct in a closed analytical form a family of entanglement witnesses which provides a sufficient condition to determine if a state of a many-body system formed by an arbitrary number of spin-1/2 particles possesses genuine tripartite entanglement, independently of the details of the model. We illustrate our method by analyzing in detail the anisotropic $XXZ$ spin chain close to its phase transitions, where we demonstrate the presence of long-range multipartite entanglement near the critical point and the breaking of the symmetries associated with the quantum phase transition.

Fidelity plays an important role in measuring distances between pairs of quantum states, of single as well as multiparty systems. Based on the concept of fidelity, we introduce a physical quantity, shared purity, for arbitrary pure or mixed quantum states of shared systems of an arbitrary number of parties in arbitrary dimensions. We find that although it detects a quantum feature of the shared state, it is different from quantum correlations. We prove that a maximal shared purity between two parties excludes any shared purity of these parties with a third party, thus ensuring its quantum nature. Moreover, we show that all generalized Greenberger-Horne-Zeilinger states are monogamous, while all generalized W states are nonmonogamous with respect to this measure. We apply the quantity to investigate the quantum XY spin-1/2 models and observe that it can faithfully detect the quantum phase transition present in these models. We perform a finite-size scaling analysis and find the scaling exponent for this quantity.

Triply differential cross sections for electron- and positron-induced ionization of the 3$a_1$ orbital of the water molecule are calculated within the second-order distorted-wave Born approximation. In this context, distorted-wave functions are numerically calculated by modeling both the initial and the final channels whereas single-center Slater-type wave functions are used for describing the molecular target. A good agreement with the existing experimental data is observed. Differences in the trends of differential cross sections are observed for the electron- and positron-impact ionization.

Ultracold atoms in one-dimensional (1D) bichromatic optical lattices constitute a surprisingly simple system for the study of topological insulators. We show that bosons in 1D bichromatic lattices present as a general feature the existence, at equal fractional filling, of Mott-insulator phases with different topological character. These different phases are a direct consequence of the bosonic and interacting nature of the particles and the topological nature of the Bloch bands. We demonstrate that the associated hidden topological transitions may occur both as a function of the superlattice strength and due to intersite interactions. We also discuss the topological character of incommensurate density-wave phases in quasiperiodic superlattices.

Evolution equations are presented and discussed for an atomic Bose-Einstein condensate in a dynamical trap formed by wide oscillating barriers. Their analytical solution reveals the existence of families of bright spatial vector solitons whose components can be in phase and antiphase.

We demonstrated high-sensitivity optical spectral imaging of a single layer of a quantum gas of ytterbium atoms in a two-dimensional optical lattice using the ultranarrow ${}^1{S}_0$-${}^3{P}_2$ transition. We successfully obtained a set of excitation-frequency-dependent fluorescence images with an excitation laser of the linewidth of 1 kHz (FWHM), and the overall features were well explained by considering the inhomogeneous light shift originating from the Gaussian beam shape of the optical lattice potential which provided the steepest potential gradient of 3.6 kHz/$\mu$m. This result is also the successful demonstration of the tunable local atom addressing along the equipotential contour depending on the excitation laser frequency with the frequency resolution of 8 kHz and the spatial resolution of approximately 2 $\mu$m. The demonstrated technique will be useful for many purposes including the measurement of interaction shift in the study of a quantum gas and quantum information processing.

We use a probability-theory approach to study the laser noise's effects on laser-atom interactions. We consider the case where the atom is described by a two-level system without spontaneous emission and the laser has both intensity and frequency noises. A stochastic differential equation is established based on the Schrödinger equation of the laser-atom interaction in the semiclassical picture. We then analyze the equation using the path-integral technique to the first order of a perturbation approach. Because of the presence of laser noises, the atom wave function at a given time is a random variable. Therefore we construct a stochastic process characterizing its time evolution. We also provide the theoretical description for the experimental realization of measuring the laser linewidth by driving a narrow atomic transition, and establish the connection between the laser noise's roles in the laser-atom interaction and laser linewidth measurement by beat signal.

Working in the limit in which the localization length scale is large compared to other relevant length scales, we examine three experimental situations with the continuous-spontaneous-localization (CSL) model, a well-motivated alternative to standard quantum theory. These are the two-slit experiment, scattering from a potential barrier, and release of two noninteracting particles simultaneously from a potential trap. In each case we calculate the diagonal part of the time-evolved density matrix giving a probability density function over final measured states. The case of the two-slit experiment is already well understood and we reproduce some known conditions for observing loss of interference. The other examples have not previously been examined in the context of CSL. For scattering from a potential barrier we find that the probability of reflection is unchanged by CSL; however, the momentum state is spread in a characteristic way. For the case of two particles released simultaneously from a trap we find that it is more likely that the particles diffuse in the same direction than would happen if the particles behaved independently. We assess the possibility of observing these effects.

We comprehensively study the subcycle interference of molecules between the back-rescattered and the nonrescattered photoelectrons in a linearly polarized laser pulse. Building on the work of Bian et al.  [X. B. Bian and A. D. Bandrauk, Phys. Rev. Lett. 108, 263003 (2012)], we show that there are four types of interference between the back-rescattered and the nonrescattered photoelectrons. Due to the higher tunneling ionization probability near the field maximum, the long rescattered trajectory plays a more important role than the short rescattered trajectory in forming the photoelectron momentum distributions of strong-field ionization of molecules. It is shown that the interference patterns of the rescattering photoelectron holography have encoded temporal information of the birth time and the recollision time of photoelectrons with subfemtosecond resolution.

This paper completes our previous studies of atomic [P. A. Batishchev, O. I. Tolstikhin, and T. Morishita, Phys. Rev. A 82, 023416 (2010)] and molecular [L. Hamonou, T. Morishita, and O. I. Tolstikhin, Phys. Rev. A 86, 013412 (2012)] Siegert states (SSs) in an electric field by presenting illustrative calculations of the transverse momentum distribution (TMD) for a molecular potential. The method of adiabatic expansion in parabolic coordinates developed in this series for calculating the SSs is summarized. Its implementation is extended to the calculation of the normalized molecular SS eigenfunction, which is required for calculating the TMD. We consider a soft-core potential modeling the hydrogen molecular ion ${{\mathrm{H}}_2}^{+}$. The behavior of the parabolic adiabatic potentials, channel functions and the total SS eigenfunction is illustrated, which was not included in the previous publications. The TMDs for the $1s\sigma$ and $2p{\pi }^{\pm }$ states are calculated. Their dependence on field and orientation of the molecule with respect to the field is compared with the predictions of the weak-field asymptotic theory. On the example of the even $2p{\pi }^{+}$ state, it is shown that TMD can rapidly change its shape in situations where there is no a single dominant ionization channel.

We explore the time evolution of two-component Bose-Einstein condensates (BECs), quasi one dimensional with respect to their spinor dynamics, following a quench from one component BECs with a $\mathrm{U}\left(1\right)$ order parameter into two-component condensates with a $\mathrm{U}\left(1\right)\times Z_2$ order parameter. In our case, these two spin components have a propensity to phase separate, i.e., they are immiscible. Remarkably, these spin degrees of freedom can equivalently be described as a single-component attractive BEC. A spatially uniform mixture of these spins is dynamically unstable, rapidly amplifying any quantum or pre-existing classical spin fluctuations. This coherent growth process drives the formation of numerous spin-polarized domains, which are far from the system's ground state. At much longer times these domains grow in size, coarsening, as the system approaches equilibrium. The experimentally observed time evolution is consistent with our fully three-dimensional stochastic-projected Gross–Pitaevskii calculation.

Recently, Yao et al. demonstrated the creation of coherent emissions in nitrogen gas with two-color (800 nm + 400 nm) ultrafast laser pulses [J. Yao, G. Li, C. Jing, B. Zeng, W. Chu, J. Ni, H. Zhang, H. Xie, C. Zhang, H. Li, H. Xu, S. L. Chin, Y. Cheng, and Z. Xu, New J. Phys. 15, 023046 (2013)]. Based on this two-color scheme, here we report on systematic investigation of temporal characteristics of the radiation emitted at 391 nm [N${}_2{}^{+}$: $B{}^2{\Sigma }_u^{+}\left(\nu =0\right)-X{}^2{\Sigma }_g^{+}\left(\nu =0\right)$] by experimentally examining its temporal profiles with the increase of the plasma channel induced by the intense 800-nm femtosecond laser pulses at a nitrogen-gas pressure of ∼25 mbar. We reveal unexpected temporal profiles of the coherent emissions, which show significant superradiance signatures owing to the cooperation of an ensemble of excited N${}_2$${}^{+}$ molecules that are coherently radiating in phase. Our findings shed more light on the mechanisms behind the coherent laserlike emissions induced by strong-field ionization of molecules.

We present a solution to the phase problem in near-field x-ray (propagation) imaging. The three-dimensional complex-valued index of refraction is reconstructed from a set of projections recorded in the near-field (Fresnel) setting at a single detector distance. The solution is found by an iterative algorithm based only on the measured data and the three-dimensional tomographic (Helgason-Ludwig) consistency constraint without the need for further a priori knowledge or other restrictive assumptions.