A multidimensional transformation design method that allows us to design a cloaking shell of multivariables for matter waves is proposed. As applications, cloaking shells for an elliptical invisible region, a region specified by the radial and angular variables, and an invisible region specified by the polar angle for the Coulomb scattering wave have been designed. It is shown that the mass parameters required for a perfect cloaking of a matter wave in the elliptical coordinate system are constant.

We carefully numerically simulate the full three-dimensional (3D), two-level Maxwell Bloch equations in a ring configuration, beyond the rotating wave and slowly varying envelope approximations. The 3D electromagnetic spatial and temporal variations are then well described up to the micrometer and femtosecond scales. Genuine dielectric waveguide boundary conditions together with no-reflection, perfectly matching layers are implemented. Besides the already known and well-described transverse instabilities of a traveling-wave solution, we observe steady zipper-state configurations characterized by the coexistence, in the laser transverse plane, of two longitudinal counter-propagating waves, with their separation plane parallel to the ring laser optical axis. The direction of propagation of the traveling wave is observed to change slowly and periodically with time.

The quantum-statistical properties of the radiation emitted from two coupled cavities containing one or two two-level atoms are discussed, and both configurations are compared. The results concerning stationary photon statistics, photon blocking, squeezing, antibunching, as well as the spectrum of the second-order correlation are presented.

In the study of open quantum systems, memory effects are usually ignored, and this leads to dynamical semigroups and Markovian dynamics. However, in practice, non-Markovian dynamics is the rule rather than the exception. With the recent emergence of quantum information theory, there is a flurry of investigations of non-Markovian dynamics, and several significant measures for non-Markovianity are introduced from various perspectives such as deviation from divisibility, information exchange between a system and its environment, or entanglement with the environment. In this work, by exploiting the correlations flow between a system and an arbitrary ancillary, we propose a considerably intuitive measure for non-Markovianity by use of correlations as quantified by the quantum mutual information rather than entanglement. The fundamental properties, physical significance, and differences and relations with existing measures for non-Markovianity are elucidated. The measure captures quite directly and deeply the characteristics of non-Markovianity from the perspective of information. A simplified version based on Jamiołkowski-Choi isomorphism which encodes operations via bipartite states and does not involve any optimization is also proposed.

A scheme for selective coherent destruction of tunneling (CDT) of strongly interacting bosons in a symmetric double-well potential, in which an arbitrarily and a priori prescribed number of bosons are allowed to tunnel from one well to the other one is theoretically proposed. As compared to the many-body CDT scheme recently proposed by Gong, Molina, and Hänggi [Phys. Rev. Lett. 103, 133002 (2009)] and based on a fast modulation of the self-interaction strength, the method suggested in this work exploits the traditional method of fast modulation of the energy level unbalance between the two wells by an external ac force.

A theory of Rydberg atom interactions is used to derive analytical forms for the spin-wave pair correlation function in laser-excited cold-atom vapors. This function controls the quantum statistics of light emission from dense, inhomogeneous clouds of cold atoms of various spatial dimensionalities. The results yield distinctive scaling behaviors on the microsecond time scale, including generalized exponential decay. A detailed comparison is presented with a recent experiment on a cigar-shaped atomic ensemble [Y. Dudin and A. Kuzmich, Science 336, 887 (2012)], in which Rb atoms are excited to a set of Rydberg levels.

The effects of statistical fluctuation and vacuum source fluctuation on the decoy-state method with an unstable decoy source and signal source are studied. The method is improved by a tightened estimation of the vacuum count. Compared with the existing results with an unstable vacuum source and statistical fluctuation, the results presented here have improved the key rate of the 3-intensity protocol for quantum key distribution.

Quantum properties are soon subject to decoherence once the quantum system interacts with the classical environment. In this paper we experimentally test how propagation losses, in a Gaussian channel, affect the bipartite Gaussian entangled state generated by a subthreshold type-II optical parametric oscillator. Experimental results are discussed in terms of different quantum markers, as teleportation fidelity, quantum discord, and mutual information, and continuous-variable (CV) entanglement criteria. To analyze state properties we have retrieved the composite system covariance matrix by a single homodyne detector. We experimentally found that, even in the presence of a strong decoherence, the generated state never disentangles and keeps breaking the quantum limit for the discord. This result proves that the class of CV entangled states discussed in this paper would allow, in principle, to realize quantum teleportation over an infinitely long Gaussian channel.

Field ionization and Coulomb explosion of small hydrocarbon molecules driven by intense laser pulses are studied in a combined theoretical and experimental framework. The spectra of ejected protons calculated by the time-dependent density functional approach are in good agreement with the experimental data. The results of the simulations give detailed insight into the correlated electron and nuclear dynamics and complement the experiment with a time-dependent physical picture. It is demonstrated that the Coulomb explosion in the studied molecular systems is a sudden, all-at-once fragmentation where the ionization step is followed by a simultaneous ejection of the charged fragments.

We develop a flexible analytical approach to describe strong-field dynamics in atoms and molecules. The approach is based on the ideas of the $R$-matrix method. Here, we illustrate and validate our approach by applying it to systems with one active electron bound by the Coulomb potential and benchmark our results against the standard theory of Perelomov, Popov, and Terent'ev [Sov. Phys. JETP 23, 924 (1966)]. We discuss corrections to the ionization amplitude associated with the interplay of the Coulomb potential and the laser field on the sub-laser cycle time scale and the shape of the tunneling wave packets associated with different instants of ionization.

Ionization of atoms and molecules in intense low-frequency fields is a multielectron process which may leave the ion in different excited states. Within the adiabatic perspective on strong-field ionization, usually referred to as optical tunneling, electrons remaining in the molecular ion are assumed to be frozen during the ionization process. In this case, the only way to excite the molecular ion during ionization is to remove an electron from a lower-lying molecular orbital. The higher ionization potential corresponding to such processes implies that such channels are exponentially suppressed during tunneling. Here we show that correlation-induced coupling between the departing electron and the core electrons removes the exponential penalty for ionic excitations, resulting in complex attosecond dynamics of core rearrangement during strong-field ionization. We develop a multichannel theory of strong-field ionization and demonstrate the importance of correlation-induced excitations in the multiphoton and tunneling regimes for N${}_2$ and CO${}_2$ molecules.

We report experimental and numerical results on the dual laser-pulse plasma excitation in molecular and noble gases at atmospheric pressure. Dilute plasma channels generated through filamentation of ultraintense femtosecond laser pulses in air, argon, and helium are densified through the application of multijoule nanosecond heater pulses. Plasma densification in molecular gases is always accompanied by the fragmentation of the plasma channels into discrete bubbles, while in atomic gases, under certain conditions, the densified channels remain smooth and continuous. The densification effect in atomic gases persists through considerably longer delays between the femtosecond and nanosecond pulses compared to that in molecular gases. Using rate equations we trace this difference in the temporal dynamics of densification to the different cooling mechanisms operative in atomic and molecular cases.

We investigate an atom interferometer in which large momentum differences between the arms are obtained by using quantum resonances in the atom-optics $\delta$-kicked rotor. The interferometer can potentially measure the Talbot time (from which $h/m$ can be deduced) and the local gravitational field or can serve as a narrow velocity filter. We present an analytical analysis in the short pulse limit and a numerical investigation for finite pulse durations. The sensitivity of the interferometer is improved by a moderate violation of the short pulse limit. Remarkably simple relations predict the optimal pulse duration and the sensitivity of the interferometer.

Matter-wave superradiance is based on the interplay between ultracold atoms coherently organized in momentum space and a backscattered wave. Here, we show that this mechanism may be triggered by Mie scattering from the atomic cloud. We show how the laser light populates the modes of the cloud and thus imprints a phase gradient on the excited atomic dipoles. The interference with the atoms in the ground state results in a grating that in turn generates coherent emission, contributing to the backward light wave onset. The atomic recoil “halos” created by the Mie-scattered light exhibit a strong anisotropy, in contrast to single-atom scattering.

We study coherent backscattering of intense laser light from three immobile two-level atoms using the master-equation approach. The master equation is solved analytically, and the triple scattering spectrum is expressed in quadratures. We show that this solution can be obtained via a self-consistent combination of single-atom spectral responses, and is equivalent to the solution following from the diagrammatic pump-probe approach. We deduce the general expressions for single-atom building blocks which can be used in simulations of multiple inelastic scattering of laser light in the bulk atomic medium.

We propose a scheme to exhibit Stern-Gerlach deflection of high-dimensional vector optical solitons at a weak-light level in a cold atomic gas via electromagnetically induced transparency. We show that the propagating velocity and generation power of such solitons can be reduced to ${10}^{-6}c$ ($c$ is light speed in vacuum) and lowered to magnitude of nanowatt, respectively. The stabilization of the solitons is realized by using an optical lattice potential formed by a far-detuned laser field, and trajectories of them are deflected significantly by using a transversal Stern-Gerlach gradient magnetic field. Deflection angles of the solitons can be of magnitude of ${10}^{-3}$ rad when propagating several millimeters. Different from atomic Stern-Gerlach deflection, deflection angles of the solitons can be distinct for different polarization components and can be manipulated in a controllable way. The result obtained can be described in terms of the Stern-Gerlach effect for vector optical solitons with quasispin and effective magnetic moment.

The influence of nondipole terms on the time delay in photoionization by an extreme-ultraviolet attosecond pulse in the presence of a near-infrared femtosecond laser pulse from 1$s$, 2$s$, and 2$p$ states in hydrogen is investigated. In this attosecond photoelectron streaking process, the relative importance of nondipole terms compared with the dipole term is varied in two ways: (i) by increasing the photon energy of the attosecond pulse, and (ii) by considering photoelectron emission in directions where the dipole contribution is suppressed due to symmetry. Even in these cases, no time delay due to nondipole terms is found. The numerical calculations are supported by a theoretical analysis of the time delay.