Search

In this paper, we consider the situation that three identical two-level atoms are separately trapped in the three single-mode cavities. Each atom resonantly interacts with cavity via a one-photon hopping. The dynamics of nonlocality in the system is investigated via Mermin-Ardehali-Belinksii-Klyshko inequality. The results show that when three atoms are initially in W state and three-cavity fields are in vacuum states both the quantum state of three atoms and that of three cavities all display nonlocality On the other hand, when three atoms are initially in Greenberger-Horne-Zeilinger state and three-cavity fields are in vacuum states, the quantum state of three atoms and that of three cavities all do not display nonlocality. [ABSTRACT FROM AUTHOR]

The present paper considers a new approach to the case of an atom in an overdamped cavity. The dissipation is modelled via a bath of harmonic oscillators coupled to the cavity mode, which is assumed to be in a coherent state when the atom enters the cavity. The path integral over both the cavity mode and the bath is taken to derive the optically active electron's influence functional, which can be used further in the study of the time asymptotic dynamics of the internal states of any atom coupled with the cavity mode by using Monte Carlo methods. More specifically the present paper considers the dynamics of the ground state of hydrogen. Oscillations are observed in the survival probability of its ground state, which for asymptotic results is always smaller than one. [ABSTRACT FROM AUTHOR]

In the present and the accompanying paper a justification of the standard model of cavity quantum electrodynamics is given in terms of a quasi-mode theory of macroscopic canonical quantization. The coupling of the cavity quasi-mode to external quasi-modes is treated for the representative case of the three-dimensional Fabry-Perot cavity. The general form of the travelling and trapped mode functions for this cavity are derived in this paper and the mode-mode coupling constants are calculated in the accompanying paper. The slow dependence of the coupling constants with the mode frequency difference demonstrates that the conditions for Markovian damping of the cavity quasimode are satisfied. As also discussed in the accompanying paper, the interaction of radiative atoms with cavity quasi-modes is associated with reversible energy exchanges between atom and cavity and represented by Rabi coupling constants. The interaction of radiative atoms located within the cavity with sideways travelling external quasi-modes involves slowly varying coupling constants and is associated with irreversible spontaneous emission dampling. The basic processes represented in the standard cavity quantum electrodynamics model and the associated coupling constant and decay rates thereby follow from the quasi-mode theory. [ABSTRACT FROM AUTHOR]

In this paper, we discuss the statistical properties of London-modified coherent states that were introduced in order to build up a resolution of the identity for London coherent states. The resolution to the identity is realized by the application of an operator to the London cohrent states. Next we find the Mandel-Q parameter that shows that there exist sub-Poissonian behaviour for a large interval of amplitudes, look at their behaviour in phase space through the Husimi-Q function and study their interaction with a two-level atom. We show that their oscillating photon distributions are responsible for the ringing revival behaviour shown by the atomic inversion. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the interaction between a vee-type three-level atom and a single mode of the electromagnetic field in the presence of a nonlinear Kerr-like medium and an intensity-dependent coupling. We have elucidated the system by a nonlinear Hamiltonian constructed from the standard Jaynes–Cummings model by deforming the field operators and adding some nonlinear terms. Using the initial conditions that the atom is prepared in an excited state and the field is in a coherent state, the state vector of the entire system is determined analytically. The time evolution of nonclassical properties such as Mandel Q, quantum entanglement and position-momentum uncertainty relation (squeezing) of the field are investigated. The quasiprobability distributions are also computed for the resultant state. The effects of the detuning parameters, generalized Kerr medium and intensity-dependent coupling on the previous nonclassicality signs are analysed, in detail. [ABSTRACT FROM AUTHOR]

In this paper we provide a systematic method of finding the higher order asymptotic expansion of the Keldysh integral using the hydrogen atom as an example. Comparisons with exact numerical integration shows that the second-order correction improves the the first-order results significantly. We extend this method to molecular ionisation in H [image omitted] and calculate the total ionisation rate. The results are in good agreement with the exact solution of the time-dependent Schrodinger equation. [ABSTRACT FROM AUTHOR]

In this paper we demonstrate that the interaction of a traveling monochromatic light wave with atoms of a dilute gas in a cell whose length is much less than the diameter of the light beam can slow down the velocity of light. This slowing down is achieved by the specific transit relaxation of particles between walls of the cell (along the wave vector). For a two-level atomic system the group index is in the order of 103. The results show that such a slow down could be achieved by a single traveling light wave in a gas medium. [ABSTRACT FROM AUTHOR]

This paper considers a two-level atom interacting with two cavity modes with equal frequencies. Applying a unitary transformation, the system reduces to the analytically solvable Jaynes–Cummings model. For some particular field states, coherent and squeezed states, the transformation between the two bare bases, related by the unitary transformation, becomes particularly simple. It is shown how to generate (the highly non-classical) entangled coherent states of the two modes, both in the zero and large detuning cases. An advantage of the zero detuning case is that the preparation is deterministic and no atomic measurement is needed. For the large detuning situation, a measurement is required, leaving the field in either of two orthogonal entangled coherent states. [ABSTRACT FROM AUTHOR]

Second-order interference effects in the spontaneous emission by two identical two-level atoms, separated a distance apart and both initially excited, are considered. On the basis of the analysis in our previous paper published in 2004, within fourth-order perturbation, detailed analysis of the second-order quantum interference in the emitted field is made. The interference arises both from single-photon states and two-photon states owing to interferences between different decaying sequences. By detailed analysis we have found some cancellations between single-photon and two-photon interference terms, and an interpretation of this is given. The contributions from the single- and the two-photon states as well as the total interference are analysed numerically for various interatomic distances and times. The contribution from a two-photon state is mostly larger than that from a single-photon state except when the atomic electric dipole is large, in which case the two contributions can be comparable. It is shown that the emission patterns from the two interacting atoms provide more information on atom–atom correlations than the decay time evolution of the atomic states population does. The number of interference fringes and the distance between them depend on the interatomic distance in a similar fashion to Young's interference fringes. [ABSTRACT FROM AUTHOR]

In this paper, we report on our first measurements of the linear magneto-optic rotation experienced by a linearly polarized weak probe field as it passes through a sample of cold sodium atoms. The results are compared with theory that does account for the residual Doppler broadening but that does not take into account the recoil experienced by the atoms. We compare the results of our theoretical model with our measurements and find that, at the time of this conference presentation, there still exists a discrepancy. Improvements for future experiments are outlined. [ABSTRACT FROM AUTHOR]

At the high laser intensities currently available, simple descriptions of multiphoton processes based on the non-relativistic Schrödinger equation and the dipole approximation can break down. The paper first discusses how non-dipole effects, of order 1/ c , due to the magnetic field component of a laser pulse, influence harmonic generation. Particular attention is devoted to photon emission by positive ions interacting with intense, few-cycle Ti: Sapphire laser pulses. It is found that for peak intensities in excess of 10 17 W cm -2 the magnetic field component of the incident pulse significantly reduces photon emission and modifies the plateau structure of the spectra. It also leads, in certain parts of the spectrum, to the emission of a single attosecond burst of X-ray photons. The influence of non-dipole effects on harmonic generation in the stabilization regime are considered. Finally, the paper reviews recent progress in the theoretical study of relativistic effects arising when atoms interact with ultrastrong laser fields. [ABSTRACT FROM AUTHOR]

In the Jaynes-Cummings model a two-level atom interacts with a single-mode electromagnetic field. Quantum mechanics predicts collapses and revivals in the probability that a measurement will show the atom to be excited at various times after the initial preparation of the atom and field. In retrodictive quantum mechanics we seek the probability that the atom was prepared in a particular state given the initial state of the field and the outcome of a later measurement on the atom. Although this is not simply the time reverse of the usual predictive problem, we demonstrate in this paper that retrodictive collapses and revivals also exist. We highlight the differences between predictive and retrodictive evolutions and describe an interesting situation where the prepared state is essentially unretrodictable. [ABSTRACT FROM AUTHOR]

In this paper, the interaction of a moving three-level atom and a two-mode quantized electromagnetic cavity field is extended to involve the effects of the atomic motion. Detuning parameters, Kerr nonlinearity, Stark shift contributions and arbitrary forms of intensity-dependent atom-field coupling have been taken into account. The constants of motion and the wave function, when the atom is initially prepared in superposition states and the field is initially prepared in squeezed coherent states, have been obtained. We calculate some statistical aspects such as atomic inversion, purity, Mandel Q-parameter, cross-correlation, momentum increment, momentum diffusion and Husimi Q-function. [ABSTRACT FROM AUTHOR]

In this paper, we study cooperative scattering of low intensity light by a cloud of N two-level systems. We include the incident laser field driving these two-level systems and compute the radiation pressure force on the center of mass of the cloud. This signature is of particular interest for experiments with laser cooled atoms. Including the complex coupling between dipoles in a scalar model for dilute clouds of two-level systems, we obtain expression for cooperative scattering forces taking into account the collective Lamb shift. We also derive the expression of the radiation pressure force on a large cloud of two-level systems from an heuristic approach and show that at lowest driving intensities this force is identical for a product and an entangled state. [ABSTRACT FROM PUBLISHER]

This paper presents a new method of purely optical spectroscopy of rubidium Rydberg states in a room-temperature gas cell. The atoms are excited into the Rydberg state from the ground state with a three-step diode laser cascade setup. The excitation of Rydberg states is monitored by observing the absorption of the laser performing the first excitation step on the strong rubidium D2 line. Different polarization schemes and possible excitation geometries are discussed. [ABSTRACT FROM AUTHOR]

The spontaneous emission from a driven four-level tripod atom embedded in an anisotropic photonic crystal is investigated in this paper. We find that time-evolution properties and components of the emitted fields are dependent on the relative position of the upper level of the atom from the band edge and the space between two lower levels. The radiation field emitted by the atom is calculated more accurately. The energy is translated from one form to another with the increase of distance from the atom and the upper level's relative position. The evolution properties and the spontaneous spectrum are also studied. The results analyzed here are consistent with the distribution of emitted fields. [ABSTRACT FROM AUTHOR]

In this paper, we study the interaction between two two-level atoms and two nondegenerate cavity modes when the atoms and the field are initially in the atomic superposition states and the pair-coherent state (PCS), respectively. We investigate the atomic inversions, tangles and joint probability distribution. We show that the system can generate long-living entanglement by controlling the values of the interaction parameters. Also we show generally that for obtaining a large amount of entanglement from two qubits interacting with a maximally entangled two-mode state one has to prepare the qubits initially in the decoupled states. Moreover, the system - at certain values of interaction parameters - can generate different types of nonclassical states, such as the mth-photon PCS, statistical mixtures of PCSs and superposition of PCS. [ABSTRACT FROM AUTHOR]

A preface for the July 20, 2007 issue of the "Journal of Modern Optics" is presented.

The generation of short, intense, mid-infrared laser pulses allows for the exploration of atom-laser interactions deep in the tunnelling regime as well as providing the ability to explore scaled interactions. In this paper we present recent experimental and theoretical results for this largely unexplored parameter space. [ABSTRACT FROM AUTHOR]

The paper reports investigations of refractive index enhancement (RIE) with zero absorption in a three-level Λ-type atom subject to a drive field, a saturation field and a probe field. As RIEs lie in the alternate points between emission and absorption peaks, one can predict their positions by employing dressed state theory and optical Bloch equations. The numerical calculations with dressed state analysis indicate that high refractive index enhancement appears mainly at two conditions: (i) off-resonance detuning of drive and saturation frequencies have the opposite sign; (ii) the saturation Rabi frequency is larger than the drive Rabi frequency. The analysis can be extended to multi-field multi-level atomic systems. [ABSTRACT FROM AUTHOR]

In this paper we discuss four different proposals of entangling atomic states of particles which have never interacted. The experimental realization proposed makes use of the interaction of Rydberg atoms with a micromaser cavity prepared in either a coherent state or in a superposition of the field Fock states |0> and |1>. We consider atoms in either a three-level cascade or lambda configuration. [ABSTRACT FROM AUTHOR]

The weak probe field spectrum of a three-level atom, in the ladder configuration, is obtained. The lower transition of atom is coupled with squeezed vacuum, while the upper transition is coupled to coherent cavity mode and a bath. In this paper, the effect of the various quantities (detuning, decay rates) on the absorption spectrum is investigated. [ABSTRACT FROM AUTHOR]

This paper deals with the conversion of atoms into molecules in optical lattices. We show that in the absence of collisional interaction, the atomic and molecular components in different lattice wells combine into states with macroscopic condensate fractions, which can be observed as a strong diffraction signal, if the particles are abruptly released from the lattice. The condensate population and the diffraction signal are governed not only by the mean number of atoms or molecules in each well, but by the precise amplitudes on state vector components with different numbers of particles. We discuss ways to control these amplitudes and to maximize the condensate fraction in the molecular formation process. [ABSTRACT FROM AUTHOR]

We continue our investigations of cavity QED with time- dependent parameters. In this paper we discuss the situation where the state of the atoms leaving the cavity is reduced but the outcome is not recorded. In this case our knowledge is limited to an ensemble description of the results only. By applying the Demkov-Kunike level-crossing model, we show that even in this case, the filtering action of the interaction allows us to prepare a pre-assigned Fock state with good accuracy. The possibilities and limitations of the method are discussed and some relations to earlier work are presented. [ABSTRACT FROM AUTHOR]

The problems related to the management of large quantum registers could be handled in the context of distributed quantum computation: unitary non-local transformations among spatially separated local processors are realized performing local unitary transformations and exchanging classical communication. In this paper, a scheme is proposed for the implementation of universal non-local quantum gates such as a controlled NOT (CNOT) and a controlled quantum phase gate (CQPG). The system chosen for their physical implementation is a cavity-quantum-electrodynamics (CQED) system formed by two spatially separated microwave cavities and two trapped Rydberg atoms. The procedures to follow for the realization of each step necessary to perform a specific non-local operation are described. [ABSTRACT FROM AUTHOR]

The paper discusses the single-mode Jaynes-Cummings model with time-dependent parameters. Solvable models for two-level systems are utilized to consider the changes in the photon distribution effected by the passage of atoms through the cavity. It is suggested that such systems may be used as filters to modify the photon distribution. The effect can be enhanced by repeatedly sending new atoms through the cavity. We show that such filters can cut out either small or large photon numbers. It is also shown that the method can be used to narrow down photon distributions and in this way achieve highly non-classical sub-Poissonian states. Some limitations and applications of the method are presented. [ABSTRACT FROM AUTHOR]

In this paper, we use the quantum field entropy to measure the degree of entanglement in the time development of a three-level atom interacting with two-mode fields including all acceptable kinds of nonlinearities of the two-mode fields. This model describes a very general situation in which the system admits two detuning parameters and includes an arbitrary form of the nonlinearity of the two modes. It is shown that when the individual modes of the field are detuned far from the intermediate atomic level, the dynamic Stark shift is induced by the nonlinear medium. The results show that the nonlinearity effect yields the superstructure of atomic Rabi oscillations and changes the quasiperiod of the field entropy evolution and entanglement between the atom and the field. The general conclusions reached are illustrated by numerical results. [ABSTRACT FROM AUTHOR]

Small tight trapping and guiding potentials can be created for neutral atoms moving microns above surfaces patterned with nanofabricated charged and current-carrying structures. Surfaces holding such structures form atom chips which, for coherent matter wave optics, may form the basis for a variety of novel applications and research tools, similar to integrated circuits in electronics. In this paper we describe the basic principles of atom chip experiments. [ABSTRACT FROM AUTHOR]

We analyse the dynamics of quantum correlations by obtaining the exact expression of Bures distance entanglement, trace distance discord, and local quantum uncertainty of two two-level atoms. Here, the atoms undergo two-photon transitions mediated through an intermediate virtual state where each atom is separately coupled to a dissipative reservoir at zero temperature in the presence of the Stark shift effect. We have investigated the dynamics of this atomic system for two different initial conditions of the environment. In the first case, we have assumed the environment's state to be in ground state and in the other case, we have assumed the state to be in the first excited state. The second initial condition is significant as it shows the role played by both the Stark shift parameters in contrast to only one of the Stark shift parameters for the first initial condition. Our results demonstrate that quantum correlations can be sustained for an extended period in the presence of Stark shift effect in the case of both Markovian and non-Markovian reservoirs. The effect in the non-Markovian reservoir is more prominent than the Markovian reservoir, even for a very small value of the Stark shift parameter. We observe that among the correlation measures considered, only local quantum uncertainty is accompanied by a sudden change phenomenon, i.e. an abrupt change in the decay rate of a correlation measure. Our findings are significant as preserving quantum correlations is one of the essential aspects in attaining optimum performance in quantum information tasks. [ABSTRACT FROM AUTHOR]

The phenomenon of telegraphing in a measurement-driven two-level atom was noted in Cresser et al. [Cresser, J.D.; Barnett, S.M.; Jeffers, J.; Pegg, D.T. Opt. Commun. 2006, 264, 352-361]. Here we introduce two quantitative measures of telegraphing: one based on the accumulated measurement record and one on the evolution of the quantum state. We use these to analyse the dynamics of the atom over a wide range of parameters. We find, in particular, that the measures provide broadly similar statistics when the measurements are frequent, but differ widely when measurements are sparse. This is in line with intuition, and demonstrates the utility of both measures. [ABSTRACT FROM AUTHOR]

We propose a new scheme for the generation of single zeptosecond pulses by using a one-dimensional muonic hydrogen atom model. Owing to the large mass of the muon, the muonic atoms can survive much stronger fields, which causes a very broad plateau in the high-order harmonic spectrum. By solving a one-dimensional time-dependent Schrodinger equation, the high-order harmonic spectrum of the muonic atom in super-intense nonlinear chirped laser pulses is obtained. It is found that the harmonic spectrum is greatly affected by the chirp rate parameters of the laser field. By adjusting the chirp rate parameters, an ultra-broad super-continuum spectrum could be obtained, from which a single zeptosecond pulse could be generated without phase compensation. [ABSTRACT FROM AUTHOR]

The dynamics of an adiabatic sweep through a Feshbach resonance in a degenerate quantum gas of fermionic atoms to produce a degenerate quantum gas of diatomic molecules are studied using many-body and mean-field methods. We demonstrate that the dependence of the remaining fraction of atoms Γ on sweep rate α varies from exponential Landau-Zener behaviour for a single pair of particles, to a power-law dependence for a large number of atoms, N. Two different power-law behaviours are obtained depending on the initial molecular fraction. The two different regimes are described in terms of quantum fluctuations: a linear power-law, Γ∝α, is obtained when the initial molecular fraction is smaller than the 1/N quantum fluctuations, and Γ∝α1/3 when it is larger. [ABSTRACT FROM AUTHOR]

Presents an erratum in the article 'Generating states by strong laser-atom interaction'.

We consider the cavity field interacting with two unidentical atoms in a perfect cavity. We study the evolution of the quasiprobability distribution for the field with a view to understand atomic entanglement. Due to the atom-field coupling the Gaussian peak of the initial coherent state evolves into one, two, or three peaks depending on the initial entanglement between two atoms. The dynamical evolution of the field also depends on the statistical nature of the state of the atoms. [ABSTRACT FROM AUTHOR]

In this article, we investigate both theoretically and experimentally the method of Ramsey interference applied to cold atoms being emitted from a 2-dimensional magneto-optical trap (2D-MOT) crossing continuous wave (cw) laser fields that drive Raman transitions between ground-state hyperfine sublevels. In our apparatus, the atomic beam divergence is large (56 mrad half-angle), necessitating the inclusion in our model of both the atomic divergence and the laser beam divergence as well as averaging over the transit time of the atoms through the laser beam. We discuss the effects of the divergence of the atomic and laser beams, and then we describe our apparatus and qualitatively compare our experimental results to the theoretical results. We find good agreement between our model and our experimental results. [ABSTRACT FROM AUTHOR]

To control the polarization of attosecond pulse trains (APTs), the most widely used way is to adjust the intensity ratio between the two components in a bicircular laser field. Here we demonstrate another effective means to obtain highly elliptically polarized APTs. For this purpose, we propose a circular-elliptical laser field, which consists of a circularly polarized field with its coplanar counter-rotating elliptical harmonic pulse, in order to generate high-order harmonics by He atom. We show that the polarization of APTs depends evidently on the ellipticity ξ of harmonic laser field. Most importantly, nearly circular APTs can be obtained with a proper ξ for driving laser field. Our results contribute to the generation of high elliptically polarized APTs with s-state atom. [ABSTRACT FROM AUTHOR]

We study the dynamics of quantum steerability between two non-interacting atoms, each of which is trapped inside one of two coupled cavities. Compared with entanglement, quantum steerability manifests sudden birth and sudden death phenomenon during the time evolution. We find that the cavity decay plays a destruction role for both steerability and entanglement. It is also shown that the survival time as well as the maximal value of steerability are sensitive to the asymmetry of the cavities. Moreover, it is found the sudden death of steerability can be controlled by the hopping rate of the coupled cavities. [ABSTRACT FROM AUTHOR]

The behaviour of atom localization in an inverted-Y atomic system is theoretically investigated. For the atoms interacting with a weak probe field and several orthogonal standing-wave fields, their position information can be obtained by measuring the probe absorption. Compared with the traditional scheme, we couple the probe field to the transition between the middle and top levels. It is found that the probe absorption sensitively depends on the detuning and strength of the relevant light fields. Remarkably, the atom can be localized at a particular position in the standing-wave fields by coupling a microwave field to the transition between the two ground levels. [ABSTRACT FROM AUTHOR]

We discuss the prospects for enhancing absorption and scattering of light from a weakly coupled atom in a high-finesse optical cavity by adding a medium with large, positive group index of refraction. The slow-light effect is known to narrow the cavity transmission spectrum and increase the photon lifetime, but the quality factor of the cavity may not be increased in a metrologically useful sense. Specifically, detection of the weakly coupled atom through either cavity ringdown measurements or the Purcell effect fails to improve with the addition of material slow light. A single-atom model of the dispersive medium helps elucidate why this is the case. [ABSTRACT FROM AUTHOR]

We present a review of theoretical studies of the simplest nonlinear photoprocesses detected in the XUV range with the use of free electron lasers: sequential double and triple ionization of atoms by two and three XUV photons. Photoelectron angular distributions and angular correlations between emitted electrons are considered. A comparison of the calculated results with recent angle-resolved photoelectron spectroscopy experiments is discussed. [ABSTRACT FROM AUTHOR]

The interplay between the superradiant emission of a cloud of cold two-level atoms and the radiation pressure force is discussed. Using a microscopic model of coupled atomic dipoles driven by an external laser, the radiation field and the average radiation pressure force are derived. A relation between the far-field scattered intensity and the force is derived, using the optical theorem. Finally, the scaling of the sample scattering cross-section with the parameters of the system is studied. [ABSTRACT FROM AUTHOR]

The fluorescence photon correlations in a driven four-level atom consisting of three upper closely lying excited states and a single lower state are investigated. It is found that in the presence of triple spontaneously generated coherence (SGC) effects, which are created by three degenerate levels coupling to the common ground state via the same vacuum mode, the correlation properties of the three fluorescence fields can be switched from strong correlation to anticorrelation or vice versa by modifying the detunings. In addition, such a system is very sensitive to the relative phases of the three fields, which can provide an effective way to control the photon correlation. Physically, these interesting phenomena can be interpreted in terms of dressed state analysis. [ABSTRACT FROM PUBLISHER]

We study an ensemble ofidentical-type atoms confined inside a cavity optomechanical system. We show that when the atoms have no absorption and dispersion the output field of the optomechanical system present a transparency phenomenon. The oscillation of the mirror does not affect the transparency of the atomic medium while the existence of the atomic medium results in two transparency windows of the output cavity field. We also show that the frequency of the oscillation mirror affects the analogy transparency of the output cavity field. [ABSTRACT FROM AUTHOR]

An investigation is reported of the collective effects and the dynamics of atom–atom entanglement in a system of two distant two-level atoms which are coupled via an optical element. In the system under consideration, the two atoms, which are trapped in the foci of a lens, are coupled to a common environment being in the vacuum state and they emit photons spontaneously. A fraction of the emitted photons from each atom is thus focused on the position of the other atom. The presence of optical element between two distant atoms leads to the occurrence of delayed collective effects, such as delayed dipole–dipole interaction and delayed collective spontaneous emission, which play the crucial role in the dynamical behaviour of the entanglement. We discuss the phenomena of entanglement sudden birth, entanglement sudden death, and revival of entanglement for both cases of initial one-photon and initial two-photon unentangled atomic states. We show that the evolution of the entanglement is sensitive not only to the interatomic distance but also to the initial state of the system as well as to the properties of the optical element. [ABSTRACT FROM PUBLISHER]

We investigate the generation of tripartite field states inside the high-Q cavities using the cavity QED. The main goal is to successfully generate the entanglement in tripartite systems by passing two-level atoms through three identical high-Q cavities. Our scheme gives the successful generation of entangled tripartite W and GHZ states for pre-determined interaction times of atoms with the cavity fields. The dynamics of initial entangled states is studied as the system evolves in the dissipative environments. [ABSTRACT FROM AUTHOR]

By using three mutually perpendicular standing-wave fields, we propose a scheme for three-dimensional (3D) subwavelength atom localization in a five-level M-type atomic system. Based on the electromagnetically induced transparency, position probability distribution of the atom in 3D space could be determined via measuring the probe absorption which is proportional to the filter function. It is shown that patterns of 3D atom localization depends sensitively on the coupling schemes of the standing-wave fields. When the standing-wave fields couple three different transitions, the same atom localization patterns are formed in the eight subspaces of the 3D space. While all the standing-wave fields are applied on one transition, we can realize different atom localization patterns in the eight subspaces. From the view of the xy plane, various symmetric or asymmetric atom localization patterns could be formed at different z positions by adjusting the parameters of the laser fields. [ABSTRACT FROM PUBLISHER]

We investigate the dynamics of quantum correlations such as entanglement and quantum discord between two noninteracting atoms, each of which is trapped inside one of two coupled cavities. We find that the cavity decay can induce both entanglement and quantum discord between the two atoms when they are initially prepared in doubly excited state. The result shows the sudden death and sudden birth of entanglement and robustness of the quantum discord to sudden death. It is also found that the doubly excited state is responsible for the sudden death of entanglement. Moreover, the sudden death of entanglement can be controlled by the intercavity hopping rate. [ABSTRACT FROM PUBLISHER]

We study the general problem of Raman resonances in arbitrary magnetic fields for realistic alkali atoms. We first present the details of a model that includes all magnetic sub-levels and their appropriate coupling strengths to two laser fields. The numerical implementation of this model and some of the results are also presented. Our experimental arrangement is described and preliminary measurements are presented. [ABSTRACT FROM PUBLISHER]