Paraxial light and atom optics are compared. To lowest order the slowly varying amplitude of a light field in a dielectric medium with a spatially dependent refractive index satisfies an equation which has the form of a Schrödinger equation: the “optical Schrödinger equation.” The unsystematic procedure of neglecting certain second-order derivatives is replaced by a systematic expansion which allows the calculation of consecutive corrections. The general theory is applied to harmonic motion in a graded index fiber and to tunneling between coupled fibers. The physical relations between wave evolution of massive particles and paraxially propagating waves are elucidated.

The use of comoving magnetic fields in Stern-Gerlach atom interferometry allows, in principle, one to reach a range of very low kinetic energies (a few tens of neV); it also allows the device to be used as an interference filter for atomic waves. The technique used to produce such fields moving at atomic velocities is described. Experimental interference patterns obtained with a beam of ${\mathrm{H}}^{*}\mathrm{}\left(2S\right)\mathrm{}$ atoms are in good agreement with the calculations, which clearly demonstrates the feasibility of the method.

We investigate the influence of a Bose-Einstein condensate on the coherence properties of a traversing atomic beam. We derive a master equation describing the interaction between beam atoms and the condensate in $s$-wave approximation. Scattering rates are calculated and compared with the case of an ordinary Boltzmann gas. Special attention is paid to the decoherence of the beam, i.e., the decay of spatial coherence in the presence of the condensate. As an application, we explicitly calculate the visibility of the interference pattern in a double-slit experiment and indicate signs for the onset of the condensation.

We investigate the position localization of a polarized atom interacting with an off-resonant quantized standing-wave field. We show that a coherent cavity field achieves a higher resolution than a classical field. An almost perfect localization is possible when the atom passes through several identically prepared cavities.

The dynamics of a two-component dilute Bose-Einstein gas of atoms at zero temperature is described in the mean-field approximation by a two-component Gross-Pitaevskii equation. We solve this equation assuming a Gaussian shape for the wave function, where the free parameters of the trial wave function are determined using a moment method. We derive equilibrium states and the phase diagrams for the stability for positive and negative $s$-wave scattering lengths, and obtain the low-energy excitation frequencies corresponding to the collective motion of the two Bose-Einstein condensates.

A Bose gas in an external potential is studied by means of the semiclassical approximation. Analytical results are derived for the energy of an interacting Bose gas in a generic power-law trapping potential. An expression for the chemical potential below the critical temperature is also obtained. The theoretical results are in agreement with a recent energy measurement.

The effects of a recently proposed quasi-one-dimensional atom cavity on dipole-dipole collisions in a trapped atomic sample are investigated. It is shown that the cavity geometry leads to a high degree of selectivity in the allowed exchange of momentum during transitions between cavity modes. Furthermore, by a temporal modulation of the trap potential at the frequency corresponding to the energy defect of the momentum-selected transition, energy selectivity can also be achieved. Hence, in a properly designed atom laser cavity, the combined effects of energy and momentum selection rules give rise to a mode selectivity which is analogous to the mode selectivity in an optical laser.

We study the interaction of light with two Bose-Einstein condensates as an open quantum system. The two overlapping condensates occupy two different Zeeman sublevels and two driving light beams induce a coherent quantum tunneling between the condensates. We derive the master equation for the system. It is shown via stochastic simulations that the measurements of spontaneously scattered photons establish the relative phase between two Bose-Einstein condensates, even though the condensates are initially in pure number states. These measurements are nondestructive for the condensates, because only light is scattered and no atoms are removed from the system. Due to macroscopic quantum interference the detection rate of photons depends strongly on the relative phase between the condensates. This may provide a way to distinguish between initial number states and initial symmetry-breaking states of the condensates.

We have measured absolute total electron emission yields for impact of carbon cluster ions ${\mathrm{C}}_i^{q+}$ on atomically clean gold, as a function of cluster size (up to $i=60\mathrm{}$), charge (up to $q=5\mathrm{}$), and kinetic energy (up to 165 keV). Besides a linear dependence on cluster size and occurrence of electron emission well below the classical kinetic emission threshold, we find no dependence on the fullerene charge, and thus a suppression of potential electron emission. This is in contrast to the interaction of multicharged atomic ions with surfaces. We present molecular-dynamics calculations which provide evidence of fast quenching of the primary excitation energy via fragmentation of the projectiles.

We investigate the effect of quantum interference between the two transition pathways from the excited doublet to the ground level of a driven V atom on the spectral features of the resonance fluorescence emission. The ultranarrow spectral line at line center, which arises due to quantum interference, occurs over a wide range of parameters. The smaller the ratio of the excited doublet splitting to the effective Rabi frequency, the more pronounced the spectral line narrowing. However, the fluorescence emission is completely quenched when the atomic dipole moments are exactly parallel and the driving field is tuned to the average frequency of the atomic transitions. The narrow line is due to the slow decay rate of one dressed state, while the quenching arises from dressed-state trapping. A finite laser linewidth destroys the spectral narrowing features and the fluorescence quenching.

We show how a nonlinear chaotic system, the parametrically kicked nonlinear oscillator, may be realized in the dynamics of a trapped, laser-cooled ion, interacting with a sequence of standing-wave pulses. Unlike the original optical scheme [G. J. Milburn and C. A. Holmes, Phys. Rev. A 44, 4704 (1991)], the trapped ion enables strongly quantum dynamics with minimal dissipation. This should permit an experimental test of one of the quantum signatures of chaos: irregular collapse and revival dynamics of the average vibrational energy.

Owing to its numerical simplicity, a two-dimensional two-electron model atom, with each electron moving in one direction, is an ideal system to study nonperturbatively a fully correlated atom exposed to a laser field. Frequently made assumptions, such as the “single-active-electron” approach and calculational approximations, e.g., time-dependent density-functional theory or (semi)classical techniques, can be tested. In this paper we examine the multiphoton short pulse regime. We observe “nonsequential” ionization, i.e., double ionization at lower field strengths as expected from a sequential, single-active-electron point of view. Since we also find nonsequential ionization in purely classical simulations, we are able to clarify the mechanism behind this effect in terms of single-particle trajectories.

This paper extends the calculation of laser cooling forces on atoms with magnetic degeneracy to the case where the excited state is composed by a multiplet of levels with arbitrary energy separation. The sub-Doppler force that arises in the ${\sigma }_{+},{\sigma }_{-}$ field configuration is found to be strongly affected if other atomic levels lie close to the excited level of the cooling transition. The paper examines in detail the case in which the excited multiplet comes from spin-orbit coupling of angular momentum $L=1\mathrm{}$ and spin $S=1,$ forming the $J_e=0,$ $J_e=1,$ and $J_e=2\mathrm{}$ energy levels. The cooling transition $J_g=1\mathrm{}\leftrightarrow J_e=2\mathrm{}$ shows the sub-Doppler structure due to magnetic degeneracy. The force is modified by the two other transitions (if sufficiently close), even if these do not provide any mechanical effect on the atom when acting alone. The paper presents a detailed scheme for the construction of the relevant optical Bloch equations for the present case, which can be generalized to treat more complex atomic structures. The solutions to these equations are then discussed; several cases of energy separation are worked out and the ensuing graphs of the radiative force are shown. The calculations were carried out in both low- and strong-field regimes.

The laser heating process of photoelectrons during the multiphoton ionization of the ${\mathrm{CrO}}_4^{2\mathrm{-}}$ ions adsorbed on a disperse silica $\left({\mathrm{SiO}}_2\right)$ surface was studied on the basis of luminescence kinetics measurements carried out by using the fundamental mode of the Nd-doped–yttrium–aluminum–garnet pulsed laser (${\lambda }_{\mathrm{exc}}=1.064\mathrm{}\mu \mathrm{m},$ ${\tau }_p=20\mathrm{}\mathrm{ns}$). The luminescence response results from an intrinsic luminescence of ${\mathrm{CrO}}_4^{2\mathrm{-}}$ ions excited during recombination process (the 640-nm band) and recombination of photoelectrons with ionized surface oxygen-deficient centers (the 540-nm band). It has been established that at a fixed multiphoton ionization order there is a time delay (Δτ) of the luminescence response in relation to the excitation pulse and this delay depends on the laser light intensity. In the current work an explanation of this phenomenon is given in terms of the laser heating of photoelectrons.

We propose the cyclotron state retrieval of an electron trapped in a Penning trap by using different measurement schemes based on suitable modifications of the applied electromagnetic fields, and exploiting the axial degree of freedom as a probe. A test for the matter-antimatter symmetry of the quantum state is proposed.

We have extended our studies of control of the branching ratio for photoionization of atomic barium. This control is based on an interference between two distinct photoexcitation routes, each of which is a resonantly enhanced two-photon process. We report our experimental studies of the dependence of the interference on atomic beam density, laser power, selection of intermediate states, and relative polarization of the two field components. We observe that the potential for product control increases dramatically with increasing atomic beam density and depends strongly on the laser pulse energies as well.

We develop an auxiliary field approximation scheme for the many-body quantum Monte Carlo wave-function method to analyze numerically the system of cold atoms undergoing laser cooling. Numerical simulations for the three-dimensional Doppler cooling of bosonic and fermionic atoms are performed, which clearly exhibit the effects of quantum statistics.

A model is presented to calculate optical forces, friction, and diffusion for three-level atoms in a ladder configuration. This model is then applied to the $2^3{S}_1{-2\mathrm{}}^3{P}_2{-3\mathrm{}}^3{D}_3$ cascade in metastable helium. It is demonstrated that metastable helium atoms can be decelerated within a much shorter distance using cascade excitation by overlapping traveling waves. The equilibrium temperature representing the final width of the velocity distribution is calculated as a function of laser detuning and intensity. This equilibrium temperature is also calculated for the situation of overlapping standing waves (one-dimension), and is found to be well above the Doppler limit for two-level $2^3{S}_1{-2\mathrm{}}^3{P}_2$ excitation. Numerical results are compared with existing experimental data.

We propose a time-dependent level-crossing approach to the generation of high harmonics by a two-level system which stresses the periodicity of the processes involved. We establish relationships between multiple Landau-Zener crossings of energy levels and features of high harmonic generation such as cutoff, conditions for a plateau, and plateau height.

We study laser-induced transparency and dark-line effects in a two-level atomic system where the upper transition level is coupled by a laser field to a dressed system consisting of two lower-energy metastable states mixed by a second laser field (Π configuration). We show that the emission (absorption) spectrum of the two-level system develops two dynamic dark lines (transparency holes) with tunable central frequencies equal to the Rabi frequency of the second field with positive and negative signs, and widths proportional to that of the first field. The detailed evolution of these effects at low- and high-field intensities and the role of quantum interferences are discussed by presenting a model based on laser-induced continuum structure and adopting a dressed-state picture. We discuss various nonlinear processes in this system and show how the dynamics of emission and absorption spectra are determined by one- and two-photon coupling processes.