We have observed the splitting of coherent population trapping resonances in Cs vapor due to the influence of the nuclear magnetic moment which is already resolved in a magnetic field of about the strength of the geostatic field. By choosing appropriate laser polarizations and field direction vector and quadrupole coupled transitions can be investigated separately. The splitting allows to determine the ratio of nuclear to electronic g-factors.

We propose an efficient mechanism for the evaporative cooling of trapped fermions directly into quantum degeneracy. Our idea is based on an electric field induced elastic interaction between trapped atoms in spin symmetric states. We discuss some novel general features of fermionic evaporative cooling and present numerical studies demonstrating the feasibility for the cooling of alkali-metal fermionic species ${}^6\mathrm{Li},$ ${}^{40}\mathrm{K},$ and ${}^{82,84,86}\mathrm{Rb}.$ We also discuss the sympathetic cooling of fermionic hyperfine spin mixtures, including the effects of anisotropic interactions.

We have nonperturbatively computed dc-field tunneling rates, linear and nonlinear dynamic polarizabilities, and two-, three-, four-, and five-photon ionization rates for He, for frequencies ω in the range ħω=4.9–26.4 eV and for intensities in the range $3.5\times {10}^{12}–1.715\times {10}^{14}{\mathrm{W}/\mathrm{c}\mathrm{m}}^2.$ The calculations systematically incorporated electronic structure and electron correlation effects in the discrete and continuous spectra, while the two-electron state symmetries were ${}^{1}S,$ ${}^{1}P,$ ${}^{1}D,$ ${}^{1}F,$ ${}^{1}G,$ and ${}^{1}H$ of even and odd parities. The calculations were made by implementing a time-independent many-electron, many-photon theory which obtains cycle-averaged energy shifts $\Delta (\omega ,F)$ and energy widths $\Gamma (\omega ,F)$ nonperturbatively, where F is the field strength. These quantities are the real and imaginary parts of a complex eigenvalue $z_0$ (the result of the overall calculation), after the subtraction of the unperturbed real energy $E_0.$

We find that inelastic collisional processes in Bose-Einstein condensates induce local variations of the mean-field interparticle interaction, and are accompanied by the creation and annihilation of elementary excitations. The physical picture is demonstrated for the case of three-body recombination in a trapped condensate. For a high trap barrier the production of high-energy trapped single-particle excitations results in a strong increase of the loss rate of atoms from the condensate.

We propose a general method for measuring an arbitrary observable of a multimode electromagnetic field using homodyne detection with a single local oscillator. In this method the local oscillator scans over all possible linear combinations of the modes. The case of two modes is analyzed in detail and the feasibility of the measurement is studied on the basis of Monte Carlo simulations. We also provide an application of this method in tomographic testing of the Greenberger-Horne-Zeilinger state.

We consider nondegenerate pump-probe spectroscopy of $V$ systems under conditions such that interference among decay channels is important. We demonstrate how this interference can result in new gain features instead of the usual absorption features. We relate this gain to the existence of a new vacuum induced quasi-trapped-state. We further show how this also results in a large refractive index with low absorption.

We elucidate the relationship between the linear oscillator with time-dependent frequency, damping, and driving, and the autonomous oscillator with unit frequency and no damping or driving. Such a relationship can be derived from a canonical transformation and a redefinition of the time. A study of the scalars of the transformation makes it possible to write down the evolving quantum states for the nonautonomous Hamiltonian given the evolving states for the autonomous harmonic oscillator.

Extensions of average Hamiltonian theory to quantum computation permit the design of arbitrary Hamiltonians, allowing rotations throughout a large Hilbert space. In this way, the kinematics and dynamics of any quantum system may be simulated by a quantum computer. A basis mapping between the systems dictates the average Hamiltonian in the quantum computer needed to implement the desired Hamiltonian in the simulated system. The flexibility of the procedure is illustrated with NMR on ${}^{13}\mathrm{C}$ labeled alanine by creating the nonphysical Hamiltonian ${\sigma }_z{\sigma }_z{\sigma }_z$ corresponding to a three-body interaction.

We propose the use of a trapped electron to implement quantum logic operations. The fundamental controlled-NOT gate is shown to be feasible. The two quantum bits are stored in the internal and external (motional) degrees of freedom.

In a three-level $\Lambda$ system, a bichromatic light field can induce a ground-state coherence that leads to vanishing absorption of the bichromatic field. Although this coherence is between ground states only, in a real atom it can nevertheless be influenced by the hyperfine structure of the excited state. We present experimental results which show that for suitable detunings of the bichromatic field from optical resonance, the specific contribution of each individual hyperfine level of the excited state can be distinguished through increased amplitude or width of the ground-state coherence.

The electron affinity of Ir is measured to be 12617.4(12) ${\mathrm{cm}}^{\mathrm{-}1}$$\left[1.56436\right(15\left)\mathrm{eV}\right],$ from photodetachment studies on ${\mathrm{Ir}}^{\mathrm{-}}.$ Previous measurements of the electron affinity of platinum reported results which were inconsistent within quoted error bars. A photodetachment study with a very improved energy resolution, signal-to-noise ratio, and signal-to-background ratio, was conducted on ${\mathrm{Pt}}^{\mathrm{-}},$ and yields a much more accurate electron affinity for Pt of 17140.1(4) ${\mathrm{cm}}^{\mathrm{-}1}$ $\left[2.12510\right(5\left)\mathrm{}\mathrm{}\mathrm{eV}\right],$ in good agreement with the most recent measurement. Possible explanations for the poor agreement between the earlier results are discussed. In both the ${\mathrm{Ir}}^{\mathrm{-}}$ and ${\mathrm{Pt}}^{\mathrm{-}}$ spectra, the data indicate that the detachment cross section deviates from the expected Wigner threshold law, even near the detachment threshold. This behavior cannot be explained by the correction terms to the Wigner law proposed by the currently available threshold detachment models.

The R-matrix method has been used to perform a five-state ${(}^1{S-}^3{P}^o{-}^3{D-}^1{D-}^1{P}^o)$ close-coupling calculation on the photodetachment of ${\mathrm{Ca}}^{-}$ ions with photon energies from threshold to 4 eV. Calculations both with and without the core-valence electron correlation are carried out. The dominant core-valence electron correlation is included by exciting one $3p$ electron to the valence orbitals. It has been found that the so-called core-valence correlation is quite crucial to the prediction of the position of the Cooper minimum and the distinct behavior of the photodetachment cross sections near ${}^3{P}^o$ and ${}^1{P}^o$ thresholds. The core-valence correlated calculation results in a Cooper minimum at 1.20 eV and a narrow shape resonance just above the $4s4p{}^1{P}^o$ threshold. These structures are in good agreement with experimental observations. The present result also supports the previous conclusion that core-valence electron correlation is responsible for reducing the electron affinity of valence-only results to much closer to the experiment.

We have measured electron number statistics of highly charged ions interacting with a clean single crystal Au(111) surface under various angles of incidence in the range from 45° to almost 0° with respect to the surface. For small angles of incidence (typically about 3°) we have also measured the scattering distribution of the reflected projectiles on a position-sensitive detector in coincidence with the number of emitted electrons. Our results allow a clear separation of above- and below-surface electron emission. By comparison with electron emission yields for very slow projectiles under normal incidence conditions, we are able to determine the number of electrons produced by potential and kinetic emission processes. Simulations of the kinetic electron emission along specific trajectories (e.g., projectiles reflected from ideally flat surface areas as opposed to those entering the crystal at target imperfections) show good agreement with our experimental results.

We propose the use of a copropagating probe pulse in experimental tests of correlated pulse theory. We present formulas for amplitudes and velocities of a self-similar pulse trio propagating in a medium with energy levels in the configuration of the letter N. Remarkably, in contrast to previous theoretical studies, we find that the inclusion of the probe pulse lifts a rigid restriction on the oscillator strengths of the transitions.

We have built a Zeeman-slower apparatus which produces a slow and cold cesium atomic beam. The atomic beam has a mean velocity in the range 35–120 m/s and a high atomic current of more than $2\times {10}^{10}$ cold atoms/s. A small longitudinal velocity spread was achieved by optimizing the termination of the slowing process. The measured value of less than 1 m/s is consistent with a numerical simulation of the slowing process. With a magnetic lens and a tilted two-dimensional optical molasses stage, the slow atomic beam is transversely compressed, collimated, and deflected. We achieve a transverse temperature below the Doppler limit. The brilliance of this beam has been determined to be $7\times {10}^{23}$ atoms ${\mathrm{s}}^{-1}{\mathrm{m}}^{-2}$ ${\mathrm{sr}}^{-1}.$ By optical pumping the slow atomic beam can be polarized in the outermost magnetic substates ${F=4,m}_F=\pm 4,$ of the cesium ground state. This brilliant beam is an ideal source for experiments in atom optics and atom lithography.

Vortex dynamics in inhomogeneous Bose-Einstein condensates are studied numerically in two and three dimensions. We simulate the precession of a single vortex around the center of a trapped condensate, and use the Magnus force to estimate the precession frequency. Vortex ring dynamics in a spherical trap are also simulated, and we discover that a ring undergoes oscillatory motion around a circle of maximum energy. The position of this locus is calculated as a function of the number of condensed atoms. In the presence of dissipation, the amplitude of the oscillation will increase, eventually resulting in self-annihilation of the ring.

We demonstrate several results for the nonlinear interferometer, that emerge from a formalism which elegantly describes the output field of the nonlinear interferometer as two-mode entangled coherent states. We clarify the relationship between squeezing and entangled coherent states, since a weak nonlinear evolution produces a squeezed output, while a strong nonlinear evolution produces a two-mode, two-state entangled coherent state. In between these two extremes exist superpositions of two-mode coherent states manifesting varying degrees of entanglement for arbitrary values of the nonlinearity. The cardinality of the basis set of the entangled coherent states is finite when the ratio χ/π is rational, where χ is the nonlinear strength. We also show that entangled coherent states can be produced from product coherent states via a nonlinear medium without the need for the interferometric configuration. This provides an important experimental simplification in the process of creating entangled coherent states.

We study the use of Brillouin-Wigner perturbation theory (BWPT) coupled with Padé approximant summation techniques to solve problems formulated as coupled (diabatic, adiabatic, “mixed”) channels. Several iterative BWPT schemes are examined. BW perturbation series demonstrate better convergence properties, making them more practical and efficient than traditional Rayleigh-Schrödinger perturbation series.

Relativistic-configuration-interaction calculations predict that the ${5d}^7{6s}^{2}J=9/2,$ 7/2, 5/2 and 3/2 ${}^{4}F$ levels of ${\mathrm{Os}}^{-}$ are all bound with binding energies 1.048, 0.508, 0.292, and 0.211 eV, respectively. To aid future experimental work, hyperfine structure constants for all levels and magnetic dipole decay rates have also been calculated.

We derive an expression for the diffusion cross section of identical atoms and use it in a report of diffusion, viscosity, total, spin-change, frequency-shift, and broadening cross sections in hydrogen, calculated with improved interaction potentials. We also report some total cross sections for spin-polarized hydrogen.