We have experimentally studied the steady-state characteristics of a cascaded quantum-optical system. The conceptually simple apparatus consists of a pair of high finesse cavities traversed by a beam of optically prepared two-level atoms. The output from the first cavity is coupled through a unidirectional device into the second cavity. The experimental results show quantitative agreement with a model that takes into account the geometric factors of the cavity modes and treats the two-level atoms as being purely radiatively broadened.

A master-equation approach to the semiconductor laser is derived. Projection-operator techniques are used to eliminate the fast motion occurring in the system, leading to a description of the system in terms of numbers of electrons and holes, with a fully quantum-mechanical description of the field. The output light statistics are calculated and compared with that appearing elsewhere [Y. Yamamoto and S. Machida, Phys. Rev. A 35, 5114 (1987)].

The optical density of a resonant medium significantly affects the output signal in time resolved nonlinear optical interactions. The resonant interaction with a medium reshapes any propagating short pulse, and the mutual interaction of several such pulses, as in four-wave mixing, must be treated self-consistently. We present a theoretical framework for the proper handling of the propagation of all pulses, input as well as generated, in the small area limit. For optically thick resonant absorbers, negative time delay signals are observed, and the apparent decay rate of the induced polarization is faster than the rate observed for thin samples. We experimentally measure degenerate four-wave mixing in an atomic medium as an example, and demonstrate the quality of the theoretical model by the excellent fit to measured signals over several orders of magnitude. The improved understanding enables us to provide a simple, but surprisingly accurate, estimate for the apparent decay rate in homogeneously broadened optically thick media: If the absorption is given by α, the propagation length is L, and the transverse relaxation time is ${\mathit{T}}_2$, the apparent decay rate 2/${\mathit{T}}_{\mathit{a}}$ of a time resolved four-wave mixing signal is given by 2/${\mathit{T}}_{\mathit{a}}$=(2/${\mathit{T}}_2$)(1+αL/2).

An atomic cascade experiment is proposed that includes the detection of a recoil atom after the emission of two photons. This would permit testing of the Bell inequality without the need for additional assumptions, provided that the quantum efficiency of single-photon detectors exceeds a threshold of 0.92. The atomic source consists of calcium atoms, first trapped and then accelerated by gravity, whose velocity is controlled before they reach the interaction region with the two counterpropagating laser beams. The procedure allows a relatively high background in the photodetectors.

It is shown that the state vector of a harmonic oscillator in a finite-dimensional Hilbert space changes sign only when the Hilbert space is of even dimension. The cyclic geometric phase for this finite-dimensional Hilbert-space harmonic oscillator is calculated. The effect of the finiteness of the Hilbert space on the dynamical and geometric phase change of a harmonic oscillator during a complete cycle is studied. In the limit of an infinite-dimensional case, the expressions reduce to the well known results.

A test of the second postulate of special relativity, the universality of the speed of light, using the Experiment on Timing Ranging and Atmospheric Sounding payload to be flown on board a terrestrial satellite is proposed. The propagation time of a light signal transmitted from one point to another without reflection would be measured directly by comparing the phases of two hydrogen maser clocks, one on board and one on the ground, using a laser or microwave time transfer system. An estimated uncertainty budget of the proposed measurements is given, resulting in an expected sensitivity of the experiment of δc/c<1.5×${10}^{\mathrm{-}9}$. The proposed test would require no equipment additional to what is already planned and so is of inherently low cost.

High-precision variational calculations using multiple basis sets in Hylleraas coordinates are presented for the 1${\mathit{s}}^2$2${\mathit{s}}^2$ ${}_{}{}^1{}_{}{}^{}$${\mathit{S}}_0$ state of beryllium. The variational bound of -14.667 350(8) a.u. for the nonrelativistic ground-state energy in the infinite-mass approximation is in good agreement with values obtained by conventional configuration-interaction calculations.

Total and state-selective charge-transfer cross sections for ${\mathrm{C}}^{4+}$-H collisions have been calculated in the energy range 0.02–1.0 keV/amu by employing the semiclassical, impact-parameter, close-coupling method based on a molecular-state description of the ${\mathrm{CH}}^{4+}$ system and including plane-wave translation factors. The calculated cross sections are in good agreement with the quantum calculations as well as with the experimental findings. The integral alignment (${\mathit{A}}_{20}$) parameter for the ${\mathrm{C}}^{3+}$(3p) state is also presented.

Near-threshold inner-shell photoionization of neon has been studied by measuring threshold photoelectron spectra in the energy regions of the 1${\mathit{s}}^{\mathrm{-}1}$ main line and the 1s2${\mathit{p}}^5$nl satellite states. The measured linewidth (0.22±0.03 eV) of the 1s→3p transition is more consistent with the observation of the 1s hole state linewidth than previous determinations. Features, assigned as doubly excited states and conjugate shakeup transitions, have been discerned in the 1s2${\mathit{p}}^5$nl satellite spectrum.

We present numerical calculations on the propagation of resonant optical pulse pairs in an absorbing medium of three-level Λ systems taking into account near dipole-dipole (NDD) interactions. We find that the NDD interactions reduce the effect of the electromagnetically induced transparency and the pulse group velocity. The NDD effect on phase modulation is also studied.

We show that a thermal field may be ‘‘purified’’ by its interaction with a flux of atoms having definite dipoles. In these circumstances, a transfer of coherence from the atoms to the field is realized. We show results for the Poissonian factor and for the purity factor (${\xi }_{\mathit{f}}$=1-${\mathit{Tr}}_{\mathit{f}}${${\mathrm{\rho }}_{\mathit{f}}^2$}). We also study the evolution of the phase distribution of the field in the framework of the Pegg-Barnett phase operator.

The saturation effects in a single-mode laser with multiplicative white noise are investigated through a full saturation laser model. The corresponding Fokker-Planck equation is transformed to a radial Schrödinger equation and the intensity correlation time and effective eigenvalues are calculated. Compared with experimental measurements, excellent agreement is obtained and the cavity decay rate is also determined. Relatively large errors occur in the third-order theory and the measured data.

The phase and frequency shifts in a Sagnac interferometer of arbitrary geometry with angular acceleration are calculated. A resonant cavity with angular acceleration is shown to display optical ringing. This phenomenon provides a direct test of electromagnetic wave propagation through a time-dependent spacetime metric. An analysis of ring lasers with angular acceleration is presented, which complements and corrects previous work.

In a recent paper, Reisfeld and Asaf [Phys. Rev. A 49, 348 (1994)] have undertaken an attempt to explain the linear dependence of the electron-atom scattering length on the atomic polarizability. They used the Born approximation, which is valid only for small atomic or molecular polarizabilities. Using the exact formula for the scattering length, we offer a simple expression for estimation of the scattering length by known values of the polarizability and ionization potential.

We have investigated the phase shift caused by a static electric field on a beam of Rb atoms carrying alignment (but no orientation) using an all optical technique with spatially separated pump and probe regions. Quantitative measurements of the phase shift agree with theoretical predictions to within 1.4%. An experimental demonstration of the velocity independence of the effect based on time-resolved measurements is given.

The double-excitation ${}_{}{}^1{}_{}{}^{}$${\mathit{P}}^{\mathit{o}}$ Rydberg series of He, converging to the N=4 to 9 thresholds, were studied by high-resolution photoionization using synchrotron radiation. Both the principal series with correlation quantum numbers K=N-2 and the secondary series with K=N-4 could be resolved up to previously unobtained n values. This allows a substantially improved analysis of the series with respect to energies and linewidths, leading to an improved understanding of the interseries interferences. The data are in excellent agreement with calculations based on the complex-rotation method.

Molecular ionization and ionic fragmentation of core excited CO valence and Rydberg states are studied by partial-ion-yield spectroscopy at vibrational resolution. The vibrational intensities of the Rydberg excitations differ significantly depending on the ionization and/or fragmentation channel. The observed intensity variations are explained by nondissociative excited final ionic states of the subsequent molecular Auger decay. The vibrational levels of these final states become selectively depopulated due to interaction with dissociative decay channels leading to ionic fragmentation.

We propose a method for copiously producing ultracold ground electronic-state molecules by two-photon absorption to a Rydberg molecular level (that spontaneously radiates to the ground molecular state) during collisions of ultracold atoms in a laser trap. Using the ${\mathrm{Na}}_2$ molecule as an example, the sequential two-photon absorption is via an intermediate high-lying vibrational level of the excited $1_{\mathit{g}}$ state and results in the formation of a given vibrational level of a ${}_{}{}^1{}_{}{}^{}\mathrm{\Pi }_{\mathit{u}}^{}{}_{}{}^{}$ Rydberg molecular state. Realistic calculations demonstrating the validity of the method are presented.