A set of equations that the kinetic-energy functional of a system of noninteracting fermions and its derivatives must satisfy are derived. These complement the hierarchy of equations derived by Kugler [Phys. Rev. A 41, 3489 (1990)]. As a consequence of these equations the kinetic energy can be expressed in terms of any of its functional derivatives.

We calculate the photoionization cross section of a ${\mathrm{BaO}}_2$ molecule in the region of the Ba 4d-f giant dipole resonance, i.e., 90–150 eV, taking into account both many-electron screening and molecular, multiple scattering effects. The potential of the oxygen ligand atoms is expanded in spherical harmonics around the central Ba atom and screening is treated within the time-dependent local-density approximation. The cross section shows prominent modulations and structure due to final-state molecular resonance effects, in good qualitative agreement with experimental results on solids.

Mean energy losses of foil-transmitted ${\mathrm{H}}_2^{+}$ ions are measured for the incidence of 9.6-MeV/amu ${\mathrm{H}}_2^{+}$ ions on carbon foils of 1.5–8.5 μg/${\mathrm{cm}}^2$ thickness. The measured ions are those that have traversed the carbon foil without loss of their original electrons. The stopping power of carbon for 9.6-MeV/amu ${\mathrm{H}}_2^{+}$ ions, derived from the energy losses, is 55.8±4.6 eV/(μg/${\mathrm{cm}}^2$). The obtained stopping power is compared with that calculated with the first Born approximation. The calculated result is slightly larger than the experimental one.

We know that the Fano profile is obtained for single-photon absorption to the ionization continuum in the presence of an autoionizing state. We have shown that, in the case of (1+1)-photon absorption to an autoionizing state embedded in the ionization continuum, the absorption profile changes radically to a mirror image of the Fano profile for the value of q=±1, q being the Fano q parameter. Moreover, for higher values of q, the (1+1)-photon absorption profile exhibits a broad minimum, while a distinct interference pattern is obtained in the profile of single-photon absorption. The absorption line shape has been found to oscillate between the Fano and a modified Fano profile for the autoionization through odd and even number of steps, respectively, via resonances.

Electric-field distributions in coplanar-electrode configurations are studied experimentally through the linear electro-optic (EO) measurements in poled EO polymers. Thermoplastic poling of an isotropic guest-host polyimide system was employed to investigate the electrostatic factors determining the field distribution inside the EO polymer. Electrostatic analysis of the field distribution shows that the introduction of a new boundary condition formed by the polymer surface is necessary to account for field distributions measured by the linear EO effect.

We study the time evolution of the atomic population inversion 〈${\mathrm{\sigma }}_3$(t)〉 of a Jaynes-Cummings model with an intensity-dependent coupling which is described by a para-Bose oscillator of the Calogero-Vasiliev type. We show that both the time and the shape of the revival signal are sensitive to the order of the para-Bose oscillator and the value of the average number of cavity photons.

It is shown that, contrary to the conclusions of a paper by Baseia, De Brito, and Bagnato [Phys. Rev. A 45, 5308 (1992)], a harmonic oscillator can be squeezed by consecutive sudden changes of its mass to and back.

We propose a technique to prepare two or more atoms in certain entangled states, based on the interaction of the atoms with a cavity mode. After the atomic state is prepared, the cavity mode is left in the vacuum state, so dissipation does not affect the generated entangled states. These states could be used for improved tests that challenge local realistic theories, and to examine related phenomena, which, thus far, have been realized only with photons.

In recent years parametric-down-conversion photon sources have been proposed and used to test local realism via Bell-type inequalities. This study shows that this technique fails to discriminate between quantum mechanics and local realism in all those tests in which polarization correlations are measured, since dichotomic observables cannot be associated satisfactorily with the state produced in these experiments. A more adequate description of these photon sources leads to an alternative inequality for Einstein locality, which is always satisfied by quantum-mechanical predictions. The result can be extended to all the experiments in which only one-half of the emitted pairs are detected.

${}_{}{}^3{}_{}{}^{}\mathrm{HeH}_{}^{+}{}_{}{}^{}$ molecular ions have been stored in an ion storage ring and allowed to interact with electrons from an electron cooler. Neutral reaction products have been counted and an absolute cross section for dissociative recombination has been measured. The spectrum reveals a prominent peak at about 18 eV and a weaker one at about 30 eV. The origin of the low-energy dissociative recombination of ${}_{}{}^3{}_{}{}^{}\mathrm{HeH}_{}^{+}{}_{}{}^{}$ is discussed, and the mechanism responsible for the high-energy peak is modeled by calculating the vibrational overlap between the ground state of the molecular ion and several repulsive states. It is concluded that ions populate primarily the singlet electronic ground state, and that the peaks at 18 and 30 eV arise predominantly from direct dissociative recombination of vibrationally cold ${}_{}{}^3{}_{}{}^{}\mathrm{HeH}_{}^{+}{}_{}{}^{}$.

We investigate the behavior of the cross section for inelastic photon scattering in the limit of high but nonrelativistic photon energies ω→∞ at helium leading to two-electron transitions. Our calculation employs fully correlated wave functions for the helium ground state and different forms for approximate two-electron final states. We determine the ω→∞ limit for the ratio of double to single ionization. We find the high-energy behavior to differ significantly from the one for photoabsorption. Our results confirm our previous estimate [Andersson and Burgdörfer, Phys. Rev. Lett. 71, 50 (1993)] but disagree with recent predictions by Hino et al. [Phys. Rev. Lett. 72, 1620 (1994)].

A framework is presented to compute absolute thermodynamic properties of complex molecules which are described algebraically. Using some basic properties of the algebraic formalism, it is pointed out that one can compute not only ensemble averages, but the absolute thermal quantities such as the density of states and partition function. Some results are presented for a simple diatomic molecule and for ${\mathrm{C}}_2$${\mathrm{H}}_2$.

We present calculations of triple-differential cross sections (TDCS) for electrons scattering on the ground state of atomic hydrogen at incident energies of 54.4 and 150 eV. The convergent close-coupling method is used. For this target the method is fully ab initio. The total wave function is expanded in an ever increasing Laguerre basis until convergence in the TDCS has been obtained. We generally find good agreement with experiment, though some small quantitative discrepancies remain.

Through a theoretical analysis combined with new experimental data, obtained through a technique that allows observation of ionization originating from a constant, sharply limited ion extraction volume, we show that double multiphoton ionization of Xe and Kr in the wavelength range 527 to 531 nm does not involve an observable direct two-electron channel but does involve an inner subshell (5s for Xe and 4s for Kr) excited state which can leave the ion in an excited state. This explains the unusual laser power dependence that had been attributed to a direct two-electron channel.

We present results for the behavior of loss rates in magneto-optical traps in strong fields. They show that the trap loss rate does not saturate along with the excitation process. On the contrary, it increases with the laser-field intensity inside the region of saturation of the laser transition. We also show that an alternative method, the adiabatic formulation of the optical Bloch equations, can be used to predict the behavior of trap loss over a wide range of temperatures and field intensities.

We study the effects of the resonant dipole interaction between identical atoms undergoing polarization-gradient laser cooling. A generalized master equation, which includes both the atom-field interaction and the dipole-dipole interaction between atoms, is derived. We then apply this equation to the particular case of two identical atoms cooled simultaneously by a one-dimensional cooling field. We show that, as the average center-of-mass separation between the two atoms is reduced to be less than an optical wavelength λ/2π, the population of the ground motional state of the atoms begins to decrease sharply, indicating a breakdown of the cooling mechanism due to the enhanced atom-atom interaction.

The generation of tunable short-pulse xuv radiation between 90 and 40 nm by nonlinear mixing of a fixed-frequency high-power Ti:sapphire laser with tunable radiation is described. As a tunable source an optical parametric generator pumped by part of the Ti:sapphire laser radiation has been used, producing tunable radiation in the range of about 520 to 650 nm with a peak power of up to 0.5 GW.

We report a new potential model for phase diffusion in class-B lasers exposed to external optical feedback. Excited relaxation oscillations cause the potential to be nonlocal. Analytical results using this new potential agree very well with the full system dynamics. We indicate the experimental conditions for which the nonlocal potential becomes manifest in semiconductor lasers.