In response to the preceding Comment by Lynch, it is pointed out that squeezing does not require that the uncertainty product be a minimum, but for higher-order squeezing two field components that differ in phase by less than π/2 may be more appropriate as canonical conjugates than the two quadratures.

Back decay in resonant $\mathrm{dd}\mu$ formation is predicted to give rise to a new phenomenon: resonant hyperfine quenching. The temperature dependence of the rate for this process is calculated. Experimental observation of resonant hyperfine quenching would provide a quantitative measure of back decay, and allow the total, as opposed to the observed, resonant molecular formation rates to be determined.

We report the first observation of a resonance induced by a submillimeter wave between circular atomic Rydberg states of maximum angular momentum ($n=25\mathrm{}$, $m_l=24\mathrm{}\to n=24\mathrm{}$, $m_l=23\mathrm{}$ transition in lithium). This experiment is the first step towards a possible measurement of the Rydberg constant directly in frequency units. The Stark shift of the resonance has also been studied and its quadratic character put in evidence.

Recent measurements by Meyer et al. [Phys. Rev. A 32, 3310 (1985)] have revealed that the charge-transfer cross section for ${\mathrm{N}}^{7+}$ +H collisions is much larger than that for ${\mathrm{N}}^{7+}$ +${\mathrm{H}}_2$ collisions below 3 keV/amu, whereas the opposite trend is seen in the measured charge-transfer cross sections for ${\mathrm{C}}^{6+}$ on H and ${\mathrm{H}}_2$ targets. These anomalous experimental findings have been investigated for the first time theoretically, using the traveling-molecular-orbital expansion approach, in the energy range from 0.14 to 9 keV/amu. Our qualitative argument based on adiabatic potentials and corresponding couplings as well as a five-state close-coupling calculation provides support for experimental findings.

We describe a powerful method for computing cross sections for multiphoton ionization of atoms. The method is especially suited to absorption above threshold.

A variational expression is introduced for transition amplitudes, that is invariant under time reversal and is independent of the phases of trial states. With the use of time-dependent Hartree-Fock (TDHF) wave functions and a linear combination of atomic orbitals, exact numerical results for He + ${\mathrm{He}}^{2+}$ → ${\mathrm{He}}^{+}$ + ${\mathrm{He}}^{+}$ obtained within a small basis set, are compared with results from the variational functional. The variational procedure leads to a very substantial improvement over the standard TDHF results.

We have measured the energy and angular distributions of electrons emitted in collisions of 40-80-keV protons with a solid surface at grazing incidence. The angular distributions were investigated in the region of the specularly reflected ion beam. A broad peak in the spectrum is observed and tentatively ascribed to electron loss from projectiles neutralized at the surface.

Collisionally induced coherence transfer is observed for the first time, to our knowledge, between levels with different orbital angular momenta. A new method of precision atomic lifetime measurement is described. While requiring only a single laser, this method permits measurements on states that differ from the ground state by three units of angular momenta ($\Delta l=3\mathrm{}$). Using this technique we have found the calcium $\mathrm{}\left(3d4p\right)\mathrm{}{}_{}{}^1{}_{}{}^{}F$ lifetime to be 58.3 ± 2.0 nsec.

When the photoelectron becomes faster than the Auger electron in a photoionization event the postcollision interaction should vanish. This vanishing effect has been investigated and confirmed in terms of both the absolute energies and line shapes for the ${\mathrm{N}}_5-{\mathrm{O}}_{23}{\mathrm{O}}_{23}{}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}$ Auger electrons from xenon.

We present measurements of the stationary, joint statistical densities of velocity and displacement in a three-dimensional system: the damped oscillator with a bistable potential driven by additive, colored noise. Approximate Fokker-Planck theories of such "higher-dimensional" systems are assessed and compared to the measurements. Because of limitations inherent in all present theories and generally available numerical techniques, analog simulators appear to offer the only effective, high-resolution means for obtaining the joint probability densities of $d=3\mathrm{}$ systems.

The problem of representation dependence in the treatment of quantum tunneling in absorptive optical bistability is considered. Disregarding this problem can lead to order-of-magnitude errors in calculated tunneling rates. A new description is presented, valid near the state-equation turning points, in which regime the discrepancies between different representations are shown to disappear. This description is also useful for treating critical fluctuations and dispersive cases.

Ways to minimize spontaneous-emission noise due to quantum fluctuations in the medium are a major consideration in experiments designed to produce squeezed states of light. Motivated by the recent experiments of Slusher et al. we present a fully quantized model of nondegenerate four-wave mixing. We show that the spontaneous-emission noise, important at higher intensities in the degenerate case, may be minimized in the nondegenerate case for certain regimes of cavity and medium parameters.

We analyze the effects which arise from frequency noise in dispersive optical bistability. Over almost all the bistable range of the deterministic theory, the stationary probability distribution is strictly one-peaked instead of showing the expected bimodal configuration.

The pair correlation function and the velocity autocorrelation function of screened-Coulomb colloidal liquids, interacting via the Derjaguin-Landau-Verweg-Overbeek potential, are calculated using molecular dynamics. Examination of the structure reveals liquidlike behavior even at the lowest density which corresponds to a volume fraction less than ${10}^{-4\mathrm{}}$. The calculated radial distribution functions are in excellent agreement with experiment. The velocity autocorrelation function exhibits distinct oscillations at all densities, which indicates that the motion of a single particle is very strongly coupled to the collective modes of the screened-Coulomb colloidal liquid.

Tip-splitting solutions are found to a Stefan problem corresponding to solidification in the absence of surface tension.

Near the critical point of two nonmiscible liquids the reduced viscosity of a polymer diverges to infinity. These very high values of the reduced viscosity must be characterized as "apparent" values because they are not due to an increase of the dimensions of the macromolecular coils but to an increase of the correlation length of the two liquids by the presence of the polymer.

Diffusion-controlled coarsening (Ostwald ripening) of precipitated solutions is studied by numerical simulation. An algorithm is devised which exploits the screening of solute concentration fields, thereby removing the restriction to small systems of previous work. Simulation of the coarsening of 5000 droplets at 10% volume fraction reveals long-ranged dynamical correlations which broaden the droplet size-distribution function and increase the coarsening-rate coefficient.

Potential-energy surfaces V($r_2$,${\mathrm{theta}}_{12}$‖$r_1$=ζ) representing the potential energy seen by one electron given that the other electron is fixed at ζ are presented graphically for He and ${\mathrm{H}}^{\mathrm{-}}$ in both Cartesian and cylindrical polar representations. These pictures are an aid in visualizing the attractive and repulsive forces which influence the dynamics of the electrons in these systems. They also help to draw the distinction between the potentials around negative ions and neutral atoms. Similar plots of the pseudopotentials of the alkaline-earth atoms show why these quasi-two-electron species tend to behave more like linear triatomic molecules than like a system of two independent electrons in orbits about a nucleus. Finally, conditional probability distributions ρ($r_2$,${\mathrm{theta}}_{12}$‖$r_1$=ζ) are presented along with their corresponding V($r_2$,${\mathrm{theta}}_{12}$‖$r_1$=ζ) to illustrate these points.

By the use of a canonical transformation the problem of the harmonic oscillator with a time-dependent mass has been transformed to that of an oscillator with a time-dependent frequency. Pseudostationary and quasicoherent states are discussed.