Using a simple model, we calculate the heating rates arising from laser intensity noise and beam-pointing fluctuations in far-off resonance optical traps. Intensity noise causes exponential heating, while beam-pointing noise causes heating at a constant rate. The achievement of heating time constants well beyond 10 sec imposes stringent requirements on the laser noise power spectra. Noise spectra are measured for a commercial argon-ion laser to illustrate the expected time scales.

The spectral properties of the ion-trap laser [Europhys. Lett. 37, 317 (1997)] are investigated for a realistic multilevel scheme containing a $\Lambda$-type subsystem. In the laser region, the linewidth of the output spectrum is up to ten times smaller than the cavity damping rate and roughly proportional to the inverse of the mean photon number. Significant modifications and photon antibunching occur for thresholdless lasing. The fluorescence spectrum displays the signature of the coherently scattered resonator field.

We report a theoretical study of the $Z$-scan technique using Gaussian-Bessel beams. First we find that even the slightest deviation from a perfect Gaussian beam can change the sensitivity of the measurements significantly. Second we demonstrate that the propagation of Gaussian beams modulated by a small Bessel profile can increase the $Z$-scan sensitivity—obtained using conventional Gaussian beams—by a factor of 40 and more.

An “optical meson”(two-photon quantum soliton) is proven to exist in a parametric waveguide. This could provide an ideal quantum soliton environment, because of more realistic formation lengths and much larger binding energies than ${\chi }^{\mathrm{}\left(3\right)\mathrm{}}$ quantum solitons. We estimate the binding energy, radius, and interaction length in comparison to the ${\chi }^{\mathrm{}\left(3\right)\mathrm{}}$ case in optical fibers.

We find and analyze bound dipole solitary solutions in media with anisotropic nonlocal photorefractive material response. The dipole solutions consist of two elliptically shaped Gaussian-type beams separated by several diameters, and with a $\pi$ phase shift between their fields. Spatial evolution of two initially round Gaussian beams and their convergence to the above dipole solution is demonstrated experimentally.

A generalized form of the Einstein Podolsky-Rosen state is defined, embracing both classical and nonclassical states. It is shown that for such states, Bell’s inequality is equivalent to a constraint on stochastic field theories. Thus violation of Bell’s inequality can be observed also for weak violation of stochastic field theories. The Schrödinger-cat state is shown to be an example of this.

Recent theoretical investigations have shown that when atoms resonantly interact with strong, phase-fluctuating fields of fairly arbitrary character there is an underlying simplicity in their temporal response to the field. Specifically, theory predicts that the atom’s response can be divided into two distinct temporal components: an adiabatic component manifesting itself in the instantaneous frame of field-atom interactions as a Bloch-vector trajectory figure-eight pattern, and a nonadiabatic component manifesting itself as population variations oscillating at the Rabi frequency. Here, we experimentally verify theoretical expectations regarding the nonadiabatic component of the field’s temporal response. In the presence of a resonant field suffering broadband phase noise we show that atomic population fluctuations display a resonant enhancement at Fourier frequencies corresponding to the Rabi frequency, and that the characteristics of this resonance are similar to those of a damped, driven harmonic oscillator.

Noninversion lasing is investigated in Λ-type three-level atomic systems that are coupled to two modes of the electromagnetic field. As a result of an external field driving the transition between the lower two closely spaced levels, laser action can be achieved in both modes simultaneously at arbitrarily small initial upper-level population (lasing without inversion) provided the pumping rate exceeds a certain threshold. The relative phase of the two modes is locked to a particular value controlled by the phase of the external field. In addition, new regimes of the laser operation arise when initial coherences between various atomic levels are also injected into the resonator. Firstly, laser action can be achieved in both modes at arbitrarily small pumping (no threshold). Secondly, the injected atomic coherence can control competition between the modes, and result in a variety of multistable steady-state behavior illustrating the very sensitive dynamics of the system.

For a system of $n$ spin-$\frac{1}{2}$ particles and for two measurement possibilities for each particle there is always a state showing Hardy’s nonlocality. Mixed states of an $n$- $(n>~3)$ particle system can only show Hardy’s nonlocality. Product states for any $n$ never show nonlocality.

It is well known in the Thomas-Fermi (TF) theory that the functional derivative $\delta T/\delta n\left(r\right),$ with $T$ the kinetic energy and $n\left(r\right)\mathrm{}$ the ground-state electron density, is proportional to $n^{2/3}\mathrm{}\left(r\right).$ But the differential equation satisfied by the TF self-consistent density for atoms is shown here to express $n^{1/3}\mathrm{}\left(r\right)\mathrm{}$ as a linear combination of ${\nabla }^{2}n/n$ and $(\nabla {n/n)}^2.$ Hence a nonlocal form for $\delta T/\delta n\left(r\right)\mathrm{}$ follows, solely in terms of these two variables.

We employ crossed-beam laser spectroscopy to measure the hyperfine structure of the $6p{}^2{P}_{1/2}$ state of atomic ${}^{133}\mathrm{Cs}$ $(I=$$\frac{7}{2}$$).\mathrm{}$ A frequency-stabilized Ti:sapphire laser with 1-GHz sidebands excites a thermal atomic cesium beam through the $6s{}^2{S}_{1/2}$ $F=3,$$4\to 6p{}^2{P}_{1/2}$ $F^{\prime }=3,4\mathrm{}$ resonance transitions at 895 nm. The hyperfine splitting of the excited state is determined from the observed fluorescence spectra. Our result for the $6p{}^2{P}_{1/2}$ $F^{\prime }=3\mathrm{}$ to $F^{\prime }=4\mathrm{}$ hyperfine splitting is 1167.54(32) MHz, yielding a magnetic dipole coefficient of $A=291.89\mathrm{}\left(8\right)\mathrm{}$ MHz. In this Brief Report we also compare our results with previous measurements and theory.

The integral equation of Holas and March [Int. J. Quantum Chem. 61, 263 (1997)] for the density-functional exchange-correlation potential (functional derivative of the energy), in terms of density matrices, is separated into its exchange and correlation components by means of the perturbation theory of Görling and Levy [Phys. Rev. B 47, 13 105 (1993)]. Implementation of the resultant partitioning is discussed for practical self-consistent calculations.

Herbst and Simon [Phys. Rev. Lett. 41, 67 (1978)] have proven that the complex-scaling method (CSM) is applicable to the Stark effect in atoms. However, their proof is limited to complex scaling with an argument <π/3. Their method makes no statement as to the validity of CSM beyond this region. This article reports on a detailed numerical study of the use of CSM for the Stark effect in hydrogen. The results suggest a limitation on the range of energies of Stark resonances that can be calculated by CSM. We find that CSM does not produce resonances with energies $\mathrm{Im}E>~\sqrt{3}\mathrm{Re}E,$ which corresponds precisely to the range of validity of the Herbst-Simon theory.

It is mathematically indicated that the widely used diabatic-by-sector recipe for solving coupled radial equations in the hyperspherical coordinate method causes non-negligible errors and these are revealed especially for extremely low-energy scattering. The intrinsic defects due to this method are illustrated for both bound state and the scattering states of $\mathrm{dt}\mu$. The calculated results are also compared with those obtained by the adiabatic expansion method.

In the present work, the molecular continuum-distorted-wave approximation is formulated for the single-electron capture reaction from ${\mathrm{H}}_2^{+}$ targets. The initial bound wave function is distorted by a projectile-electron continuum factor. In the exit channel, the final electronic wave function is distorted by a product of the continuum factors corresponding to the interaction between the electron and each one of the nuclei of the target. The doubly differential cross sections as a function of the projectile scattering angle are evaluated for different molecular alignments for the case of proton impact.

The Bose-Einstein gas in an external potential is studied by means of the local-density approximation. An analytical result is derived for the dependence of the critical temperature of Bose-Einstein condensation on the mutual interaction in a generic power-law potential.

Antiphase dynamics of an optically pumped ${\mathrm{NH}}_3$ bidirectional ring laser under the chaotic, phase-sensitive mode coupling is experimentally observed. Our experimental result suggests strongly that the dynamics is a generic behavior of the laser.

The paper of Yunjie, Kezhu, and Xianghe [Phys. Rev. A 55, 1548 (1997)] points out an error in the conclusions of Lynch and Mavromatis [Phys. Rev. A 52, 55 (1995)]. In the present paper it is shown how, with the appropriate modifications, the results of Lynch and Mavromatis may still be used.

Alter and Yamamoto [Phys. Rev. A 53, R2911 (1996)] claimed to consider “protective measurements” that we have recently introduced. We show that the measurements discussed by Alter and Yamamoto are not the protective measurements we proposed. Therefore, their results are irrelevant to the nature of protective measurements.

The adiabatic “protective measurement” suggested by Aharonov, Anandan, and Vaidman [Phys. Lett. A 178, 38 (1993)] is a measurement of a discrete energy eigenstate, in which the entanglement between the measured state and the quantum probe is avoided approximately when they interact adiabatically, and the measured state is left approximately unchanged (up to a phase factor) for all measured observables. This measurement scheme, however, does not overcome the reduction of the measured state, because this state is only approximately, and not exactly, disentangled from the quantum probe. Our recent analysis of a measurement scheme of a squeezed harmonic-oscilllator state [Phys. Rev. A 53, R2911 (1996)], in which the entanglement between the measured state and the probe is avoided exactly, and the measured state is left exactly unchanged (up to a phase factor) for all measured observables, suggests that in order to measure the quantum state of a single system without changing this state, full a priori information about this state is required.