In this paper, we study triple-ionization-induced dissociation in ${\mathrm{N}}_2$ and ${\mathrm{O}}_2$ for laser polarization aligning either parallel or perpendicular along the molecular axis. For the first time, we demonstrate that vertical or nonvertical transition can be turned on and off by simply switching the laser polarization between being perpendicular and parallel to the molecular axis. We also show that the dependence of kinetic energy release on intensity can be used to distinguish vertical from nonvertical transition in triple-ionization-induced dissociation.

We experimentally demonstrate the creation and characterization of Einstein-Podolsky-Rosen (EPR) correlation between optical beams in a time-gated fashion. The correlated beams are created with two independent continuous-wave optical parametric oscillators and a half beam splitter. We define the temporal modes using a square temporal filter with duration $T$ and make time-resolved measurements on the generated state. We observe correlations between the relevant conjugate variables in the temporal mode which correspond to EPR correlation. Our scheme is extendable to continuous-variable quantum teleportation of a non-Gaussian state defined in the time domain such as a superposition of coherent states.

We extend the validity of Hardy’s nonlocality without inequalities proof to cover the case of special one-parameter classes of nonpure statistical operators. These mixed states are obtained by mixing the Hardy states with a completely chaotic noise or with a colored noise and they represent a realistic description of imperfect preparation processes of (pure) Hardy states in nonlocality experiments. Within such a framework we are able to exhibit a precise range of values of the parameter measuring the noise affecting the nonoptimal preparation of an arbitrary Hardy state, for which it is still possible to put into evidence genuine nonlocal effects. Equivalently, our work exhibits particular classes of bipartite mixed states whose constituents do not admit any local and deterministic hidden variable model reproducing the quantum mechanical predictions.

The $m{\alpha }^6$ correction to energy is expressed in terms of an effective Hamiltonian $H^{\left(6\right)}$ for an arbitrary state of helium. Numerical calculations are performed for $n=2$ levels, and the previous result for the $2{}^{3}P$ centroid is corrected. While the resulting theoretical predictions for the ionization energy are in moderate agreement with experimental values for $2{}^{3}S_1$, $2{}^{3}P$, and $2{}^{1}S_0$ states, they are in significant disagreement for the singlet state $2{}^{1}P_1$.

We report results from collinear time-dependent close-coupling (TDCC), distorted-wave (DW), and $R$ matrix with pseudostates calculations for the electron-impact ionization of H-like ions up to $Z=6$ within an $s$-wave model. We compare the results of these calculations with those from a collinear classical trajectory Monte Carlo calculation to investigate the correspondence between the quantal and classical ionization probabilities as the principal quantum number of the initial state increases. In these model calculations, the electron-electron interaction is represented by the collinear $s$-wave potential given by $1∕(r_1+r_2)$. We study the ionization probability from the ground state and highly excited states up to $n=25$ as a function of incident energy and the charge of the ion. We show that the fully quantal ionization probability converges to the classical results rapidly for hydrogen. The higher ion stages exhibit much slower convergence with respect to $n$. We observed good agreement between the DW and TDCC for the $n$ range we have considered for ${\mathrm{B}}^{4+}$. For hydrogen, we found fairly good agreement between the DW and TDCC for the ground state, but the worsening disagreement with increasing $n$. There is reasonable agreement between the results from the $R$-matrix calculations and the results from the TDCC calculations confirming the convergence of the TDCC results.

Cross sections have been measured for $K\alpha$ x-ray production in targets of Al, Ti, Cu, Zr, Ag, Sm, and Ta by Ar, Kr, and Xe ions ranging in energy from $2.5\text{to}25\mathrm{MeV}∕\mathrm{amu}$. In addition, the degree of simultaneous $L$-shell ionization and the enhancement of the $K\alpha$ diagram lines due to secondary ionization processes were assessed by performing high-resolution spectral measurements on Al, Ti, V, Co, and Cu targets. This information was used to correct for the $K\alpha$ x-ray yield produced by electron bombardment and photoionization, and to calculate the fluorescence yields needed to convert the $K\alpha$ x-ray production cross sections into $K$-vacancy production cross sections. The resulting cross sections were compared with the predictions of the perturbed stationary state approximation with corrections for projectile energy loss, Coulomb deflection, and relativistic effects (ECPSSR theory). Also, the scaling properties of the $K\alpha$ x-ray production cross sections were examined and a semiempirical (universal) curve was deduced that reproduces the measured cross sections to within $\pm 30\%$ on average.

We have measured longitudinal nuclear relaxation rates of ${}^{129}\mathrm{Xe}$ in $\mathrm{Xe}\text{−}{\mathrm{N}}_2$ mixtures at densities below 0.5 amagats in a magnetic field of $8.0\mathrm{T}$. We find that intrinsic spin relaxation in this regime is principally due to fluctuations in the intramolecular spin-rotation (SR) and chemical-shift-anisotropy (CSA) interactions, mediated by the formation of ${}^{129}\mathrm{Xe}\text{−}\mathrm{Xe}$ persistent dimers. Our results are consistent with previous work done in one case at much lower applied fields where the CSA interaction is negligible and in another case at much higher gas densities where transient xenon dimers mediate the interactions. We have verified that a large applied field suppresses the persistent-dimer mechanism, consistent with standard relaxation theory, allowing us to measure room-temperature gas-phase relaxation times $T_1$ for ${}^{129}\mathrm{Xe}$ greater than $25\mathrm{h}$ at $8.0\mathrm{T}$. These data also yield a maximum possible low-field $T_1$ for pure xenon gas at room temperature of $5.45\pm 0.2\mathrm{h}$. The coupling strengths for the SR and CSA interactions that we extract are in fair agreement with estimates based both on previous experimental work and on ab initio calculations. Our results have potential implications for the production and storage of large quantities of hyperpolarized ${}^{129}\mathrm{Xe}$ for use in various applications.

We give a detailed account of an ab initio computational treatment of multiphoton single ionization (with or without excitation) as well as double ionization of two-electron atoms exposed to short-wavelength electric fields. This treatment is time dependent and based on a spectral method of configuration interaction type combined with Jacobi or $J$-matrix calculations. It involves a complete treatment of electron-electron correlation in the initial and final states as well as during the time propagation. The atom eigenvalue problem is first solved by means of the spectral method. It consists of expanding the atom wave function in a basis of products of complex Coulomb-Sturmian functions of the electron radial coordinates and bipolar harmonics of the angular coordinates. This method allows a high-resolution study of many atomic states, in particular high-lying singly excited states as well as many doubly excited states. Results for He are presented and discussed in detail. The time-dependent Schrödinger equation is then solved by means of an explicit scheme of Runge-Kutta type. An accurate calculation of the probability of single and double ionization is carried out by projecting the ionizing wave packet on fully correlated multichannel scattering wave functions generated by means of the $J$-matrix method. After a detailed analysis of the accuracy of this method, we show that our results for the total cross section of one-photon single and double ionization of He and ${\mathrm{H}}^{-}$ are in very good agreement with those obtained by the most sophisticated approaches. Two-photon double ionization of He is then considered, and results are presented in a frequency regime where substantial discrepancies subsist between all existing calculations. Our results demonstrate that electron correlations in the final state play a significant role.

We present a quantitative theory with detailed calculations pertaining to multiphoton ionization of helium under moderately strong uv radiation of photon energy $13\mathrm{eV}$. Employing both, the nonperturbative solution of the time-dependent Schrödinger equation, as well as perturbation theory, we obtain detailed results for all processes expected to be of quantitative relevance within the range of intensities and pulse durations in this work, which have been chosen so as to match the conditions of a recent experiment on exactly this problem [T. Laarman et al., Phys. Rev. A 72, 023409 (2005)]. The conclusion, in connection with the experimental data, which our results lead to is that, without the presence of the second harmonic of the fundamental in the radiation, it is impossible to reconcile the reported observations with fundamental features of the processes involved. A more general conclusion seems to be that the presence of these harmonics, even at intensities less than 1% of that of the fundamental, are apt to produce profound side effects that will mask multiphoton processes by the fundamental.

We predict the existence and study the basic properties of strongly asymmetric matter wave solitons that form at the interface produced by regions with different interatomic interaction strengths in pancake Bose-Einstein condensates. We address several types of surface solitons featuring topologically complex structures, including vortex and dipole-mode solitons. We found that the soliton becomes significantly asymmetric for a high number of particles in the condensate. Yet we reveal that under suitable conditions, that we elucidate, even such strongly asymmetric dipole and vortex solitons can be dynamically stable over wide regions of their existence domains.

We study the detection of weak coherent forces by means of an optomechanical device formed by a highly reflecting isolated mirror shined by an intense quasimonochromatic laser beam. Radiation pressure excites a vibrational mode of the mirror, inducing sidebands of the incident field, which are then measured by heterodyne detection. We show that the sensitivity of such a scheme can surpass the standard quantum limit. In particular the use of an entangled input state of the two sideband modes improves the detection, even in the presence of damping and noise acting on the mechanical mode.

We investigate the time evolution of atomic population in a two-level atom driven by a monochromatic radiation field, taking spontaneous emission into account. The Rabi oscillation exhibits amplitude damping in time caused by spontaneous emission. We show that the semiclassical master equation leads in general to an overestimation of the damping rate and that a correct quantitative description of the damped Rabi oscillation can thus be obtained only with a full quantum mechanical theory.

We consider Bose-Einstein-condensed atoms confined in a toroidal trap. Under conditions of one-dimensional behavior, the density distribution of the atoms may be exponentially localized or delocalized, even for very small variations in the trapping potential along the torus. For similar reasons, small irregularities of the trap may also have a very pronounced effect on the density of the cloud. The excitation spectrum is also affected by the presence of some spatially varying potential and/or irregularities in the trap.

It is shown that the propagator and wave function recently found by are not complete and the results are not correct for constant coefficients of a time-dependent general quantum quadratic Hamiltonian for the case of . We presented the correct evolution operator, propagator, and wave function of the general time-dependent quantum quadratic Hamiltonian system.

In reply to the Comment by Zheng [Phys. Rev. A 68, 052108 (2003)], it is reaffirmed that the propagator and wave function derived originally are correct.

We present calculations of the electronic structure of various atoms and molecules in strong magnetic fields ranging from $B={10}^{12}\mathrm{G}\text{to}2\times {10}^{15}\mathrm{G}$, appropriate for radio pulsars and magnetars. For these field strengths, the magnetic forces on the electrons dominate over the Coulomb forces, and to a good approximation the electrons are confined to the ground Landau level. Our calculations are based on the density functional theory, and use a local magnetic exchange-correlation function which is tested to be reliable in the strong field regime. Numerical results of the ground-state energies are given for ${\mathrm{H}}_N$ (up to $N=10$), ${\mathrm{He}}_N$ (up to $N=8$), ${\mathrm{C}}_N$ (up to $N=5$), and ${\mathrm{Fe}}_N$ (up to $N=3$), as well as for various ionized atoms. Fitting formulae for the $B$ dependence of the energies are also given. In general, as $N$ increases, the binding energy per atom in a molecule, $\mid E_N\mid ∕N$, increases and approaches a constant value. For all the field strengths considered in this paper, hydrogen, helium, and carbon molecules are found to be bound relative to individual atoms (although for $B$ less than a few $\times {10}^{12}\mathrm{G}$, carbon molecules are very weakly bound relative to individual atoms). Iron molecules are not bound at $B\lesssim {10}^{13}\mathrm{G}$, but become energetically more favorable than individual atoms at larger field strengths.

We present calculations of the electronic structure of one-dimensional infinite chains and three-dimensional condensed matter in strong magnetic fields ranging from $B={10}^{12}\mathrm{G}\text{to}2\times {10}^{15}\mathrm{G}$, appropriate for observed magnetic neutron stars. At these field strengths, the magnetic forces on the electrons dominate over the Coulomb forces, and to a good approximation the electrons are confined to the ground Landau level. Our calculations are based on the density functional theory, and use a local magnetic exchange-correlation function appropriate in the strong field regime. The band structures of electrons in different Landau orbitals are computed self-consistently. Numerical results of the ground-state energies and electron work functions are given for one-dimensional chains ${\mathrm{H}}_{\infty }$, ${\mathrm{He}}_{\infty }$, ${\mathrm{C}}_{\infty }$, and ${\mathrm{Fe}}_{\infty }$. Fitting formulae for the $B$ dependence of the energies are also provided. For all the field strengths considered in this paper, hydrogen, helium, and carbon chains are found to be bound relative to individual atoms (although for $B$ less than a few $\times {10}^{12}\mathrm{G}$, carbon infinite chains are very weakly bound relative to individual atoms). Iron chains are significantly bound for $B\gtrsim {10}^{14}\mathrm{G}$ and are weakly bound if at all at $B\lesssim {10}^{13}\mathrm{G}$. We also study the cohesive property of three-dimensional condensed matter of H, He, C, and Fe at zero pressure, constructed from interacting chains in a body-centered tetragonal lattice. Such three-dimensional condensed matter is found to be bound relative to individual atoms, with the cohesive energy increasing rapidly with increasing $B$.

We report the observation of the very narrow $4d^{10}5s{}^{2}S_{1∕2}\to 4d^{9}5s^2{}^{2}D_{5∕2}$ transition in atomic silver. The frequencies of the hyperfine components in ${}^{107}\mathrm{Ag}$ and ${}^{109}\mathrm{Ag}$ have been measured using Doppler-free two-photon laser spectroscopy of a thermal beam and heterodyne calibration with respect to the $a_1$ component of the $62P\left(4\text{−}5\right)$ line in molecular iodine near $661\mathrm{nm}$. For the center of gravity of a mixture of natural abundance, we deduce the value $906641295.77\left(19\right)\mathrm{MHz}$. For the isotope shift, we obtain $\nu \left({}^{109}\mathrm{Ag}\right)-\nu \left({}^{107}\mathrm{Ag}\right)=564.15\left(37\right)\mathrm{MHz}$, from which we deduce the frequency and isotope shift of the $4d^{10}5s{}^{2}S_{1∕2}\to 4d^{10}6p{}^{2}P_{3∕2}$ transition at $206\mathrm{nm}$.

Within the framework of the asymptotic theory the matrices for the exchange interaction potentials of the nitrogen ion, with electron shell $p^2$, and nitrogen atom, with electron shell $p^3$, are constructed. The hierarchy of interactions in the nitrogen molecular ion at large internuclear distances is constructed for different electronic states. On the basis of these interaction potentials, the cross sections of resonant charge exchange in slow collisions are evaluated for different values of electron momentum projections and then averaged over these momentum projections. The mobilities of nitrogen ions in atomic nitrogen are also derived.