Relativistic many-body calculations of energies of n=3 states in aluminumlike ions

Energies of 3l3l′3l″ states of aluminumlike ions with Z=14?100 are evaluated to second order in relativistic many-body perturbation theory starting from a 1s22s22p6 Dirac-Fock potential. Intrinsic three-particle contributions to the energy are included in the present calculation and found to contribute about 10?20 % of the total second-order energy. Corrections for the frequency-dependent Breit interaction and the Lamb shift are included in lowest order. A detailed discussion of contributions to the energy levels is given for aluminumlike germanium (Z=32). Comparisons are made with available experimental data. We obtain excellent agreement for term splitting, even for low-Z ions. These calculations are presented as a theoretical benchmark for comparison with experiment and theory

Electric-dipole, electric-quadrupole, magnetic-dipole, and magnetic-quadrupole transitions in the neon isoelectronic sequence

Excitation energies for 2l-3l′ hole-particle states of Ne-like ions are determined to second order in relativistic many-body perturbation theory (MBPT). Reduced matrix elements, line strengths, and transition rates are calculated for electric-dipole (E1), magnetic-quadrupole (E2), magnetic-dipole (M1), and magnetic-quadrupole (M2) transitions in Ne-like ions with nuclear charges ranging from Z=11 to 100. The calculations start from a 1s22s22p6 closed-shell Dirac-Fock potential and include second-order Coulomb and Breit-Coulomb interactions. First-order many-body perturbation theory (MBPT) is used to obtain intermediate-coupling coefficients, and second-order MBPT is used to determine the matrix elements. Contributions from negative-energy states are included in the second-order E1, M1, E2, and M2 matrix elements. The resulting transition energies are compared with experimental values and with results from other recent calculations. Trends of E1, E2, M1, and M2 transition rates as functions of nuclear charge Z are shown graphically for all transitions to the ground state

Relativistic many-body calculations of electric-dipole matrix elements, lifetimes and polarizabilities in rubidium

Electric-dipole matrix elements for ns-n'p, nd-n'p, and 6d-4f transitions in Rb are calculated using a relativistic all-order method. A third-order calculation is also carried out for these matrix elements to evaluate the importance of the high-order many-body perturbation theory contributions. The all-order matrix elements are used to evaluate lifetimes of ns and np levels with n=6, 7, 8 and nd levels with n=4, 5, 6 for comparison with experiment and to provide benchmark values for these lifetimes. The dynamic polarizabilities are calculated for ns states of rubidium. The resulting lifetime and polarizability values are compared with available theory and experiment.Comment: 8 pages, 2 figure

Relativistic calculations of isotope shifts in highly charged ions

The isotope shifts of forbidden transitions in Be- and B-like argon ions are calculated. It is shown that only using the relativistic recoil operator can provide a proper evaluation of the mass isotope shift, which strongly dominates over the field isotope shift for the ions under consideration. Comparing the isotope shifts calculated with the current experimental uncertainties indicates very good perspectives for a first test of the relativistic theory of the recoil effect in middle-Z ions

Calculation of nuclear spin-dependent parity-nonconserving amplitude for (7s,F=4) --> (7s,F=5) transition in Fr

Many-body calculation of nuclear spin-dependent parity-nonconserving amplitude for (7s,F=4) --> (7s,F=5) transition between hyperfine sublevels of the ground state of $^{211}$Fr is carried out. The final result is <7s,F=5 ||d_PNC|| 7s,F=4> = -0.49 10^{-10} i kappa a.u., where kappa is the dimensionless coupling constant. This is approximately an order of magnitude larger than similar amplitude in Cs. The dominant contribution to kappa is associated with the anapole moment of the nucleus.Comment: 4 pages, submitted to Phys.Rev.

Optimizing the fast Rydberg quantum gate

The fast phase gate scheme, in which the qubits are atoms confined in sites of an optical lattice, and gate operations are mediated by excitation of Rydberg states, was proposed by Jaksch et al. Phys. Rev. Lett. 85, 2208 (2000). A potential source of decoherence in this system derives from motional heating, which occurs if the ground and Rydberg states of the atom move in different optical lattice potentials. We propose to minimize this effect by choosing the lattice photon frequency \omega so that the ground and Rydberg states have the same frequency-dependent polarizability \alpha(omega). The results are presented for the case of Rb.Comment: 5 pages, submitted to PR

Energy levels and lifetimes of Gd IV and enhancement of the electron dipole moment

We have calculated energy levels and lifetimes of 4f7 and 4f6 5d configurations of Gd IV using Hartree-Fock and configuration interaction methods. This allows us to reduce significantly the uncertainty of the theoretical determination of the electron electric dipole moment (EDM) enhancement factor in this ion and, correspondingly, in gadolinium-containing garnets for which such measurements were recently proposed. Our new value for the EDM enhancement factor of Gd+3 is -2.2 +- 0.5. Calculations of energy levels and lifetimes for Eu~III are used to control the accuracy.Comment: Submitted to Phys. Rev. A 6 pages, 0 figures, 3 table

Measurement of the 6s - 7p transition probabilities in atomic cesium and a revised value for the weak charge Q_W

We have measured the 6s - 7p_{1/2,3/2} transition probabilities in atomic cesium using a direct absorption technique. We use our result plus other previously measured transition rates to derive an accurate value of the vector transition polarizability \beta and, consequently, re-evaluate the weak charge Q_W. Our derived value Q_W=-72.65(49) agrees with the prediction of the standard model to within one standard deviation.Comment: 4 pages, 2 figure

High-precision calculations of van der Waals coefficients for heteronuclear alkali-metal dimers

Van der Waals coefficients for the heteronuclear alkali-metal dimers of Li, Na, K, Rb, Cs, and Fr are calculated using relativistic ab initio methods augmented by high-precision experimental data. We argue that the uncertainties in the coefficients are unlikely to exceed about 1%.Comment: 11 pages, 2 figs, graphicx.st

Off-Diagonal Hyperfine Interaction and Parity Non-conservation in Cesium

We have performed relativistic many-body calculations of the hyperfine interaction in the $6s$ and $7s$ states of Cs, including the off-diagonal matrix element. The calculations were used to determine the accuracy of the semi-empirical formula for the electromagnetic transition amplitude $$ induced by the hyperfine interaction. We have found that even though the contribution of the many-body effects into the matrix elements is very large, the square root formula $= \sqrt{ }$ remains valid to the accuracy of a fraction of $10^{-3}$. The result for the M1-amplitude is used in the interpretation of the parity-violation measurement in the $6s-7s$ transition in Cs which claims a possible deviation from the Standard model.Comment: 13 pages, 4 figures, LaTeX, Submitted to Phys. Rev.