526 research outputs found
Relativistic many-body calculations of the Stark-induced amplitude of the 6P1/2 -7P1/2 transition in thallium
Stark-induced amplitudes for the 6P1/2 - 7P1/2 transition in Tl I are
calculated using the relativistic SD approximation in which single and double
excitations of Dirac-Hartree-Fock levels are summed to all orders in
perturbation theory. Our SD values alpha S = 368 a0 3 and beta S= 298 a 0 3 are
in good agreement with the measurements alpha S=377(8) a 0 3$ and beta S =
313(8) a 0 3 by D. DeMille, D. Budker, and E. D. Commins [Phys. Rev. A 50, 4657
(1994)]. Calculations of the Stark shifts in the 6P1/2 - 7P1/2 and 6P1/2 -
7S1/2 transitions are also carried out. The Stark shifts predicted by our
calculations agree with the most accurate measured values within the
experimental uncertainties for both transitions
Blackbody radiation shift in 87Rb frequency standard
The operation of atomic clocks is generally carried out at room temperature,
whereas the definition of the second refers to the clock transition in an atom
at absolute zero. This implies that the clock transition frequency should be
corrected in practice for the effect of finite temperature of which the leading
contributor is the blackbody radiation (BBR) shift. Experimental measurements
of the BBR shifts are difficult. In this work, we have calculated the blackbody
radiation shift of the ground-state hyperfine microwave transition in 87Rb
using the relativistic all-order method and carried out detailed evaluation of
the accuracy of our final value. Particular care is taken to accurately account
for the contributions from highly-excited states. Our predicted value for the
Stark coefficient, k_S=-1.240(4)\times 10^{-10}\text{Hz/(V/m)}^{2} is three
times more accurate than the previous calculation [1].Comment: 7 page
Frequency-dependent polarizabilities of alkali atoms from ultraviolet through infrared spectral regions
We present results of first-principles calculations of the
frequency-dependent polarizabilities of all alkali atoms for light in the
wavelength range 300-1600 nm, with particular attention to wavelengths of
common infrared lasers. We parameterize our results so that they can be
extended accurately to arbitrary wavelengths above 800 nm. This work is
motivated by recent experiments involving simultaneous optical trapping of two
different alkali species. Our data can be used to predict the oscillation
frequencies of optically-trapped atoms, and particularly the ratios of
frequencies of different species held in the same trap. We identify wavelengths
at which two different alkali atoms have the same oscillation frequency.Comment: 6 pages, 2 figure
Electric Quadrupole Moments of Metastable States of Ca+, Sr+, and Ba+
Electric quadrupole moments of the metastable nd3/2 and nd5/2 states of Ca+,
Sr+, and Ba+ are calculated using the relativistic all-order method including
all single, double, and partial triple excitations of the Dirac-Hartree-Fock
wave function to provide recommended values for the cases where no experimental
data are available. The contributions of all non-linear single and double terms
are also calculated for the case of Ca+ for comparison of our approach with the
CCSD(T) results. The third-order many body perturbation theory is used to
evaluate contributions of high partial waves and the Breit interaction. The
remaining omitted correlation corrections are estimated as well. Extensive
study of the uncertainty of our calculations is carried out to establish
accuracy of our recommended values to be 0.5% - 1% depending on the particular
ion. Comprehensive comparison of our results with other theoretical values and
experiment is carried out. Our result for the quadrupole moment of the 3d5/2
state of Ca+ ion, 1.849(17)ea_0^2, is in agreement with the most precise recent
measurement 1.83(1)ea_0^2 by Roos et al. [Nature 443, 316 (2006)].Comment: 7 page
Excitation energies, hyperfine constants, E1, E2, M1 transition rates, and lifetimes of (6s2)nl states in Tl I and Pb II
Energies of np (n=6-9), ns (n=7-9), nd (n=6-8), and nf (n=5-6) states in Tl I
and Pb II are obtained using relativistic many-body perturbation theory.
Reduced matrix elements, oscillator strengths, transition rates, and lifetimes
are determined for the 72 possible electric-dipole transitions.
Electric-quadrupole and magnetic-dipole matrix elements are evaluated to obtain
np(3/2) - mp(1/2) (n,m=6,7) transition rates. Hyperfine constants A are
evaluated for a number of states in 205Tl. First-, second-, third-, and
all-order corrections to the energies and matrix elements and first- and
second-order Breit corrections to energies are calculated. In our
implementation of the all-order method, single and double excitations of
Dirac-Fock wave functions are included to all orders in perturbation theory.
These calculations provide a theoretical benchmark for comparison with
experiment and theory.Comment: twelve tables, no figure
Breit Interaction and Parity Non-conservation in Many-Electron Atoms
We present accurate {\em ab initio} non-perturbative calculations of the
Breit correction to the parity non-conserving (PNC) amplitudes of the
and transitions in Cs, and transitions in
Fr, transition in Ba, transition in Ra, and
transition in Tl. The results for the transition
in Cs and transition in Fr are in good agreement with other
calculations while calculations for other atoms/transitions are presented for
the first time. We demonstrate that higher-orders many-body corrections to the
Breit interaction are especially important for the PNC amplitudes. We
confirm good agreement of the PNC measurements for cesium and thallium with the
standard model .Comment: 9 pages, 1 figur
Magic wavelengths for the transition in rubidium
Magic wavelengths, for which there is no differential ac Stark shift for the
ground and excited state of the atom, allow trapping of excited Rydberg atoms
without broadening the optical transition. This is an important tool for
implementing quantum gates and other quantum information protocols with Rydberg
atoms, and reliable theoretical methods to find such magic wavelengths are thus
extremely useful. We use a high-precision all-order method to calculate magic
wavelengths for the transition of rubidium, and compare the
calculation to experiment by measuring the light shift for atoms held in an
optical dipole trap at a range of wavelengths near a calculated magic value
State-insensitive bichromatic optical trapping
We propose a scheme for state-insensitive trapping of neutral atoms by using
light with two independent wavelengths. In particular, we describe the use of
trapping and control lasers to minimize the variance of the potential
experienced by a trapped Rb atom in ground and excited states. We present
calculated values of wavelength pairs for which the 5s and 5p_{3/2} levels have
the same ac Stark shifts in the presence of two laser fields.Comment: 5 pages, 4 figure
Calculation of parity nonconserving amplitude and other properties of Ra+
We have calculated parity nonconserving 7s - 6d_{3/2} amplitude E_PNC in
223Ra+ using high-precision relativistic all-order method where all single and
double excitations of the Dirac-Fock wave functions are included to all orders
of perturbation theory. Detailed study of the uncertainty of the parity
nonconserving (PNC) amplitude is carried out; additional calculations are
performed to estimate some of the missing correlation corrections. A systematic
study of the parity conserving atomic properties, including the calculation of
the energies, transition matrix elements, lifetimes, hyperfine constants,
quadrupole moments of the 6d states, as well as dipole and quadrupole ground
state polarizabilities, is carried out. The results are compared with other
theoretical calculations and available experimental values.Comment: 10 page
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