Precise calculation of the light shift in optical frequency standards

摘要

Frequency shifts of the spin-forbidden ~3P_J - ~1S_0 transitions for Mg, Sr and Yb atoms due to external laser field are calculated, based on a combination of measured atomic parameters (transition energies) and perturbation theory. Calculations of the higher-order dynamic Stark effect have been performed in connection with precise measurements on cooled and trapped atoms and the design of ultra stable optical clock in an engineered light shift trap. Dispersion properties of the polarizability and hyperpolarizability components and their behavior in the vicinity of both resonances and so-called "crossing points" for the upper and lower atomic states, are analyzed. The calculation of the radial matrix elements is carried out with the use of the Green's function method on the model potential approximation. The Green's function in this approach has a simply analytical representation and enables one obtain the matrix elements in the form of rapidly convergent hypergeometric-type series.