Theory of the ac Stark Effect on the Atomic Hyperfine Structure and Applications to Microwave Atomic Clocks

Abstract

Microwave atomic clocks are based on the intrinsic hyperfine energy interval in the ground state of an atom. In the presence of an oscillating electric field, the atomic system&mdash;namely, the hyperfine interval&mdash;becomes perturbed (the ac Stark effect). For the atomic sample in a clock, such a perturbation leads to an undesired shift in the clock frequency and, ultimately, to an inaccuracy in the measurement of time. Here a consistent perturbation formalism is presented for the theory of the ac Stark effect on the atomic hyperfine structure. By further implementing relativistic atomic many-body theory, this formalism is then utilized for two specific microwave atomic clock applications: a high-accuracy calculation of the blackbody radiation shift in the <super>133</super>Cs primary frequency standard and a proposal for microwave clocks based on atoms in an engineered optical lattice.