The Study of Ramsey and Rabi Frequency Pulling Shift

Ramsey and Rabi frequency pulling shift is one of frequency corrections in cesium atomic fountain primary frequency standard. Due to its very small value, we need novel computing methods and experimental techniques. By calculating transition probability in Ramsey configuration and solving time-evolution operator's differential equation, we derived this frequency shift. By means of feeding in two microwaves with different frequencies to selection cavity, we got initial atomic coherence with the population difference of 4.22%, and by magnifying this frequency shift experimentally, we measured it with the increase of compensation coil current, which verified the theoretical conclusion: this frequency shift versus coherent phase is a trigonometric function. At last we evaluated the maximum Ramsey and Rabi frequency pulling shift of NTSC-Fl in normal operation is $2.6\times 10^{-18}$.