Simultaneous observation of semi-continuous and Ramsey-coherent population trapping resonances using the Ramsey pulse sequence with drive current modulation

Abstract

Abstract In this study, we proposed a method to observe the semi-cw excited coherent population trapping (SCW-CPT) and the Ramsey-CPT resonance during a Ramsey pulse sequence. By simultaneously observing the Ramsey-CPT and SCW-CPT resonances, which have distinct light shift coefficients, it is easy to detect light shift from the resonance frequency ratio of these two atomic resonances. Experimental results demonstrated the capability of the proposed method to simultaneously observe both the Ramsey-CPT and SCW-CPT resonances. The frequency difference attributable to the light shift was 308.9 Hz, indicating the successful detection of the light shift. Long-term measurements revealed that the frequency drift rates of the two atomic resonances differ by a factor of 3.5, and the variation in the frequency ratio enabled the detection of fluctuations in these two resonance frequencies.