Computational Studies of Light Shift in Raman-Ramsey Interference-Based Atomic Clock

摘要

Determining light shift in Raman-Ramsey interference is important for thedevelopment of atomic frequency standards based on a vapor cell. We haveaccurately calculated light shift in Raman-Ramsey interference using thedensity-matrix equations for a three-level system without invoking theadiabatic approximation. Specifically, phase shifts associated with coherentdensity-matrix terms are studied as they are relevant to the detection ofRaman-Ramsey interference in transmission (or absorption) through the medium.For the single-velocity case, the numerically computed results are comparedwith the analytical results obtained using the adiabatic approximation. Theresult shows light shift suppression in conformity with the closed-formanalytic solutions. The computational studies have also been extended toinvestigate Raman-Ramsey interference for a Doppler-broadened vapor medium.Importantly, a velocity-induced frequency shift is found at the fringe centeras an additional source of frequency error for a vapor cell Raman clock.