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

TL;DR

This paper accurately models light shifts in Raman-Ramsey interference for atomic clocks using density-matrix equations, revealing velocity-induced frequency shifts in vapor cells.

Contribution

It provides a detailed computational analysis of light shifts without adiabatic approximation, including effects in Doppler-broadened media, advancing atomic clock accuracy.

Findings

Light shift suppression aligns with analytical solutions.

Velocity-induced frequency shifts are identified as a source of error.

Numerical results match analytical predictions for single-velocity cases.

Abstract

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