Coherent population trapping in a Raman atom interferometer

TL;DR

This paper studies how coherent population trapping affects phase measurements in a Raman atom interferometer gravimeter, revealing potential accuracy issues and proposing a mitigation technique using k-reversal to ensure precise inertial sensing.

Contribution

It demonstrates the impact of CPT on phase shifts in Raman interferometers and shows that the k-reversal technique effectively rejects this effect for accurate measurements.

Findings

CPT causes phase shifts of a few milliradians in the interferometer.

The k-reversal technique cancels CPT-induced phase shifts.

Maintaining identical internal states is crucial for the technique's effectiveness.

Abstract

We investigate the effect of coherent population trapping (CPT) in an atom inter-ferometer gravimeter based on the use of stimulated Raman transitions. We find that CPT leads to significant phase shifts, of order of a few mrad, which may compromise the accuracy of inertial measurements. We show that this effect is rejected by the k-reversal technique, which consists in averaging inertial measurements performed with two opposite orientations of the Raman wavevector k, provided that internal states at the input of the interferometer are kept identical for both configurations.