Raman pulse duration effect in gravity gradiometers composed of two atom interferometers

TL;DR

This paper examines how the duration of Raman pulses affects phase shifts in gravity gradiometers with two atom interferometers, revealing a significant systematic offset that impacts measurements of the gravitational constant G.

Contribution

It identifies and quantifies the impact of Raman pulse duration on phase shifts, explaining potential measurement errors in atom interferometer-based gravity experiments.

Findings

Raman pulse duration causes measurable phase shifts in gravity gradiometers.

The effect can lead to systematic offsets in G measurements up to -49ppm.

Underestimating G can be partly attributed to this pulse duration effect.

Abstract

We investigated the Raman pulse duration effect in a gravity gradiometer with two atom interferometers. Since the two atom clouds in the gradiometer experience different gravitational fields, it is hard to compensate the Doppler shifts of the two clouds simultaneously by chirping the frequency of a common Raman laser, which leads to an appreciable phase shift. When applied to an experiment measuring the Newtonian gravitational constant G, the effect contributes to a systematic offset as large as -49ppm in Nature 510, 518 (2014). Thus an underestimated value of G measured by atom interferometers can be partly explained due to this effect.