Cold atom gravimetry with a Bose-Einstein Condensate

TL;DR

This paper demonstrates a Bose-Einstein condensate-based cold atom gravimeter using Mach-Zehnder interferometry with large momentum transfer, achieving high fringe visibility and analyzing the effects of wavefront aberrations and atomic interactions.

Contribution

It introduces a novel gravimeter setup employing Bose-condensed atoms with enhanced sensitivity through large momentum transfer techniques.

Findings

Achieved 83% fringe visibility with Bose-condensed atoms.

Observed reduced visibility with thermal sources due to wavefront aberrations.

Theoretical analysis suggests interaction effects won't limit sensitivity with current parameters.

Abstract

We present a cold atom gravimeter operating with a sample of Bose-condensed Rubidium-87 atoms. Using a Mach-Zehnder configuration with the two arms separated by a two-photon Bragg transition, we observe interference fringes with a visibility of 83% at T=3 ms. We exploit large momentum transfer (LMT) beam splitting to increase the enclosed space-time area of the interferometer using higher-order Bragg transitions and Bloch oscillations. We also compare fringes from condensed and thermal sources, and observe a reduced visibility of 58% for the thermal source. We suspect the loss in visibility is caused partly by wavefront aberrations, to which the thermal source is more susceptible due to its larger transverse momentum spread. Finally, we discuss briefly the potential advantages of using a coherent atomic source for LMT, and present a simple mean-field model to demonstrate that with currently available experimental parameters, interaction-induced dephasing will not limit the sensitivity of inertial measurements using freely-falling, coherent atomic sources.