Matterwave interferometric velocimetry of cold Rb atoms

TL;DR

This paper presents a matterwave interferometric technique to measure atomic velocities in cold rubidium atoms, combining theoretical analysis and experimental validation, with enhanced sensitivity to velocity direction.

Contribution

It introduces a novel interferometric method for velocity measurement that accounts for residual Doppler effects and enables discrimination of velocity direction in cold atom samples.

Findings

Successful measurement of velocity distribution in a 20 μK Rb cloud

Use of Raman transitions for quadrature measurements

Technique effectively distinguishes positive and negative velocities

Abstract

We consider the matterwave interferometric measurement of atomic velocities, which forms a building block for all matterwave inertial measurements. A theoretical analysis, addressing both the laboratory and atomic frames and accounting for residual Doppler sensitivity in the beamsplitter and recombiner pulses, is followed by an experimental demonstration, with measurements of the velocity distribution within a 20 $\mu$K cloud of rubidium atoms. Our experiments use Raman transitions between the long-lived ground hyperfine states, and allow quadrature measurements that yield the full complex interferometer signal and hence discriminate between positive and negative velocities. The technique is most suitable for measurement of colder samples.