Velocimetry of cold atoms by matterwave interferometry

TL;DR

This paper demonstrates a novel matterwave interferometry technique for measuring the velocity distribution of cold atoms, providing high fidelity results and insights into standard methods, with applications in precision sensing.

Contribution

The authors introduce a Fourier-transform-like interferometric method for cold atom velocimetry, offering improved accuracy and revealing artefacts in traditional Doppler techniques.

Findings

Successfully measured velocity distributions of ultracold rubidium atoms.

Compared favorably with conventional Doppler and time-of-flight methods.

Provided a foundation for interferometric matterwave accelerometry and gravimetry.

Abstract

We present an elegant application of matterwave interferometry to the velocimetry of cold atoms whereby, in analogy to Fourier transform spectroscopy, the 1-D velocity distribution is manifest in the frequency domain of the interferometer output. By using stimulated Raman transitions between hyperfine ground states to perform a three-pulse interferometer sequence, we have measured the velocity distributions of clouds of freely-expanding $^{85}$Rb atoms with temperatures of 33 $\mu$K and 17 $\mu$K. Quadrature measurement of the interferometer output as a function of the temporal asymmetry yields velocity distributions with excellent fidelity. Our technique, which is particularly suited to ultracold samples, compares favourably with conventional Doppler and time-of-flight techniques, and reveals artefacts in standard Raman Doppler methods. The technique is related to, and provides a conceptual foundation of, interferometric matterwave accelerometry, gravimetry and rotation sensing.