Interferometric laser cooling of atomic rubidium

TL;DR

This paper demonstrates a novel interferometric laser cooling technique for rubidium atoms that cools atoms from 21 μK to 3 μK using Ramsey matter-wave interferometry, potentially surpassing traditional methods in efficiency and applicability.

Contribution

Introduces a pulsed interferometric laser cooling method based on Ramsey interferometry, effective at near recoil temperatures and suitable for species without closed radiative transitions.

Findings

Cooled rubidium atoms from 21 μK to 3 μK

Demonstrated effectiveness of interferometric cooling at recoil limit

Potential for faster cooling with augmented pulses

Abstract

We report the 1-D cooling of $^{85}$Rb atoms using a velocity-dependent optical force based upon Ramsey matter-wave interferometry. Using stimulated Raman transitions between ground hyperfine states, 12 cycles of the interferometer sequence cool a freely-moving atom cloud from $21~\mu$K to $3~\mu$K. This pulsed analog of continuous-wave Doppler cooling is effective at temperatures down to the recoil limit; with augmentation pulses to increase the interferometer area, it should cool more quickly than conventional methods, and be more suitable for species that lack a closed radiative transition.