A misaligned magneto-optical trap to enable miniaturized atom chip systems

TL;DR

This paper introduces misaligned beam configurations in a mirror-based magneto-optical trap to facilitate miniaturized, portable atom chip systems with limited optical access, achieving significant atom trapping and low temperatures.

Contribution

It presents novel geometries of beam displacement, including a hybrid-MOT, for improved miniaturization and performance in atom trapping systems with limited optical access.

Findings

Trapped around 6 million and 26 million $^{85}$Rb atoms in vortex-MOT and hybrid-MOT.

Achieved sub-Doppler cooling in vortex-MOT without additional cooling stages.

Attained atom temperatures suitable for quantum sensor applications.

Abstract

We describe the application of displaced, or misaligned, beams in a mirror-based magneto-optical trap (MOT) to enable portable and miniaturized atom chip experiments, where optical access is limited to a single window. Two different geometries of beam displacement are investigated: a variation on the well-known 'vortex-MOT', and the other a novel 'hybrid-MOT' combining Zeeman-shifted and purely optical scattering force components. The beam geometry is obtained similar to the mirror-MOT, using a planar mirror surface but with a different magnetic field geometry more suited to planar systems. Using these techniques, we have trapped around 6$\times 10^6$ and 26$\times 10^6$atoms of $^{85}$Rb in the vortex-MOT and hybrid-MOT respectively. For the vortex-MOT the atoms are directly cooled well below the Doppler temperature without any additional sub-Doppler cooling stage, whereas the temperature of the hybrid-MOT has been measured slightly above the Doppler temperature limit. In both cases the attained lower temperature ensures the quantum behaviour of the trapped atoms required for the applications of portable quantum sensors and many others.