Evaporative cooling from an optical dipole trap in microgravity

TL;DR

This paper demonstrates that evaporative cooling of cold atoms in an optical dipole trap is equally effective in microgravity as on Earth, confirmed through experiments and simulations, enabling advanced ultra-cold atom research in space.

Contribution

It provides the first experimental evidence that evaporative cooling efficiency in optical dipole traps is unaffected by microgravity conditions, supported by numerical simulations.

Findings

Evaporative cooling efficiency is similar in microgravity and on Earth.

Numerical simulations confirm three-dimensional evaporation due to trap anharmonicity.

Successful trapping of up to 1 million rubidium-87 atoms in microgravity.

Abstract

In recent years, cold atoms could prove their scientific impact not only on ground but in microgravity environments such as the drop tower in Bremen, sounding rockets and parabolic flights. We investigate the preparation of cold atoms in an optical dipole trap, with an emphasis on evaporative cooling under microgravity. Up to $ 1\times10^{6} $ rubidium-87 atoms were optically trapped from a temporarily dark magneto optical trap during free fall in the droptower in Bremen. The efficiency of evaporation is determined to be equal with and without the effect of gravity. This is confirmed using numerical simulations that prove the dimension of evaporation to be three-dimensional in both cases due to the anharmonicity of optical potentials. These findings pave the way towards various experiments on ultra-cold atoms under microgravity and support other existing experiments based on atom chips but with plans for additional optical dipole traps such as the upcoming follow-up missions to current and past spaceborne experiments.