Quasi one-dimensional diffuse laser cooling of atoms

TL;DR

This paper demonstrates a novel diffuse laser cooling method in a quasi one-dimensional setup, producing cold rubidium atoms with high optical density and low temperature, suitable for advanced quantum experiments.

Contribution

It introduces a new diffuse laser cooling technique in a long, slender tube that achieves high-density, low-temperature atomic samples over a meter scale.

Findings

Achieved a 4-fold increase in optical density.

Produced atomic temperatures as low as 25 microkelvin.

Maintained stable cold atom numbers for 30 ms free-fall.

Abstract

We demonstrate experimentally the generation of one-dimensional cold gases of $^{87}$Rb atoms by diffuse laser cooling (DLC). A horizontal slender vacuum glass tube with length of 105~cm and diameter of 2~cm is used in our experiment. The diffuse laser light inside the tube, which is generated by multi-reflection of injected lasers, cools the background vapor atoms. With 250~mW of cooling light and 50~mW of repumping light, an evenly distributed meter-long profile of atom cloud is obtained. We observe a factor 4 improvement on the atomic OD for a typical cooling duration of 170~ms and a sub-Doppler atomic temperature of 25~$\mu$k. The maximum number of detected cold atoms remain constant for a free-fall duration of 30~ms. Such samples are ideal for many quantum optical experiments involving electromagnetically induced transparency, electronically highly excited (Rydberg) atoms and quantum precision measurements.