Dark-state sideband cooling in an atomic ensemble

We utilize the dark state in A-type three-level system to cool an ensemble of Rb-85 atoms in an optical lattice [Morigi et al., Phys. Rev. Lett. 85, 4458 (2000)]. The common suppression of the carrier transition of atoms with different vibrational frequencies allows them to reach a subrecoil temperature of 100 nK after being released from the optical lattice. A nearly zero vibrational quantum number is determined from the time-of-flight measurements and adiabatic expansion process. The features of sideband cooling are examined in various parameter spaces. Our results show that dark-state sideband cooling is a simple and compelling method for preparing a large ensemble of atoms into their vibrational ground state of a harmonic potential and can be generalized to different species of atoms and molecules for studying ultracold physics that demands recoil temperature and below.

Automated summary

This study utilizes dark-state sideband cooling to cool an ensemble of Rb-85 atoms in an optical lattice, achieving subrecoil temperatures below 100 nK. The results demonstrate that this method is a simple and effective way to prepare a large number of atoms in their vibrational ground state, and can be applied to different species of atoms and molecules for studying ultracold physics.