Efficient all-optical production of large $^6$Li quantum gases using D$_1$ gray-molasses cooling

TL;DR

This paper demonstrates an efficient all-optical method using D$_1$ gray-molasses cooling to rapidly produce large degenerate quantum gases of $^{6}$Li, including Bose-Einstein condensates and degenerate Fermi gases.

Contribution

The study introduces a fast, effective D$_1$ gray-molasses cooling technique for $^{6}$Li that enhances the production of large quantum gases in a short cycle.

Findings

Achieved cooling from 500 to 40 μK in 2 ms for 10^9 atoms.

Produced molecular BECs of up to 5×10^5 molecules.

Created degenerate Fermi gases with over 7×10^5 atoms at T/T_F<0.1.

Abstract

We use a gray molasses operating on the D$_1$ atomic transition to produce degenerate quantum gases of $^{6}$Li with a large number of atoms. This sub-Doppler cooling phase allows us to lower the initial temperature of 10$^9$ atoms from 500 to 40 $\mu$K in 2 ms. We observe that D$_1$ cooling remains effective into a high-intensity infrared dipole trap where two-state mixtures are evaporated to reach the degenerate regime. We produce molecular Bose-Einstein condensates of up to 5$\times$10$^{5}$ molecules and weakly-interacting degenerate Fermi gases of $7\times$10$^{5}$ atoms at $T/T_{F}<0.1$ with a typical experimental duty cycle of 11 seconds.