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

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 $\hat{I}¼$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.

5 pages, 3 figures