Efficient all-optical production of large Li 6 quantum gases using D1 gray-molasses cooling

Abstract

We use a gray molasses operating on the D1 atomic transition to produce degenerate quantum gases of Li6 with a large number of atoms. This sub-Doppler cooling phase allows us to lower the initial temperature of 109 atoms from 500 to 40 μK in 2 ms. We observe that D1 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 × 105 molecules and weakly interacting degenerate Fermi gases of 7×105 atoms at T/TF<0.1 with a typical experimental duty cycle of 11 s.