Subrecoil Raman laser cooling of ⁶Li atoms

We realize an efficient one-dimensional Raman cooling of ⁶Li atoms using 2S → 2P Raman transition pulses and 2S → 3P ultraviolet (UV) optical repumping. In this cooling scheme, we directly cool an initial cold atomic sample of 350 μK released from a standard magneto-optical trap down to a velocity spread of 0.8 recoil velocity, corresponding to an effective temperature of 4.5 μK, an increase of almost an order of magnitude in the phase space density with respect to ordinary laser sub-Doppler cooling. This technique may provide an ideal initial sub-recoil atomic sample for the application of the large-momentum-transfer in the recoil-sensitive lithium atom interferometers.