A novel scheme for efficient cooling below the photon recoil limit

We have theoretically studied a one-dimensional light field configuration which combines velocity-selective coherent-population trapping with the action of a novel kind of sub-Doppler force providing efficient cooling below the recoil limit. The force is based on velocity-induced non-adiabatic passage of atomic population from the non-coupling state to the light-shifted coupling state. We show for⁸⁷Rb that within 0.88 ms 35% of an initial distribution of 12ℏk width can be cooled into a 0.5ℏk momentum interval, and that more than 90% of the initial distribution are still confined to 12ℏk width.