Increased trapping efficiency with force-assisted velocity-selective coherent population trapping

We study a class of laser cooling schemes that combine velocity-selective coherent population trapping (VSCPT) with Doppler cooling mechanisms. The Doppler mechanism prevents the atoms from diffusing into the region of high momentum, thereby removing the characteristic long-time asymptotic behaviour of VSCPT where, in the end, all the atoms escape from the trap. It is shown that the transition J(g) = 2 to J(e) = 1 while maintaining the simple field configuration present in the original VSCPT case provides the additional Doppler mechanism and leads to virtually zero temperature without the loss of atoms that characterize the original VSCPT dynamics.