Runaway evaporation for optically dressed atoms

Abstract

Forced evaporative cooling in a far-off-resonance optical dipole trap is proved to be an efficient method to produce fermionic-or bosonic-degenerated gases. However, in most of the experiments, the reduction of the potential height occurs with a diminution of the collision elastic rate. Taking advantage of a long-living excited state, like in two-electron atoms, I propose a new scheme, based on an optical knife, where the forced evaporation can be driven independently of the trap confinement. In this context, the runaway regime might be achieved leading to a substantial improvement of the cooling efficiency. The comparison with the different methods for the forced evaporation is discussed in the presence or absence of three-body recombination losses. © 2010 IOP Publishing Ltd.