Bichromatic force measurements using atomic beam deflections - art. no. 023408

The spontaneous decay rate gamma of excited atomic states limits the radiat ive force on atoms to (h) over bar k gamma/2. This bottleneck in the dissip ative exchange of momentum between atoms and light can be overcome by coher ent control of the momentum exchange interactions. The bichromatic force pr ovides such control by using stimulated instead of spontaneous emission to produce the force, while at the same time exploiting spontaneous emission t o enable a dissipative interaction. It is implemented with two counterpropa gating light beams, each containing two frequencies, whose phases, amplitud es, and frequency difference are carefully chosen. We have made precise mea surements of the extremely large magnitude and velocity range of this bichr omatic force, and have shown that its velocity dependence near the edge of its range is suitable for atomic beam slowing and laser cooling. Our measur ements have corroborated various models and calculations of this bichromati c force.