Observation of three-level rectified dipole forces acting on trapped atoms

We have observed rectified dipole forces acting on three-level atoms in the cascade configuration. Laser cooled and trapped rubidium atoms are illuminated with an intense bichromatic standing wave (780 and 776 nm) tuned near resonance with the 5S1/2{→}5P3/2{→}5D5/2 transitions. The resulting rectified forces produce periodic potential wells (71-{μ}m period), which localize the cold atoms. Experimental results are in reasonable agreement with theoretical predictions. These forces may be useful in atom optics and laser traps.