Published in Physical Review A Rapid Communications, vol 51 no 6, R4325-R4328, June 1995.
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 micron 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.