First observation of forces on three-level atoms in Raman resonant standing-wave optical fields

A sodium atomic beam is deflected by two optical standing-wave fields which excite near resonance Raman transitions. Observed deflections are consistent with theoretical predictions of a long-range dc component of the force on a three-level atom in the {Λ} configuration. The low laser intensities (and small detunings) used, combined with observed evidence of damping in the three-level {Λ} system, may ultimately lead to the design of high-density, all optical traps wherein the atoms would be mostly in the dark state.