Measurement of the bichromatic optical force on Rb atoms

The limit of (h) over bar k gamma/2 imposed on the magnitude of radiative f orces by the spontaneous decay rate gamma of the excited state can be overc ome by coherent control of the momentum exchange between atoms and the ligh t field. This can be implemented with two light beams, each containing two frequencies whose phases, amplitudes, and frequency difference are carefull y chosen. We have made precise measurements of the extremely large magnitud e and velocity range of this bichromatic force, and have shown that its vel ocity dependence near the edge of its range is suitable for atomic beam slo wing and laser cooling. Our measurements have corroborated various models a nd calculations of this bichromatic force. [S1050-2947(99)51009-3].