A spin-dependent kick using a single 20 ps laser pulse

We report the observation of impulsive momentum kicks of trapped ions whose sign depends upon the electron's spin projection. Using a pair of perpendicular beams from a mode-locked, 532 nm laser, we drive a stimulated Raman transition between two Zeeman levels that completely flips the ion's spin as well as applies a spin-dependent momentum kick in tens of picoseconds. The spin-dependent nature of the force is verified by the decay and subsequent revival of Ramsey fringe contrast when a pair of such kicks is separated by a trap period. Impulsive, state-dependent kicks of this type may be useful for interferometric inertial sensing and high-speed quantum gates.