U. Shim

Optical Nutation in Cold 85Rb Atoms

We have observed optical nutation in cold 85Rb atoms with a negligible Doppler broadening. The optical nutation of a two-level atom arranged by optical pumping has been studied as a function of detuning frequency and Rabi frequency. The change of the nutation signal caused by magnetic substate degeneracy has also been observed for σ and π excitations. This can be explained by optical nutation beatings from different transition probabilities among magnetic sublevels. Absolute transition probabilities with σ and π transitions and a branching ratio between them have been measured.

Optical free induction decay in cold 85Rb atoms

We have observed optical free induction decay (FID) in cold 85Rb atoms. The shortening of the FID lifetime with increasing optical depth of the trap has been found. This shortening is explained by an anomalous absorption for FID propagating in a homogeneous and resonant sample. Theoretical calculations are consistent with experimental results. The Rabi oscillations of FID amplitude have been observed by increasing the pulse area.

Collisional revival of magnetic grating free-induction decay

Summary form only given. A ground-state coherence grating involving the magnetic sublevels of the F=3 ground state in /sup 85/Rb is created in Doppler-broadened vapor using an excitation pulse that consists of two traveling waves with orthogonally polarized wave vectors. The decay of the grating that is due to thermal motion is probed by a traveling-wave readout pulse. This results in a scattered signal magnetic grating free-induction decay (MGFID) that is detected using a heterodyne technique. In our experiment, collisional revival can be expected when the mean free path is less than the grating spacing.