Observation of transient electromagnetically induced transparency in a rubidium Λ system

Observation of transient effects in electromagnetically induced transparency (EIT) is reported in Rb-85 cooled in a magneto-optical trap. The transmission of a weak probe beam in resonance with the 5S(1/2)(F=3) to 5P(3/2)(F=3) hyperfine transition increased transiently when a relatively strong coupling field in resonance with the 5S(1/2)(F=2) to 5P(3/2)(F=3) hyperfine transition was switched on rapidly using a Pockels cell. The probe transient showed an initial Rabi half-cycle overshoot before settling down to steady-state EIT. The results agreed well with computations using a three-state model of the Lambda system. The computations also suggest that transient gain should be observed with coupling field power only four times larger than that presently available to us. [S1050-2947(98)03308-3].