Measurement of ground-state decoherence via interruption of coherent population trapping

Abstract

We examine the role of ground-state coherence on the fluorescence from the excited state in a three-level Λ system under continuous-wave excitation. When resonantly pumped, the fluorescence is strongly affected by any perturbation in the ground-state coherent population trapping. From our analytical results, we suggest how to use this strong dependence of fluorescence on the ground-state decays as a new method for the measurement of the ground-state decoherence rates. Our calculations should work well for a wide range of systems such as atomic vapors with a buffer gas, active dopants in solids, and quantum dots, etc. We present a proof of principle experiment using ⁸⁷Rb vapor.