We use a density-matrix formalism to illustrate the possibilities of detecting quantum-beat phenomena in the frequency domain. In a pump-probe absorption-saturation experiment, the differential-transmission spectrum is shown to have features at frequencies that are separated from the laser frequency by the quantum-beat frequency. We show the conditions under which these features are observable.

• Received 28 December 1992

DOI:https://doi.org/10.1103/PhysRevA.48.702