Perturbation analysis of Raman echo

Abstract

A time-dependent perturbational approach is used to study the Raman echo generated by an inhomogeneous ensemble of three-level atomic systems in the Λ configuration. The sixth-order perturbative solution for coherence between the two lower states contains eight echo terms that are visualized with double Feynman diagrams. The echo is interpreted as a response of the ensemble to six short single-frequency optical pulses whose timing satisfies a special condition. Nonperturbative numerical simulation confirms the predictions of the perturbation analysis about the main characteristics of the echo. When the excitation pulses vary adiabatically with respect to fast optical coherence decay the echo amplitude depends on interference of the eight terms. A computational scheme developed for the higher-order perturbative analysis is also discussed.