Stimulated Raman adiabatic passage in a $\Lambda$ system in the presence of quantum noise

We exploit a microscopically derived master equation for the study of Stimulated Rapid Adiabatic Passage in the presence of spontaneous decay from the intermediate state toward the initial and final states, and compare our results with the predictions obtained from a phenomenological model previously used [P. A. Ivanov, N. V. Vitanov, and K. Bergmann, Phys. Rev. A 72, 053412 (2005)]. It is shown that our approach predicts a much higher efficiency for counterintuitively ordered pulses, while no significant difference between the two approaches is found for intuitively ordered pulses. These features are readily explained in the dressed-state picture.