Sensitivity of the extended STIRAP method of selective population transferto coupling to background states

The Kobrak-Rice extended STIRAP approach for selective population transfer has been tested for robustness vis a vis coupling to background states by e xamining preferential transfer to one or the other of nearly degenerate tar get states in the thiophosgene molecule. The calculations were carried out first within the original Kobrak-Rice five state scheme and then with inclu sion of successively larger numbers of background states that have off-reso nance radiative coupling with the original five states. Population transfer s were calculated with and without use of the rotating wave approximation t o determine if inclusion of the background states degraded the accuracy of that approximation. It is shown that the selective population transfer to a particular one of a pair of degenerate states is insensitive to the coupli ngs with the background states and to the use of the rotating wave approxim ation.