Cyclic population transfer in quantum systems with broken symmetry -: art. no. 183002

We show that quantum systems with broken symmetry can be selectively excited due to the coexistence of one- and two-photon transitions between the same states. Discrimination between two mirror-symmetric quantum wells or left- and right-handed chiral molecules can be accomplished by a cyclic population transfer process, in which one optically couples three system states \1) <----> \2) <----> \3) <----> \1), and completely transfers population from state \1) to state \2) and \3)(M) (i.e., state \3) of the mirror imaged system) or state \3) and \2)(M), depending on the laser phases.