Quantum interference from spontaneous decay in Λ systems:: realization in the dressed-state picture

We show that quantum interference from spontaneous decay in a three-level Lambda-type system can be realized in the dressed-state picture of coherently driven systems. The physical realization relaxes the stringent conditions upon the level spacing and quantum numbers of the lower-level doublet. Since the physical realization means the equivalence between the Lambda systems with quantum interference and the driven systems, the equivalence may be conveniently used to illustrate the physical pictures of some phenomena. We give two interesting examples. The first is the dynamically induced population inversion, which originates from quantum interference between dressed states. The second is the disappearance of a dark state in a bare Lambda system with quantum interference, which is due to a disparity in coupling intensities on two transitions of the equivalent V system