ON THE POPULATION LOSS DYNAMICS OF A STRONGLY EXCITED 4-LEVEL SYSTEM

The population dynamics of a strongly excited four-level quantum syste m with allowed loss out of the system from the highest state are analy sed. This work has been stimulated by the paper of Cardimona et al. an d represents a more general treatment of the problem studied by them. In particular, we show that the reduction in the ground-state populati on decay rate for large losses is not a consequence of the two-level b ehaviour but is a more general phenomenon. On the basis of numerical a nd analytical solutions we demonstrate that for an arbitrary excitatio n regime, at sufficiently large decay rate, the population loss dynami cs of the four-level system is reduced to that of a slowly damped thre e-level system. We demonstrate also that the detailed knowledge of the coherent population dynamics enables us to predict the effect of deca y rate on the population's time evolution for arbitrary choice of dyna mic parameters.