To the theory of effects associated with electromagnetically induced transparency: composition of A- and V-types

摘要

The main phenomena of interest here - the strong reduction of the probe pulse group speed and a similar pulse regeneration after the dark pause - are shown to be quite possible, together with the coherent states repopulation, in case of the energy levels degeneration. The result about the probe field disappearance everywhere inside a sample during the dark pause is confirmed. It is established that atomic coherence during the dark pause is stored by off-diagonal density matrix elements of A-components, whereas V-components play a destructive role. Thus, the MA-type (without V- components) is the best one, among the types considered, to get the greatest group speed reduction of a probe pulse.