Slowing and storing light processes without a trapping dark state in a double two-level system. Theoretical study

We present a detailed theoretical study of a method for slowing light based on the oscillations of Zeeman coherences in a double two-level system [Hashmi, F.A.; Bouchene, M.A. Phys. Rev. A 2008, 77, 051803(R)]. This method does not require the presence of any trapping state. We focus on the properties and the limitations of such a method and compare it to previous ones. We also investigate the possibility of obtaining fast light and to store the light with such a method.