Self-induced transparency of the optical phonons

We show that the self-induced transparency of optical phonons may appear in a systems consisting of a two level atoms interacting with elastic waves. The presence of the gap in phonon spectrum substantially enhances the pulse delay in respect to the acoustic self induced transparency phenomena. One of the main characteristics of the predicted phenomenon is the appearance of the critical velocity of the self-induced transparency pulse which, in the absorbing media, represents the upper limit which pulse may reach. Its magnitude is determined by the ratio of the phonon gap and the energy difference of the two level system. This feature opens a new way for the control of the speed of elastic waves. We believe that, in the view of the emerging new quantum technologies relying on creation and trapping of the coherent phonons interacting with artificial atoms, some practical implementations of interest for the storage and manipulation of quantum information may be realised on the basis of our work.