Non-Markovian effects on quantum superpositions in a nanostructure

We consider a laser driven nanostructure such a single (SQD) or double quantum dot (DQD) of any shape, which is coupled to photon and phonon baths. These baths provide the basic sources of pure dephasing and relaxation of QD states. We present results which demonstrate that the second order correlation function (g((2))) of emitted photons shows enhanced antibunching features on a time scale, where non-Markov signatures are indeed important for a SQD. This latter feature is only observable when the initial QD state is of a superposition kind thus providing a remarkable sensitivity to state preparation. For a DQD we show that the dipole-dipole interaction is the responsible for superfluorescence at very short times when the driven laser is turned off. (C) 2004 Elsevier Ltd. All rights reserved.