  We present a theoretical study of vacuum-induced coherence in a pair of
vertically stacked semiconductor quantum dots. The process consists in a
coherent excitation transfer from a single-exciton state localized in one dot
to a delocalized state in which the exciton occupation gets trapped. We study
the influence of the factors characteristic of quantum dot systems (as opposed
to natural atoms): energy mismatch, coupling between the single exciton states
localized in different dots, different and non-parallel dipoles due to subband
mixing, as well as coupling to phonons. We show that the destructive effect of
the energy mismatch can be overcome by an appropriate interplay of the dipole
moments and coupling between the dots which allows one to observe the trapping
effect even in a structure with technologically realistic energy splitting on
the order of milli-electron-Volts. We also analyze the impact of phonon
dynamics on the occupation trapping and show that phonon effects are suppressed
in a certain range of system parameters. This analysis shows that the vacuum
induced coherence effect and the associated long-living trapped excitonic
population can be achieved in quantum dots.
