Influence of excitonic effects on dynamic localization in semiconductor superlattices in combined dc and ac electric fields

We investigate the influence of excitonic effects on dynamic localization in an optically excited semiconductor superlattice in combined dc and ac electric fields. We use an excitonic basis to calculate both the quasienergy spectrum and the intraband dynamics of the system. We find that for moderate to high dc electric fields, where the Wannier-Stark ladder is only weakly disturbed by excitonic effects, the signature of dynamic localization is found in the quasienergy spectrum, the time-integrated terahertz (THz) signal, and in the decay rate of the carrier-generated THz intensity signal. However, in contrast to what is predicted by the models employing the semiconductor Bloch equations, we find that for low dc electric fields, the dynamic localization can be almost completely destroyed via excitonic effects.