Ultrafast carrier dynamics in semiconductor nanostructures: interplay between coherence and relaxation

The strong coupling between coherent and incoherent ultrafast phenomena in the electro-optical response of semiconductor nanostructures is discussed theoretically within a density matrix formalism. In particular, the problem of scattering-induced damping of Bloch oscillations in superlattices is reviewed. Moreover, a generalization to ‘open systems’ of the conventional semiconductor Bloch equations is discussed. The presence of spatial boundary conditions manifests itself through self-energy corrections and additional source terms in the kinetic equations. As an example, some simulated experiments of quantum transport phenomena through double-barrier structures are reviewed.