Radiative cascades from charged semiconductor quantum dots

We measured two-photon radiative cascades due to sequential recombination of quantum-dot confined electron-hole pairs in the presence of an additional spectator charge carrier. We use temporally resolved polarization sensitive intensity correlation measurements to fully characterize these radiative cascades. We identified direct, all optical cascades involving spin-blockaded intermediate states, and indirect cascades, in which nonradiative relaxation precedes the second radiative recombination. Our measurements provide spin dephasing rates of confined single carriers.