Correlated photon-pair emission from a charged single quantum dot

The optical creation and recombination of charged biexciton and trion complexes in an (In,Ga)As∕GaAs quantum dot is investigated by microphotoluminescence spectroscopy. Under the condition of quasiresonant pulsed excitation into the p shell we find nearly background-free photoluminescence from single quantum dots where multiple-photon $(>1)$ emission is fully suppressed. This reflects almost perfect triggered single-photon emission. Photon cross-correlation measurements demonstrate the temporally correlated decay of charged biexciton and trion states. Our calculations provide strong evidence for radiative decay from the excited trion state, thus indicating a long-lived p-electron spin configuration.