Four-photon cascade from quadexcitons in a single GaAs quantum dot

We demonstrate the generation of temporally correlated four photons emitted by the cascade recombination of a quadexciton in a self-assembled GaAs quantum dot (QD) by performing single photon correlation measurements. The cascade decay of the quadexciton involves a triexciton, a biexciton, and an exciton. The emissions of these states are identified in the photoluminescence (PL) spectrum of the QD by cross-correlation measurements. Polarization-resolved cross-correlation measurements show that the polarizations of the four photons are partly correlated. Radiative, nonradiative, and polarization flipping rates in the QD are estimated from the bunching visibilities of the cross-correlation measurements and the PL lifetimes.