Highly indistinguishable photons from a quantum dot in a microcavity

We investigated the indistinguishability of photons emitted by single self-assembled (In,Ga)As/GaAs quantum dots (QDs) coupled to the fundamental mode (FM) of a pillar microcavity. By systematic pre-characterization, optimum conditions with respect to fast radiative decay (Purcell enhancement), long coherence time, and close to background-free single-photon emission have been derived. For different spectral detunings between QD and FM emission, Hong-Ou-Mandel-type (HOM) two-photon interference has been measured as a function of temporal photon wavepacket overlap. Detailed analysis of our data (under consideration of setup limitations) anticipates the generation of highly indistinguishable photons with up to V HOM = 0.82 visibility.