On-chip generation and in-plane transmission of indistinguishable photons

We report the on-chip generation and in-plane transmission of indistinguishable photons from a semiconductor quantum dot embedded in a photonic crystal waveguide. We demonstrate the indistinguishability of the in-plane photons by performing two-photon interference with light collected from the exit of the photonic crystal waveguide. Under continuous wave optical excitation, the interference visibility is measured to be 0.40 ± 0.04, limited by the temporal resolution of our single-photon detectors. Our results are in excellent agreement with our theoretical model, in which all the parameters are determined experimentally.