Single-Photon Generation from Single Quantum Dots

Single photons from single quantum dots have already found their way into many important realizations in quantum information processing. In this chapter, we review several demonstrations using a deterministic single-photon source based on InP/GalnP quantum dots. Single-photon generation is described and verified by auto-correlation measurements. Additionally, photon pairs and triplets from multi-exciton cascades are observed. Using a Michelson interferometer, an efficient separation of photon pairs can be achieved allowing multiplexing on the single-photon level. We also show the generation of non-classical states of light from electrically pumped quantum dots. The applicability of our sources in quantum information experiments is demonstrated in quantum key distribution and in a realization of a two-qubit Deutsch-Jozsa algorithm which uses different degrees of freedom of a single photon. By encoding the quantum information in appropriate bases, we implement passive error correction in the presence of phase fluctuations.