InP/GaInP Quantum Dots as Single-Photon Sources for Quantum Information Processing

Many important realizations and proposals for applications in quantum information processing require single photons as carriers of quantum information. Here, we review different demonstrations of quantum applications using a deterministic single-photon source based on InP/GaInP quantum dots. First, the single-photon generation is described and verified by autocorrelation measurements. A modification of the correlation setup allows the simultaneous observation of wave and particle properties of the photons. Additional to single-photon emission, photon pairs and triplets from multiexciton cascades were observed, as well. Using a Michelson interferometer an efficient separation of photon pairs can be achieved allowing multiplexing on a single-photon level. The applicability was demonstrated in a quantum key distribution experiment. As another application, different degrees of freedom of a single photon were used to realize a two-qubit Deutsch-Jozsa algorithm. Encoding the quantum information in appropriate bases, an operation of the setup resistant to phase fluctuation was demonstrated.