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.