Quantum Information Processing with Photons from a Single Molecule

The quantum mechanical nature of a single photon allows it to exist in the superposition of two distant spatial modes. Consequently, it can exhibit non-local properties. This has given birth to two important aspects in modern quantum optics, namely photon entanglement and quantum interference. While the former opens the door to schemes such as quantum communication and quantum teleportation, the latter forms the basis for a variety of quantum gates. In particular, Hong-Ou-Mandel interference which describes the coalescence of two photons on a 50/50 beam-splitter, has been used to characterize the suitability of different single photon sources to perform linear optical quantum gates. This thesis analyzes a variety of photon sources such as coherent light (laser), single-photon emitters, and parametric down-conversion sources. It explores the contribution of both the wave and particle nature of the sources to define a criterion for their usability in linear optical quantum computing and networking. As an illustration, laser light, in consequence of its wave nature, can mimic the interference observed in a Hong-Ou-Mandel experiment. A relevant question is whether such interference can be considered as a quantum effect. Similarly, interference of photons is also observed in other experiments, such as the so called delayed choice [quantum] eraser, and the same question arises again. Hence, a criterion to identify quantumness in an interference pattern is a key for implementing quantum protocols using photons. The experiments described in this thesis comprehensively characterize the molecular photons for their use in a future quantum Internet, and attest their efficient interaction with a next subsequent quantum node. The introduced experiments are based on a hybridization of solid state quantum optics, atomic systems, and all-optical quantum information processing. The theoretical calculations present the correlation measurements on a general class of gates with a uniform format. Consequently, these results provide a precise characterization of the photon's properties in quantum interference and their suitability in a quantum network.