John Rarity pioneered the experimental one-photon and two-photon optics, both to the study of fundamental physical phenomena and also in the development of prototype devices. This requires specially designed sources and detectors, the former including parametric down-conversion and single-deffect emitters. Rarity has made leading advances both to detector design and to such exotic sources and was, with his collaborators, for many years the sole UK representative in experimental quantum optics, his research telling us much about the nature of photons. He spotted early the potential for experimental quantum information and has become a leading figure in this field.