Three studies will be undertaken of fundamental problems in quantum optics, involving interference effects of single photons and collective interactions of atoms and light. One project deals with a new experimental test of locality violations; a second project deals with the observation of a quantum condition for interference that has no classical analogy, and the third project involves investigation of the discontinuous phase transition in the dye ring laser, particularly near the critical point. The first two projects utilize the phenomena of spontaneous parametric down conversion.
