This award will support U.S.-Irish research in theoretical physics. The principal investigators are Dr. Robert O'Connell, Louisiana State University, Dr. G. W. Ford, University of Michigan, Dr. John Lewis, Dublin Institute for Advanced Studies, and Dr. D. M. Heffernan, National Institute for Higher Education, Dublin, Ireland. The proposed work focuses on quantum stochastic processes, with special emphasis on systems in such areas as quantum optics and laser, atomic and condensed matter physics, which involve the presence of a heat bath as an integral element of a quantum system. Drs. O'Connell and Lewis have worked together on this topic since 1983. In the present project, they will apply results obtained for a general oscillator heat bath to such problems as non-Markovian effects on time decay, as well as to an investigation of improved heat bath models for quantum optics. Two major new elements in this study will be 1) the pursuit of new ideas in relation to the spin boson problem and 2) the formulation of quantum dissipations in terms of a master equations (the von Neumann equation of motion for the density matrix). This work will enable the investigators to study the effect of quantum dissipation on systems exhibiting the phenomenon of chaos. The participation of Heffernan, since he is a well-recognized expert in the phenomenon of chaos in semiconductor lasers, will be of importance.