PHASE COHERENCE IN QUANTUM BROWNIAN-MOTION

The quantum theory of Brownian motion is discussed in the Schwinger ve rsion wherein the notion of a coordinate moving forward in time x(t) i s replaced by two coordinates, x(+)(t) moving forward in time and x_(t ) moving backward in time. The role of the doubling of the degrees of freedom is illustrated for the case of electron beam two slit diffract ion experiments. interference is computed with and without dissipation (described by a thermal bath). The notion of a dissipative interferen ce phase, closely analogous to the Aharonov-Bohm magnetic field induce d phase, is explored. (C) 1998 Academic Press.