A kinetic theory of quantum state diffusion

Abstract

A kinetic theory is formulated for quantum state diffusion in a simple polyatomic gas not at equilibrium. The analogs of the Stefan–Maxwell equations are derived in two representations: in the first, a basis set for expanding the density matrix is chosen that is closest to the phenomenological description of quantum state diffusion and yields easily recognizable generalizations of the binary diffusion coefficients, now tensors, as well as source–sink terms, which is a new feature. In the second, a rotationally adapted basis set is used. Finally, the effect of exchange symmetry is discussed briefly.