ABSTRACT
Hamiltonian in the boson operators of the modes, the time evolution selects oneparameter subgroups of the quantum-mechanical symplectic group Sp(2; R) with time as the additive parameter. For open systems, one has master equations for density operators (e.g, [34,46, 60]) instead of the von Neumann equation and the dynamics is described by quantum-mechanical Liouville operators acting in spaces of linear operators instead of the usual operators acting in the Hilbert space of states.
