Transport in open quantum systems: comparing classical and quantum phase space dynamics

Transport in open quantum systems is of great interest. We show that the discrete states of an open quantum system may be classified into three distinct groups, dependent upon the manner in which they influence transport when connected to an external environment. A first class of states is current-carrying states, which are naturally strongly connected to the environment. A second class of states is discrete, but stable and isolated, and thought to be the pointer states of decoherence theory. Finally, we identify backscattered states, which do not propagate through the system.