Nonlinear extensions of Schroedinger-von Neumann quantum dynamics: a set of necessary conditions for compatibility with thermodynamics

We propose a list of conditions that consistency with thermodynamics imposes on linear and nonlinear generalizations of standard unitary quantum mechanics that assume a set of true quantum states without the restriction that the density operator be idempotent even for strictly isolated systems and that are to be considered in experimental tests of the existence of intrinsic (spontaneous) decoherence at the microscopic level. As part of the discussion, we present a general description of nonequilibrium states.