Non-equilibrium steady states.

This paper deals with some thermodynamical aspects of a class of models in nonequilibrium quantum statistical mechanics (QSM) which are commonly used to describe the behaviour of infinite quantum systems perturbed by a time-dependent periodic force. We are interested to the thermodynamical properties of the set of non-equilibrium steady states (NESS) of the perturbed system. We extend the construction of the C-Liouvillean originally introduce in [1] to our time-dependent situation to define the C-Liouvillean of Floquet K[sub F]. The NESS are thus described by zero-resonance eigenvectors of K[sub F, sup *]. We also give a time dependent version of the rate of entropy production [2] for the perturbed system based on the relative entropy as defined by Araki [3] in terms of the relative modular operator. [ABSTRACT FROM AUTHOR]