  With the help of time-dependent scattering theory on the observable algebra
of infinitely extended quasifree fermionic chains, we introduce a general class
of so-called right mover/left mover states which are inspired by the
nonequilibrium steady states for the prototypical nonequilibrium configuration
of a finite sample coupled to two thermal reservoirs at different temperatures.
Under the assumption of spatial translation invariance, we relate the 2-point
operator of such a right mover/left mover state to the asymptotic velocity of
the system and prove that the system is thermodynamically nontrivial in the
sense that its entropy production rate is strictly positive. Our study of these
not necessarily gauge-invariant systems covers and substantially generalizes
well-known quasifree fermionic chains and opens the way for a more systematic
analysis of the heat flux in such systems.
