Bach V., Froehlich J., Sigal I.M.
Return to Equilibrium
(935K, postscript)
ABSTRACT. We study an atom with finitely many energy levels in contact with a
heat bath consisting of photons (black body radiation) at a
temperature T >0. The dynamics of this system is described by a
Liouville operator, or thermal Hamiltonian, which is the sum of an
atomic Liouville operator, of a Liouville operator describing the
dynamics of a free, massless Bose field, and a local operator
describing the interactions between the atom and the heat bath.
We show that an arbitrary initial state which is normal with respect
to the equilibrium state of the uncoupled system at temperature T
converges to an equilibrium state of the coupled system at the same
temperature, as time tends to infinity ({\em return to equilibrium}).