In my doctoral years, we sought to develop a theory of thermodynamic measurements for quantum systems far from equilibrium. I was advised by Prof. Charles A. Stafford, Department of Physics at the University of Arizona.
A long-standing question in this area had been to provide consistent and meaningful definitions of thermodynamic quantities such as temperature and chemical potential for a nonequilibrium quantum system. Our description of the problem was in the framework of nonequilibrium Green's functions. We established rigorous notions of thermodynamic variables by relying upon local measurements made by a probe for nonequilibrium systems in a steady state. We proved existence and uniqueness theorems for temperature and voltage measurements for quantum fermion systems arbitrarily far from equilibirum, with arbitrary interactions within the quantum system (the nature of interactions in fact appears only in the higher order terms and does not affect measurements made in the tunneling regime).
The work was nominated as an outstanding thesis by the University of Arizona and was published in the Springer Theses Series.