Fluctuation theorems: work is not an observable.
The characteristic function of the work performed by an external time-dependent force on a Hamiltonian quantum system is identified with the time-ordered correlation function of the exponentiated system's Hamiltonian. A similar expression is obtained for the averaged exponential work which is related to the free energy difference of equilibrium systems by the Jarzynski work theorem.
Talkner
Peter
P
Institute of Physics, University of Augsburg, Augsburg, Germany.
Lutz
Eric
E
Hänggi
Peter
P