Supersymmetry and Nonequilibrium Work Relations

We give a field-theoretic proof of the nonequilibrium work relations for a space dependent field with stochastic dynamics. The path integral representation and its symmetries allow us to derive Jarzynski's equality. In addition, we derive a set of exact identities that generalize the fluctuation-dissipation relations to far-from equilibrium situations. These identities are prone to experimental verification. Furthermore, we show that supersymmetry invariance of the Langevin equation, which is broken when the external potential is time-dependent, is partially restored by adding to the action a term which is precisely Jarzynski's work. Jarzynski's equality can also be deduced from this supersymmetry