Fluctuating systems driven between nonequilibrium states: Extractability of work and constraints on the final distribution

This work deals with fluctuating systems taken out-of-equilibrium by some “activating event”, and then driven by acting upon selected parameters. First we establish general conditions under which an average amount of work can be extracted during the driven transformation; this is what we term extractability of work. Second, from the premise that work is extracted on average, we derive a mutual bound between a measure of the final system’s disequilibrium, the free energy variation, and the average amount of energy involved in the activation phase. As a special case, we consider the situation in which the disequilibrium is quantified by the polarization over an a priori unbiased periodic degree of freedom.