“…In boundary or field driven systems [8,13,38,39,40,14], for instance, this entropy flow is simply proportional to the particle current flowing through the system, the proportionality constant being the force driving the system out of equilibrium (a chemical potential or a temperature gradient, an applied field, etc.). It is characterized by a nontrivial large deviation function only for nonequilibrium systems (more precisely those breaking detailed balance but for which W (C → C ′ ) = 0 only if W (C ′ → C) = 0).…”