Coupling-reentrant phase transition, complex hysteretic behavior, and efficiency optimization in coupled phase...

A recent mean-field analysis of a model consisting of N nonlinear phase oscillators-under the joint influence of global periodic coupling with strength K0 and of local multiplicative and additive noises-has shown a nonequilibrium phase transition towards a broken-symmetry phase exhibiting noise-induced transport, or "ratchet" behavior. In a previous paper we focused on the relationship between the character of the (mean velocity vs load force F) hysteresis loop, the number of "homogeneous" mean-field solutions, and the shape of the stationary mean-field probability distribution function (PDF). Here we assume that the multiplicative noises of the model are Ornstein-Uhlenbeck with common strength Q and self-correlation time tau. By resorting to an effective Markovian approximation, we study the tau dependence of the phase boundary, and that of the line signaling the transition from the "interaction-driven regime" to the "noise-driven regime." We also study-for selected representative points of the K0 vs Q phase diagram-the tau dependence of the transport properties induced by coupling and colored multiplicative noise (including the efficiency epsilon of the mechanical rectification process) and that of the above-mentioned PDF.