Diffusion and coherence in tilted piecewise linear double-periodic potentials.
In the present paper we study the overdamped motion of Brownian particles in tilted periodic piecewise linear potentials of two maxima per period. This system allows one to observe additional phenomena with respect to the case of single-periodic potentials. We show that for certain types of potentials the effective diffusion coefficient D (F) can be enhanced or suppressed compared to the simple sawtooth case. As the most unexpected result it is found that the curve of diffusion coefficient vs tilt can have two maxima. In the region of Poissonian hopping processes we demonstrate the possibility to have a resonantlike peak in the Péclet number Pe(F) . At the tilting force corresponding to the maximum of Pe(F) , the curve of Péclet number vs temperature possesses two maxima.