ENSLAVING RANDOM FLUCTUATIONS IN NONEQUILIBRIUM SYSTEMS

Several physical models have recently been proposed to obtain unidirec tional motion of an overdamped Brownian particle in a periodic system. The asymmetric ratchetlike form of the periodic potential and the pre sence of correlated nonequilibrium fluctuating forces are considered e ssential to obtain such a macroscopic motion in homogeneous systems. I n the present work, instead, inhomogeneous systems are considered, whe rein the friction coefficient and/or temperature could vary in space. We show that unidirectional motion can be obtained even in a symmetric nonratchetlike periodic potential system in the presence of white noi se fluctuations. We consider four different cases of system inhomogene ity. We argue that all these different models work under the same basi c principle of alteration of relative stability of otherwise locally s table states in the presence of temperature inhomogeneity.