Energetics of a Forced Thermal Ratchet

Abstract

We formulate energetics of the forced thermal ratchet [M. O. Magnasco, Phys. Rev. Lett. 71, 1477 (1993)] and evaluate its efficiency of energy transformation. We show that the presence of thermal fluctuation cannot increase the efficiency of the energy transformation in the original system of Magnasco, which is contrary to his claim that “There is a region of the operating regime where the efficiency is optimized at finite temperatures.” We also discuss the maximum efficiency of the forced thermal ratchet.