Enhanced thermodynamic efficiency in time asymmetric ratchets

Abstract

The energetic efficiency of an overdamped Brownian particle in a sawtooth potential in the presence of time asymmetric forcing is studied in the adiabatic limit. An error made in earlier work on the same problem in the literature is corrected. We find that asymmetry in the potential together with temporal asymmetry in the forcing leads to much enhanced efficiency without fine-tuning of the parameters. The origin of this is traced to the suppression of the backward current. We also present a comparative study of the roles of continuous and discontinuous ratchet forces as regards these measurable quantities. We find that the thermal fluctuations can optimize the energy transduction, the range of parameters, however, being very small. This ratchet model also displays current reversals on tuning of parameters even in the adiabatic regime. The possible relationships between the nature of the currents, entropy production and input energy are also addressed.