Obtaining enhanced outputs from coupled stochastic heat engines

Recent works on coupling of two simple heat engines have shown that it may lead to non-monotonic variations in the efficiency and power with parameters like driving amplitudes and asymmetries in cycle periods. Motivated by this study, we investigate the effect of the coupling between two stochastic heat engines where colloidal particles have been trapped in harmonic potentials. The stiffness parameters of each engine are varied cyclically, but with different cycle periods, with a common thermal bath that acts as a sink for the first engine but as a source for the second. We consider two types of protocols, first where trap strength is varied linearly and the second that has sudden jumps in the trap strengths. In both we find several non-trivial effects, like the enhanced performance of the coupled engine with respect to a single effective engine, and the non-monotonic functional dependence of the engine outputs on several parameters used in the setup. A general relation of the efficiency of an arbitrary number of coupled engines driven quasistatically has been provided.