Optimal diffusion of chiral active particles with strategic reorientations.

Abstract

We investigate the competing effects of the simultaneous presence of chirality and generalized tumbles in the dynamics of an active Brownian particle. Chiral active particles perform circular motions that give rise to slow transport at late times. By interrupting these circular trajectories at the right time by performing a tumble at the correct angle, we show that particles can enhance their diffusion. After deriving exact expressions for the orientational propagator and correlations, we use this to calculate the first two moments of displacement. For the effective diffusion coefficient, we study various optimal tumbling strategies. We show that under optimization of the tumbling rate, the case of symmetrically distributed tumbles always gives rise to enhanced diffusion, with an effective diffusion coefficient taking a universal value. Next, two cases are considered in detail, namely, directional reversal and tumbles at an arbitrary but fixed angle. We discuss how asymmetric tumbles can enhance diffusion beyond that of symmetric tumbles. Finally, we discuss a situation where the reorientations are realized dynamically in finite time.