Symmetry-breaking transport in coupled systems: Role of skewed active fluctuations and interparticle interactions

Abstract

We investigate the directed transport of coupled particles driven by active fluctuations in symmetric periodic potentials, revealing transport behaviors beyond thermal equilibrium predictions. A systematic numerical analysis of the center-of-mass velocity demonstrates that even without spatial asymmetry, active fluctuations induce a range of transport regimes under high potential barriers, including enhancement, suppression, and quasi-free transport. The velocity exhibits maxima or minima at optimal coupling strengths, dictated by the skewness of the pulse distribution. Additionally, the interplay between spiking rate and pulse amplitude induces velocity reversals with a non-monotonic dependence on the spiking rate, while at a fixed mean of active fluctuations, distinct non-monotonic behaviors emerge, featuring pronounced velocity valleys and peaks. To explain these transport phenomena, we identify two novel mechanisms arising from the discrete nature of active fluctuations: dual-mode motion, where impulsive jumps combine with potential-gradient sliding, and passive drag, where passive particles are transported via forced coupling. These findings provide fundamental insights into cooperative transport in active systems and offer guiding principles for designing biomimetic micro- and nanoscale devices capable of collective operation in complex environments.