Emergent Rotation of Passive Clusters in a Chiral Active Bath

TL;DR

This paper explores how passive particles in a chiral active bath can form rotating clusters due to collective interactions, with rotation depending on system parameters and chirality uniformity.

Contribution

It reveals the conditions under which passive clusters exhibit persistent rotation and how chirality heterogeneity affects this behavior.

Findings

Passive clusters can exhibit sustained rotation within specific parameter regimes.

Chirality heterogeneity disrupts rotational coherence.

Uniform chirality promotes superdiffusive angular dynamics.

Abstract

We investigate the dynamics of passive particles immersed in a bath of chiral active particles, focusing on the emergence of collective rotational motion. Using numerical simulations, we show that passive particles aggregate into clusters that can exhibit persistent rotation within a well-defined regime of size ratio and active particle packing fraction. This rotational state is characterized by the coexistence of internal structural order, enhanced shape fluctuations, and a coherent net torque generated by the surrounding active bath. Outside this regime, the dynamics remain predominantly diffusive, highlighting that sustained rotation is not ubiquitous but arises from a delicate interplay between geometry, activity, and chirality. Furthermore, we demonstrate that chirality heterogeneity disrupts rotational coherence, while a uniform chiral bath promotes strongly superdiffusive angular dynamics. These results provide new insights into the role of chirality and collective interactions in shaping the emergent behavior of active-passive mixtures.