Inertial chiral active Brownian particle: Transition from Gaussian to platykurtic distribution

TL;DR

This study explores how the position distribution of an inertial chiral active Brownian particle changes from Gaussian to platykurtic under harmonic confinement, revealing a non-monotonic MSD behavior and potential applications in particle control.

Contribution

The paper demonstrates the transition from Gaussian to platykurtic distribution in confined chiral active particles and provides analytical and numerical insights into kurtosis and MSD behavior.

Findings

Distribution transitions from Gaussian to platykurtic at specific frequencies.

Kurtosis exhibits a dip when harmonic and chiral frequencies match.

MSD shows a non-monotonic dependence with a maximum at frequency matching.

Abstract

We investigate the dynamics of an inertial chiral active Brownian particle in the presence of a harmonic confinement. Through numerical simulation, we observe that when the harmonic frequency becomes comparable to the chiral frequency, the position distribution transitions from a Gaussian to a platykurtic distribution, corresponding to short tails with a nearly uniform probability near the minimum of the potential. This result is further confirmed by analyzing the kurtosis of the position of the particle as a function of harmonic frequency, which exhibits a dip when the harmonic frequency matches the chiral frequency. At the same time, the steady state mean square displacement (MSD) shows a non-monotonic feature with the harmonic frequency and shows a maximum only when the harmonic frequency is of the same order as the chiral frequency. In the rotational overdamped limit of the same model, we have calculated the exact expression for kurtosis, steady state MSD and find that the qualitative behavior remains the same. Kurtosis still exhibits a dip in the matching of chiral and harmonic frequencies, but the feature is less pronounced with a higher minimum. These findings might be relevant for controlling the transport and spatial distribution of chiral microswimmers in optical or acoustic traps, where confinement can be tuned to optimize particle distribution.