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arXiv2026

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

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.

cond-mat.soft↗

arXiv2025

Chiral active gyrator: Memory induced direction reversal of rotational motion

We theoretically explore the dynamics of a chiral active Ornstein Uhlenbeck particle confined in a two-dimensional anisotropic harmonic trap. The particle is driven by chirality and is coupled to two orthogonal heat baths, potentially at two different temperatures. Using both analytical approach and numerical simulation, we explore the rotational dynamics of the particle in both viscous and viscoelastic environments. While the particle is suspended in a viscoelastic bath, characterized by a finite memory time scale, we interestingly observe that even in the absence of a temperature gradient, the angular momentum changes its sign as a function of the memory timescale, reflecting the direction reversal of rotational motion of the particle, and it is solely due to the interplay between memory and chirality. This direction reversal is a distinct memory-induced phenomenon and does not occur in the viscous limit. Moreover, increasing (or decreasing) the temperature gradient shifts the magnitude of the angular momentum further into the negative (or positive) direction, selecting a unique direction of rotation for the particle throughout the activity-memory parameter space. However, in the viscous limit, the direction reversal of the rotational motion is still possible but occurs only across a neutral line in parameter space, along which the contributions from both chirality and thermal anisotropy to the net angular momentum exactly cancel. These results highlight a distinct mechanism for directional control in active systems, with memory enabling reversal phenomena unique to viscoelastic media.

cond-mat.soft↗