Nonlinear Physics Seminar: "Dynamics and escape of active particles in a harmonic trap"

Date: 
Wed, 07/04/2021 12:00 to 13:30
Lecturer: Prof. Golan Bel from the Department of Solar Energy and Environmental Physics, Ben-Gurion University, Sede Boqer, Israel     
Abstract:


The dynamics of active particles is of interest at many levels and is the focus of theoretical and experimental research. 
There have been many attempts to describe the dynamics of particles affected by random active forces in terms of an effective temperature. 
This kind of description is tempting due to the similarities (or lack thereof) to systems in or near thermal equilibrium. 
However, the generality and validity of the effective temperature is not yet fully understood. 
We study the dynamics of trapped, undersamped particles subjected to both thermal and active forces. 
Expressions for the effective temperature due to the potential and kinetic energies are derived, and they differ from each other. 
A third possible effective temperature can be derived from the Kramers-like expression for the mean escape time of the particle from the trap. 
We find that over a large fraction of the parameter space, the potential energy effective temperature is in agreement with the escape temperature, while the kinetic effective temperature only agrees with the former two in the overdamped limit. Moreover, we show that the specific implementation of the random active force, and not only its first two moments and the two point autocorrelation function, affects the escape-time distribution.