Title: Enhanced diffusion of tracer particles in nonequilibrium mixtures

Speaker: Pierre Illien (Sorbonne University)

Abstract:

In many situations of biophysical interest, describing accurately the dynamics of tagged particles (or ‘tracers’) in nonequilibrium suspensions is of crucial importance. From a theoretical perspective, it represents a major challenge, since the combination of interparticle couplings and nonequilibrium drive requires refined levels of descriptions. We design a generic analytical framework to study the dynamics of a tracer in a dense mixture of particles which evolves far from equilibrium. Starting from the overdamped Langevin equations that describe the evolution of the system, we derive the expression of the self-diffusion coefficient of a tagged particle in the suspension, in the limit of soft interactions between the particles. Our derivation relies on the linearization of the Dean-Kawasaki equations obeyed by the density fields and on a path-integral representation of the dynamics of the tracer. We apply this scheme to two types of nonequilibrium mixtures which have received a lot of interest recently: two-temperature mixtures, and non-reciprocal mixtures. In both situations, our analytical model combined with Brownian dynamics reveals the emergence of enhanced diffusion, and the condition for its observation.

References:

• Jardat et al., Phys. Rev. E 106, 064608 (2022), arXiv:2209.00929
• Benois et al., to appear in Phys. Rev. E (2023), arXiv:2307.05408

This seminar will take place in room C3.165