Speaker
Aleksei Chechkin
(Akhiezer Institute for Theoretical Physics)
Description
A growing number of biological, soft, and active matter systems are observed to exhibit normal diffusive dynamics with a linear growth of the mean-squared displacement, yet with a non-Gaussian distribution of increments. Based on the Chubinsky-Slater idea of a diffusing diffusivity, we here establish and analyze a minimal model framework of diffusion processes with fluctuating diffusivity. In particular, we demonstrate
the equivalence of the diffusing diffusivity process with a superstatistical approach with a distribution of diffusivities, at times shorter than the diffusivity correlation time. At longer times, a crossover to a Gaussian distribution with an effective diffusivity emerges. Specifically, we establish a subordination picture of Brownian but non-Gaussian diffusion processes, which can be used for a wide class of diffusivity fluctuation statistics. Our results are shown to be in excellent agreement with simulations and numerical evaluations.
$ $
Aleksei V. Chechkin, Flavio Seno, Ralf Metzler, and Igor M. Sokolov, PHYSICAL REVIEW X 7, 021002 (2017).
Primary author
Aleksei Chechkin
(Akhiezer Institute for Theoretical Physics)
Co-authors
Flavio Seno
(University of Padova)
Igor Sokolov
(Humboldt University Berlin)
Ralf Metzler
(University of Potsdam)
