- Non-equilibrium transitions between metastable patterns in populations of motile bacteria
- 02/16/2017
- 4:10 PM - 5:00 PM
- C304 Wells Hall
- Eric Vanden-Eijnden, NYU
Active materials can self-organize in many more ways than their
equilibrium counterparts. For example, self-propelled particles whose
velocity decreases with their density can display motility-induced
phase separation (MIPS), a phenomenon building on a positive feedback
loop in which patterns emerge in locations where the particles slow
down. Here, we investigate the effects of intrinsic fluctuations in
the system's dynamics on MIPS, using a field theoretic description
building on results by Cates and collaborators. We show that these
fluctuations can lead to transitions between metastable patterns. The
pathway and rate of these transitions is analyzed within the realm of
large deviation theory, and they are shown to proceed in a very
different way than one would predict from arguments based on
detailed-balance and microscopic reversibility. Specifically, we show
that these transitions involve fluctuations in diffiusivity of the
bacteria followed by fluctuations in their population, in a specific
sequence. The methods of analysis proposed here, including their
numerical components, can be used to study noise-induced
non-equilibrium transitions in a variety of other non-equilibrium
set-ups, and lead to predictions that are verifiable experimentally.