The Many Guises of Absorbing-State Phase Transitions: Evolutionary Dynamics and Driven Amorphous Solids
February 13, 2018 -
3:00pm to 4:00pm
University of Tennessee
Certain non-equilibrium systems, including growing microbial colonies, amorphous solids under oscillatory shear, turbulent liquid crystals, and avalanches undergo dynamical phase transitions across which we observe fluctuating, active regions of the system either propagate and grow with time, or go extinct, forcing the system into an absorbing state.
We will focus on such transitions in two very different systems: a microbial colony in which a fit strain irreversibly converts to a less fit one (leading to the possibility of strain extinction), and a dense, amorphous solid under oscillatory shear. In the case of the microbial colony, we show that the spatial distribution and geometry of the colony profoundly impacts the phase transition, with spatial fluctuations driving extinction of the fit strain.
In the driven amorphous solid, we show that the dynamical phase transition competes with another phase transition at which the solid loses rigidity: the jamming point. We show that as the jamming point is approached, the absorbing states associated with reversible, quiescent dynamical behavior become more and more complex.