Title: Effects of Activity on approaching Glassiness

Author (Table Talk): Chetan Yadav, University of Massachusetts, Amherst

Abstract:

We are interested in understanding how the approach to the glassy regime will change with the introduction of activity in a fraction of particles in a system. In particular, we would like to know if the dynamics are merely sped up by activity or whether there is some qualitative change. To address these questions, we conduct experiments on a bidisperse mixture of discs in a plane, fluidized by vibration from a shaker. The discs are designed so that they can be chosen to have isotropic motions in the plane, or have a preferred polar mobility. We compare dynamics in 50:50 mixtures of large and small passive grains to 50:50 mixtures of large active and small passive grains as the total area fraction is increased. By studying the dynamic susceptibility, we see stronger and broader heterogeneity in the active mixture, where dynamics is fastest along long-lived chains.