Active colloids that mix and mingle

Active matter describes nonequilibrium systems that consist of "elementary particles" that consume energy to move. Examples include dynamically self-organized molecular motors in the cytoskeleton, swarming bacteria, flocks of birds and crowds of people. However, most studies so far have focused on monodisperse systems. Active matter of mixtures of particles with distinct active driving forces remains surprisingly largely unexplored. Would materials scientists today fathom constraining themselves to purely single-component metals? Alloying active matter adds a whole new dimension to our exploration of mesoscopic building blocks. Today there is a striking gap both in our theoretical understanding and experimental endeavors in this domain. In this talk I will discuss my group's efforts in understanding active mixtures using the Active Brownian Particle (ABP) model. I will show results for systems where the concentrations of the two active species are 50:50, as well as the limiting cases of doping a passive material with a very small percentage of active particles in order to control the material's properties.