Numerical simulation of interface roughening in multicomponent mixtures of active and passive matter

Interface roughening and growth is of interest in a wide variety of physical processes across many fields from crystalline surfaces, systems undergoing phase separation, and molecular beam epitaxy. It is well-studied that several universality classes arise in these processes (Barabasi and Stanley 1995 Cambridge Univ. Press). Interfaces are ubiquitous in active matter, such as activity in the presence of cellular membranes or bacterial colony growth on surfaces. Recently, it has been predicted that a phase-separating unary active system presents a new universality class for the roughening of the dense-dilute interface (Besse et al. 2023 PRL). Active matter is readily observed in biological environments which are necessarily multicomponent, and mixtures of active and passive matter have become increasingly of interest in the field. In this talk, we present particle-based numerical simulations of interfaces in active systems, both unary and mixtures with a passive species. The interface roughening dynamics are studied in detail to examine the scale invariance of these systems. We also address possible mechanisms for anomalous interface roughening observed in these systems.