Physics Colloquium: Dislocation Machines: Topological Defects for Organizing Shape Change in Crystalline Metamaterials

The Department of Physics is pleased to welcome Dr. Bryan VanSaders for a virtual colloquia presentation. Dr. Bryan VanSaders is a Kadanoff-Rice Postdoctoral Fellow of the James Franck Institute at the University of Chicago, with a particular interest in the intersection of active matter and topological defects in dense crystalline colloidal assemblies, and the role of information in emergent swarm dynamics.

This is a virtual colloquium. Please contact phyadmin@syr.edu for the link.

Abstract

Colloidal nanoparticles capable of exerting microscopic forces (known as active matter) suggest a future class of robotic swarm metamaterials with attractive lifelike properties. These microscopic swarms must coordinate their actions to accomplish useful tasks, such as changing the swarm shape or engulfing an object. Contrary to their macroscopic counterparts, microscopic swarms must achieve this coordination without complex inter-particle communication. Therefore, active matter for robotic applications requires emergent behaviors with a minimum of explicit computation, a form of physical intelligence derived from the interactions and dynamics of the swarm. Following this principle, I explore through computer simulation how cycles of local non-conservative interaction between constituents can control the dynamics of topological defects in 2D metamaterials. Such defects link microscopic and macroscopic system length scales, allowing for local work expenditure to drive system-wide mechanical reconfigurations. I examine two examples of local work cycles – controlled dislocation creation reactions through local bond stretching and self-propelled dislocations arising from local bond torsion. These examples highlight how emergent phenomena can organize local work dissipation for system-spanning reconfigurations.