Cyclic Memories in Matter– Physics Colloquium Friday Nov. 9, 2018

Friday, Nov 9, 2018, 2pm in P-148

 

Cyclic driving occurs all around us. For example, buildings and bridges are repeatedly loaded and unloaded, and temperatures change between day and night. This kind of driving can change a material, but in some cases it also forms memories that can be recalled later. I present two remarkable examples of matter that, when deformed repeatedly, “learns” the magnitudes of those deformations: a suspension of particles in liquid, and a jammed solid made of closely packed particles. Their memories follow different rules, with jammed solids showing a behavior best known in magnetic materials. Against intuition, these materials’ disordered structures, and sometimes even the presence of noise, is essential for the fidelity of their memories.