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Mathematical Physics Seminar

Memory formation in out of equilibrium systems

Sidney Nagel - The University of Chicago

Location:  Zoom
Date & time: Wednesday, 25 May 2022 at 10:45AM - 11:45AM

Out-of-equilibrium systems preserve memories of their formation and training history in a variety of ways allowing for an innovative classification of material and dynamics. I will discuss one case where a cyclically sheared suspension of particles or a charge-density-wave solid (or even a walk in the park!) remembers multiple values from a series of training inputs yet forgets all but two of them at long times despite their continued repetition; however, if noise is added all the memories can be encoded indefinitely! When the packing density is increased, so that the particles become jammed, the evolution takes place in a very rugged energy landscape where scores of local energy minima are visited during each applied oscillation. Nevertheless the jammed solid can readily find the periodic orbits. Memory formation in such a system not only sheds light on how glassy ground states are selected and communicate with one another but also shows a form of memory that allows a new probe of the interactions within a material.