MSE 298 Seminar: Non-equilibrium Free Energetics of Active Filaments From Variational Time Reversal

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Abstract: The interplay between dynamics, structure and function of active systems is central to inquiries ranging from spontaneous organization inside the cell nucleus to macroscopic collective organization of self-driven agents. In this talk, we introduce a method to estimate deviations from equilibrium of arbitrary structural properties of active systems through the solution of a stochastic optimal control problem for non-equilibrium free-energy profiles along order parameters. We find a physical interpretation for a unique optimal control policy as that which achieves a nondissipative time reversal of the driven system, and use this knowledge to design ansätze that lead to rapid convergence in a variational reinforcement learning implementation of the control problem. Applications of this scheme to coarse-grained models of active semi-flexible filaments swimming freely and under confinement allow us to map out non-equilibrium density enhancements of structural dynamic motifs as functions of the distribution and intensity of active forces along the filament's backbone.

Bio: Jorge L. Rosa-Raíces obtained his bachelor's degree in chemical engineering from the University of Puerto Rico, Mayagüez and his doctorate from Caltech in path-space MCMC methods for molecular simulation under the supervision of Thomas F. Miller, III. He currently works in the research group of David Limmer at UC Berkeley on control-theoretic methods for simulating rare events in the non-equilibrium stationary states of active materials.