Speaker: Dr. Momcilo Gavrilov, John Hopkins University
Title: Direct Measurement of a Weakly Nonequilibrium System Entropy using a Feedback Trap
Abstract: Gavrilov abstract The entropy function for an equilibrium system has a Gibbs-Shannon form; however, there is a long, sometimes contentious debate as to whether the Gibbs-Shannon form applies to systems out of equilibrium. Here, I present the first direct measurement of the entropy function for a system out of equilibrium. In a feedback trap, I confine a silica bead immersed in water in a virtual double-well potential that models a two-state system capable of storing maximum one bit of information. By measuring the average work to erase a controlled fraction of the information, I isolate directly the change in entropy in a nonequilibrium system and show its compatibility with the Gibbs-Shannon form. Further, by measuring the reversibility of slow protocols used to transform the system, I show how to distinguish unambiguously between protocols that can and cannot reach the expected thermodynamic bounds.