Thermodynamics of information and control: the twin legacies of James Clerk Maxwell

John Bechhoefer, Dept. of Physics, Simon Fraser University, Burnaby, British Columbia, Canada

Abstract:  One hundred and fifty years ago, Maxwell’s demon was first posed as a fundamental challenge to the newly developed field of statistical physics.  Just two months later, Maxwell’s paper “On governors” gave the first analysis of a feedback system.  These two foundational works reflect the fundamental and practical aspects of control theory.  Here, I will present an experiment that unites the two:  using feedback to create “impossible” dynamics, we make a Maxwell demon that can reach the fundamental limits to control set by thermodynamics.  We test—and then extend—Rolf Landauer’s 1961 prediction that information erasure requires at least as much work as can be extracted from a system  by virtue of information.  These fundamental thermodynamic limits are benchmarks for evaluating the performance of practical information engines, such as those active within cells and other complex systems.