Hunting for Maxwell's demon in the wild

Synopsis

The thought experiment of Maxwell's demon, and subsequent work by Szilard, Landauer and others, revealed deep connections between information and thermodynamics. Since then, the theoretical development of stochastic thermodynamics, in addition to technological advances, has enabled researchers to physically realize Maxwell demons, also known as information engines. Such systems achieve performance similar to biological molecular machines, which must perform their functions in the fluctuating environment of the cell, where information is a relevant free-energy resource. This, in addition to other experimental evidence and theoretical work, poses the question of whether molecular machines have evolved to function as information engines that rectify fluctuations. In this talk, I will discuss ongoing work by the Sivak and Bechhoefer groups to investigate this question for transport motors, which consume chemical energy to pull cargo in the cell. Typically, determining whether such a molecular motor operates as a conventional or information engine requires detailed knowledge of the energy flows of the cargo-motor system, which cannot be determined by current experimental techniques. We have developed an estimator which allows us to infer the operational mode of the motor using only experimentally accessible measurements of the cargo's mean square displacement. I will give an overview of this work, discuss the experiments that are being done to benchmark our estimator, and conclude by considering potential application of our work to determine whether, and under which conditions, kinesin operates as a Maxwell demon. Along the way, I will provide an accessible discussion of Maxwell demons and the relationship between internal energy flows of bipartite engines and the mode of operation of such engines.