Maxwell's Daemon: information versus particle statistics.

Martin Plesch,Oscar Dahlsten,Vlatko Vedral,John Goold

doi:10.1038/srep06995

Abstract

Maxwell's daemon is a popular personification of a principle connecting information gain and extractable work in thermodynamics. A Szilard Engine is a particular hypothetical realization of Maxwell's daemon, which is able to extract work from a single thermal reservoir by measuring the position of particle(s) within the system. Here we investigate the role of particle statistics in the whole process; namely, how the extractable work changes if instead of classical particles fermions or bosons are used as the working medium. We give a unifying argument for the optimal work in the different cases: the extractable work is determined solely by the information gain of the initial measurement, as measured by the mutual information, regardless of the number and type of particles which constitute the working substance.

Highlights

Maxwell’s daemon is a popular personification of a principle connecting information gain and extractable work in thermodynamics
We investigate the role of particle statistics in the whole process; namely, how the extractable work changes if instead of classical particles fermions or bosons are used as the working medium
We find that the extractable work is determined by the information gained during the initial measurement, regardless of whether the working medium consists of distinguishable, bosonic or fermionic particles

Summary

Introduction

Maxwell’s daemon is a popular personification of a principle connecting information gain and extractable work in thermodynamics. A Szilard Engine is a particular hypothetical realization of Maxwell’s daemon, which is able to extract work from a single thermal reservoir by measuring the position of particle(s) within the system. Our work clarifies why the basics of thermodynamics are independent of particle statistics, a fact that makes thermodynamical laws all the more remarkable. It emphasises that the second law ought to most appropriately be phrased in terms of a trade-off between information gained and work done and holds for all types of particles. Maxwell’s daemon systems make use of extra knowledge beyond that of a thermal observer to extract work Investigating such systems has helped to clarify and develop statistical mechanics.

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