Notes on Landauer's principle, Reversible Computation and Maxwell's Demon

TL;DR

This paper defends Landauer's principle as a fundamental and pedagogically valuable concept in thermodynamics of information, countering criticisms and clarifying its role in understanding Maxwell's Demon and the Second Law.

Contribution

It provides a rebuttal to criticisms of Landauer's principle and emphasizes its importance in the conceptual framework of thermodynamics and information theory.

Findings

Landauer's principle is a valid and useful restatement of the Second Law.

Reversible computation can be thermodynamically reversible, aligning with the principle.

The principle has significant pedagogic and explanatory value in physics.

Abstract

Landauer's principle, often regarded as the foundation of the thermodynamics of information processing, holds that any logically irreversible manipulation of information, such as the erasure of a bit or the merging of two computation paths, must be accompanied by a corresponding entropy increase in non-information bearing degrees of freedom of the information processing apparatus or its environment. Conversely, it is generally accepted that any logically reversible transformation of information can in principle be accomplished by an appropriate physical mechanism operating in a thermodynamically reversible fashion. These notions have sometimes been criticized either as being false, or as being trivial and obvious, and therefore unhelpful for purposes such as explaining why Maxwell's Demon cannot violate the Second Law of thermodynamics. Here I attempt to refute some of the arguments against Landauer's principle, while arguing that although in a sense it is indeed a trivial and obvious restatement of the Second Law, it still has considerable pedagogic and explanatory power, especially in the context of other influential ideas in 19'th and 20'th century physics. Similar arguments have been given by Jeffrey Bub [arXiv:quant-ph/0203017].