The fundamental difference between logical and thermodynamic irreversibilities, or, Why Landauer's result cannot be a physical principle

TL;DR

This paper argues that Landauer's principle, linking information erasure to heat dissipation, is not a universal physical law but results from conceptual confusions and unnecessary constraints, opening possibilities for reversible computing.

Contribution

The paper clarifies the distinction between logical and thermodynamic irreversibilities and challenges the universality of Landauer's principle, proposing alternative erasure methods.

Findings

Landauer's principle is not a general physical law.

Logical and thermodynamic irreversibilities are distinct concepts.

Reversible erasure procedures are theoretically possible.

Abstract

Landauer's "principle" claims that erasing one bit of information necessarily dissipates at least Tln2 of heat into the surroundings, making a possibly logically irreversible operation also thermodynamically irreversible. It is commonly accepted that this result is a fundamental principle of physics that definitively establishes the link between information and energy. Here we show that this result cannot be general. In fact it comes: 1) from a confusion between logical and thermodynamic irreversibilities and between logical and thermodynamic states, which is reminiscent of the classic Gibbs' paradox about the joining of two volumes of the same gas; and 2) from two unnecessary constraints imposed on the erase procedure. Clarifying these points permits: to dissociate the notions of logical and thermodynamic irreversibilities; to invalidate Landauer's result as being a general physical principle; and to open the door to hardware implementations allowing erasure to follow a thermodynamically reversible, or at least quasistatic, path.