Comment on "Catalytic Coherence"

TL;DR

This paper critiques a claim that a quantum reservoir's coherence can be reused indefinitely without loss, demonstrating that repeated use reduces accuracy and increases thermodynamic costs, impacting quantum thermodynamics applications.

Contribution

It provides a critical analysis showing that the repeated use of a coherence reservoir diminishes accuracy and incurs higher thermodynamic costs, countering prior claims.

Findings

Repeated use of the reservoir reduces the coherence accuracy.

Thermodynamic costs increase with each use.

Prior claims of unlimited coherence reuse are invalid.

Abstract

Aberg has claimed in a recent Letter," Phys. Rev. Lett. 113, 150402 (2014)", that the coherence of a reservoir can be used repeatedly to perform coherent operations without ever diminishing in power to do so. The claim has particular relevance for quantum thermodynamics because, as shown in "Phys. Rev. Lett. 113, 150402 (2014)", latent energy that is locked by coherence may be extractable without incurring any additional cost. We show here, however, that repeated use of the reservoir gives an overall coherent operation of diminished accuracy and is necessarily accompanied by an increased thermodynamic cost.