Comment on "Steady-State Coherences by Composite System-Bath Interactions"

TL;DR

This paper critiques a recent study claiming steady-state coherence generation via a thermal bath, highlighting technical errors and limitations in the original analysis that challenge its conclusions.

Contribution

It provides a critical analysis identifying flaws in the methodology and conceptual understanding of the original work on steady-state coherences.

Findings

Identifies technical errors in the original calculations.

Highlights issues with negativity in the master equation used.

Challenges the validity of the original conclusions.

Abstract

In a recent Letter, Guarnieri et al. [1] reported on the possibility of generating steady-state coherence (SSC) in the energy basis of a two-level system by the sole action of a single thermal bath also for weak system-bath coupling and due to a composite form of this interaction. The results are based on a time-local Bloch-Redfield master equation without secular approximation and the associated set of Bloch equations, all derived in the Supplemental Material (SM) of Ref. [1]. We comment that the results reported by the authors present both technical flaws and conceptual limitations that substantially impact some of their main conclusions. Our objections mainly concern (a) technical errors in the calculation of SSC (Eqs.(2)-(4) in [1]) and (b) negativity issues associated with the weak-coupling master equation employed by the authors.