Davies equation without the secular approximation: Reconciling locality with quantum thermodynamics for open quadratic systems
Phys. Rev. A 113, 052212 – Published 12 May, 2026
DOI: https://doi.org/10.1103/m1zr-7rmv
Abstract
We derive a thermodynamically consistent quantum master equation that satisfies locality for quadratic systems coupled to independent and identical baths at each site. We show that the quasilocal Redfield equation coincides exactly with the Davies equation, which satisfies the detailed balance condition, due to cancellation of quantum coherence generated by each bath. This derivation does not rely on the secular approximation, which fails in systems with vanishing energy-level spacings. We discuss generalizations of our result to slowly driven quadratic systems and generic quantum many-body systems. Our result paves the way to a thermodynamically consistent description of quantum many-body systems.
