Extending quantum detailed balance through optimal transport
Rocco Duvenhage, Samuel Skosana, Machiel Snyman
TL;DR
This work addresses how to quantify and extend quantum detailed balance to non-equilibrium settings by embedding systems into a transport framework. It introduces transport plans between systems on possibly different observable algebras and defines Wasserstein distances that measure how closely a system reflects a model with detailed balance, even across noncommutative boundaries. The paper develops a comprehensive theory—including $W$, $W_\sigma$, and $W_{\sigma\sigma}$—proving existence of optimal plans and establishing metric properties, dualities, and bounds that connect deviations from detailed balance to transport distance, with concrete classical and quantum examples. The proposed approach provides a structured, quantitative pathway to analyze non-equilibrium steady states and common structural features across complex quantum systems, offering potential applications in non-equilibrium statistical mechanics and noncommutative ergodic theory.
Abstract
We develop a general approach to setting up and studying classes of quantum dynamical systems close to and structurally similar to systems having specified properties, in particular detailed balance. This is done in terms of transport plans and Wasserstein distances between systems on possibly different observable algebras.
