Assessing the validity of the thermodynamic uncertainty relation in quantum systems

TLDR

The thermodynamic uncertainty relation (TUR) is a cost‑precision trade‑off relationship in transport systems. The authors derive a condition on the validity of the TUR for general nonequilibrium systems based on fluctuation symmetry, and show that quantum coherent systems not described by a population Markovian master equation violate the TUR. They exemplify the condition by deriving the TUR for noninteracting quantum systems using the transmission function formalism. The first non‑zero contribution to the TUR beyond equilibrium can be positive or negative, so the TUR can be affirmed or violated depending on system details, and quantum coherent systems that support high‑order tunneling or rely on coherences indeed violate the TUR.

Abstract

We examine the so-called thermodynamic uncertainty relation (TUR), a cost-precision trade-off relationship in transport systems. Based on the fluctuation symmetry, we derive a condition on the validity of the TUR for general nonequilibrium (classical and quantum) systems. We find that the first non-zero contribution to the TUR beyond equilibrium, given in terms of nonlinear transport coefficients, can be positive or negative, thus affirming or violating the TUR depending on the details of the system. We exemplify our results for noninteracting quantum systems by deriving the thermodynamic uncertainty relation in the language of the transmission function. We demonstrate that quantum coherent systems that do not follow a population Markovian master equation, e.g. by supporting high order tunneling processes or relying on coherences, violate the TUR.