On the validity of the thermodynamic uncertainty relation in quantum systems

TL;DR

This paper investigates the conditions under which the thermodynamic uncertainty relation (TUR) holds in classical and quantum nonequilibrium systems, revealing that quantum coherence can lead to violations of TUR.

Contribution

It derives a general condition for TUR validity based on fluctuation symmetry and demonstrates quantum coherence effects that violate TUR.

Findings

Nonlinear transport coefficients determine TUR validity.

Quantum coherent systems can violate TUR.

High-order tunneling processes affect TUR validity.

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.