The role of coherence in the non-equilibrium thermodynamics of quantum systems

TL;DR

This paper investigates how quantum coherence influences the energetics of non-equilibrium quantum systems, providing a way to quantify and analyze the coherent contribution during driven transformations.

Contribution

It introduces an operational criterion to quantify coherence in non-equilibrium quantum processes and links coherence generation to non-adiabaticity, supported by models like qubits and kicked rotors.

Findings

Coherent and incoherent parts of irreversible work can be separated.

Coherence generation correlates with process non-adiabaticity.

Coherence change satisfies a fluctuation theorem.

Abstract

Exploiting the relative entropy of coherence, we isolate the coherent contribution in the energetics of a driven non-equilibrium quantum system. We prove that a division of the irreversible work can be made into a coherent and incoherent part, which provides an operational criterion for quantifying the coherent contribution in a generic non-equilibrium transformation on a closed quantum system. We then study such a contribution in two physical models of a driven qubit and kicked rotor. In addition, we also show that coherence generation is connected to the non-adiabaticity of a processes, for which it gives the dominant contribution for slow-enough transformation. The amount of generated coherence in the energy eigenbasis is equivalent to the change in diagonal entropy, and here we show that it fulfills a fluctuation theorem.