Efficiency large deviation function of quantum heat engines

TL;DR

This paper investigates the efficiency large deviation functions of quantum heat engines, revealing that universal efficiency fluctuation theory applies only in nonadiabatic regimes, with adiabatic engines showing unique anticorrelation effects.

Contribution

It demonstrates the breakdown of universal efficiency fluctuation theory in adiabatic quantum heat engines and links this to perfect work-heat anticorrelation.

Findings

Universal theory applies in nonadiabatic regimes

Adiabatic engines exhibit perfect work-heat anticorrelation

Fluctuation suppression in scale-invariant adiabatic engines

Abstract

The efficiency of small thermal machines is typically a fluctuating quantity. We here study the efficiency large deviation function of two exemplary quantum heat engines, the harmonic oscillator and the two-level Otto cycles. While the efficiency statistics follows the 'universal' theory of Verley et al. [Nature Commun. 5, 4721 (2014)] for nonadiabatic driving, we find that the latter framework does not apply in the adiabatic regime. We relate this unusual property to the perfect anticorrelation between work output and heat input that generically occurs in the broad class of scale-invariant adiabatic quantum Otto heat engines and suppresses thermal as well as quantum fluctuations.