Universal features in the efficiency of ultra hot quantum Otto engines

TL;DR

This paper investigates the efficiency of ultra hot quantum Otto engines, revealing universal features and independence from engine specifics in the high-temperature regime, with implications for optimization constraints and perturbative analysis.

Contribution

It uncovers universal efficiency characteristics in quantum Otto engines at high temperatures, independent of engine details, and discusses the limitations of perturbative approaches.

Findings

Efficiency depends only on optimization constraints in the ultra hot regime.

Universal features resemble classical power optimization.

Perturbative approach may have zero radius of convergence under certain constraints.

Abstract

We study internal work optimization over the energy levels of a generic hot quantum Otto engine. We find universal features in the efficiency that resembles the classical external power optimization over the coupling times to the thermal baths. It is shown that in the ultra hot regime the efficiency is determined solely by the optimization constraint, and independent of the engine details. We show that for some constraints the radius of convergence of the perturbative approach used in the classical analysis is zero even for very arbitrarily low efficiencies at small temperature difference.