Quantum Otto engines at relativistic energies

TL;DR

This paper investigates how relativistic effects influence the performance of quantum Otto engines, revealing higher work output but lower efficiency compared to non-relativistic engines, with efficiency at maximum power matching the Curzon-Ahlborn limit.

Contribution

It introduces a relativistic quantum Otto engine model and analyzes its thermodynamic performance, highlighting the impact of relativistic dynamics on work output and efficiency.

Findings

Relativistic engines produce higher work output.

Efficiency is reduced due to a smaller effective compression ratio.

Efficiency at maximum power equals the Curzon-Ahlborn efficiency.

Abstract

Relativistic quantum systems exhibit unique features not present at lower energies, such as the existence of both particles and antiparticles, and restrictions placed on the system dynamics due to the light cone. In order to understand what impact these relativistic phenomena have on the performance of quantum thermal machines we analyze a quantum Otto engine with a working medium of a relativistic particle in an oscillator potential evolving under Dirac or Klein-Gordon dynamics. We examine both the low-temperature, non-relativistic and high-temperature, relativistic limits of the dynamics and find that the relativistic engine operates with higher work output, but an effectively reduced compression ratio, leading to significantly smaller efficiency than its non-relativistic counterpart. Using the framework of endoreversible thermodynamics we determine the efficiency at maximum power of the relativistic engine, and find it to be equivalent to the Curzon-Ahlborn efficiency.