Otto engine beyond its standard quantum limit

TL;DR

This paper introduces a quantum Otto cycle utilizing a two-level system in a non-equilibrium electromagnetic environment, achieving efficiencies surpassing the standard quantum limit and approaching unit efficiency at finite power without active environmental control.

Contribution

It presents a novel quantum Otto cycle that operates in a realistic out-of-thermal-equilibrium field, outperforming standard cycles and reaching near-perfect efficiency.

Findings

Over-performs standard Otto cycle even with finite-time transformations

Achieves asymptotic unit efficiency at finite power

Operates without active control of the environment

Abstract

We propose a quantum Otto cycle based on the properties of a two-level system in a realistic out-of-thermal-equilibrium electromagnetic field acting as its sole reservoir. This steady configuration is produced without the need of active control over the state of the environment, which is a non-coherent thermal radiation, sustained only by external heat supplied to macroscopic objects. Remarkably, even for non-ideal finite-time transformations, it largely over-performs the standard ideal Otto cycle, and asymptotically achieves unit efficiency at finite power.