Otto engine beyond its standard quantum limit

Phys Rev E. 2016 Feb;93(2):022122. doi: 10.1103/PhysRevE.93.022122. Epub 2016 Feb 16.

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 noncoherent thermal radiation, sustained only by external heat supplied to macroscopic objects. Remarkably, even for nonideal finite-time transformations, it largely over-performs the standard ideal Otto cycle and asymptotically achieves unit efficiency at finite power.