Squeezing light to get nonclassical work in quantum engines

TL;DR

This paper demonstrates how quantum squeezing of light can be harnessed to extract mechanical work in quantum engines, revealing new insights into work definitions and optimizing work production from non-thermal quantum resources.

Contribution

It introduces a method to extract work from quantum squeezing in a photon engine and highlights limitations of standard work definitions in quantum thermodynamics.

Findings

Work can be extracted from squeezing without thermal gradients.

Standard work definitions do not account for quantum leakage of energy.

Optimal work occurs at a specific squeezing-dependent temperature.

Abstract

Light can be squeezed by reducing the quantum uncertainty of the electric field for some phases. We show how to use this purely quantum effect to extract net mechanical work from radiation pressure in a simple quantum photon engine. Along the way, we demonstrate that the standard definition of work in quantum systems does not capture the extractable mechanical work, as it does not reflect the energy leaked to these quantum degrees of freedom. We use these results to design an Otto engine able to produce mechanical work from squeezing baths, in the absence of a thermal gradient. Interestingly, while work extraction from squeezing generally improves for low temperatures, there exists a nontrivial squeezing-dependent temperature for which work production is maximal, demonstrating the complex interplay between thermal and squeezing effects.