Optimal measurement-based quantum thermal machines in a finite-size system

TL;DR

This paper introduces a measurement-based quantum thermal machine using a coupled two-level system, optimizing work extraction through universal criteria and demonstrating robustness and efficiency in a platform-agnostic setup.

Contribution

It develops universal optimization criteria and numerical algorithms for a measurement-based quantum engine with coupled two-level systems, advancing practical quantum thermal machines.

Findings

Efficiency peaks with projective measurements.

Symmetry breaking enlarges energy gap.

Performance remains >50% of optimum under feedback errors.

Abstract

We present a measurement-based quantum thermal machine that extracts work from the back-action of generalized quantum measurements whose working medium is a coupled two-level quantum system. Specifically, we derive universal optimization criteria for a three-stroke measurement-based engine cycle with coupled two-level system of Ising-like interaction as a working medium. Furthermore, we present two numerical algorithms to optimize the engine work extraction and enhance its performance. Our numerical results demonstrate: (i) efficiency peaks in the projective-measurement limit; (ii) symmetry breaking (detuning or weak coupling) enlarges the exploitable energy gap; and (iii) performance remains robust ($>50\%$ of optimum) under $\sim\!10^\circ$ feedback-pulse errors. The framework is platform-agnostic and directly implementable with current superconducting, trapped-ion, or NMR technologies, providing a concrete route to scalable, measurement-powered quantum thermal machines.