Double quantum-dot engine fueled by entanglement between electron spins

TL;DR

This paper introduces a quantum thermodynamic engine using entangled electron spins in a double quantum dot system, demonstrating work extraction based on entropy differences of entangled states, with optimal long-term performance and finite-time analysis.

Contribution

It presents a novel quantum engine that exploits electron spin entanglement in quantum dots for thermodynamic work extraction, including a microscopic bath model and finite-time performance analysis.

Findings

Engine operates using entangled singlet states as fuel.

Work can be extracted from entropy differences despite identical single-dot measurements.

Engine is optimal in the long-time limit with realistic parameters.

Abstract

The laws of thermodynamics allow work extraction from a single heat bath provided that the entropy decrease of the bath is compensated for by another part of the system. We propose a thermodynamic quantum engine that exploits this principle and consists of two electrons on a double quantum dot (QD). The engine is fueled by providing it with singlet spin states, where the electron spins on different QDs are maximally entangled, and its operation involves only changing the tunnel coupling between the QDs. Work can be extracted since the entropy of an entangled singlet is lower than that of a thermal (mixed) state, although they look identical when measuring on a single QD. We show that the engine is an optimal thermodynamic engine in the long-time limit. In addition, we include a microscopic description of the bath and analyze the engine's finite-time performance using experimentally relevant parameters.