Autonomous quantum Maxwell's demon based on two exchange-coupled quantum dots

TL;DR

This paper proposes an autonomous quantum Maxwell's demon using two exchange-coupled quantum dots that operate via coherent spin oscillations, enabling electron pumping against bias and demonstrating local entropy reduction.

Contribution

It introduces a quantum Maxwell's demon based on exchange-coupled quantum dots utilizing coherent spin oscillations as a quantum iSWAP gate, linking quantum information transfer with thermodynamics.

Findings

Demonstrates electron pumping against bias due to quantum feedback control.

Shows entropy production can be locally negative in the quantum system.

Establishes a thermodynamic framework for quantum information flow in the setup.

Abstract

I study an autonomous quantum Maxwell's demon based on two exchange-coupled quantum dots attached to the spin-polarized leads. The principle of operation of the demon is based on the coherent oscillations between the spin states of the system which act as a quantum iSWAP gate. Due to the operation of the iSWAP gate one of the dots acts as a feedback controller which blocks the transport with the bias in the other dot, thus inducing the electron pumping against the bias; this leads to the locally negative entropy production. Operation of the demon is associated with the information transfer between the dots, which is studied quantitatively by mapping the analyzed setup onto the thermodynamically equivalent auxiliary system. The calculated entropy production in a single subsystem and information flow between the subsystems are shown to obey a local form of the second law of thermodynamics, similar to the one previously derived for classical bipartite systems.