Confined free-electrons in an applied electric field: Discontinuous electron density

TL;DR

This paper studies how an applied electric field causes abrupt changes in electron density in quantum dots, proposing a new electrical method to control exchange coupling for quantum computing.

Contribution

It reveals the discontinuous electron density response to electric fields in quantum dots and suggests a novel electrical control mechanism for quantum gate operations.

Findings

Electric field induces abrupt electron density changes.

Discontinuous electron density affects exchange coupling.

Potential for electrical control in quantum computing.

Abstract

We consider free electrons in rectangular quantum dots, with either hard wall boundary conditions or anharmonic confinement. In both cases, due to finite size effects, a homogeneous electric field applied along one of the rectangular axis is shown to induce abrupt changes in the electron density, parallel and perpendicularly to the field direction: the electron density jumps from one configuration to another. Making use of this property, we propose a purely electrical mechanism to control the magnitude of the effective exchange coupling between two quantum dots. This system has been proposed recently as a quantum gate for quantum computation.