Electrical manipulation of an electronic two-state system in Ge/Si quantum dots

TL;DR

This paper demonstrates how electric fields can control the two-state electron system in Ge/Si quantum dots, enabling tunable electronic, optical, and magnetic properties for potential quantum computing applications.

Contribution

It introduces a method to electrically manipulate the localized electron states in Ge/Si quantum dots, offering precise control over their properties.

Findings

Electric fields can switch the electron state between apex and base localization.

The electronic ground state shift affects optical and magnetic properties.

Spin-spin coupling between dots can be controlled electrically.

Abstract

We calculate that the electron states of strained self-assembled Ge/Si quantum dots provide a convenient two-state system for electrical control. An electronic state localized at the apex of the quantum dot is nearly degenerate with a state localized at the base of the quantum dot. Small electric fields shift the electronic ground state from apex-localized to base-localized, which permits sensitive tuning of the electronic, optical and magnetic properties of the dot. As one example, we describe how spin-spin coupling between two Ge/Si dots can be controlled very sensitively by shifting the individual dot's electronic ground state between apex and base.