Single, double, and triple quantum dots in Ge/Si nanowires

TL;DR

This paper demonstrates highly tunable quantum dots in Ge/Si nanowires, including single, double, and triple configurations, with observable excited states and Pauli spin blockade, paving the way for hole spin qubit experiments.

Contribution

It introduces a method to create and control multiple quantum dot configurations in Ge/Si nanowires with observable quantum phenomena.

Findings

Observation of low hole occupation numbers in single quantum dots

Detection of Pauli spin blockade in double quantum dots

Creation of triple quantum dot arrays

Abstract

We report highly tunable control of holes in Ge/Si core/shell nanowires (NWs). We demonstrate the ability to create single quantum dots (QDs) of various sizes, with low hole occupation numbers and clearly observable excited states. For the smallest dot size we observe indications of single-hole occupation. Moreover, we create double and triple tunnel-coupled quantum dot arrays. In the double quantum dot configuration we observe Pauli spin blockade (PSB). These results open the way to perform hole spin qubit experiments in these devices.