Highly tuneable hole quantum dots in Ge-Si core-shell nanowires

TL;DR

This paper demonstrates the creation and control of highly tunable hole quantum dots in Ge-Si core-shell nanowires, highlighting their potential for spin-based quantum computing applications.

Contribution

It introduces a method to define and manipulate single and double quantum dots with tunable lengths and coupling in Ge-Si nanowires, advancing quantum dot control.

Findings

Quantum dots with lengths from 60 nm to 480 nm were successfully defined.

Charging energies ranged from 18 to 4 meV, inversely proportional to dot length.

Stable single and double quantum dot configurations with precise electrostatic control were achieved.

Abstract

We define single quantum dots of lengths varying from 60 nm up to nearly half a micron in Ge-Si core-shell nanowires. The charging energies scale inversely with the quantum dot length between 18 and 4 meV. Subsequently, we split up a long dot into a double quantum dot with a separate control over the tunnel couplings and the electrochemical potential of each dot. Both single and double quantum dot configurations prove to be very stable and show excellent control over the electrostatic environment of the dots, making this system a highly versatile platform for spin-based quantum computing.