Incorporation of random alloy GaBixAs1–x barriers in InAs quantum dot molecules: Alloy strain, orbital effects, and enhanced tunneling

Published

April 8, 2024

Author(s)

Arthur Lin, Matthew Doty, Garnett W. Bryant

Abstract

Self-assembled InAs quantum dots (QDs), which have long hole-spin coherence times and are amenable to optical control schemes, have long been explored as building blocks for qubit architectures. One such design consists of vertically stacking two QDs to create a quantum dot molecule (QDM). The two dots can be resonantly tuned to form "molecule-like" coupled hole states from the hybridization of hole states of each respective dot. Furthermore, by using the spin-mixing properties of the hybridized states in offset dots, qubit rotation can be driven optically, alloying for an alloptical qubit control scheme. To enhance the tunnel coupling and spin-mixing across the dots, we introduce Bi in the GaAs inter-dot barrier. Previously, we showed how to model InAs/GaBixAs1–x in an atomistic tight-binding formalism, and how the dot energy levels are affected by the alloy. In this paper, we discus the lowering of the tunnel barrier, which results in a three fold increase of hole tunnel coupling strength a 7% alloy. Additionally, we show how an asymmetric strain between the two dots caused by the alloy shifts the resonance. Finally, we will discuss device geometries for which the introduction of Bi is most optimized.

Citation

Physical Review B

Volume

109

Issue

16

Pub Type

Journals

Download Paper

https://doi.org/10.1103/PhysRevB.109.165303

Local Download

Keywords

quantum dots, hole spins, optical control, alloys, qubits

Citation

Lin, A. , Doty, M. and Bryant, G. (2024), Incorporation of random alloy GaBixAs1–x barriers in InAs quantum dot molecules: Alloy strain, orbital effects, and enhanced tunneling, Physical Review B, [online], https://doi.org/10.1103/PhysRevB.109.165303, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=936868 (Accessed September 16, 2024)