Structures with Vertically Stacked Ge/Si Quantum Dots for Logical Operations

TL;DR

This paper models vertically stacked Ge/Si quantum dots to create quantum computer elements, demonstrating the potential for deep electron potential wells and vertical tunnel coupling through atomistic simulations.

Contribution

It introduces a detailed atomistic simulation approach for Ge/Si quantum dot structures aimed at quantum computing applications, highlighting the feasibility of multilayer structures for quantum logic.

Findings

Deep potential wells for electrons are achievable.

Vertical tunnel coupling can be realized in multilayer structures.

Strain energy and electron potential distributions are characterized.

Abstract

Ge/Si structures with vertically stacked quantum dots are simulated to implement the basic elements of a quantum computer for operation with electron spin states. Elastic-strain fields are simulated using the conjugate gradient method and an atomistic model based on the Keating potential. Calculations are performed in the cluster approximation using clusters containing about three million atoms belonging to 150 coordination spheres. The spatial distributions of the strain energy density and electron potential energy are calculated for different valleys forming the bottom of the silicon conduction band. It is shown that the development of multilayer structures with vertically stacked quantum dots makes it possible to fabricate deep potential wells for electrons with vertical tunnel coupling.