Voltage controlled exchange energies of a two electron silicon double quantum dot with and without charge defects in the dielectric

TL;DR

This paper investigates how charge defects influence the voltage-controlled exchange energies in silicon double quantum dots, which are crucial for quantum computing, using detailed configuration interaction calculations that include atomic-scale charge perturbations.

Contribution

It introduces a comprehensive method to analyze the impact of charge defects on exchange energies in silicon DQDs, incorporating complex valley physics and atomic-scale perturbations.

Findings

Charge defects significantly alter exchange energy curves.

Atomic-scale charge perturbations can be modeled accurately.

Valley physics plays a crucial role in energy spectrum modifications.

Abstract

Quantum dots are artificial atoms used for a multitude of purposes. Charge defects are commonly present and can significantly perturb the designed energy spectrum and purpose of the dots. Voltage controlled exchange energy in silicon double quantum dots (DQD) represents a system that is very sensitive to charge position and is of interest for quantum computing. We calculate the energy spectrum of the silicon double quantum dot system using a full configuration interaction that uses tight binding single particle wavefunctions. This approach allows us to analyze atomic scale charge perturbations of the DQD while accounting for the details of the complex momentum space physics of silicon (i.e., valley and valley-orbit physics). We analyze how the energy levels and exchange curves for a DQD are affected by nearby charge defects at various positions relative to the dot, which are consistent with defects expected in the metal-oxide-semiconductor system.