Fidelity of Optically Controlled Single- and Two-Qubit Operations on Coulomb-Coupled Quantum Dots

TL;DR

This paper analyzes how Coulomb interactions affect the fidelity of quantum gates and Bell state creation in Coulomb-coupled quantum dots, considering radiative damping effects and optimizing parameters to minimize errors.

Contribution

It provides a detailed calculation of gate fidelities and error sources, demonstrating how to optimize Coulomb coupling and external fields for improved quantum operation accuracy.

Findings

Error rates of about 10^{-3} achievable with optimization

Radiative dephasing causes larger errors around 10^{-2}

Bell state generation can reach low error rates despite dephasing

Abstract

We investigate the effect of the Coulomb interaction on the applicability of quantum gates on a system of two Coulomb-coupled quantum dots. We calculate the fidelity for a single- and a two-qubit gate and the creation of Bell states in the system. The influence of radiative damping is also studied. We find that the application of quantum gates based on the Coulomb interaction leads to significant input state-dependent errors which strongly depend on the Coulomb coupling strength. By optimizing the Coulomb matrix elements via the material and the external field parameters, error rates in the range of $10^{-3}$ can be reached. Radiative dephasing is a more serious problem and typically leads to larger errors on the order of $10^{-2}$ for the considered gates. In the specific case of the generation of a maximally entangled Bell state, error rates in the range of $10^{-3}$ can be achieved even in the presence of radiative dephasing.