Theoretical Studies of Graphene Nanoribbon Quantum Dot Qubits

TL;DR

This paper provides a theoretical analysis of graphene nanoribbon quantum dot qubits, focusing on their electronic structure and exchange coupling, highlighting the role of Klein tunneling in enhancing qubit interactions for quantum computing.

Contribution

It introduces a theoretical framework for analyzing the electronic properties and exchange interactions of graphene nanoribbon quantum dots using the Dirac equation and Hartree-Fock methods.

Findings

Klein tunneling significantly enhances exchange coupling between qubits.

Electronic structures are modeled by solving the Dirac equation with boundary conditions.

Implications for practical qubit design and operation are discussed.

Abstract

Graphene nanoribbon quantum dot qubits have been proposed as promising candidates for quantum computing applications to overcome the spin-decoherence problems associated with typical semiconductor (e.g. GaAs) quantum dot qubits. We perform theoretical studies of the electronic structures of graphene nanoribbon quantum dots by solving the Dirac equation with appropriate boundary conditions. We then evaluate the exchange splitting based on an unrestricted Hartree-Fock method for the Dirac particles. The electronic wave function and long-range exchange coupling due to the Klein tunneling and the Coulomb interaction are calculated for various gate configurations. It is found that the exchange coupling between qubits can be significantly enhanced by the Klein tunneling effect. The implications of our results for practical qubit construction and operation are discussed.