Theoretical studies of graphene nanoribbon quantum dot qubits

Chih-Chieh Chen and Yia-Chung Chang
Phys. Rev. B 92, 245406 – Published 7 December 2015

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.

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  • Received 16 June 2015
  • Revised 17 November 2015

DOI:https://doi.org/10.1103/PhysRevB.92.245406

©2015 American Physical Society

Authors & Affiliations

Chih-Chieh Chen1,2 and Yia-Chung Chang2,3,*

  • 1Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
  • 2Research Center for Applied Sciences, Academic Sinica, Taipei 11529, Taiwan
  • 3Department of Physics, National Cheng-Kung University, Tainan 70101, Taiwan

  • *yiachang@gate.sinica.edu.tw

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Issue

Vol. 92, Iss. 24 — 15 December 2015

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