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Rashba-controlled two-electron spin-charge qubits as building blocks of a quantum computer

A. Kregar

Institute of Physical and Theoretical Chemistry, Graz University of Technology, Stremayrgasse 9, A-8010 Graz, Austria

Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, 1000 Ljubljana, Slovenia

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and

A. Ramšak

Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia

Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia

E-mail Address: anton.ramsak@fmf.uni-lj.si

Corresponding author.

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https://doi.org/10.1142/S0217984920400588Cited by:3 (Source: Crossref)

This article is part of the issue:

SPECIAL ISSUE: Electron Correlation in Superconductors and Nanostructures
Guest Editors: Sergei Kruchinin and Janez Bonča

Abstract

The spin-sensitive charge oscillation, controlled by an external magnetic field, was recently proposed as a mechanism of transformations of qubits, defined as two-electron spin-charge Wannier molecules in a square quantum dot.¹ The paper expands this idea by including the effects of Rashba-type spin-orbit coupling. The problem is studied theoretically by mapping the system to an analytic effective Hamiltonian for 8 low-energy states, comprising singlet and triplet on each dot diagonal. The validity of mapping is confirmed by comparing the energy and spin of full and mapped system, and also by the reproduction of charge-oscillation dynamics in the presence of magnetic flux. The newly introduced Rashba coupling significantly enriches the system dynamics, affecting the magnitude of charge oscillations and allowing the controlled transitions between singlet and triplet states due to the spin rotations, induced by spin-orbit coupling. The results indicate the possibility for use of the studied system for quantum information processing, while possible extensions of the system to serve as a qubit in a universal quantum computer, fulfilling all five Di Vincenzo criteria, is also discussed.

Keywords:

PACS: 03.65.Vf, 71.70.Ej, 73.63.Kv, 05.40.Ca

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