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Controlled operations in a strongly correlated two-electron quantum ring
Stockholm University, Faculty of Science, Department of Physics. (Atomic Physics)
Stockholm University, Faculty of Science, Department of Physics. (Atomic Physics)
Department of Physics and Technology, University of Bergen, N-5020 Bergen, Norway. (Atomic Physics)
Department of Physics and Technology, University of Bergen, N-5020 Bergen, Norway.
2009 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 79, no 11, 115318- p.Article in journal (Refereed) Published
Abstract [en]

We have analyzed the electronic spectrum and wave-function characteristics of a strongly correlated two-electron quantum ring with model parameters close to those observed in experiments. The analysis is based on an exact diagonalization of the Hamiltonian in a large B-spline basis. We propose a qubit pair for storing quantum information, where one component is stored in the total electron spin and one multivalued “quMbit” is represented by the total angular momentum. In this scheme the controlled-NOT quantum gate is demonstrated with near 100% fidelity for a realistic far-infrared electromagnetic pulse.

Place, publisher, year, edition, pages
American Physical Society , 2009. Vol. 79, no 11, 115318- p.
Keyword [en]
Quantum Rings, Quantum Dots, Electron structure, Electron correlation, Configuration Interaction, Quantum Computing, quantum gates, CNOT, Controlled operations, angular momentum, electron spin, quantum entanglement, strongly correlated electron systems, wave functions
National Category
Atom and Molecular Physics and Optics Other Physics Topics Condensed Matter Physics Condensed Matter Physics
Research subject
Physics
Identifiers
URN: urn:nbn:se:su:diva-32133DOI: 10.1103/PhysRevB.79.115318ISI: 000264768900100OAI: oai:DiVA.org:su-32133DiVA: diva2:279548
Available from: 2010-01-25 Created: 2009-12-04 Last updated: 2017-12-12Bibliographically approved
In thesis
1. On the role of the electron-electron interaction in two-dimensional quantum dots and rings
Open this publication in new window or tab >>On the role of the electron-electron interaction in two-dimensional quantum dots and rings
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Many-Body Perturbation Theory is put to test as a method for reliable calculations of the electron-electron interaction in two-dimensional quantum dots. We show that second order correlation gives qualitative agreement with experiments on a level which was not found within the Hartree-Fock description. For weaker confinements, the second order correction is shown to be insufficient and higher order contributions must be taken into account. We demonstrate that all order Many-Body Perturbation Theory in the form of the Coupled Cluster Singles and Doubles method yields very reliable results for confinements close to those estimated from experimental data. The possibility to use very large basis sets is shown to be a major advantage compared to Full Configuration Interaction approaches, especially for more than five confined electrons.

Also, the possibility to utilize two-electron correlation in combination with tailor made potentials to achieve useful properties is explored. In the case of a two-dimensional quantum dot molecule we vary the interdot distance, and in the case of a two-dimensional quantum ring we vary the ring radius, in order to alter the spectra. In the latter case we demonstrate that correlation in combination with electromagnetic pulses can be used for the realization of quantum logical gates.

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University, 2010. 99 p.
Keyword
quantum dot, quantum ring, quantum dot molecule, electronic structure, two-dimensional, many-body physics, many-body perturbation theory, coupled cluster, coupled cluster singles and doubles, quantum logical gates, quantum computing, quantum control, quantum control algorithm
National Category
Condensed Matter Physics
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-38862 (URN)978-91-7447-086-4 (ISBN)
Public defence
2010-06-02, FB52, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (English)
Opponent
Supervisors
Note
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 5: Manuscript.Available from: 2010-05-11 Created: 2010-05-02 Last updated: 2010-05-03Bibliographically approved

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