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Performance of the coupled cluster singles and doubles method on two-dimensional quantum dots
Stockholm University, Faculty of Science, Department of Physics. (atomic physics)
Stockholm University, Faculty of Science, Department of Physics. (atomic physics)
(English)Manuscript (preprint) (Other academic)
Abstract [en]

An implementation of the coupled-cluster single- and double excitations (CCSD) method on two-dimensional quantum dots is presented. Advantages and limitations are studied through comparison with other high accuracy approaches for two to eight confined electrons. The possibility to effectively use a very large basis set is found to be an important advantage compared to full configuration interaction implementations. For the two to eight electron ground states, with a confinement strength close to what is used in experiments, the error in the energy introduced by truncating triple excitations and beyond is shown to be on the same level or less than the differences in energy given by two different Quantum Monte Carlo methods. Convergence of the iterative solution of the coupled cluster equations is, for some cases, found for surprisingly weak confinement strengths even when starting from a non-interacting basis. The limit where the missing triple and higher excitations become relevant is investigated through comparison with full Configuration Interaction results.

Keyword [en]
electronic structure, electron correlation methods, coupled cluster, coupled cluster singles and doubles, quantum dot, two-dimensional, many-body physics, many-body perturbation theory
National Category
Condensed Matter Physics
Research subject
Physics
Identifiers
URN: urn:nbn:se:su:diva-38861OAI: oai:DiVA.org:su-38861DiVA: diva2:317058
Available from: 2010-05-02 Created: 2010-05-02 Last updated: 2010-05-03Bibliographically 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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http://arxiv.org/abs/1004.4081

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