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Structure of lateral two-electron quantum dot molecules in electromagnetic fields
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2007 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 76, no 3, 035303- p.Article in journal (Refereed) Published
Abstract [en]

The energy levels of laterally coupled parabolic double quantum dots are calculated for varying interdot distances. Electron-electron interaction is shown to dominate the spectra: In the diatomic molecule limit of large interdot separation, the two nearly degenerate singlet and triplet ground states are followed by a narrow band of four singlet and four triplet states. The energy spacing between the ground state and the first band of excited states scales directly with the confinement strength of the quantum wells. Similar level separation and band structure are found when the double dot is exposed to a perpendicular magnetic field. Conversely, an electric field parallel to the interdot direction results in a strong level mixing and a narrow transition from a localized state to a covalent diatomic molecular state.

Place, publisher, year, edition, pages
2007. Vol. 76, no 3, 035303- p.
URN: urn:nbn:se:su:diva-12392DOI: 10.1103/PhysRevB.76.035303ISI: 000248500800078OAI: diva2:178912
Available from: 2008-01-15 Created: 2008-01-15 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.
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
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)
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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Lindroth, E.Waltersson, E.
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