In this Ph.D thesis, electronic structure and transport properties of quantum dots are studied using advanced numerical techniques based on fundamental many-body theory. In fact, in such nanostructures, correlation and quantization effects dominate motion of electrons like in real atoms, hence an exact treatment is often necessary to understand and predict their electronic properties. Moreover, experimental realization of quantum dots in the presence of magnetic field gives rise to several new many-body physics that are inaccessible in real atoms, and they provide a crucial testing ground for important concepts of mesoscopic and nanoscopic phenomena. The many-body tools used in this work include exact diagonalization, quantum Monte Carlo, Hartree-Fock, and Keldysh Nonequilibrium Green's function analysis. Each of these methods have their advantages and inconveniences. For studying closed systems with small number of electrons, exact diagonalization is the best choice, since it provides complete information about the total energy, wave functions and correlations for not only the ground state but also for excited states. We used exact diagonalization method to study in detail circular parabolic and ring shaped quantum dots containing up to 8 electrons, and we have found that spatial localization of electrons inside the dot gives rise to interesting new physics. On the other hand, for studying disordered quantum dots exact diagonalization method becomes powerless due to the broken spatial symmetry. Thus, we developed a fixed-phase quantum Monte Carlo algorithm combined with Hartree-Fock solutions, which allowed us to investigate the effect of impurities on electronic properties inside parabolic dots containing up to 13 electrons. To investigate open systems and transport properties, we have expanded exact diagonalization solutions in terms of Keldysh Green's functions which allowed us to discover a new transport blockade regime. Finally, again using Keldysh Green's function formalism, we have studied a double quantum dot system in the presence of Kondo resonance, and we have shown that multi-channel transport gives rise to particularly interesting competition effects between resonant tunneling and Kondo effect.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.19775 |
| Date | January 2003 |
| Creators | Güçlü, Alev Devrim |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Physics) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 002022832, Theses scanned by McGill Library. |
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