Advanced

Tunneling through Nanostructures - Interactions, Interference and Broadening

Pedersen, Jonas LU (2008)
Abstract
In this thesis, quantum transport through nanostructures is addressed theoretically by considering simplified model systems representing the most important features of quantum dots or molecules. The generic model consists of a central region coupled to noninteracting leads. The key ingredients are a discrete level spectrum of the central region and complicated many-body interactions present therein, the coupling between the leads and the dot, and the finite temperatures of the leads.

After a general introduction to quantum transport through nanostructures, different theoretical methods are briefly reviewed with a particular focus on density-matrix based approaches. Then a new method denoted the second order von Neumann (2vN)... (More)
In this thesis, quantum transport through nanostructures is addressed theoretically by considering simplified model systems representing the most important features of quantum dots or molecules. The generic model consists of a central region coupled to noninteracting leads. The key ingredients are a discrete level spectrum of the central region and complicated many-body interactions present therein, the coupling between the leads and the dot, and the finite temperatures of the leads.

After a general introduction to quantum transport through nanostructures, different theoretical methods are briefly reviewed with a particular focus on density-matrix based approaches. Then a new method denoted the second order von Neumann (2vN) approach is presented, which forms the core of this thesis. By working in a basis of many-particle states for the central region, Coulomb interactions are taken fully into account and correlated transitions by up to two different contact states are included. The latter extends standard rate equation approaches by including level-broadening effects and interference due to different transport paths through the nanostructure. The method is applied to various model systems in three of the four papers, Paper II-IV, contained in the thesis, and supplementary material is presented in the main part of the thesis. The models discussed are the spinless single and double quantum dot models, the Anderson model, and, finally, a spintronics model with a single spin-degenerate level coupled to ferromagnetic contacts and subjected to a magnetic field. Furthermore, cotunneling through single quantum dots is treated using the 2vN method. In Paper I, experimental data obtained from measurements on an InAs-InP nanowire containing a double quantum is analyzed on a microscopic basis using a capacitance model. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Brandes, Tobias, TU Berlin, Germany
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Quantum transport, Quantum dots, Coulomb blackade, Nanoscience
pages
164 pages
publisher
Department of Physics, Lund University
defense location
Lecture Hall B
defense date
2008-12-17 10:15
ISBN
978-91-628-7643-2
language
English
LU publication?
yes
id
4b9e1cfa-cd48-4aff-b34b-6e0006b52320 (old id 1267313)
date added to LUP
2008-11-19 12:02:49
date last changed
2016-09-19 08:45:12
@phdthesis{4b9e1cfa-cd48-4aff-b34b-6e0006b52320,
  abstract     = {In this thesis, quantum transport through nanostructures is addressed theoretically by considering simplified model systems representing the most important features of quantum dots or molecules. The generic model consists of a central region coupled to noninteracting leads. The key ingredients are a discrete level spectrum of the central region and complicated many-body interactions present therein, the coupling between the leads and the dot, and the finite temperatures of the leads. <br/><br>
After a general introduction to quantum transport through nanostructures, different theoretical methods are briefly reviewed with a particular focus on density-matrix based approaches. Then a new method denoted the second order von Neumann (2vN) approach is presented, which forms the core of this thesis. By working in a basis of many-particle states for the central region, Coulomb interactions are taken fully into account and correlated transitions by up to two different contact states are included. The latter extends standard rate equation approaches by including level-broadening effects and interference due to different transport paths through the nanostructure. The method is applied to various model systems in three of the four papers, Paper II-IV, contained in the thesis, and supplementary material is presented in the main part of the thesis. The models discussed are the spinless single and double quantum dot models, the Anderson model, and, finally, a spintronics model with a single spin-degenerate level coupled to ferromagnetic contacts and subjected to a magnetic field. Furthermore, cotunneling through single quantum dots is treated using the 2vN method. In Paper I, experimental data obtained from measurements on an InAs-InP nanowire containing a double quantum is analyzed on a microscopic basis using a capacitance model.},
  author       = {Pedersen, Jonas},
  isbn         = {978-91-628-7643-2},
  keyword      = {Quantum transport,Quantum dots,Coulomb blackade,Nanoscience},
  language     = {eng},
  pages        = {164},
  publisher    = {Department of Physics, Lund University},
  school       = {Lund University},
  title        = {Tunneling through Nanostructures - Interactions, Interference and Broadening},
  year         = {2008},
}