Abstract
This dissertation investigates properties of twodimensional manybody systems. Studies are performed using the SpinDensity Functional Theory with the Local SpinDensity Approximation, and numerical exact diagonalization. The properties studied include symmetrybreaking states in fewelectron quantum dots, gaps in confined fewbody systems, magnetic properties of cold fermionic atoms in optical lattices, and vortex formation in fewbody systems. The dissertation also studies the properties of the SDFTLSDA method for manybody calculations itself.
The dissertation comprises five original papers, which are presented following an introduction to the fields of research, and the methods used, and the systems studied.
Paper I investigates symmetrybreaking states in quantum dots, and the reliability of SDFTLSDA for such systems. It is found that SDFTLSDA may introduce artificial energy splittings between the members of a degenerate spin multiplet in the ground state.
Paper II investigates the reliability of SDFTLSDA when used to calculate gaps, and addition and removal energies in fewbody systems. It is found that, contrary to studies of atoms and bilk solids, KohnSham eigenvalues can be used to calculate addition and removal energies in parabolically confined systems. Also, in Paper II, van der Waals blockade is predicted to occur in systems of cold atoms, in analogy to Coulomb blockade in electronic systems.
In Papers III and IV, meanfield theory is used to study the magnetic properties of cold fermionic atoms in an optical lattice. The results are compared with a similar study for quantumdot lattices. It is found that there is a rich magnetic phase diagram, with nonmagnetic, ferromagnetic, and antiferromagnetic states. The phase diagram of the optical lattice is found to be very similar to the phase diagram of the quantumdot lattice.
Paper V uses exact diagonalization to study vortex formation in rotating fewbody quantum systems. Systems consisting of Coulombinteracting fermions (electrons), Coulombinteracting bosons, and bosons with a shortrange interaction are studied. It is found that vortex formation in these systems has universal properties.
The dissertation comprises five original papers, which are presented following an introduction to the fields of research, and the methods used, and the systems studied.
Paper I investigates symmetrybreaking states in quantum dots, and the reliability of SDFTLSDA for such systems. It is found that SDFTLSDA may introduce artificial energy splittings between the members of a degenerate spin multiplet in the ground state.
Paper II investigates the reliability of SDFTLSDA when used to calculate gaps, and addition and removal energies in fewbody systems. It is found that, contrary to studies of atoms and bilk solids, KohnSham eigenvalues can be used to calculate addition and removal energies in parabolically confined systems. Also, in Paper II, van der Waals blockade is predicted to occur in systems of cold atoms, in analogy to Coulomb blockade in electronic systems.
In Papers III and IV, meanfield theory is used to study the magnetic properties of cold fermionic atoms in an optical lattice. The results are compared with a similar study for quantumdot lattices. It is found that there is a rich magnetic phase diagram, with nonmagnetic, ferromagnetic, and antiferromagnetic states. The phase diagram of the optical lattice is found to be very similar to the phase diagram of the quantumdot lattice.
Paper V uses exact diagonalization to study vortex formation in rotating fewbody quantum systems. Systems consisting of Coulombinteracting fermions (electrons), Coulombinteracting bosons, and bosons with a shortrange interaction are studied. It is found that vortex formation in these systems has universal properties.
Original language  English 

Qualification  Doctor 
Awarding Institution 

Supervisors/Advisors 

Award date  2007 Apr 27 
Publisher  
ISBN (Print)  9789162871345 
Publication status  Published  2007 
Bibliographical note
Defence detailsDate: 20070427
Time: 10:15
Place: Lecture hall F, Department of Physics, Sölvegatan 14A Lund University Faculty of Engineering
External reviewer(s)
Name: Guðmundsson, Viðar
Title: Professor
Affiliation: Department of Physics, Faculty of Science, University of Iceland, Iceland.

The information about affiliations in this record was updated in December 2015.
The record was previously connected to the following departments: Mathematical Physics (Faculty of Technology) (011040002)
Subject classification (UKÄ)
 Physical Sciences
Free keywords
 magnetiska och optiska)
 egenskaper (elektriska
 Cold atoms
 Quantum dots
 Optical lattices
 classical mechanics
 Mathematical and general theoretical physics
 Exact diagonalization
 Density Functional Theory
 Vortices
 relativity
 quantum mechanics
 termodynamik
 statistisk fysik
 relativitet
 kvantmekanik
 klassisk mekanik
 Matematisk och allmän teoretisk fysik
 thermodynamics
 statistical physics
 Condensed matter:electronic structure
 gravitation
 supraledare
 magnetisk resonans
 electrical
 magnetic and optical properties
 supraconductors
 magnetic resonance
 relaxation
 spectroscopy
 Kondenserade materiens egenskaper:elektronstruktur
 spektroskopi
 Fysicumarkivet A:2007:Borgh