Bachelor Defense: Carl Jordan Eriksen

Title: Exact Diagonalisation of a Triple-Quantum Dot Toy Model

A recent experiment has demonstrated Nagaoka’s ferromagnetism in a quantum dot system. This thesis investigates the ferromagnetism of a toy model of a three-site quantum dot system using the Hubbard model and an exact diagonalisation method. Two cases are considered: two-electron filling and four-electron filling. The former is found not to lead to ferromagnetism. The latter, conversely, is found to lead to ferromagnetism in large parts of the four-electron system’s phase space. A method is proposed for spin measurements based on a spin-to-charge conversion.