Berlin 2015 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 39: Posters II (Topological insulators; Graphene; Spintronics and spin physics; Quantum information science)
HL 39.38: Poster
Tuesday, March 17, 2015, 14:00–20:00, Poster F
Small nuclear spin environments in graphene quantum dots — •Daniel Hetterich, Moritz Fuchs, and Björn Trauzettel — Institute for Theoretical Physics IV , University of Würzburg
Graphene based quantum dots (QD) constitute interesting systems for both quantum computation and the physics of quantum information. An electron spin confined to such a QD is in contact with a bath of nuclear spins via an anisotropic hyperfine interaction (HI). If the HI is the most important interaction, the spins form a star-like system with the electron spin in its center. Most interestingly, isotopic purification allows to change the ratio of spin carrying 13C with respect to spinless 12C and, hence, to control the number K of nuclear spins. In order to complement previous studies of the anisotropic HI in graphene for large bath sizes, we investigate the spin dynamics for a small number of nuclear spins by means of exact diagonalization. Considering different types of initial states and various configurations of the nuclei within the dot, we analyze the time evolution of the electron spin with a focus on equilibration. The results of our simulations are in accordance with analytical estimations.