Dresden 2014 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 76: Quantum Information Systems I (organized by HL)
TT 76.7: Talk
Wednesday, April 2, 2014, 16:30–16:45, POT 006
Ultra long spin decoherence times in graphene quantum dots with a small number of nuclear spins — •Moritz Fuchs1, John Schliemann2, and Björn Trauzettel1 — 1Institut für Theoretische Physik und Astrophysik, Universität Würzburg, 97074 Würzburg — 2Institut für Theoretische Physik, Universität Regensburg, 93053 Regensburg
We study the dynamics of an electron spin in a graphene quantum dot, which is interacting with a bath of less than ten nuclear spins via the anisotropic hyperfine interaction. Due to substantial progress in the fabrication of graphene quantum dots, the consideration of such a small number of nuclear spins is experimentally relevant. This choice allows us to use exact diagonalization to calculate the longtime average of the electron spin as well as its decoherence time. We investigate the dependence of spin observables on the initial states of nuclear spins and on the position of nuclear spins in the quantum dot. Moreover, we analyze the effects of the anisotropy of the hyperfine interaction for different orientations of the spin quantization axis with respect to the graphene plane. Interestingly, we then predict remarkable long decoherence times of more than 10ms in the limit of few nuclear spins.