Berlin 2012 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 13: Transport: Poster Session
TT 13.6: Poster
Montag, 26. März 2012, 15:00–19:00, Poster B
Limitations of pulse-gating schemes for extracting relaxation times in graphene quantum dots — •Sebastian Kazarski1, Christian Volk1,2, Christoph Neumann1, Fabian Hassler3, and Christoph Stampfer1,2 — 1JARA-FIT and II. Institute of Physics B, RWTH Aachen, 52074 Aachen, Germany — 2Institute for Bio- and Nanosystems, Forschungszentrum Jülich, 52425 Jülich, Germany — 3Institute for Quantum Information, RWTH Aachen, 52074 Aachen, Germany
Solid state quantum dots are interesting candidates for future spin-based quantum information technology. In particular carbon materials, such as graphene and nanotubes are interesting for hosting quantum dots since these materials exhibit weak spin-orbit coupling and weak hyperfine interaction promising long spin coherence times. Here, we present low-temperature pulse-gating transport experiments on a graphene quantum dot, which potentially allow us to estimate relaxation times. The experimental data are compared with a detailed numerical simulation of the pulse-gating experiment to extract relaxation times which arise in a graphene quantum dot considering excited (ES) to ground state (GS) transitions. The simulation is based on solving the involved rate equations, taking into account tunnel coupling rates ΓL,R, the relaxation rate Γτ from ES to GS, and a number different pulse-gate configurations. The average current I through the ES and GS, and the averaged electron number per cycle ⟨n⟩ are calculated numerically. We can find reasonable agreement with the experiment and discuss the limits of the used technique.