Freiburg 2019 – wissenschaftliches Programm

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FM: Fall Meeting

FM 81: Enabling Technologies: Quantum Materials

FM 81.1: Invited Talk

Donnerstag, 26. September 2019, 14:00–14:30, 3042

Electrostatically defined quantum devices in bilayer graphene — •Christoph Stampfer — JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074 Aachen Germany — Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany, E

Graphene and bilayer graphene (BLG) are attractive platforms for quantum circuits. This has motivated substantial efforts in studying quantum dot (QD) devices based on graphene and BLG. The major challenge in this context is the missing band-gap in graphene, which does not allow confining electrons by means of electrostatics. A widely used approach to tackle this problem was to introduce a hard-wall confinement by etching the graphene sheet. However, the influence of edge disorder, turned out to be a road block for obtaining clean QDs. The problem of edge disorder can be circumvented in clean BLG, thanks to the fact that this material offers a tuneable band-gap in the presence of a perpendicularly applied electric field, a feature that allows introducing electrostatic soft confinement in BLG. Here we present gate-controlled single, double, and triple dot operation in electrostatically gaped BLG. We show a remarkable degree of control of our device, which allows the implementation of two different gate-defined electron-hole double-dot systems with very similar energy scales. In the single dot regime, we reach the very few hole regime, extract excited state energies and investigate their evolution in a parallel and perpendicular magnetic field.