Electron counting in bilayer graphene quantum dots

Annika Kurzmann, Hiske Overweg, Marius Eich, Peter Rickhaus, Riccardo Pisoni, Yongjin Lee, Thomas Ihn, and Klaus Ensslin

Department of Physics, ETH Zürich, Otto-Stern-Weg 1, 8093 Zürich, Switzerland

Electrostatically defined quantum dots in bilayer graphene (BLG) are promising candidates as hosts for spin qubits. BLG consists of nuclear spin-free C12 with a low atomic weight, which should lead to long coherence times of the electron spins; a prerequisite for a quantum computation.

We show here transport measurements on electrostatically defined quantum dots and quantum point contacts in bilayer graphene. A quantum point contact can be used as sensitive detector for measuring the charging state of a quantum dot. A combination of both can be used for time-resolved measurements of electron tunneling through the dot. Full counting statistics will derive than the full information about the tunneling process, as it was used in GaAs based dots to study for example level degeneracies and thermodynamics of charge carriers in confined systems. The presence of both spin and valley degree of freedom, might make the physical phenomena even richer in bilayer graphene in comparison to GaAs based devices.

kurzmann — Figure: (a) Counting device in bilayer graphene: two channels are formed, where the first forms a quantum dot, while the second will be used to form a charge detector. (b) Charge stability diagram of an electrostatically defined quantum dot in bilayer graphene.