Bilayer graphene double quantum dots tuned in for single-electron control

Atomic force microscope image, showing the gate layout of the device. The source (S) and drain (D) contacts are connected to the BLG through etched vias in the hBN. The gate stack contains split gates (SG) with a separation of 50 nm and on top, separated by Al2O3, six parallel finger gates with a gate separation of 50 nm and a width of 100 nm. The gates GL and GR (color coded) are used to control the QDs discussed in this work. Credit: Nano Letters

A researchers team at RWTH Aachen and the National Institute of Materials Science in Japan work with bilayer graphene, which can be tuned to be a semiconductor. A voltage applied to specific regions of a bilayer graphene flake can switch those regions to behave as insulators, electrostatically defining a quantum dot that has no edge states nearby.

Although this level of control has been demonstrated in single quantum dots, this is the first demonstration in graphene double quantum dots, which are particularly useful as spin qubits.

These results could prove key to future implementations of quantum computing based on graphene. 

This first demonstration of graphene double quantum dots in which it is possible to control the number of electrons down to zero has been reported in Nano Letters. (Phys.org)

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