Dispersive sensing of charge states in a bilayer graphene quantum dot

We demonstrate dispersive readout of individual charge states in a gate-defined few-electron quantum dot in bilayer graphene. We employ a radio frequency reflectometry circuit, where an LC resonator with a resonance frequency close to 280MHz is directly coupled to an Ohmic contact of the quantum dot device. The detection scheme based on changes in the quantum capacitance operates over a wide gate-voltage range and allows us to probe excited states down to the single-electron regime. Crucially, the presented sensing technique avoids the use of an additional, capacitively coupled quantum device such as a quantum point contact or single electron transistor, making dispersive sensing particularly interesting for gate-defined graphene quantum dots.

Automated summary

The research demonstrates dispersive readout of individual charge states in gate-defined few-electron quantum dots in bilayer graphene. By utilizing a radio frequency reflectometry circuit, changes in quantum capacitance can be detected over a wide gate-voltage range, allowing probing of excited states down to the single-electron regime without the need for additional quantum devices.