Dispersive sensing of charge states in a bilayer graphene quantum dot
Banszerus, Luca, Möller, Samuel Werner Hermann, Icking, Eike Thomas, Steiner, Corinne, Daniel Neumaier, Otto, Maike, Kenji Watanabe, Takashi Taniguchi, Volk, Christian, Stampfer, Christoph
Abstract
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 280 MHz 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 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.