Progress on hybrid cQED with Graphene Quantum Dots

Max J. Ruckriegel, Lisa M. Gächter, Chuyao Tong, Rebekka Garreis, Benedikt Kratochwil, Thomas Ihn, Klaus Ensslin, Wister Wei Huang
ETH Zürich, Switzerland

Electrostatically defined quantum dots (QD) in bilayer graphene are an increasingly promising platform to host spin qubits. Long relaxation times of up to 50 ms have been demonstrated with single-shot readout using a nearby quantum dot as a charge detector. The measurement bandwidth of this technique is typically limited to the kHz regime due to the RC time constant. Further investigation of graphene QDs and their spin- and valley-states requires fast and high-fidelity charge sensing, which can be performed by dispersively coupling electrons in a double QD to microwave photons in a superconducting resonator. Here we report on progress towards integrating graphene QD devices with on-chip superconducting microwave resonators in a hybrid circuit QED architecture. We outline our main advances in design and fabrication of graphene-based hybrid devices and highlight the key challenges. We show first device characterizations and proof-of-principle measurements towards dispersive charge sensing.