Characterization of Magic-angle Twisted Bilayer Graphene using Microwave Techniques

Abstract

Magic-angle twisted bilayer graphene (MATBG) is a highly tunable material platform that exhibits a wide range of novel phases, including correlated insulating states and unconventional superconductivity. Its tunability and potentially high kinetic inductance in the superconducting state are desirable properties for high-coherence, small-form-factor superconducting qubits. This thesis presents a promising experimental method to characterize MATBG in the gigahertz-frequency regime, the operating regime of superconducting qubits. A hybrid on-chip DC-microwave circuit, which integrates a DC four-probe measurement and microwave resonator readout functionalities, enables the investigation of DC transport response and microwave response in the same twisted bilayer graphene device. By measuring the frequency shift of a standard Aluminum coplanar waveguide resonator terminated by a twisted bilayer graphene device, we can extract the contribution of the twisted bilayer graphene inductance. We expect that the experimental method can be utilized to measure MATBG kinetic inductance and superfluid density in a non-invasive manner. This experiment will also be a crucial step towards realizing MATBG-based superconducting qubit circuits.