Measuring AC Conductivity of 2D Superconductors at Microwave Frequencies

2D superconductor characterization at microwave frequencies is a prerequisite for designing and implementing superconducting circuits that boast the benefits of 2D superconductors, such as small-footprints, low-loss, and gate-tunability. These features make 2D superconductors favorable for use as high-quality factor inductive or capacitive components that help to detect photons, amplify minute signals at the quantum limit, and process quantum information. Here, we present an advanced characterization that can probe the AC conductivity and quality factor of 2D superconductors to sub-ppm precision using a high-quality factor transmission line resonator. We test and verify our novel technique by analyzing the equivalent model and comparing our data to Mattis-Bardeen theory. We shall present our latest progress towards the measurement of superfluid density in order to obtain some insights on the pairing mechanisms in 2D superconductors by probing the superfluid density to high precision.