Hybrid Superconducting Qubit Based on Topological Insulator Junction

Superconducting quantum circuits offer a new platform to study quantum materials by leveraging the precise microwave control using the tools of circuit quantum electrodynamics (QED). Hybrid circuit devices incorporating novel quantum materials could also lead to new qubit functionalities like gate tunability and topological noise resilience. Here, we discuss progress towards a transmon-like qubit made with a superconductor-topological insulator-superconductor (S-TI-S) Josephson junction using exfoliated BiSbTeSe₂. We present a design that enables us to perform systematic characterization of the hybrid device, from DC transport of the S-TI-S junction, to RF spectroscopy, to full circuit QED control and detection of the hybrid qubit. In addition, we use a high quality-factor superconducting cavity to characterize material and fabrication-induced losses in our devices, to guide our efforts to improve the device quality. I will also discuss future plans to probe topological materials and excitations in our hybrid circuit platform.