Voltage Tunable Superconducting qubit with Sn based hybrid nanowire Josephson junction
Abstract: Conventional transmon qubits use insulator-based Josephson junctions (Al-AlOx-Al) that provide the nonlinearity required for qubit operations. Frequency tunability in these qubits is typically achieved by applying magnetic flux through JJs in a superconducting quantum interference device (SQUID) loop, which requires current-biased flux lines. An attractive alternative is the transmon architecture that incorporates hybrid superconductor-semiconductor JJs, enabling all-electric control. The use of semiconductor weaklinks also allows exploration of junction superconductors beyond aluminum, including higher-Tc materials that could support higher-frequency and potentially higher-temperature operation. In this talk, I will present my work on indium arsenide nanowires coated with thin superconducting shells of β-Sn to realize transmon qubits. By tuning the Josephson energy with a gate voltage, I demonstrate that both the qubit frequency and the anharmonicity can be adjusted. I then present results from relaxation and dephasing measurements of these qubits and discuss the mechanisms currently limiting their coherence.
Bio: Amrita Purkayastha is a postdoctoral research associate working on building superconducting quantum circuits with disordered superconductors in Dr. Angela Kou’s group.