Abstract: Aluminum-based Josephson junctions (JJs) are currently the leading source of nonlinearity for superconducting circuits. However, Al JJs have a relatively low critical temperature (1.2 K), limiting their operating temperatures to << 1 K and operating frequencies to << 70 GHz. In this talk, I will introduce phase slip junctions as an alternative source of nonlinearity. Phase-slip junctions are fabricated from highly disordered superconductors with larger energy gaps than Al. Such junctions not only expand the class of possible superconducting circuits but also promise higher temperature and frequency operation. Here, I demonstrate the control and readout of a flux-based superconducting qubit. The qubit is composed of a phase slip junction and an inductance made from titanium nitride. I will demonstrate operation of the qubit at zero flux, where its frequency is approximately 17 GHz. I will also present time-domain measurements of the qubit and show that it can operate at temperatures up to 300 mK. Finally, I will share some of our latest experimental results and outline our future efforts to further improve this type of qubit.
Bio: Cheeranjeev Purmessur is a 5th year physics graduate student working for Angela Kou researching high kinetic inductance disordered superconductors for applications in quantum information.