SQMS nanofabrication taskforce: Towards fabrication of high coherence quantum devices

Since its inception, SQMS Center has carried out extensive materials characterization and modeling of superconducting qubits yielding new knowledge and high impact results. The Center has recently launched SQMS Nanofabrication Taskforce to implement novel materials and fabrication processes for high coherence superconducting quantum devices. The Taskforce brings together experts in nanofabrication and materials science from Fermilab, NIST, Rigetti, Northwestern University, and Ames Lab and has access to state-of-the-art foundries at Boulder Microfabrication Facility at NIST, Pritzker Nanofabrication Facility at the University of Chicago, Riggeti nanofab facilities, and NuFab facility at Northwestern University. The first coordinated study of the taskforce has been to inhibit the surface oxides of Nb, believed to be a significant source of decoherence in Nb based superconducting quantum devices. A wide range of materials, such as Al, Ta, and TiN, has been explored as a passivation layer. The preliminary results of microwave loss measurements of superconducting transmission line resonators and coherence measurements of transmon qubit devices will be presented. This material is based upon work supported by the U.S. Department of Energy, Office of Science, National Quantum Information Science Research Centers, Superconducting Quantum Materials and Systems Center (SQMS) under contract number DE-AC02-07CH11359.