Characterization of a fabrication process for the integration of superconducting qubits andrapid-single-flux-quantum circuits

Abstract

In order to integrate superconducting qubits with rapid-single-flux-quantum (RSFQ)control circuitry, it is necessary to develop a fabrication process that simultaneouslyfulfils the requirements of both elements: low critical current density, very lowoperating temperature (tens of millikelvin) and reduced dissipation on the qubit side;high operation frequency, large stability margins, low dissipated power on theRSFQ side. For this purpose, VTT has developed a fabrication process based onNb trilayer technology, which allows the on-chip integration of superconductingqubits and RSFQ circuits even at very low temperature. Here we present thecharacterization (at 4.2 K) of the process from the point of view of the Josephsondevices and show that they are suitable to build integrated superconducting qubits.