Josephson Parametric Amplifiers Fabricated in Wafer-scale with Side-wall Passivated Spacer Junction Technology*

We present our latest experimental results on Josephson parametric amplifiers (JPAs) fabricated with our Nb/Al-AlO_x/Nb junction process. The fabrication relies on UV photolithography and semi-automated 150-mm wafer processing steps, while minimizing the amount of deposited lossy dielectric materials [1]. The first JPA category is a flux-driven reflection amplifier for sub-GHz frequencies. It has found applications in the rf reflectometry of quantum dots, as well as in the rf readout of microwave nanobolometers [2] and charge detectors. Secondly, we report on the development of a 4-8 GHz traveling wave parametric amplifier tailored for the readout of superconducting quantum bits.

[1] Leif Grönberg et al., Superconductor Science and Technology 30, 125016 (2017)
[2] Roope Kokkoniemi et al., Communications Physics 2, 124 (2019)