Fabrication and characterization of Josephson parametric amplifiers based on micron-scale Josephson junctions

Josephson parametric amplifiers (JPAs) with quantum limited noise performance have become essential components in superconducting quantum circuits. We describe a fabrication process to yield micrometer-scale Josephson junctions [1].  The room temperature characterization of junctions will be presented as a function of oxidation dose and junction geometry. Low temperature current-voltage characteristics indicate that our fabrication process yields high quality junctions. Next, we design and fabricate JPAs. Our fabrication process yields low loss frequency tunable JPAs with typical gain of ~30 dB. The noise characterization of our JPAs reveal near quantum limited noise performance. 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.

[1] M. Bal et al.,  “Overlap junctions for superconducting quantum electronics and amplifiers”, Appl. Phys. Lett. 118, 112601 (2021)