Flux-Driven Josephson Parametric Amplifier Fabricated Using the Nb/AlOx/Nb Trilayer Process

In this paper, we report a flux-driven Josephson parametric amplifier (JPA) fabricated using the Nb/AlO
_x
/Nb Josephson junction process. The JPA consists of a parallel-plate type coupling capacitor and quarter-wavelength resonator terminated with a DC-SQUID. We adopt a simple process using well-established Nb trilayer technology. The overall configuration time of the Nb-based JPA can be shortened by measuring resonant frequency and its bias dependence in liquid helium. Amplification of the pre-tested device was demonstrated, showing a gain of 20 dB in a −3 dB bandwidth of 17 MHz in a 10 mK dilution fridge.