Expanding Scanning Frequency Range of Josephson Parametric Amplifier Axion Haloscope Readout with Schottky Diode Bias Circuit

The axion search experiments in the microwave frequency range require high sensitive detectors with intrinsic noise close to quantum noise limit. Josephson parametric amplifiers (JPAs) are the most valuable candidates for the role of the first stage amplifier in the measurement circuit of the microwave frequency range, as they are well-known in superconducting quantum circuits readout. To increase the frequency range, a challenging scientific task involves implementing an assembly with parallel connection of several single JPAs, which requires matching the complex RF circuit at microwaves and ensuring proper DC flux bias. In this publication, we present a new DC flux bias setup based on a Schottky diode circuit for a JPA assembly consisting of two JPAs. We provide a detailed characterization of the diodes at cryogenic temperatures lower than 4 K. Specifically, we selected two RF Schottky diodes with desirable characteristics for the DC flux bias setup, and our results demonstrate that the Schottky diode circuit is a promising method for achieving proper DC flux bias in JPA assemblies.