Superconducting amplifiers for axion dark matter search experiments

Synopsis

Superconducting quantum interference devices or SQUIDs can work as microwave amplifiers with noise temperature close to the standard quantum limit (SQL), TSQL = hf/kB ≈ 48 mK at 1 GHz. This is why SQUID-based microwave amplifiers have been chosen for axion search experiments. In our Center for Axion and Precision Physics research, (IBS/CAPP), we are working on two types of RF amplifier based on SQUIDs. We are developing Josephson Parametric Amplifiers (JPA) and Microstrip SQUID Amplifiers (MSA)in a collaboration with RIKEN, Japan, and IPHT, Jena, correspondingly. The JPA showed near SQL noise properties at our frequency of interest about 2.3 GHz and with MSA we obtained a very wide bandwidth of 1 GHz.  Low temperature operation, amplifier thermalization below 1 K and noise characterization of the new wideband microwave amplifiers as well as their implementation in the experiment will be demonstrated and discussed in this presentation.