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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.