Near-Quantum-Limited SQUID Amplifier

Manuel A. Castellanos-Beltran, Konrad W. Lehnert

Sergey V. Uchaikin, Andrei N. Matlashov, Doyu Lee +11 more

We report results of our development of two types of microwave amplifiers based on Superconducting quantum interference devices (SQUIDs) for CAPP (Center for Axion and Precision Physics Research) axion search experiments. The first amplifier, Microstrip SQUID Amplifier (MSA) has a wide bandwidth. Power dissipation in resistive shunts results in a device overheating and limits the MSA performances. A thermal models of shunt cooling processes is developed and recommendations for a future design is provided. The second amplifier, Josephson Parametric Amplifier (JPA), at limited bandwidth showed a low noise near the standard quantum limit (SQL) of 196 mK. Implementation of a JPA in CULTASK (CAPP's Ultra-Low Temperature Axion Search in Korea) experiment is planned in the end of 2019.

Roy Therrien

Michael Mück, Jan B. Kycia, John L. Clarke

A dc superconducting quantum interference device (SQUID) with a resonant microstrip input is operated as an amplifier at temperatures down to 20 mK. A second SQUID is used as a postamplifier. Below about 100 mK, the noise temperature is 52±20 mK at 538 MHz, estimated from measurements of signal-to-noise ratio, and 47±10 mK at 519 MHz, estimated from the noise generated by a resonant circuit coupled to the input. The quantum-limited noise temperatures are 26 and 25 mK, respectively. The measured noise temperature is limited by hot electrons generated by the bias current.

M. P. DeFeo, B. L. T. Plourde

G.V. Prokopenko, V. P. Koshelets, J. Mygind