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arXiv · 1206.2235

Superconducting microstrip amplifiers with sub-Kelvin noise temperature near 4 GHz

M. P. DeFeo·B. L. T. Plourde
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Abstract

We present measurements of an amplifier operating at 3.8 GHz with 150 MHz of bandwidth based on the microstrip input-coil resonance of a dc superconducting quantum interference device (SQUID) with submicron Josephson junctions. The noise temperature is measured using two methods: comparing the signal-to-noise ratio of the system with and without the SQUID in the amplifier chain, and using a modified Y-factor technique where calibrated narrowband noise is mixed up to the SQUID amplifier operating frequency. With the SQUID cooled to 0.35 K we observe a minimum system noise temperature of 0.55 $\pm~0.13$ K, dominated by the contribution from the SQUID amplifier.

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M. P. DeFeo, B. L. T. Plourde. 2012-06-11. Superconducting microstrip amplifiers with sub-Kelvin noise temperature near 4 GHz. https://doi.org/10.1063/1.4742164

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