噪声温度在4GHz附近的超导微带放大器
Superconducting microstrip amplifiers with sub-Kelvin noise temperature near 4 GHz
摘要：
我们提出了测量的放大器工作在3.8 GHz的150 MHz的带宽的基础上的微带输入线圈谐振的直流超导量子干涉器件（SQUID）与亚微米约瑟夫森结。噪声温度的测量使用两种方法：比较系统的信噪比的SQUID和没有在放大器链，并使用一个修改的Y因子技术，校准的窄带噪声被混合到SQUID放大器的工作频率。随着SQUID冷却到0.35 K，我们观察到的最小系统噪声温度为0.55 $\pm~0.13$ K，占主导地位的贡献从SQUID放大器。
英文摘要：
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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