Noise Performance of Lumped Element Direct Current Superconducting Quantum Interference Device Amplifiers in the 4 GHz-8 GHz Range

摘要

We report on the noise of a lumped element Direct Current SuperconductingQuantum Interference Device amplifier. We show that the noise temperature inthe 4 GHz-8 GHz range over ranges of 10's of MHz is below 1 kelvin (threephotons of added noise), characterize the overall behavior of the noise as afunction of bias parameters, and discuss potential mechanisms which determinethe noise performance in this amplifier. We show that this device can providemore than a factor of 10 improvement in practical system noise over existingphase-preserving microwave measurement systems in this frequency band.