Calibration of the cryogenic measurement system of a resonant haloscope cavity* *Measurements were performed at Hunan Normal University in Changsha. This work was supported in part by the Scientific Instrument Developing Project of the Chinese Academy of Sciences (YJKYYQ20190049), the International Partnership Program of Chinese Academy of Sciences for Grand Challenges (112311KYSB20210012), the National Natural Science Foundation of China (12074117,

Abstract

Possible light bosonic dark matter interactions with the Standard Model photon have been searched using microwave resonant cavities. In this paper, we describe the cryogenic readout system calibration of a 7.138 GHz copper cavity with a loaded quality factor whose operation at a temperature of 22 mK is based on a dilution refrigerator. Our readout system consists of High Electron Mobility Transistors working as cryogenic amplifiers at 4 K, plus room-temperature amplifiers and a spectrum analyzer for signal power detection. We tested the system with a superconducting two-level system based on a single-photon source in the microwave frequency regime. We obtained an overall 95.6 dB system gain and –71.4 dB attenuation in the cavity's input channel. The effective noise temperature of the measurement system is 7.5 K.