2025/07/15 by Michael T. Hatzon, E.N. Ivanov, Hatzon, Michael T +5
Physics and Astronomy · #FOS: Physical sciences #Gyrotron and Vacuum Electronics Research #Instrumentation and Detectors (physics.ins-det)
paper · pdf · doi:10.48550/arxiv.2507.10997
openalex publication_date 2025/07/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/02
We report high-resolution measurements of thermal fluctuations in microwave and mechanical resonators using a dual-channel readout system. The latter comprises a low-noise amplifier, an I/Q-mixer, and a cross-correlator. We discovered that, under certain conditions, the intrinsic fluctuations of the low-noise amplifier, which are common to both channels of the readout system, are averaged out when computing the voltage noise cross-spectrum between the mixer's outputs. The suppression of the amplifier's technical fluctuations significantly improves the contrast of the thermal noise peaks exhibited by the resonators. Thus, for the room-temperature-stabilized 9 GHz sapphire-loaded cavity resonator, we observed more than 16 dB improvement in the thermal noise peak contrast relative to the single-channel measurements. The ability of the dual-channel readout system to discriminate between the broad- and narrow-band fluctuations may benefit the search for dark matter, which relies on the use of cryogenic microwave resonators.