Characteristics of noises in high-temperature YBCO Josephson junctions

In this work, the characteristics of the noises for high-temperature YBCO Josephson junctions and SQUIDs were studied. The noise power spectrum densities showed complicated behaviors, which may be attributed to many causes. In order to realize the contributions of these causes to the noise, the noise power spectra were detected at various bias currents. Thus, the noises owing to the critical current fluctuation, resistance fluctuation or apparent flux motion can be investigated. By comparing these noise power spectra under the different conditions, the origins of the noises for the junctions and SQUIDs can be clarified.