Progress in understanding of high-transition-temperature SQUIDs

In this overview, we compare experimental results with predictions of analy tical theories of rf SQUIDs and de SQUIDs, valid up to the limit of high th ermal fluctuations, and also with extensive de SQUIDs simulations. Data der ived from measurements of amplitude-frequency characteristics of if SQUIDs, plus direct characterization of junctions after opening the SQUID loop, ga ve a satisfactory quantitative agreement with theory. For de SQUIDs, white noise was typically higher and the transfer function lower than predicted b y analytical theory and by simulations. The origin of these discrepancies r emains unknown.