Heterodyne Detection of Microwaves Using Granular-Type Y1Ba2Cu3O7-x Superconductors

Abstract
A heterodyne mixing experiment of microwaves at about 20 GHz was performed using a microwave detector made from granular-type Y1Ba2Cu3O7-x (YBCO) superconductors. Although the bridge included many boundaries, voltage steps corresponding to the Josephson frequency and step height dependence for microwave power similar to those of a single weak-link bridge were clearly observed. The IF signal showed peak amplitudes corresponding to the peak dynamic resistantance due to nonlinearity resulting from the Josephson effect. It was confirmed for the first time that this detector operates stably for the heterodyne mixer at 60 K or below and has a potential for high sensitivity due to its large dynamic resistance.