SUPERCONDUCTING MILLIMETER WAVE COMPONENTS

EXTREME CURRENT-VOLTAGE (I-V) NONLINEARITY OF A SUPERCONDUCTORINSULATOR-SUPERCONDUCTOR (SIS) TUNNEL JUNCTION IMPLIES QUANTUM LIMIT BEHAVIOR AT MILLIMETER WAVELENGTHS. IN PARTICULAR, THEORETICAL CONSIDERATION OF SUCH JUNCTIONS INDICATES THAT ABOVE FREQUENCIES WHERE CURVATURE OF THE I-V CHARACTERISTIC BECOMES APPRECIABLE OVER A PHOTON POTENTIAL K W/E (THE QUANTUM LIMIT), CLASSICAL RESISTIVE MIXER ANALYSIS BECOMES INVALID AND A QUANTUM MECHANICAL TREATMENT MUST BE SUBSTITUTED. THE FULL QUANTUM THEORY OF NONLINEAR HETERODYNE MIXER PREDICTS THE AVAILABILITY OF CONVERSION GAIN THE THE QUANTUM LIMIT, AND THIS PREDICTED GAIN HAS BEEN OBSERVED. IT IS FELT THAT THE EXISTING THEORY ADEQUATELY DESCRIBES THE PERFORMANCE CHARACTERISTICS OF TUNNEL JUNCTION MIXERS, AND THEREFORE IT IS POSSIBLE TO QUANTITATIVELY PREDICT PERFORMANCE LEVELS OF TUNNEL JUNCTION MIXER AND DETECTOR SYSTEMS ENGINEERED FOR SPECIFIC APPLICATIONS. SYSTEM PERFORMANCE IS DEPENDENT UPON THE QUALITY OF THE SIS DEVICES AVAILABLE, AS WELL AS THE OVERALL COUPLING EFFICIENCY OF THE SIGNAL TO THE JUNCTIONS. WE AT HYPRES PROPOSE TO USE OUR ACQUIRED EXPERTISE TO PRODUCE SIS DEVICES FOR THE BUILDING OF PRIMARY MIXER SYSTEMS. THESE ULTRA WIDEBAND DEVICES WILL HAVE MULTIPLE APPLICATIONS IN SCIENCE AND ENGINEERING.