SIS (Superconductor-Insulator-Superconductor) Mixer Research.
Final rept. 15 Nov 85-14 Nov 86,
VIRGINIA UNIV CHARLOTTESVILLE DEPT OF ELECTRICAL ENGINEERING
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Theoretical and experimental research has been conducted to elucidate the basic physics behind the properties of superconductor-insulator-superconductor SIS tunnel junction receiving devices. The quantum theory of mixing was employedto calculate the saturation behavior of the SIS mixer and the SIS direct detector. The direct detector was found to saturate at far higher powers than previously believed, allowing the possibility of practical application of this device. Experiments verified the saturation theory. The mixer saturation expression led to the formulation of frequency scaling regions. The origin of quantum noise sources are completely minimized. The mixer quantum noise limit was shown to be reached in only two special cases. Computer calculations determined that the behavior of SIS receivers divides into two regimes, low and high frequencies, the cross-over frequency depending upon junction quality. The properties of these two regimes were delineated. All previous SIS receivers have operated in the low frequency regime. Plasma-etched niobium nitride edge junctions have been fabricated using a novel barrier formation process. These junctions have excellent current-voltage characteristics, but their precise physical nature has not yet been determined. Author
- Electrical and Electronic Equipment
- Solid State Physics