SIS (Superconductor-Insulator-Superconductor) Mixer Research
Abstract
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 saturation behavior of the SIS mixer and the SIS direct detector was calculated. The direct detector was found to saturate at far higher powers than previously believed, allowing the possibility of practical application. SIS mixer saturation was measured using both monochromatic and thermal signals, and these experiments dramatically verified the theoretical expression. Quantum noise in the quantum theory of mixing was identified as the residual remaining when the usual noise sources are minimized. The 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 frequencies regimes, the cross-over frequency depending upon junction quality. The properties of these two regimes were delineated. A study of the role of the image termination of SIS mixers found that the nonlinear quantum reactance results in an effective time delay at the input port. Many aspects of the operation of SIS mixers at submillimeter wavelengths were clarified. Niobium nitride edge junctions with excellent current-voltage characteristics were fabricated using a novel barrier formation process.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1989
- Accession Number
- ADA211607
Entities
People
- Marc J. Feldman
Organizations
- University of Virginia