Investigation of Superconducting Quasiparticle Mixers for Astronomical Receivers

基于超导体-绝缘体-超导体(SIS)准粒子隧道结混合器的接收器在灵敏度上已经超过了传统的肖特基二极管接收器，并对毫米波天文学产生了直接的影响。即便如此，在这项技术能够充分发挥其潜力之前，还需要进行更深入的研究。因此，根据混频的量子理论，对作为毫米波和亚毫米波探测器的SIS结进行广泛的实验研究，将更好地分析和直观地理解SIS混频器和相关现象，并特别关注噪声现象，最佳混频器设计参数，调谐结构，以及SIS结的适当电容。对不太被广泛接受的检测方案的研究，如正弦混频器、次谐波泵浦和SIS直接检测，将进行实验研究。这项工作将利用实验室制作的具有极低漏电流的Nb/AlO/Nb结。这些交汇点将提供给射电天文学团体，用于SIS接收器的开发。这项研究将极大地有助于实用SIS接收器的设计和最终灵敏度；并可能导致用于毫米和亚毫米波长天文学的其他探测器的发展。

Receivers based upon the superconductor-insulator-superconductor (SIS) quasiparticle tunnel junction mixer have now surpassed conventional Schottky-diode receivers in sensitivity, and are having an immediate impact on millimeter-wavelength astronomy. Even so, much further research is needed before this technology can reach its full potential. Therefore, an extensive experimental study of SIS junctions as millimeter-and submillimeter-wave detectors will be undertaken better analytical and intuitive understanding of SIS mixers and related phenomena, relying on the quantum theory of mixing, with special attention to noise phenomena, optimum mixer design parameters, tuning structures, will be sort, as will the appropriate capacitance for SIS junctions. Investigation of less widely accepted detection schemes, such as SIN mixers, subharmonic pumping, and SIS direct detection will be Experimentally studied. The Nb/AlO/Nb juctions made in laboratory, which have extraordinarily low leakage currents, will be utilized in this work. These junctions will be made available to the radio astronomy community for SIS receiver devleopment. This investigation should greatly contribute to the design and ultimate sensitivity of practical SIS receivers; and may lead to the development of other detectors for millimeter and submillimeter wavelength astronomy.