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Fabrication of Ultra Low Noise Quasiparticle Mixer for Submillimeter Wave

亚毫米波超低噪声准粒子混合器的制作

基本信息

批准号：
61840001
负责人：
IMAI Syozo
金额：
$ 6.34万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1987
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-61840001/
关键词：
Quasiparticle Mixer Submillimeter Wave 準粒子ミキサーサブミリ波磁性バリア

项目摘要

In this project, we aim firstly to fabricate superconducting tunnel junctions with a magnetic barrier, Which have vanishing Josephson current by itselr, and then using these Junctions, we aim finnaly to develop a quasiparticle mixer working in the submillimeter wave region with ultra low noise temperature. Especailly, we fabricate tunnel junctions made of Nb, which is robust and has high critical temperature, Tc. We obtained following results. 1. We evaluated the performance of quasiparticle mixer theoretically. We found that ultra low noise performnce can be realized, even if the junction I-V characteristics is not superior.2. To establish basic techniques of junction fabrication, we tried to fabricate Pb/TaOx/Nb Josephson tunnel junctions. The fabricated junctions, however, have too large leak current. We tried to fabricate tunnel junctions with a magnetic barrier, Pb/TaOx/NiOx/TaOx/Nb junctions, and Nb/TaOx/Nb josephson junctions. In both cases, the junctions are of poor quality. Thus, we need to develop techniques of junction fabrication further.3. To investigate high frequency characteristics of junctions made of high Tc superconductors, we measured submillimeter wave response of Nb/YBaCuO junctions up to frequency of 525 GHz. The junctions turned out to be bridge type Josephson junctions and their response is simmilar to taht of junctions made of ordinary superconductors.

在本计画中，我们的目标是先制作出具有磁性障壁的超导隧道结，使约瑟夫森电流自行消失，然后利用这些结，我们的目标是发展出工作在亚毫米波超低噪声温度的准粒子混合器。特别地，我们制备了由Nb制成的隧道结，其是坚固的并且具有高临界温度Tc。我们得到了以下结果。1.从理论上对准粒子混合器的性能进行了评价。我们发现，即使结的I-V特性并不优越，也可以实现超低噪声性能.为了建立结制备的基本技术，我们尝试制备Pb/TaOx/Nb约瑟夫森隧道结。然而，所制造的结具有太大的漏电流。我们尝试制作具有磁势垒的隧道结、Pb/TaOx/NiOx/TaOx/Nb结和Nb/TaOx/Nb约瑟夫森结。在这两种情况下，接合处的质量都很差。因此，我们需要进一步发展结的制造技术.为了研究由高Tc超导体制成的结的高频特性，我们测量了Nb/YBaCuO结的亚毫米波响应，频率高达525 GHz。结果表明，这种结是桥式约瑟夫森结，其响应与普通超导体结相似。