| Co-Investigator(Kenkyū-buntansha) |
TAKEUTI Yosihisa Professor, Reseach Institute of Electrical Communication, Tohoku Univ., 電気通信研究所, 教授 (60006210)
MIKOSHIBA Nobuo Professor, Research Institute of Electrical Communication, Tohoku Univ., 電気通信研究所, 教授 (70006279)
MORITA Seizo Associate Professor, Research Institute of Elecrical Communication, Tohoku Univ., 電気通信研究所, 助教授 (50091757)
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| Budget Amount *help |
¥9,900,000 (Direct Cost: ¥9,900,000)
Fiscal Year 1987: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1986: ¥9,000,000 (Direct Cost: ¥9,000,000)
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| Research Abstract |
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.
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