2011 Fiscal Year Final Research Report
Study on a high-precision current multiplier applicable to the quantum current standard
| Project/Area Number |
21360040
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied physics, general
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| Research Institution | The University of Electro-Communications |
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Principal Investigator |
SHIMADA Hiroshi 電気通信大学, 情報理工学研究科, 准教授 (60216067)
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| Co-Investigator(Kenkyū-buntansha) |
MIZUGAKI Yoshinao 電気通信大学, 情報理工学研究科, 教授 (30280887)
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| Project Period (FY) |
2009 – 2011
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| Keywords | 量子電流標準 / 微小ジョセフソン接合列 |
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| Research Abstract |
A small-current 10-time multiplier using one-dimensional arrays of small Al/Al2O3/Al Josephson junctions and based on the quantum-current-mirror effect have been fabricated and tested. It showed the expected 10-time current multiplication function. The accuracy of the multiplication, however, was not good. It was most likely due to the small coupling capacitance. In order to substantially improve the accuracy, a fabrication process of a large coupling capacitance between the arrays has been successfully installed. A 10-time current multiplier with strong coupling has been fabricated using the process. A strongly coupled quantum-current-mirror devices were also fabricated and tested, and the quantitative relationship between the strength of the coupling and accuracy of the current duplication has been obtained. In such devices current induction with 0 bias voltage on the secondary array has been observed for the first time. Moreover, novel reversal of the induced current was observed : the direction of the induced current was the same as the primary current(input current) while applied magnetic field was small and Cooper-pair tunneling was dominant, and it changed to the opposite direction when applied magnetic field was large and quasiparticle(or electron) tunneling was dominant.
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