2005 Fiscal Year Final Research Report Summary
Research of Superconductive Chaos Generator Device "Josephson Tetrode"
| Project/Area Number |
15560305
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Electron device/Electronic equipment
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| Research Institution | Takushoku University |
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Principal Investigator |
YOSHIMORI Shigeru Takushoku University, Faculty of Engineering, Professor, 工学部, 教授 (00167024)
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| Project Period (FY) |
2003 – 2005
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| Keywords | Josephson Tetrode / Josephson effect / Chaos / Nonlinear dynamics / Chaos attractor / GL theory / Margin of generation / Bifurcation diagram |
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| Research Abstract |
In this research project, the generation of chaos in "Josephson tetrode", a four-terminal superconductive device made of five Josephson weak-link junctions was numerically demonstrated. This novel superconductive device can be applied to ultra-fast random signal generations at frequencies of hundreds of gigahertz.
In the Josephson tetrode, two weak-link junctions are series-connected and other three junctions are parallel-connected. The dynamics of electrical voltages across the junctions were calculated when one of the normal resistances was varied. The generation of chaos was confirmed by using a bifurcation diagram, three-dimensional attractors and the Poincare sections.
The bifurcation diagram can be interpreted as the quasi-periodicity-breakdown scenerio to chaos. The mechanism of chaos generation is a nonlinear frequency mixing among three independent voltages across the junctions.
The Josephson tetrode was made of five step-edge type Josephson junctions. So two-dimensional Ginzburg-Landau equation was applied to the step-edge Josephson junction and the solution was analytically derived. The current-phase relationship and temperature dependence of the critical current were calculated.
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