| Project/Area Number |
16540304
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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 |
Condensed matter physics II
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| Research Institution | Tohoku University |
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Principal Investigator |
KOYAMA Tomio Tohoku University, Institute for Materials Research, Research Associate, 金属材料研究所, 助手 (30153696)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUMOTO Hideki Tsukuba University, Physics, Professor, 物理学系, 教授 (40209648)
KATO Masaru Osaka Prefecture University, Mathematical Sciences, Associate Professor, 工学研究科, 助教授 (90204495)
MACHIDA Masahiko Japan Atomic Research Institute, CCSE, Fellow, 計算科学技術センター, 研究主幹 (60360434)
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| Project Period (FY) |
2004 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2005: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2004: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | high-Tc cuprates / 0-pi Josephson junction / nano-superconductors / quantum bit / d-dot / GL theory / 0-πジョセフソン効果 / 酸化物高温超電導体 / 固有ジョセフソン効果 / ジョセフソンプラズマ / 量子2準位 |
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| Research Abstract |
In this research project we studied the Josephson effects in small complex systems composed of unconventional d-wave and conventional s-wave superconductors from viewpoints of both basic physics and quantum devise applications. When a d-wave superconductor with d(x^2-y^2)-symmetry of square shape is embedded in a s-wave superconducting matrix, the system forms a closed 0-π Josephson junction in which vortices with half-flux quanta appear spontaneously. We construct a theory describing the phase dynamics in this complex system. When the size of the system is small enough, the quantum fluctuations dominate the system. We rigorously prove that this system behaves as a quantum two-level system in the quantum regime. The qubit applications were discussed. In this research project we also investigated the intrinsic Josephson effect observed in Bi-2212 high temperature superconductor. The origin of unusual field dependence of the microwave resonance absorption spectrum observed in Bi-2212 under a magnetic field parallel to the layers was clarified. The I-V characteristics and terahertz emission in a stack of intrinsic Josephson junctions were also discussed.
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