| Project/Area Number |
11640361
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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 |
固体物性Ⅱ(磁性・金属・低温)
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| Research Institution | Kinki University |
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Principal Investigator |
NAKAHARA Mikio Kinki University, Department of Physics, Professor, 理工学部, 教授 (90189019)
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| Co-Investigator(Kenkyū-buntansha) |
OHMI Tetsuo Kyoto University, Graduate School of Science, Professor, 大学院・理学研究科, 教授 (70025435)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 2000: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1999: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | Bose Condensation / Alkali atoms / Hyperfine Spin / Vortices / Homotopy Group / Textures / 渦糸 / 永久流 / 基本群 / テクスチャー |
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| Research Abstract |
・It is shown that a vortex can be continuously created in a Bose-Einstein condensate (BEC) of alkali atoms with |F|=1 confined in a multiply connected region by making use of a spin degree of freedom of the order parameter of a BEC.The mutiple-connecedness is realised by introducing an optical plug along the center of the vortex. The BEC stays within a weak-field seeking state during the time evolution thanks to the optical plug. This is demonstrated explicitly by solving the generalised Gross-Pitaevskii (GP) equation numerially.
・This scenario is also analysed from a topological point of view. It is shown that the fundamental group π_1(SO(3))=Z_2 makes it possible to create a doubly-quantised vortex continuously from a vortex-free state.
・An optical plug must be introduced in the above scenario since the weakfield seeking state and the strong-field seeking state have degenerate levels along the axis when the axial magnetic field vanishes during the creation of a vortex. It should be noted, however, that this happens only at a moment of time and at a single point in a plane. Thus it is expected that those particles taking part in the Majorana flops are negligible This conjecture is assured by solving the generalised GP equation numerically.
・We also studied a BEC with |F|=2 and found that a vortex with four units of circulation is created in the present scenario.
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