| Project/Area Number |
16540359
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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 |
原子・分子・量子エレクトロニクス・プラズマ
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| Research Institution | Gakushuin university |
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Principal Investigator |
KUWAMOTO Takeshi Gakushuin univ., science, research associate, 理学部, 助手 (10337909)
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| Co-Investigator(Kenkyū-buntansha) |
HIRANO Takuya Gakushuin univ., science, research associate, 理学部, 教授 (00251330)
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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 |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2005: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2004: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Keywords | Bose-Einstein condensation / superfluid / quantum vortex / laser cooling / topological phase / ボース・アインシュタイン凝縮体 / 幾何学位相 |
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| Research Abstract |
We have studied the dynamics of the multi-charged single quantum vortex in gaseous Bose-Einstein condensates. The vortices were created by topological way which was realized by controlling the atomic spin in the condensates confined in a magnetic trap. First, we created the condensates of atomic ^<87>Rb in the magnetic trap by well known evaporative cooling procedure. Second, we reversed the atomic spins in the condensate by changing the magnetic bias field from 0.5G to -0.5G. We searched the most efficient time for vortex generation by changing the field-reverse time from 1ms to 10ms. The vortices were created in 100-% efficiency when the reverse time was 5ms. Because of the atomic spin of two, the charge of vortices is four in our case.
The vortices were disappeared for about 10ms, because the condensates were elongated due to a deformation of magnetic trap potential resulting in the field reversal. In order to avoid this, we tried to transfer the condensates with vortex in the optical trap. Since the potential shape does not change by the magnetic fields for this trap, condensates would be stably confined in the trap, and the lifetime of vortex would be expected to lengthen.
We successfully transferred the condensates with vortex from the magnetic trap to optical trap. As a result, the enlargement of the condensates was suppressed, and the measured lifetime of vortices was about 20ms. We sometimes measured two vortices in a condensate at the trap time of about 20ms. We expect that these vortices are due to decay of a four-charge single vortex. As a future work, we would like to demonstrate this dynamics in detail.
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