| Project/Area Number |
18540392
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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 | University of Fukui |
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Principal Investigator |
KUMAKURA Mitsutaka University of Fukui, DEPARTMENT OF ENGINEERING, ASSOCIATE PROFESSOR (30324601)
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| Co-Investigator(Kenkyū-buntansha) |
MORITA Norio UNIVERSITY OF FUKUI, DEPARTMENT OF ENGINEERING, PROFESSOR (30134654)
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| Project Period (FY) |
2006 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,510,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥210,000)
Fiscal Year 2007: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2006: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Keywords | LASER COOLING / LASER TRAPPING / MAGNETO-OPTICAL TRAP / ATOMIC ULTRACOLD GAS / SISYPHUS LASER COOLING / RUBIDIUM / FREQUENCY STABILIZATION / ATOM OPTICS / 光トラップ / 光双極子力トラップ / 暗状態 / 磁気光学トラップ / 光格子 / 希薄原子気体 / 蒸発冷却 / ドレスド状態 |
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| Research Abstract |
In order to optically cool 87Rb atoms below such a low temperature as to be confined in an optical trap, we made two frequency-stabilized single-mode cw lasers whose frequencies were nearly resonant to the 5s 2S1/2(F=2)→5p 2P3/2(F=3) and 5s 2S1/2(F=1)→5p 2P3/2(F=2) transitions. The laser frequency width less than 1 MHz, which is necessary for the successful laser cooling of Rb atoms, was achieved for both lasers. We also made a new ultra-high vacuum (UHV) chamber for trapping cold atoms for a long enough time to observe evaporative cooling process in the optical trap.
With this new experimental apparatus we operated the double magneto-optical trap system. Initially, Rb atoms were magneto-optically collected from the atomic vapor at a room temperature and optically cooled in the magneto-optical trap (MOT) below 2 mK. The cold atoms were released from the MOT, and were transferred into the other MOT in the UHV chamber by the radiation pressure of the pushing laser beam. Repeating this loading procedure about 200 times, we confined about 8×10_8 atoms in the UHV-MOT at a temperature of 1 mK. For efficiently confining the cold atoms into an optical trap, we further optically cooled the atoms by the polarization gradient cooling and achieved a temperature of 100 μK, which was comparable to the typical trap depth of an optical trap.
We also estimated atom heating and loss rates due to background gases by monitoring a trap lifetime and a thermalization rate in a magnetic trap. The obtained lifetime was approximately 1 min, and the trapped atoms were cooled from 1 mK to 10 μK in about 2 min by the rf evaporative cooling. From these facts we successfully confirmed that even in an optical trap further laser cooling could be applied against the trap heating and losses.
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