1993 Fiscal Year Final Research Report Summary
Study of Collision Process of Ultracold Ions by Means of Quantum Jump Signals
| Project/Area Number |
04452054
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
物理学一般
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| Research Institution | The University of Tokyo |
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Principal Investigator |
TACHIKAWA Maki The University of Tokyo Graduate School of Science Research Assistant, 大学院・理学系研究科, 助手 (60201612)
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| Co-Investigator(Kenkyū-buntansha) |
SHIMIZU Tadao The University of Tokyo Graduate School of Science Professor, 大学院・理学系研究科, 教授 (90011668)
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| Project Period (FY) |
1992 – 1993
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| Keywords | Ion Trap / Laser Cooling / Ion Collision / Quantum Jump |
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| Research Abstract |
The present research has been carried out in order to clarify characteristics of collision processes of cold ions with atoms and molecules by means of the laser-induced-fluorescence (LIF) spectroscopy and the laser-cooling technique. Major outcomes are described below.
1. Collision Cooling of Trapped Ions
Mg^+ ions confined in a rf trap were cooled via elastic collisions with buffer gas at room temperature. We investigated dependences of the ion temperature, which was measured from the Doppler broadening of the LIF spectrum, on the mass and the pressure of the buffer gas. A theoretical model describing the rf heating induced by the collision with the buffer gas was successfully applied to reproduce the observed results.
2. Laser Cooling of Trapped Ions
The LIF spectrum from several tens of laser-cooled ions was observed. The spectrum has a narrow and asymmetric profile because of the effects of the laser cooling in the red-shifted region and the laser heating in the blue-shifted region. The analysis based on our model revealed that the cooling limit was several K.and that the ions were little heated by the collisions with neutral atoms under strong laser radiation.
3. Observation of Ion Cluster
A few ions were laser-cooled down to 10 mK, and localized on the equilibrium points of the Coulomb potential, forming a cluster. We observed two-dimensional images of the fluorescence from the clusters consisting of up to three ions. The fluorescence images enabled a real-time observation of breakdown of the cluster caused by the collision with residual gas.
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