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Statistical properties of laser-cooled Ca ions in a quadrupole toroidal rf trap

四极环形射频阱中激光冷却 Ca 离子的统计特性

基本信息

批准号：
13680555
负责人：
SAKAWA Youichi
金额：
$ 2.3万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13680555/
关键词：
toroidal rf trap laser cooling one component plasma statistical properties

项目摘要

In our experiments, ions are confined in a toroidal rf trap and Coulomb coupling parameter >1 is achieved by laser cooling. In order to cool Ca+ ions, the 397 nm radiation, obtained by frequency doubling of the 794 nm radiation using a LBO crystal placed in the external cavity, and the 866 nm radiation are constructed using diode lasers.In 2001, to achieve stable radiations of 397 nm and 866 nm from diode lasers, we have constructed grating-laser-stabilization systems by means of feedback from holographic gratings in the Littrow configuration for both diode lasers. As a result, stabilization of diode lasers in frequency, intensity, and pointing has been achieved. We have controlled the Ca+ ion temperature by means of He buffer-gas-cooling ; and measured confinement time, velocity distribution function, and density profile of Ca+ ions using laser-induced fluorescence (LIF) method.In 2002, we have constructed the second 397 nm laser as a probe laser in addition to the cooling laser, in order to measure the statistical properties of laser-cooled Ca+ ions, such as velocity distribution function and density profile using LIF method. The optical feedback phase and the frequency of the grating-stabilized laser are simultaneously controlled by 1f and 3f electric feedback, respectively, using a proportional and integral (PI) feedback method, and the frequency scan of nearly 5 GHz is achieved.We have conducted LIF measurements of Ca+ ions using two toroidal rf traps ; one is 2 mm and the other is 4 mm in the distance between the neighboring electrodes (the major radius is 40 mm in both traps). Whereas the 2 mm trap has shown no LIF signals without the buffer-gas cooling, the 4 mm trap has shown the evidence for trapped Ca+ ions even at the base pressure. Laser-cooling experiments are in progress using the 4 mm trap.

在我们的实验中，离子被限制在环形射频陷阱中，库仑耦合参数&gt；1是通过激光冷却获得的。为了冷却钙离子，利用置于外腔的LBO晶体对794 nm和866 nm的激光进行倍频，得到了397 nm和866 nm的激光辐射。2001年，为了获得稳定的397 nm和866 nm的激光辐射，我们利用Littrow结构的全息光栅的反馈构建了这两种半导体激光器的光栅-激光稳定系统。因此，实现了半导体激光器在频率、强度和指向方面的稳定。利用激光诱导荧光(LIF)方法测量了钙离子的限制时间、速度分布函数和密度分布。2002年，我们在冷却激光的基础上搭建了第二台397 nm激光作为探测激光器，用激光诱导荧光(LIF)方法测量了激光冷却的钙离子的统计性质，如速度分布函数和密度分布。采用比例积分(PI)反馈方法，分别用1f和3f电反馈同时控制光反馈的相位和频率，实现了近5 GHz的频率扫描。我们用两个环形射频陷阱对钙离子进行了激光诱导荧光测量，其中一个为2 mm，另一个为4 mm(两个陷阱的主半径均为40 mm)。在没有缓冲气体冷却的情况下，2 mm的陷阱没有显示出激光诱导荧光信号，而4 mm的陷阱已经显示出即使在基压下也有捕获的Ca+离子的证据。使用4毫米陷阱的激光冷却实验正在进行中。