Crystallization of Ca + ions in a linear rf octupole ion trap
Crystallization of Ca + ions in a linear rf octupole ion trap
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DOI：
10.1103/physreva.75.033409
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发表时间：
2007-03
影响因子：
2.9
通讯作者：
K. Okada;K. Yasuda;T. Takayanagi;M. Wada;H. Schuessler;S. Ohtani
中科院分区：
文献类型：
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作者：
K. Okada;K. Yasuda;T. Takayanagi;M. Wada;H. Schuessler;S. Ohtani
本文介绍了在线性射频八极子离子阱中捕获${\ mathm {Ca}}^{+}$离子的激光冷却实验。通过激光诱导荧光光谱的突然下降观察到激光冷却的${\mathrm{Ca}}^{+}$离子从云到晶体态的相变，并表明获得了mK温度。我们还进行了各种条件下的分子动力学模拟，通过推导库仑晶体的轴对称结构和评估激光冷却离子的平移温度来证实这一性质。模拟结果表明，对于少量离子，可以产生新的环状晶体。随着离子数量的增加，环状晶体中的圆柱形层依次形成。对于超过100个离子，在大尺寸离子晶体的某些部分也会出现六角形和螺旋结构，在目前的几何排列和电压下，离子晶体的长度约为毫米。线性射频八极阱的一个优点是在阱的中间有一个大的几乎无场的区域，在那里被捕获的离子的微运动幅度很小。这些结果表明，这种多极阱在量子计算和超冷离子原子碰撞研究中具有吸引人的特点。
A laser-cooling experiment with ${\mathrm{Ca}}^{+}$ ions trapped in a linear rf octupole ion trap is presented. The phase transition of the laser-cooled ${\mathrm{Ca}}^{+}$ ions from the cloud to the crystal state is observed by an abrupt dip of the laser-induced fluorescence spectrum and indicates that mK temperatures are obtained. We have also performed molecular dynamics simulations under various conditions to confirm this property by deducing axially symmetric structures of Coulomb crystals and by evaluating the translational temperatures of the laser-cooled ions. The simulation results show that for small numbers of ions novel ring-shaped crystals are produced. As the number of ions is increased, cylindrical layers in the ring crystal are sequentially formed. For more than 100 ions, also hexagonal and spiral structures emerge in parts of the large-size ion crystal, which has a length on the order of millimeters for the present geometrical arrangement and voltages. An advantage of the linear rf octupole trap is its large almost-field-free region in the middle of the trap, where the micromotion amplitude is small for trapped ions. These results demonstrate that such a multipole trap has attractive features for quantum computing and ultracold ion-atom collision studies.