Secular Motion Frequencies of $^{9}$Be$^{+}$ Ions and $^{40}$Ca$^{+}$ Ions in Bi-component Coulomb Crystals
Hai-Xia Li1,2, Min Li1,2, Qian-Yu Zhang1,2, Xin Tong1**
1State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 2University of Chinese Academy of Sciences, Beijing 100049
Abstract：We obtain bi-component Coulomb crystals using laser-cooled $^{40}$Ca$^{+}$ ions to sympathetically cool $^{9}$Be$^{+}$ ions in a linear Paul trap. The shell structures of the bi-component Coulomb crystals are investigated. The secular motion frequencies of the two different ions are determined and compared with those in the single-component Coulomb crystals. In the radial direction, the resonant motion frequencies of the two ionic species shift toward each other due to the strong motion coupling in the ion trap. In the axial direction, the motion frequency of the laser-cooled $^{40}$Ca$^{+}$ is impervious to the sympathetically cooled $^{9}$Be$^{+}$ ions because the spatially separation of the two different ionic species leads to the weak motion coupling in the axial direction.
2019, Vol. 36 
