The 7 Li + ion is one of the most important candidates for verifying QED theory and obtaining the precise value of the fine-structure constant α. However, direct laser cooling of trapped Li + ions will lead to strong background fluorescence which will influence the spectrum detection. The sympathetic cooling technique is a good choice to solve the problem. In this work, we report sympathetic cooling of 7 Li + ions to few mK using 40 Ca + ions in a linear Paul trap. A mixed ion crystal of 40 Ca + ions and 7 Li + ions are obtained. We also analyze the motion frequency spectra of pure 40 Ca + ions and mixed ions.The 7 Li + ion is one of the most important candidates for verifying QED theory and obtaining the precise value of the fine-structure constant α. However, direct laser cooling of trapped Li + ions will lead to strong background fluorescence which will influence the spectrum detection. The sympathetic cooling technique is a good choice to solve the problem. In this work, we report sympathetic cooling of 7 Li + ions to few mK using 40 Ca + ions in a linear Paul trap. A mixed ion crystal of 40 Ca + ions and 7 Li + ions are obtained. We also analyze the motion frequency spectra of pure 40 Ca + ions and mixed ions.

Chinese Physics LettersAug 1, 20156 citations

Ion–neutral-atom sympathetic cooling in a hybrid linear rf Paul and magneto-optical trap

D. S. Goodman, I. Sivarajah, James E. Wells +2 more

Long-range polarization forces between ions and neutral atoms result in large elastic scattering cross sections (e.g., $\ensuremath{\sim}\phantom{\rule{-0.16em}{0ex}}\phantom{\rule{-0.16em}{0ex}}{10}^{6}\phantom{\rule{0.28em}{0ex}}\mathrm{a}.\mathrm{u}.$ for $\mathrm{Na}$ - ${\mathrm{Na}}^{+}$ or $\mathrm{Na}$ - ${\mathrm{Ca}}^{+}$ at cold and ultracold temperatures). This suggests that a hybrid ion-neutral trap should offer a general means for significant sympathetic cooling of atomic or molecular ions. We present simion 7.0 simulation results concerning the advantages and limitations of sympathetic cooling within a hybrid trap apparatus consisting of a linear rf Paul trap concentric with a $\mathrm{Na}$ magneto-optical trap (MOT). This paper explores the impact of various heating mechanisms on the hybrid system and how parameters related to the MOT, Paul trap, number of ions, and ion species affect the efficiency of the sympathetic cooling.Long-range polarization forces between ions and neutral atoms result in large elastic scattering cross sections (e.g., $\ensuremath{\sim}\phantom{\rule{-0.16em}{0ex}}\phantom{\rule{-0.16em}{0ex}}{10}^{6}\phantom{\rule{0.28em}{0ex}}\mathrm{a}.\mathrm{u}.$ for $\mathrm{Na}$-${\mathrm{Na}}^{+}$ or $\mathrm{Na}$-${\mathrm{Ca}}^{+}$ at cold and ultracold temperatures). This suggests that a hybrid ion-neutral trap should offer a general means for significant sympathetic cooling of atomic or molecular ions. We present simion 7.0 simulation results concerning the advantages and limitations of sympathetic cooling within a hybrid trap apparatus consisting of a linear rf Paul trap concentric with a $\mathrm{Na}$ magneto-optical trap (MOT). This paper explores the impact of various heating mechanisms on the hybrid system and how parameters related to the MOT, Paul trap, number of ions, and ion species affect the efficiency of the sympathetic cooling.

arXiv:1207.1810Physical Review ASep 10, 201233 citations

\mathrm{Na}

{\mathrm{Na}}^{+}

\mathrm{Na}

{\mathrm{Ca}}^{+}

at cold and ultracold temperatures). This suggests that a hybrid ion-neutral trap should offer a general means for significant sympathetic cooling of atomic or molecular ions. We present simion 7.0 simulation results concerning the advantages and limitations of sympathetic cooling within a hybrid trap apparatus consisting of a linear rf Paul trap concentric with a

\mathrm{Na}

magneto-optical trap (MOT). This paper explores the impact of various heating mechanisms on the hybrid system and how parameters related to the MOT, Paul trap, number of ions, and ion species affect the efficiency of the sympathetic cooling.