Fig. 5
Experimental procedure and results of the sympathetic cooling experiment. After loading the coolant ions and trapping the hot ions through sympathetic cooling, the species of the sympathetically cooled ions was identified via Doppler cooling. The upper panels show the schematics, the middle panels show the operational settings of the lasers, and the lower panels show the ion images. Only one 397-\(\textrm{nm}\) and one 866-\(\textrm{nm}\) laser were used. During the detuning stage before detection, it was observed that when \(^{40}{\textrm{Ca}}^+\) were the coolant ions, they escaped due to laser heating, whereas when \(^{44}{\textrm{Ca}}^+\) were the coolant ions, they were not affected by laser heating but often escaped during the few seconds while the 397-\(\textrm{nm}\) laser frequency was far from the resonance frequency of \(^{44}{\textrm{Ca}}^+\) and \(^{40}{\textrm{Ca}}^+\) ions. In the middle panels, the arrows indicate which isotope (\(^{40}{\textrm{Ca}}^+\) or \(^{44}{\textrm{Ca}}^+\)) the laser frequency targets.
