In the first step the ion is prepared (and cooled) in the |0〉 = 3s1/2(F = 3, M = 3) state by optical pumping with a continuous wave laser. Then Zeno spectroscopy is performed by observing the damping of Rabi flopping of the |0〉 = 3s1/2(F = 3, M = 3) → |1〉 = 3s1/2(F = 2, M = 2) driven with a radio frequency of 1.785 GHz (see Fig. 3). Zeno spectroscopy also works for the non-cycling transition to |2′〉 (dashed). Since the spectroscopy laser in this case is a frequency comb, we see both transitions convolved with the comb (see Fig. 6). In the last step the population remaining in the initial state is determined. At this point we simply use the same laser as cooling/preparation laser on its cycling transition for a demonstration whereas in a real application such a laser would not exist (otherwise the usual shelving or fluorescence detection scheme seem to be simpler). The preparation and state detection would have to be done by other means such as state dependent trap losses18.