Collecting more than half the fluorescence photons from a single ion

We demonstrate the trapping of a single ion in the focus of a deep parabolic mirror that covers 81$%$ of the solid angle surrounding the ion. Accounting for the reflectivity of the mirror we infer a photon collection efficiency of 54.8$%$ for our setup. The underlying experimentally detected maximum fluorescence rate is 1.91×10⁶ s^-1 from a single ¹⁷⁴Yb⁺ ion, mainly limited by the quantum efficiency of our photon detector. Besides the high collection efficiency, the integration of an ion trap into a parabolic mirror is a key ingredient for efficient coupling of light to a single ion in free space.