Resonant photo-ionization of Yb+ to Yb2+

We demonstrate the controlled creation of a ${}^{174}\mathrm{Y}{\mathrm{b}}^{2+}$ ion by photo-ionizing ${}^{174}\mathrm{Y}{\mathrm{b}}^{+}$ with weak continuous-wave lasers at ultraviolet wavelengths. The photo-ionization is performed by resonantly exciting transitions of the ${}^{174}\mathrm{Y}{\mathrm{b}}^{+}$ ion in three steps. Starting from an ion crystal of two laser-cooled ${}^{174}\mathrm{Y}{\mathrm{b}}^{+}$ ions localized in a radio-frequency trap, the verification of the ionization process is performed by characterizing the properties of the resulting mixed-species ion-crystal. The obtained results facilitate fundamental studies of physics involving $\mathrm{Y}{\mathrm{b}}^{2+}$ ions.