  The demand for efficient preparation methods for dual-species ion crystals is
rapidly expanding across quantum technology and fundamental physics
applications with trapped ions. We present a deterministic and efficient
technique to produce such crystals, utilizing the segmented structure of a
linear Paul trap. By precisely tailoring the trapping potentials, we can split,
move, and discard parts of an ion chain. This process is automated in a
sequence that converts a larger ion sample into the desired configuration. A
critical component of our approach is the accurate identification of crystal
constituents. This is achieved by matching the measured positions of
fluorescing ions against theoretical expectations for larger crystals, thus
facilitating the detection of non-fluorescing ions and enabling accurate ion
counting. We demonstrate that our method reliably produces two-ion crystals
within minutes. These results represent a significant advance in the production
of two-species ion crystals with applications ranging from quantum logic
spectroscopy and optical clocks to quantum computing and simulation with
trapped ions.
