Towards Fast Ground State to Ground State Separation of Small Ion Crystals

Rapid separation of linear crystals of trapped ions into different subsets is critical for speeding up trapped ion quantum computing architectures where ions are shuttled between trap zones to achieve all-to-all connectivity between qubits. We introduce a general theoretical framework that can be used to describe the motional state evolution of same-species and mixed-species crystals as they are separated or recombined. We explore time-dependent trapping potentials suitable for separation of a mixed species three-ion crystal on timescales similar to that of free expansion driven by Coulomb repulsion, with all motional modes along the crystal axis starting and ending close to their ground states. We report on experimental progress towards realizing these protocols.