European Conference on Trapped Ions (ECTI)

An attractive proposition to extend the capabilities of quantum information systems is to fully utilise their high-dimensional Hilbert space. The internal electronic structure of trapped atomic ions offers a natural way to encode information not just in a two-level system, but in a high-dimensional qudit instead. One of the challenges of this approach is to achieve high fidelity interactions between them. We experimentally demonstrate a native qudit entangling gate between two ${}^{40}$Ca${}^{+}$ ions in up to 5 dimensions by exploiting a novel generalization of the light-shift gate. We achieve gate fidelities of $99.6(1)\mathrm{\%},98.7(2)\mathrm{\%},97.0(3)\mathrm{\%},93.7(3)\mathrm{\%}$ for dimensions of $d=2,3,4,5$ respectively. This gate is able to generate genuine qudit entanglement in a single application which makes it scale favorably with dimension in terms of calibration overheads compared to previous approaches.