Erbium-Implanted Materials for Quantum Communication*

Erbium-doped materials can form spin-photon interfaces wwith optical transitions in the 1.5μm telecom window, making them an exciting class of materials for long-distance quantum communication (QC). Advances in nanophotonic integration have enabled the observation and manipulation of single Er³⁺ ions, a key result for constructing quantum repeaters. However, these single-ion experiments have also highlighted materials challenges, such as spectral diffusion and magnetic noise-limited spin coherence times.

Using ion-implantation, we introduce Er³⁺ into a wide array of host materials in a surface-specific manner suited to nanophotonic integration. This approach allows us not only to readily identify a number of promising candidates for QC applications, but also enables us to explore the effect of materials properties, such as symmetry and lattice parameter, on the QC-relevant properties of the implanted Er³⁺. The principles we develop here can be extended beyond Er³⁺, to other rare-earth ions, transition metals, and color centers.