C-band single photons from a trapped ion via two-stage frequency conversion

Fiber-based quantum networks require photons at telecommunications wavelengths to interconnect qubits separated by long distances. Trapped ions are leading candidates for quantum networking with high-fidelity two-qubit gates, long coherence times, and the ability to emit photons entangled with the ions internal qubit states. However, trapped ions typically emit photons at wavelengths incompatible with telecommunications fiber. Here, we demonstrate frequency conversion of visible photons emitted from a trapped ion into the telecommunications C-band. These results are an important step towards enabling a long-distance trapped ion quantum internet.