  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
ion's 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.
