  The ultimate realization of a global quantum internet will require advances
in scalable technologies capable of generating, storing, and manipulating
quantum information. The essential devices that will perform these tasks in a
quantum network are quantum repeaters, which will enable the long-range
distribution of entanglement between distant network nodes. In this
perspective, we provide an overview of the primary functions of a quantum
repeater and discuss progress that has been made toward the development of
repeaters with rare-earth ion doped materials while noting challenges that are
being faced as the technologies mature. We give particular attention to erbium,
which is well suited for networking applications. Finally, we provide a
discussion of near-term benchmarks that can further guide rare-earth ion
platforms for impact in near-term quantum networks.
