Towards quantum interference between NV centers and Rare-earth ion solid-state memories

Large-scale quantum networks, allowing the transmission of quantum information over large distances, are of great interest for both fundamental research as well as practical applications. Their realization, however, still poses a range of challenges, including the demonstration of interfaces between disparate quantum systems, such as network processing nodes and long-distance quantum repeaters. Here we present our work towards interfering photons emitted from a Nitrogen Vacancy (NV) center, which is well suited to act as a local processing network node, with light emitted from a Tm-based rare-earth quantum memory, which may enable long-range quantum repeaters. As a first step, we convert photons from 795nm to 637nm, the emission wavelengths of Tm and NV centers, respectively, to show that this conserves their quantum nature. By interfacing these two key network components we aim to demonstrate an important step towards the realization of long range quantum networks.