Rare Earth quantum memories for quantum repeaters
Future quantum networks will enable a series of improvements in communication and information science. Quantum key distribution will allow highly secure communication and quantum computers in distant nodes will be able to share quantum states, to cite a few. As for the carrier of this information, light is so far the strongest candidate, and optical fibres the best medium of transport on the ground. Nonetheless, the communication rates in direct fibre connections are still limited by losses, but they can be improved by the implementation of quantum repeaters between the nodes of the network. In this talk, I will first introduce an experimental scheme for a quantum memory-based repeater. I will then present results of spin-photon correlations in an ensemble of Europium ions embedded in a solid state host. I will conclude by presenting the results of a recent study on the coherence properties of an Ytterbium-doped crystal, which could greatly increase the bandwidth and multimode capacity of solid-state quantum repeaters.