Q u a n t u m R e p e a t e r s
Our long term goal is to achieve quantum networking based on telecommunications quantum repeater. We have proposed a new strategy for a quantum repeater at telecommunications wavelengths with long-lived atomic memory, and we have experimentally demonstrated its critical elements in a cold atomic ensemble. Using atomic cascade emission in rubidium-85, we generated an entangled pair of 1.53 µm and 780 nm photons. The former is ideal for long-distance quantum communication, while the latter is naturally suited for mapping to a long-lived atomic memory.
We have made significant advances in the generation, distribution, and storage of qubit entanglement using narrow-band 780/795 nm photons, including atom-photon entanglement and matter-light qubit conversion, Bell inequality violation between a collective atomic qubit and a photon, storage and retrieval of single photons transmitted between remote quantum memories, and light-matter qubit conversion and entanglement of remote atomic qubits. Together, these works have realized the essential elements of a telecommunications quantum repeater.