A cold-atom quantum memory for long distance quantum networks

A long-distance quantum network that could enable distributed quantum computing and unconditionally secure communication will require a quantum memory capable of supporting entanglement swapping over long distances. The memory qubit must preserve its entanglement to the communication qubit sent to a repeater for at least long enough to swap entanglement with an adjacent node. The most important figures-of-merit for a quantum memory are: fidelity, entanglement rate, and memory lifetime. Though many varieties of memories and repeaters are currently being researched (for a review see [1]) it remains an outstanding challenge to develop one that simultaneously meets all the necessary criteria to enable a practical long distance quantum network. We propose to use laser-cooled and trapped rubidium atoms, with Rydberg excitations, coupled to an optical cavity, to address these issues.