Long-distance quantum communication with neutral atoms

The architecture proposed by Duan, Lukin, Cirac, and Zoller (DLCZ) for entangling distant atomic ensembles is addressed and analyzed. Its performance, in terms of fidelity and throughput, is compared to that of the quantum communication architecture using trapped rubidium-atom quantum memories that has been proposed by a team from the Massachusetts Institute of Technology and Northwestern University (MIT/NU). It is shown that the DLCZ protocol for entanglement distribution achieves a better throughput versus distance behavior than does the MIT/NU architecture, with both being capable of high entanglement fidelities. The DLCZ scheme also admits to a conditional teleportation scheme based on its entangled atomic ensembles, whereas the MIT/NU architecture affords unconditional teleportation based on its trapped-atom quantum memories. It is shown that achieving unity fidelity in DLCZ teleportation requires photon-number resolving detectors; the maximum teleportation fidelity that can be realized with non-resolving detectors is 1/2.