Robust and Efficient Quantum Repeater with Atomic Ensembles and Linear Optics

The work presented in this thesis is the theoretical and experimental investigation of long-distance quantum communication with atomic ensembles and linear optics. A robust and efficient quantum repeater architecture building on the original Duan-Lukin-Cirac-Zoller protocol (DLCZ) is proposed. The new architecture is based on two-photon Hong-Ou-Mandel-type interference, which relaxes the long distance stability requirements by about 7 orders of magnitude. Moreover, by exploiting the local generation of quasi-ideal entangled pair, the new architecture is much faster than all the previous protocols with similar ingredients. We then report our recent experimental efforts towards the quantum repeater with atomic ensembles and linear optics. By exploiting the nonclassical correlation, we demonstrated a deterministic single photon source, Hong-Ou-Mandel dip between two single photons, long-lived quantum memory with optical trap, and quantum teleportation between a photonic qubit and a memory qubit. Moreover, by the aid of the new atom-photon entanglement source, a building block of the robust quantum repeater is realized. The theoretical and experimental progress presented in this work allows a faithfully implementation of a robust quantum repeater, and enables a realistic avenue for relevant long-distance quantum communication