Fault-tolerant quantum repeater with atomic ensembles and linear optics
  We present a detailed analysis of a new robust quantum repeater architecture building on the original DLCZ protocol [L.M. Duan \textit{et al.}, Nature (London) \textbf{414}, 413 (2001)]. The new architecture is based on two-photon Hong-Ou-Mandel-type interference which relaxes the long-distance interferometric stability requirements by about 7 orders of magnitude, from sub-wavelength for the single photon interference required by DLCZ to the coherence length of the photons, thereby removing the weakest point in the DLCZ schema. Our proposal provides an exciting possibility for robust and realistic long-distance quantum communication. 
Zeng-Bing Chen, Bo Zhao, Yu-Ao Chen, Joerg Schmiedmayer, Jian-Wei Pan