We demonstrate a novel way to efficiently and very robust create an entanglement between an atomic and a photonic qubit. A single laser beam is used to excite one atomic ensemble and two different spatial modes of scattered Raman fields are collected to generate the atom-photon entanglement. With the help of build-in quantum memory, the entanglement still exists after 20.5 μs storage time which is further proved by the violation of CHSH type Bell's inequality. Our entanglement procedure is the building block for a novel robust quantum repeater architecture [Zhao et al, Phys. Rev. Lett. 98, 240502 (2007)]. Our approach can be easily extended to generate high dimensional atom-photon entanglements.
@article{arxiv.0706.2327,
title = {A Robust Atom-Photon Entanglement Source for Quantum Repeaters},
author = {Shuai Chen and Yu-Ao Chen and Bo Zhao and Zhen-Sheng Yuan and Joerg Schmiedmayer and Jian-Wei Pan},
journal= {arXiv preprint arXiv:0706.2327},
year = {2007}
}