We report the observation of entanglement between a single trapped atom and a single photon at a wavelength suitable for low-loss communication over large distances, thereby achieving a crucial step towards long range quantum networks. To verify the entanglement we introduce a single atom state analysis. This technique is used for full state tomography of the atom-photon qubit-pair. The detection efficiency and the entanglement fidelity are high enough to allow in a next step the generation of entangled atoms at large distances, ready for a final loophole-free Bell experiment.
@article{arxiv.quant-ph/0511183,
title = {Atom-Photon Entanglement},
author = {Juergen Volz and Markus Weber and Daniel Schlenk and Wenjamin Rosenfeld and Johannes Vrana and Karen Saucke and Christian Kurtsiefer and Harald Weinfurter},
journal= {arXiv preprint arXiv:quant-ph/0511183},
year = {2007}
}