We report the observation of entanglement between a single trapped atom and a single photon at remote locations. The degree of coherence of the entangled atom-photon pair is verified via appropriate local correlation measurements, after communicating the photon via an optical fiber link of 300 m length. In addition we measured the temporal evolution of the atomic density matrix after projecting the atom via a state measurement of the photon onto several well defined spin states. We find that the state of the single atom dephases on a timescale of 150 μs, which represents an important step toward long-distance quantum networking with individual neutral atoms.
@article{arxiv.0808.3538,
title = {Long-distance atom-photon entanglement},
author = {W. Rosenfeld and F. Hocke and F. Henkel and M. Krug and J. Volz and M. Weber and H. Weinfurter},
journal= {arXiv preprint arXiv:0808.3538},
year = {2009}
}