High-fidelity transmission of entanglement over a high-loss free-space channel

Author(s): A. Fedrizzi, R. Ursin, T. Herbst, M. Nespoli, R. Prevedel, T. Scheidl, F. Tiefenbacher, T. Jennewein, A. Zeilinger

Journal: Nature Physics

Volume: 5

Page(s): 389-392

Year: 2009

DOI Number: 10.1038/nphys1255

Link: Link to publication

Abstract:

Quantum entanglement enables tasks not possible in classical physics. Many quantum communication protocols1 require the distribution of entangled states between distant parties. Here, we experimentally demonstrate the successful transmission of an entangled photon pair over a 144 km free-space link. The received entangled states have excellent, noise-limited fidelity, even though they are exposed to extreme attenuation dominated by turbulent atmospheric effects. The total channel loss of 64 dB corresponds to the estimated attenuation regime for a two-photon satellite communication scenario.We confirm

that the received two-photon states are still highly entangled by violating the Clauser–Horne–Shimony–Holt inequality by more than five standard deviations. From a fundamental point of view, our results show that the photons are subject

to virtually no decoherence during their 0.5-ms-long flight through air, which is encouraging for futureworldwide quantum communication scenarios.

Note: http://arxiv.org/abs/0902.2015

File: Link to PDF

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