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

Nature Physics volume 5, pages 389–392 (2009)Cite this article

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 future worldwide quantum communication scenarios.

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Figure 1: Satellite image (NASA World Wind) of the Canary Islands of Tenerife and La Palma and overview of the experimental scheme.
Figure 2: Coincidence histograms and the respective accumulated coincidence events for measurements on two different Bell states.
Figure 3: Scan of the phase ϕ of the entangled two-photon state in one measurement night.

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Acknowledgements

We are grateful to H. Weinfurter, J. G. Rarity, T. Schmitt-Manderbach, C. Barbieri, F. Sanchez, A. Alonso, J. Perdigues and Z. Sodnik, T. Augusteijn and the staff of the Nordic Optical Telescope in La Palma for their support at the trial sites. This work was supported by ESA under the General Studies Programme (No. 18805/04/NL/HE), the European Commission through Project QAP (No. 015846), the DTO-Funded US Army Research Office, the Austrian Science Foundation (FWF) under project number SFB1520 and the ASAP-Programme of the Austrian Space Agency (FFG).

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Authors and Affiliations

  1. Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria

    Alessandro Fedrizzi, Rupert Ursin, Thomas Herbst, Matteo Nespoli, Robert Prevedel, Thomas Scheidl, Felix Tiefenbacher, Thomas Jennewein & Anton Zeilinger

  2. Quantum Optics, Quantum Nanophysics and Quantum Information, Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria

    Robert Prevedel & Anton Zeilinger

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  1. Alessandro Fedrizzi
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  2. Rupert Ursin
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  3. Thomas Herbst
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Correspondence to Alessandro Fedrizzi or Anton Zeilinger.

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Fedrizzi, A., Ursin, R., Herbst, T. et al. High-fidelity transmission of entanglement over a high-loss free-space channel. Nature Phys 5, 389–392 (2009). https://doi.org/10.1038/nphys1255

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