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Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE

143 km free-space quantum teleportation

Thomas Herbst, Xiao‐Song Ma, Thomas Scheidl, Bernhard Wittmann, Rupert Ursin, Anton Zeilinger

Published Oct 8, 2014• 1 citation

Abstract

In the field of quantum communication the teleportation1 of single quanta plays a fundamental role in numerous quantum information-processing protocols. Quantum teleportation allows to faithfully transfer unknown quantum states over arbitrary distances and constitutes a method to circumvent the no-cloning theorem2. Even formally completely independent particles can become entangled via the process of entanglement swapping3. In a future quantum communication network4 this will be of utmost importance, enabling quantum computers to become globally interconnected. In order to prove the feasibility of quantum teleportation under optical link attenuations that will arise in a future space-application scenario, we extended the communication distance to 143 km, employing an optical free-space link between the two Canary Islands of La Palma and Tenerife. This work proofs the feasibility of ground-based freespace quantum teleportation. With our setup we were able to achieve coincidence production rates and fidelities to cope with the optical link attenuation, resulting from various experimental and technical challenges, which will arise in a quantum transmission between a ground-based transmitter and a low-earth-orbiting satellite receiver5. In our experiment we gained an average state fidelity for the teleported quantum states of more than 6 standard deviations beyond the classical limit of 2/3 and a process fidelity of 0.710(42). We expect that many of the features implemented in this experiment will be key blocks for future investigations.

DOI: 10.1117/12.2061981

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We present a high-fidelity quantum teleportation experiment over a high-loss free-space channel between two laboratories.We teleported six states of three mutually unbiased bases and obtained an average state fidelity of 0.82(1), well beyond the classical limit of 2/3.With the obtained data, we tomographically reconstructed the process matrices of quantum teleportation.The free-space channel attenuation of 31 dB corresponds to the estimated attenuation regime for a down-link from a low-earth-orbit satellite to a ground station.We also discussed various important technical issues for future experiments, including the dark counts of single-photon detectors, coincidence-window width etc.Our experiment tested the limit of performing quantum teleportation with state-of-the-art resources.It is an important step towards future satellite-based quantum teleportation and paves the way for establishing a worldwide quantum communication network.

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