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A quantum access network


The theoretically proven security of quantum key distribution (QKD) could revolutionize the way in which information exchange is protected in the future1,2. Several field tests of QKD have proven it to be a reliable technology for cryptographic key exchange and have demonstrated nodal networks of point-to-point links3,4,5. However, until now no convincing answer has been given to the question of how to extend the scope of QKD beyond niche applications in dedicated high security networks. Here we introduce and experimentally demonstrate the concept of a ‘quantum access network’: based on simple and cost-effective telecommunication technologies, the scheme can greatly expand the number of users in quantum networks and therefore vastly broaden their appeal. We show that a high-speed single-photon detector positioned at a network node can be shared between up to 64 users for exchanging secret keys with the node, thereby significantly reducing the hardware requirements for each user added to the network. This point-to-multipoint architecture removes one of the main obstacles restricting the widespread application of QKD. It presents a viable method for realizing multi-user QKD networks with efficient use of resources, and brings QKD closer to becoming a widespread technology.

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Figure 1: Downstream and upstream quantum access network.
Figure 2: Experimental set-up.
Figure 3: Stable operation of quantum access network.
Figure 4: Quantum access network with varying capacity.

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This research is partly supported by Research and Development of Secure Photonic Network Technologies, the Commissioned Research of the National Institute of Information and Communications Technology (NICT), Japan.

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Authors and Affiliations



B.F. performed the measurements and simulations. B.F., J.F.D. and A.W.S. developed the system. M.L. performed calculations for the security analysis. Z.Y. and A.J.S. conceived the experiment and guided the work. B.F. wrote the manuscript with contributions from the other authors. All authors discussed experiments, results and the interpretation of results.

Corresponding authors

Correspondence to Bernd Fröhlich, Zhiliang Yuan or Andrew J. Shields.

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The authors declare no competing financial interests.

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Fröhlich, B., Dynes, J., Lucamarini, M. et al. A quantum access network. Nature 501, 69–72 (2013).

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