A quantum access network

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B. Fröhlich, J. F. Dynes, M. Lucamarini, A. W. Sharpe, Z. Yuan and A. J. Shields
Nature 501, 69-72 (2013)

QKD guarantees secure communication against unbounded eavesdroppers and represents a mature quantum
technology. However, so far no convincing answer has been given to the question of how to extend the scope
of QKD beyond applications in dedicated high security networks.

In their work, Fröhlich and colleagues show that adopting simple and cost-effective telecommunication
technologies to form a quantum access network can greatly expand the number of users in quantum networks
and therefore vastly broaden their appeal. They demonstrate that a high-speed single-photon detector
positioned at the network node can be shared between up to 64 users, thereby significantly reducing the
hardware requirements for each user added to the network. This shared receiver architecture removes one of
the main obstacles restricting the widespread application of QKD.

This work presents a viable method for realising multi-user QKD networks with resource efficiency and
brings QKD closer to becoming the first widespread technology based on quantum physics.