Abstract

A major road-block in bringing QKD to the market is the missing scalability of a single QKD-link connecting two users to a use-case with many users in the same metropolitan area network (MAN). The typical trusted node concept [1] used for this, beyond requiring the trust on all intermediate nodes, is not able to distribute entanglement without the help of quantum manipulations that have yet to be demonstrated. Here we extend the concept of entanglement to many pairs of users by the introduction of novel structures [2]. The goal of this work is the design of a MAN for quantum and co-propagating classical signals to allow an arbitrarily high number of users not bounded by e.g. the number of CWDM or DWDM channels in the ITU grid. The number of coexistent multiplexed links is clearly limited by this usable fibre bandwidth, but the network must be able to select the corresponding user out of a large pool of possible communication partners (as in mobile phone networks).

© 2015 IEEE