Multi-user frequency-time coded quantum key distribution network using a plug-and-play system

In this paper, we propose and analyse a multi-user wavelength division multiplexing technique of frequency-time coded quantum key distribution that uses a plug and play scheme. Numerical simulation results show that the influence of the channel noise is reduced. At the same time, the final key rate per user is enhanced to be close to that of point-to-point link. This performance is the result of simultaneous communications between Alice and four Bobs.