  Quantum key distribution (QKD) which enables information-theoretically
security is now heading towards quantum secure networks. It requires
high-performance and cost-effective protocols while increasing the number of
users. Unfortunately, qubit-implemented protocols only allow one receiver to
respond to the prepared signal at a time, thus cannot support multiple users
natively and well satisfy the network demands. Here, we show a 'protocol
solution' using continuous-variable quantum information. A coherent-state
point-to-multipoint protocol is proposed to simultaneously support multiple
independent QKD links between a single transmitter and massive receivers. Every
prepared coherent state is measured by all receivers to generate raw keys, then
processed with a secure and high-efficient key distillation method to remove
the correlations between different QKD links. It can achieve remarkably high
key rates even with a hundred of access points and shows the potential
improvement of two orders of magnitude. This scheme is a promising step towards
a high-rate multi-user solution in a scalable quantum secure network.

Quantum Physics