  To construct a quantum network with many end users, it is critical to have a
cost-efficient way to distribute entanglement over different network ends. We
demonstrate an entanglement access network, where the expensive resource, the
entangled photon source at the telecom wavelength and the core communication
channel, is shared by many end users. Using this cost-efficient entanglement
access network, we report experimental demonstration of a secure multiparty
computation protocol, the privacy-preserving secure sum problem, based on the
network quantum cryptography.
