  Quantum key distribution (QKD), harnessing quantum physics and
optoelectronics, may promise unconditionally secure information exchange in
theory. Recently, theoretical and experimental advances in
measurement-device-independent (MDI-) QKD have successfully closed the physical
backdoor in detection terminals. However, the issues of scalability, stability,
cost and loss prevent QKD systems from widespread application in practice.
Here, we propose and experimentally demonstrate a solution to build a
star-topology quantum access network with an integrated server. By using
femtosecond laser direct writing technique, we construct integrated circuits
for all the elements of Bell state analyzer together and are able to integrate
several such analyzers on single photonic chip. The measured high-visibility
Bell state analysis suggests integrated server a promising platform for the
practical application of MDI-QKD network.
