  Quantum network facilitates the secure transmission of information between
different users. Establishing communication links among multiple users in a
scalable and efficient way is important for realizing a large-scale quantum
network. Here we develop an energy-time entanglement-based dense wavelength
division multiplexed network based on an integrated silicon nitride micro-ring
resonator, which offers a wide frequency span (covering at least the entire
C-band) and narrow bandwidth modes (~ 650MHz). Six pairs of photons are
selected to form a fully and simultaneously connected four-user quantum
network. The observed quantum interference visibilities are well above the
classical limits among all users. Each pair of users perform the BBM92 protocol
for quantum key distribution. Our results pave the way for realizing
large-scale quantum networks with integrated photonic architecture.
