  We propose a wavelength-saving topology of quantum key distribution(QKD)
network based on passive optical elements, and report the field test of this
network on the commercial telecom optical fiber. In this network, 5 nodes are
supported with 2 wavelengths, and every two nodes can share secure keys
directly at the same time. All QKD links in the network operate at the
frequency of 20 MHz. We also characterized the insertion loss and crosstalk
effects on the point-to-point QKD system after introducing this QKD network.

Quantum Physics