ABSTRACT
This chapter discusses the developments in the field of integrated nanophotonics for multi-user quantum key distribution (QKD) networks. It begins with the significance of QKD and presents some of the challenges faced by researchers and system developers, especially regarding the key rate, transmission distance, and implementation cost. The chapter considers various options to implement a multi- user QKD network compatible with the existing fiber-optic network infrastructure. It describes entanglement-based QKD and its wavelength-multiplexed implementation enabling efficient use of the available optical fiber bandwidth for QKD. The chapter shows how a centralized broadband entangled-photon source can be shared by many users in an access network and explains the benefits of wavelength- multiplexed entanglement distribution. It looks at recent advances in integrated broadband entangled-photon sources, waveguide-integrated photon detectors, and low-loss integrated passive devices. The chapter also provides an outlook for future research and development in this direction.
