Quantum Key Distribution with Imperfect Devices

Abstract

In this Chapter we outline some of the experimental flaws that allow a potential eavesdropper to successfully breach the security of a QKD protocol. We then focus on the solutions to such problems, which are given by a combination of theoretical advances and clever experimental design. In particular, in Sects. 5.1 and 5.2 we discuss how security can be proven when the BB84 protocol is implemented with weak coherent pulses instead of single-photon sources, with a particular mention to the decoy-state method. We then introduce measurement-device-independent (MDI) QKD in Sect. 5.3 and consider a practical implementation of it in Sect. 5.4.