Reducing the hardware requirements while mitigating side-channels in polarisation-based decoy-state BB84 quantum key distribution

As quantum communications (QC), in particular quantum key distribution (QKD) transitions from lab curiosity to commercial implementation, cost reduction will become essential to increase the user number and thus make commercialisation viable. QC is hardware intensive, meaning new and novel techniques and technologies are essential to that cost reduction strategy. We present an experimental demonstration of a polarisation-based decoy-state BB84 QKD protocol utilising a single laser source (enabled by application of cascaded electro-optic modulator to perform the pulse-carving and encoding) and single single-photon avalanche diode (enabled by the application of space-to-time multiplexing), which reduced the hardware requirements for the QKD transmitter and receiver, is presented.