Implementation of a quantum cryptographic key distribution system

Details of the implementation of a quantum cryptographic key distribution system are described. Waveforms of detected pulses due to single photons, and quantum key sequences obtained from the QKD system are given. The aim of the QKD testbed is to provide the University of Canberra (UC) researchers a facility for evaluating various optical and electronic sub-systems for their suitability as part of a practical secure QKD system. The testbed has allowed us to investigate the properties of light emitting diodes as single photon emitters, and the characteristics of photo-multiplier tubes as single photon detectors.