  An energy-time entanglement-based dispersive optics quantum key distribution
(DO-QKD) is demonstrated experimentally over optical fibers of 20 km. In the
experiment, the telecom band energy-time entangled photon pairs are generated
through spontaneous four wave mixing in a silicon waveguide. The arrival time
of photons are registered for key generating and security test. High
dimensional encoding in the arrival time of photons is used to increase the
information per coincidence of photon pairs. The bin sifting process is
optimized by a three level structure, which significantly reduces the raw
quantum bit error rate (QBER) due to timing jitters of detectors and
electronics. A raw key generation rate of 151kbps with QBER of 4.95% is
achieved, under a time-bin encoding format with 4 bits per coincidence. This
experiment shows that entanglement-based DO-QKD can be implemented in an
efficient and convenient way, which has great potential in quantum secure
communication networks in the future.
