New methods are proposed for extending the range of fiber-optic one-way quantum key distribution (QKD), inspired by classical optical communication formats. A new time-domain technique based on pulse position modulation (PPM) is combined with differential phase-shift keying to optically implement a six-state protocol. Finally, some recently proposed PPM schemes are critically reviewed and applied to synthesize a new QKD asymmetric optical realization, applicable to local or metropolitan area networks.
© 2005 Optical Society of America
Moshe Nazarathy, "Quantum key distribution over a fiber-optic channel by means of pulse position modulation," Opt. Lett. 30, 1533-1535 (2005)