Abstract
We prove the unconditional security of a quantum key distribution protocol in which bit values are encoded in the phase of a weak coherent-state pulse relative to a strong reference pulse. In contrast with implementations in which a weak pulse is used as a substitute for a single-photon source, the achievable key rate is found to decrease only linearly with the transmission of the channel.
- Received 25 March 2004
DOI:https://doi.org/10.1103/PhysRevLett.93.120501
©2004 American Physical Society