title: Unconditional security of single-photon differential phase shift quantum key distribution.
abstract: In this Letter, we prove the unconditional security of the single-photon differential phase shift quantum key distribution (DPS-QKD) protocol, based on the conversion to an equivalent entanglement-based protocol. We estimate the upper bound of the phase error rate from the bit error rate, and show that the DPS-QKD protocol can generate an unconditionally secure key when the bit error rate is not greater than 4.12%. This proof is the first step to the unconditional security proof of a coherent state DPS-QKD.
authors.affiliation: Edward L. Ginzton Laboratory, Stanford University, Stanford, California 94305, USA.
authors.forename: Kai
authors.initials: K
authors.lastname: Wen
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Tamaki
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Yamamoto