title: Differential-phase quantum key distribution experiment using a series of quantum entangled photon pairs.
abstract: We report what we believe to be the first differential-phase quantum key distribution experiment using a series of quantum entangled photon pairs. We employed two outstanding techniques. As an entangled photon source, we used a 1.5 microm band entangled photon pair source based on spontaneous four-wave mixing in a cooled dispersion-shifted fiber. As receivers, photon pairs were actively phase modulated with LiNbO3 phase modulators followed by very stable planar light-wave circuit Mach-Zehnder interferometers, which provided two nonorthogonal measurements. As a consequence, we successfully generated sifted keys with a quantum bit error rate of 8.3% and a key generation rate of 0.3 bit/s and revealed the feasibility of this QKD scheme.
authors.affiliation: NTT Basic Research Laboratories, NTT Corporation, Kanagawa, Japan. honjo@will.brl.ntt.co.jp
authors.forename: Toshimori
authors.initials: T
authors.lastname: Honjo
authors.forename: Hiroki
authors.initials: H
authors.lastname: Takesue
authors.forename: Kyo
authors.initials: K
authors.lastname: Inoue