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Proceedings Paper

Differential phase-shift quantum key distribution
Author(s): Kyo Inoue; Edo Waks; Yoshihisa Yamamoto
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Paper Abstract

This paper presents novel quantum key distribution (QKD) schemes that use differential phases of sequential pulses as an information carrier. Alice sends a photon in a linear superposition state of three temporal slots, in which each amplitude is phase-modulated by {0,π}. Bob measures the phase difference of an asymmetric interferometer, and tells Alice time-instance at which the photon was counted. From this time information and her modulation data, Alice knows which detector counted the photon in Bob s site. Then, the two parties create a secret key. The scheme is suitable for fiber transmission systems and offers key creation efficiency higher than conventional phase-encoding QKD. The above scheme utilizes fully non-orthogonal four states. Differential phase shift QKD utilizing two non-orthogonal states is also presented. Alice sends a coherent pulse train with less than one photon per pulse, which is phase modulated by {0,π} for each pulse, and Bob measures the pulse train by a one-bit delay circuit. The system has a simple configuration such that Alice has no interferometer and sends no intense reference pulse, unlike to conventional QKD scheme using two non-orthogonal states, and also has an advantage of high key creation efficiency.

Paper Details

Date Published: 13 September 2002
PDF: 8 pages
Proc. SPIE 4917, Quantum Optics in Computing and Communications, (13 September 2002); doi: 10.1117/12.483037
Show Author Affiliations
Kyo Inoue, NTT Basic Research Labs. and Stanford Univ. (Japan)
Edo Waks, Stanford Univ. (United States)
Yoshihisa Yamamoto, NTT Basic Research Labs. and Stanford Univ. (United States)

Published in SPIE Proceedings Vol. 4917:
Quantum Optics in Computing and Communications
Songhao Liu; Guangcan Guo; Hoi-Kwong Lo; Nobuyuki Imoto, Editor(s)

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