title: Two-dimensional distributed-phase-reference protocol for quantum key distribution.
abstract: Quantum key distribution (QKD) and quantum communication enable the secure exchange of information between remote parties. Currently, the distributed-phase-reference (DPR) protocols, which are based on weak coherent pulses, are among the most practical solutions for long-range QKD. During the last 10 years, long-distance fiber-based DPR systems have been successfully demonstrated, although fundamental obstacles such as intrinsic channel losses limit their performance. Here, we introduce the first two-dimensional DPR-QKD protocol in which information is encoded in the time and phase of weak coherent pulses. The ability of extracting two bits of information per detection event, enables a higher secret key rate in specific realistic network scenarios. Moreover, despite the use of more dimensions, the proposed protocol remains simple, practical, and fully integrable.
authors.affiliation: Technical University of Denmark, Department of Photonics Engineering, 2800 Kgs. Lyngby, Denmark.
authors.forename: Davide
authors.initials: D
authors.lastname: Bacco
authors.affiliation: Technical University of Denmark, Department of Photonics Engineering, 2800 Kgs. Lyngby, Denmark.
authors.forename: Jesper Bjerge
authors.initials: JB
authors.lastname: Christensen
authors.affiliation: Technical University of Denmark, Department of Photonics Engineering, 2800 Kgs. Lyngby, Denmark.
authors.forename: Mario A Usuga
authors.initials: MA
authors.lastname: Castaneda
authors.affiliation: Technical University of Denmark, Department of Photonics Engineering, 2800 Kgs. Lyngby, Denmark.
authors.forename: Yunhong
authors.initials: Y
authors.lastname: Ding
authors.affiliation: Technical University of Denmark, Department of Photonics Engineering, 2800 Kgs. Lyngby, Denmark.
authors.forename: Søren
authors.initials: S
authors.lastname: Forchhammer
authors.affiliation: Technical University of Denmark, Department of Photonics Engineering, 2800 Kgs. Lyngby, Denmark.
authors.forename: Karsten
authors.initials: K
authors.lastname: Rottwitt
authors.affiliation: Technical University of Denmark, Department of Photonics Engineering, 2800 Kgs. Lyngby, Denmark.
authors.forename: Leif Katsuo
authors.initials: LK
authors.lastname: Oxenløwe