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.
@article{arxiv.1606.08375,
title = {Two-dimensional distributed-phase-reference protocol for quantum key distribution},
author = {Davide Bacco and Jesper Bjerge Christensen and Mario A. Usuga Castaneda and Yunhong Ding and Søren Forchhammer and Karsten Rottwitt and Leif Katsuo Oxenløwe},
journal= {arXiv preprint arXiv:1606.08375},
year = {2016}
}