Most Quantum Key Distribution protocols use a two-dimensional basis such as HV polarization as first proposed by Bennett and Brassard in 1984. These protocols are consequently limited to a key generation density of 1 bit per photon. We increase this key density by encoding information in the transverse spatial displacement of the used photons. Employing this higher-dimensional Hilbert space together with modern single-photon-detecting cameras, we demonstrate a proof-of-principle large-alphabet Quantum Key Distribution experiment with 1024 symbols and a shared information between sender and receiver of 7 bit per photon.
@article{arxiv.1808.02823,
title = {Spatially encoded light for Large-alphabet Quantum Key Distribution},
author = {T. B. H. Tentrup and W. M. Luiten and R. van der Meer and P. Hooijschuur and P. W. H. Pinkse},
journal= {arXiv preprint arXiv:1808.02823},
year = {2020}
}
Comments
9 pages, 6 figures, Added references, Updated Fig. 1 in the main text, Updated Fig.1 in supplementary material, Added section Trojan-horse attacks in supplementary material, title changed, Added paragraphs about final key rate and overfilling the detector to result section