Using polarization-entangled photons from spontaneous parametric downconversion, we have implemented Ekert's quantum cryptography protocol. The near-perfect correlations of the photons allow the sharing of a secret key between two parties. The presence of an eavesdropper is continually checked by measuring Bell's inequalities. We investigated several possible eavesdropper strategies, including pseudo-quantum non-demolition measurements. In all cases, the eavesdropper's presence was readily apparent. We discuss a procedure to increase her detectability.
@article{arxiv.quant-ph/9912105,
title = {Entangled state quantum cryptography: Eavesdropping on the Ekert protocol},
author = {D. S. Naik and C. G. Peterson and A. G. White and A. J. Berglund and P. G. Kwiat},
journal= {arXiv preprint arXiv:quant-ph/9912105},
year = {2009}
}
Comments
4 pages, 2 encapsulated postscript files, PRL (tentatively) accepted