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Entangled state quantum cryptography: Eavesdropping on the Ekert protocol

D. S. Naik·C. G. Peterson·A. G. White·A. J. Berglund·P. G. Kwiat
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Abstract

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.

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D. S. Naik, C. G. Peterson, A. G. White, A. J. Berglund, P. G. Kwiat. 1999-12-23. Entangled state quantum cryptography: Eavesdropping on the Ekert protocol. https://doi.org/10.1103/physrevlett.84.4733

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