Entangled state quantum cryptography: Eavesdropping on the ekert protocol

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

Research output: Contribution to journalArticlepeer-review


Using polarization-entangled photons from spontaneous parametric down-conversion, 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-nondemolition measurements. In all cases, the eavesdropper’s presence was readily apparent. We discuss a procedure to increase her detectability.

Original languageEnglish (US)
Pages (from-to)4733-4736
Number of pages4
JournalPhysical review letters
Issue number20
StatePublished - 2000
Externally publishedYes

ASJC Scopus subject areas

  • General Physics and Astronomy


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