Entangled State Quantum Cryptography: Eavesdropping on the Ekert Protocol

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

doi:10.1103/PhysRevLett.84.4733

Entangled State Quantum Cryptography: Eavesdropping on the Ekert Protocol

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

Phys. Rev. Lett. 84, 4733 – Published 15 May 2000

Abstract

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.

Received 18 October 1999

DOI:https://doi.org/10.1103/PhysRevLett.84.4733

Authors & Affiliations

D. S. Naik¹, C. G. Peterson¹, A. G. White^1,2, A. J. Berglund¹, and P. G. Kwiat^1,*

¹Physics Division, P-23, Los Alamos National Laboratory, Los Alamos, New Mexico 87545
²Department of Physics, University of Queensland, Brisbane, Queensland 4072, Australia