Einstein, Podolsky, Rosen, and Shannon

Krzysztof Wódkiewicz

It is shown that the Einstein-Podolsky-Rosen (EPR) correlations for arbitrary spin s and the Greenberger-Horne-Zeilinger (GHZ) correlations for three particles can be described by nonlocal joint and conditional quantum probabilities. The nonlocality of these probabilities makes the Bell inequalities void. A description that exhibits the relation between the randomness and the nonlocality of entangled correlations is introduced. Entangled EPR and GHZ correlations are studied using the Gibbs-Shannon entropy. The nonlocal character of the EPR correlations is tested using the information Bell inequalities. Relations between the randomness, the nonlocality, and the entropic information for the EPR and the GHZ correlations are established and discussed.

Guangqiang He, Jun Ping Zhu, Guihua Zeng

A quantum secure communication protocol using correlations of continuous variable Einstein-Podolsky-Rosen (EPR) pairs is proposed. The proposed protocol may implement both quantum key distribution and quantum message encryption by using a nondegenerate optical parametric amplifier (NOPA). The general Gaussian-cloner attack strategy is investigated in detail by employing Shannon information theory. Results show that the proposed scheme is secure, which is guaranteed physically by the correlations of the continuous variable EPR entanglement pairs generated by the NOPA.

Zhu Jun, Guangqiang He, Zeng Gui-Hua

In this paper security of the quantum key distribution scheme using correlations of continuous variable Einstein–Podolsky–Rosen (EPR) pairs is investigated. A new approach for calculating the secret information rate Δ I is proposed by using the Shannon information theory. Employing an available parameter F which is associated with the entanglement of the EPR pairs, one can detect easily the eavesdropping. Results show that the proposed scheme is secure against individual beam splitter attack strategy with a proper squeeze parameter.

Ali Sanayei, Otto E. Rössler