Classical Analogs of Quantum Entanglement

R. J. C. Spreeuw

K. Hess

Daniel Collins, Sandu Popescu

We show that quantum entanglement has a very close classical analog, namely, secret classical correlations. The fundamental analogy stems from the behavior of quantum entanglement under local operations and classical communication and the behavior of secret correlations under local operations and public communication. A large number of derived analogies follow. In particular, teleportation is analogous to the one time pad, the concept of ``pure state'' exists in the classical domain, entanglement concentration and dilution are essentially classical secrecy protocols, and single-copy-entanglement manipulations have such a close classical analog that the majorization results are reproduced in the classical setting. This analogy allows one to import questions from the quantum domain into the classical one, and vice versa, helping to get a better understanding of both. Also, by identifying classical aspects of quantum entanglement, it allows one to identify those aspects of entanglement that are uniquely quantum mechanical.

Sandu Popescu

Entanglement is considered to be a quintessential quantum effect. We show however that, surprisingly, there exists a very close classical analog of quantum entanglement. We explicitly show how many results of entanglement manipulations give interesting new results in the classical setting. We also show how the classical results shed light upon the nature of the quantum ones, and lead to more intuitive proofs of some entanglement results.

Manuel Aschwanden

Klaus Mølmer