Equivalence between Two-Qubit Entanglement and Secure Key Distribution

Antonio Acín, Lluis Masanes, Nicolas Gisin
2003 Physical Review Letters  
We study the problem of secret key distillation from bipartite states in the scenario where Alice and Bob can only perform measurements at the single-copy level and classically process the obtained outcomes. Even with these limitations, secret bits can be asymptotically distilled by the honest parties from any two-qubit entangled state, under any individual attack. Our results point out a complete equivalence between two-qubit entanglement and secure key distribution: a key can be established
more » ... rough a one-qubit channel if and only if it allows to distribute entanglement. These results can be generalized to higher dimension for all those states that are one-copy distillable.
doi:10.1103/physrevlett.91.167901 pmid:14611441 fatcat:ihc4yvlpivd4pevx6t276komuq