Distributed Entanglement
Abstract
Consider three qubits A, B, and C which may be entangled with each other. We show that there is a trade-off between A's entanglement with B and its entanglement with C. This relation is expressed in terms of a measure of entanglement called the "tangle," which is related to the entanglement of formation. Specifically, we show that the tangle between A and B, plus the tangle between A and C, cannot be greater than the tangle between A and the pair BC. This inequality is as strong as it could be, in the sense that for any values of the tangles satisfying the corresponding equality, one can find a quantum state consistent with those values. Further exploration of this result leads to a definition of the "three-way tangle" of the system, which is invariant under permutations of the qubits.
Cite
@article{arxiv.quant-ph/9907047,
title = {Distributed Entanglement},
author = {Valerie Coffman and Joydip Kundu and William K. Wootters},
journal= {arXiv preprint arXiv:quant-ph/9907047},
year = {2008}
}
Comments
13 pages LaTeX; references added, derivation of Eq. (11) simplified