The existence of correlations between the parts of a quantum system on the one hand, and entanglement between them on the other, are different properties. Yet, one intuitively would identify strong N-party correlations with N-party entanglement in an N-partite quantum state. If the local systems are qubits, this intuition is confirmed: The state with the strongest N-party correlations is the Greenberger-Horne-Zeilinger (GHZ) state, which does have genuine multipartite entanglement. However, for high-dimensional local systems the state with strongest N-party correlations may be a tensor product of Bell states, that is, partially separable. We show this by introducing several novel tools for handling the Bloch representation.
@article{arxiv.1908.04220,
title = {Maximum $N$-body correlations do not in general imply genuine multipartite entanglement},
author = {Christopher Eltschka and Jens Siewert},
journal= {arXiv preprint arXiv:1908.04220},
year = {2020}
}
Comments
11 pages, 1 figure, accepted for publication in Quantum