arXiv:1309.0626 · Physical Review A
Genuine multipartite entanglement in the XY model
S. M. Giampaolo, Beatrix C. Hiesmayr
Abstract
We analyze the $XY$ model characterized by an anisotropy $\ensuremath{\gamma}$ in an external magnetic field, $h$, with respect to its genuine multipartite entanglement content (in the thermodynamic and finite-size case). Despite its simplicity we show that the quantity---detecting genuine multipartite entanglement through permutation operators and being a lower bound on measures---witnesses the presence of genuine multipartite entanglement for nearly all values of $\ensuremath{\gamma}$ and $h$. We further show that the phase transition and scaling properties are fully characterized by this multipartite quantity. Consequently, we provide a useful toolbox for other condensed-matter systems, where bipartite entanglement measures are known to fail.