1206.4928 (F. Troiani et al.)

Energy as witness of multipartite entanglement in spin clusters    [PDF]

F. Troiani, I. Siloi

We derive energy minima for biseparable states in three- and four-spin systems, with Heisenberg Hamiltonian and s <= 5/2. These provide lower bounds for tripartite and quadripartite entanglement in chains and rings with larger spin number N. We demonstrate that the ground state of an $N$-spin Heisenberg chain is $N$-partite entangled, and compute the energy gap with respect to biseparable states for N <= 8.

View original: http://arxiv.org/abs/1206.4928