We study entanglement, purity and fidelity in the anisotropy (1/2,1) mixed-spin Heisenberg chain. We find that negativity, as a measure of entanglement, displays a dip at the SU(2) isotropic point of the system, which is in contrast to the peak appearance of concurrence in the spin-1/2 XXZ...

By using the concept of negativity, we investigate entanglement in (12,1) mixed-spin Heisenberg systems. We obtain the analytical results of entanglement in small isotropic Heisenberg clusters with only nearest-neighbor (NN) interactions up to four spins and in the four-spin Heisenberg model...

We obtain an exact expression of the negativity for SU(2)-invariant bipartite spin-(1,s) states via the partial time reversal method. Studies of thermal states show that the threshold temperature of entanglement may be arbitrary high when s is sufficient large, indicating that the entanglement...

We study pairwise entanglements in spin-half and spin-one Heisenberg chains with an open boundary condition, respectively. We find out that the ground-state and the first-excited-state entanglements are equal for the three-site spin-one chain. When the number of sites L3, the concurrences and...