Entanglement between atomic condensates in an optical lattice : Effects of interaction range

We study the area-dependent entropy and two-site entanglement for two-state Bose-Einstein condensates in a two-dimensional optical lattice. We consider the case where the array of two-component condensates behaves like an ensemble of spin-half particles with the interaction to its nearest neighbors and next-nearest neighbors. We show how the Hamiltonian of their Bose-Einstein condensate lattice with nearest-neighbor and next-nearest-neighbor interactions can be mapped onto a harmonic lattice. We use this to determine the entropy and entanglement content of the lattice.