Quantum Correlations of Few Dipolar Bosons in a Double-Well Trap

We consider N interacting dipolar bosonic atoms at zero temperature in a double-well potential. This system is described by the two-space-mode extended Bose-Hubbard Hamiltonian which includes (in addition to the familiar BH terms) the nearest-neighbor interaction, correlated hopping and bosonic-pair hopping. For systems with and particles, we calculate analytically both the ground state and the Fisher information, the coherence visibility, and the entanglement entropy that characterize the correlations of the lowest energy state. The structure of the ground state crucially depends on the correlated hopping . On one hand, we find that this process makes possible the occurrence of Schrodinger-cat states even if the onsite interatomic attraction is not strong enough to guarantee the formation of such states. On the other hand in the presence of a strong onsite attraction, sufficiently large values of destroy the cat-like state in favor of a delocalized atomic coherent state.