Bose-Hubbard MI-SF critical ratio (strong-coupling): (U/J)_c = 2·√(2·n·(n+1)) at integer filling n

Mott-insulator to superfluid critical hopping ratio in the strong-coupling perturbation limit. Setup: Bose-Hubbard Hamiltonian from framework F9. At the tip of the n-th Mott lobe the system crosses the MI-SF boundary when the particle-hole…