Mean-field scaling of the superfluid to Mott insulator transition in a 2D optical superlattice

The mean-field treatment of the Bose-Hubbard model predicts that the properties of lattice-trapped gases are insensitive to the specific lattice geometry once system energies are scaled by the coordination number $z$. We test this prediction by studying the superfluid to Mott insulator transition in an ultracold gas of rubidium atoms trapped in a two-dimensional optical superlattice which can be tuned from triangular ($z=6$) to kagome ($z=4$) geometries. We observe the coherent fraction to be less robust in the kagome lattice by tuning the ratio of the interaction energy $U$ to the tunneling energy $J$. Comparison of the coherent fraction in the triangular lattice to that in the kagome lattice in terms of the scaled ratio $U/Jz$ is consistent with the mean-field prediction.