Exploration of strongly-correlated quantum phases in ultracold fermi atoms loaded on optical lattices with staggered U alternation

Yamamoto, Atsushi; Yamada, Susumu  ; Machida, Masahiko  

It is well known that atomic Fermi gas loaded on optical lattice can be described by a single-band Hubbard model in the simplest case. A remarkable feature is that the on-site interaction U is experimentally tunable parameter ranging from strongly attractive to repulsive. Moreover, the parameter U is spatially tunable, i.e., U is spatially dependent on the site. Thus, an interest aroused by the spatial tuning ability is quantum phases and transition between phases in Hubbard models whose parameter U spatially varies. In this study, we numerically examine a model with site alternative variation, i.e., U=U and U' in even and odd site, respectively. By using DMRG method, we reveal in the model that Mott-insulator transition occurs in half-filling phase diagram expanded by U and U' and compressibility diverges in the vicinity of the transition.