Persistent nearest-neighbor coherence of a Mott insulator in a trimerized Kagome lattice*

Mott insulating states are characterized by the absence of long range phase coherence, whilst short range coherence is typically extinguished as the tunneling is suppressed. We report a persistent nearest-neighbor phase coherence in a two dimensional Mott insulator of ultracold $^{87}$Rb atoms. We realize an optical trimerized Kagome lattice, with strong intra-trimer tunneling and weak inter-trimer tunneling and create a novel Mott insulating state of strongly coupled local orbitals. Evidence for this state comes from interpreting the momentum-space distribution obtained from time of flight. As the inter-trimer tunneling is suppressed, we see a persistent nearest-neighbor coherence. Furthermore we show an asymmetry between the intra-trimer, and inter-trimer coherences by imprinting a phase pattern on the lattice. Finally, we discuss the possibility of engineering insulating states with fractional number and angular momentum.