Phase coherence properties of ultracold Bose gas in optical trimerized Kagome lattice

The trimerized (breathing) Kagome lattice, which can be seen as a triangular lattice of trimers, has attracted significant theoretical interests in recent years. This lattice is an extension of the normal Kagome lattice that it has different intra- (J) and inter-trimer (J') tunneling, leading to a richer spatial structure and possibility to host novel quantum states. We report the experimental realization of the Bose-Hubbard model in an optical trimerized Kagome lattice with $^{\mathrm{87}}$Rb atoms and optical superlattice techniques, with the capability of independently tuning the inter- and intra-trimer tunneling, as well as the relative offsets in a trimer. By studying time-of flight images, we measure the coherence of the system as it crosses the superfluid to Mott insulator transition and show that short-range coherence within trimers could persist in certain parameter regimes. We make comparisons and show a clear difference between the trimerized Kagome lattice and the normal Kagome lattice. Furthermore, we modify the local wavefunction in a trimer using phase imprinting techniques and show asymmetric diffraction patterns, revealing asymmetric correlations in the system.