Unconventional superfluid order in the F band of a bipartite optical square lattice.

摘要: We report on the first observation of bosons condensed into energy minima an $F$ band a bipartite square optical lattice. Momentum spectra indicate that truly complex-valued staggered angular momentum superfluid order is established. The corresponding wave function composed alternating local ${F}_{2{x}^{3}\ensuremath{-}3x}\ifmmode\pm\else\textpm\fi{}i{F}_{2{y}^{3}\ensuremath{-}3y}$ orbits and $S$ residing in deep shallow wells lattice, which are arranged as black white areas checkerboard. A pattern vortical currents arises, breaks time-reversal symmetry translational lattice potential. have measured populations higher Bragg peaks for varying relative depths find remarkable agreement with calculations.