U(1)times U(1) Symmetry Protected Topological Order in Gutzwiller Wave Functions

Gutzwiller projection is a way to construct many-body wave functions that could carry topological order or symmetry protected topological (SPT) order. However, an important issue is to determine whether or not a given Gutzwiller-projected wave functions (GWF) carries a non-trivial SPT order, and which SPT order is carried by the wavefunction. In this paper, we numerically study the SPT order in a spin S = 1 GWF on the Kagome lattice. Using the standard Monte Carlo method, we directly confirm that the GWF has (1) gapped bulk with short-range correlations, (2) a trivial topological order via nondegenerate ground state, and zero topological entanglement entropy, (3) a non-trivial U(1)times U(1) SPT order via the Hall conductances of the protecting U(1)times U(1) symmetry, and (4) symmetry protected gapless boundary. This represents numerical evidence of continuous symmetry protected topological order in two-dimensional bosonic lattice systems.