We present a study of a simple model antiferromagnet consisting of a sum of nearest neighbor SO(N) singlet projectors on the Kagome lattice. Our model shares some features with the popular S=1/2 Kagome antiferromagnet but is specifically designed to be free of the sign-problem of quantum Monte Carlo. In our numerical analysis, we find as a function of N a quadrupolar magnetic state and a wide range of a quantum spin liquid. A solvable large-N generalization suggests that the quantum spin liquid in our original model is a gapped Z2 topological phase. Supporting this assertion, a numerical study of the entanglement entropy in the sign free model shows a quantized topological contribution.
@article{arxiv.1906.06246,
title = {Kagome model for a ${\mathbb Z}_2$ quantum spin liquid},
author = {Matthew S. Block and Jonathan D'Emidio and Ribhu K. Kaul},
journal= {arXiv preprint arXiv:1906.06246},
year = {2020}
}