Classification of symmetry-enriched topological quantum spin liquids

Abstract

We present a systematic framework to classify symmetry-enriched topological quantum spin liquids in two spatial dimensions. This framework can deal with all topological quantum spin liquids, which may be either Abelian or non-Abelian, chiral or non-chiral. It can systematically treat a general symmetry, which may include both lattice symmetry and internal symmetry, may contain anti-unitary symmetry, and may permute anyons. The framework applies to all types of lattices, and can systematically distinguish different lattice systems with the same symmetry group using their Lieb-Schultz-Mattis anomalies. We apply this framework to classify $U(1)_{2N}$ chiral states and non-Abelian Ising$^{(\nu)}$ states enriched by a $p6\times SO(3)$ or $p4\times SO(3)$ symmetry, and $\mathbb{Z}_N$ topological orders and $U(1)_{2N}\times U(1)_{-2N}$ topological orders enriched by a $p6m\times SO(3)\times\mathbb{Z}_2^T$, $p4m\times SO(3)\times\mathbb{Z}_2^T$, $p6m\times\mathbb{Z}_2^T$ or $p4m\times\mathbb{Z}_2^T$ symmetry, where $p6$, $p4$, $p6m$ and $p4m$ are lattice symmetries, while $SO(3)$ and $\mathbb{Z}_2^T$ are spin rotation and time reversal symmetries, respectively. In particular, we identify symmetry-enriched topological quantum spin liquids that are not easily captured by the usual parton-mean-field approach, including examples with the familiar $\mathbb{Z}_2$ topological order.