I\ Introduction to topological orders The 2D Topological order is a quantum state with the following key properties 4 All excitations are gapped g Topological degeneracy 今 Exotic statistics . Stable against all kinds of perturbations X.G. Wen prB. 65 ,o No global symmetry 165113(2002)I、 Introduction to topological orders The 2D Topological order is a quantum state with the following key properties : ❖ All excitations are gapped ❖ Topological degeneracy ❖ Exotic statistics ❖ Stable against all kinds of perturbations ❖ No global symmetry X. G. Wen PRB, 65, 165113 (2002)