title: Topological order parameters for interacting topological insulators.
abstract: We propose a topological order parameter for interacting topological insulators, expressed in terms of the full Green's functions of the interacting system. We show that it is exactly quantized for a time-reversal invariant topological insulator, and it can be experimentally measured through the topological magneto-electric effect. This topological order parameter can be applied to both interacting and disordered systems, and used for determining their phase diagrams.
authors.affiliation: Department of Modern Physics, University of Science and Technology of China, Hefei, 230026, PR China.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Wang
authors.forename: Xiao-Liang
authors.initials: XL
authors.lastname: Qi
authors.forename: Shou-Cheng
authors.initials: SC
authors.lastname: Zhang