Detecting one-dimensional interacting topological phases by edge-state pinning

In density matrix renormalization group (DMRG) simulations, edge states are often identified by computing edge-edge or bulk-edge two-point correlation functions. Since this approach involves computing the square of the local order parameter, very large systems at high precision are required to obtain reliable results when the order parameter is small, which is true, for instance, near a phase boundary. Moreover, the computational cost of this method increases drastically with the bulk entanglement. In this work, we propose and demonstrate an efficient method for detecting the topological edge states with DMRG. That is, we study edge states by pinning one edge with appropriate fields and observing the corresponding local order parameter of the other edge. The method is validated here for antiferromagnetic Heisenberg model, the simplest realization of the Haldane phase. It would be interesting to study other one-dimensional topological phases using this method.