Detection of topological phases by quasilocal operatorsDetection of topological phases by quasilocal operators Peer-Reviewed Journal Publication Δημοσίευση σε Περιοδικό με Κριτές 2020-07-092019enIt was proposed recently by some of the authors that the quantum phase transition of a topological insulator like the Su-Schrieffer-Heeger (SSH) model may be detected by the eigenvalues and eigenvectors of the reduced density matrix. Here we further extend the scheme of identifying the order parameters by considering the SSH model with the addition of triplet superconductivity. This model has a rich phase diagram due to the competition of the SSH "order" and the Kitaev "order," which requires the introduction of four order parameters to describe the various topological phases. We show how these order parameters can be expressed simply as averages of projection operators on the ground state at certain points deep in each phase and how one can simply obtain the phase boundaries. A scaling analysis in the vicinity of the transition lines is consistent with the quantum Ising universality class.http://creativecommons.org/licenses/by/4.0/Physical Review B9911 Yu Wing Chi Sacramento Pedro D.S. Li Yanchao Aggelakis Dimitrios Αγγελακης Δημητριος Lin Haiqing American Physical Society Eigenvalues and eigenfunctions Ground state Quantum theory Phase transition