Dynamically Characterizing Topological Phases By High-Order Topological Charges

We propose a theory to characterize equilibrium topological phase with nonequilibrium quantum dynamics by introducing the concept of high-order topological charges, with novel phenomena being predicted. Through a dimension reduction approach, we can characterize a d-dimensional (dD) integer-invariant topological phase with lower dimensional topological number quantified by high-order topological charges, of which the sth-order topological charges denote the monopoles confined on the (s - 1)th-order band inversion surfaces (BISs) that are (d - s + 1)D momentum subspaces. The bulk topology is determined by the sth-order topological charges enclosed by the sth-order BISs. By quenching the system from trivial phase to topological regime, we show that the bulk topology of postquench Hamiltonian can be detected through a high-order dynamical bulk-surface correspondence, in which both the high-order topological charges and high-order BISs are identified from quench dynamics. This characterization theory has essential advantages in two aspects. First, the highest (dth) order topological charges are characterized by only discrete signs of spin polarization in zero dimension (i.e., the 0th Chern numbers), whose measurement is much easier than the first-order topological charges that are characterized by the continuous charge-related spin texture in higher dimensional space. Second, a more striking result is that a first-order high integer valued topological charge always reduces to multiple highest order topological charges with unit charge value, and the latter can be readily detected in experiments. The two fundamental features greatly simplify the characterization and detection of the topological charges and also topological phases, which shall advance the experimental studies in the near future.