Dynamic bulk-boundary correspondence for anomalous Floquet topology

Periodically driven systems with internal and spatial symmetries can exhibit a variety of anomalous boundary behaviors at both the zero and pi quasienergies despite the trivial bulk Floquet bands. These phenomena are called anomalous Floquet topology (AFT) as they are unconnected from their static counterpart, emerging from the winding of the time-evolution unitary rather than the bulk Floquet bands at the end of the driving period. In this paper, we systematically derive the first and inversion-symmetric second-order AFT bulk-boundary correspondence for Altland-Zirnbauer (AZ) classes BDI, D, DIII, and AII. For each AZ class, we start a dimensional hierarchy with a parent dimension having Z classification, then use it as an interpolating map to classify the lower-dimensional descendants. From the Atiyah-Hirzebruch spectral sequence, we identify the subspace that contains topological information and faithfully derive the AFT bulk-boundary correspondence for both the parent and descendants. Our theory provides analytic tools for out-of-equilibrium topological phenomena.

Automated summary

This paper systematically investigates the first and inversion-symmetric second-order anomalous Floquet topology (AFT) bulk-boundary correspondence for Altland-Zirnbauer (AZ) classes BDI, D, DIII, and AII. By analyzing the Atiyah-Hirzebruch spectral sequence of the parent and descendants, we identify the subspace that contains topological information.