Fig. 1: Schematic comparison between static and Floquet higher-order topological insulators.
From: Time-periodic corner states from Floquet higher-order topology
a In a conventional second-order topological insulator, a corner state is localised at the corner with a time-invariant spatial distribution. b In a time-periodically driven, or Floquet, second-order topological insulator, the corner state oscillates in time near the corner. The corner state oscillation period can be different from the driving period. The schematic illustrates the scenario of a doubled period.
