Emergence of Tamm states from Thouless pumping
Localized states universally appear when a periodic potential is perturbed by defects or terminated at its surface. In one-dimensional systems, these localized states are commonly called Tamm states. In this paper, we theoretically and experimentally demonstrate a mechanism that generates Tamm states through Thouless pumping. We consider a continuous translation of the periodic potential as the pumping and prove a topological bulk-edge correspondence without relying on any symmetry protection. Based on the correspondence, we show that Tamm states emerge as topological edge states. The mechanism is experimentally verified in microwave photonic crystals.