Good Wannier bases in Hilbert modules associated to topological insulators
Good Wannier bases in Hilbert modules associated to topological insulators
For a large class of physically relevant operators on a manifold with discrete group action, we prove general results on the (non-)existence of a basis of well-localized Wannier functions for their spectral subspaces. This turns out to be equivalent to the freeness of a certain Hilbert module over the group …