Tight-Binding realization of non-abelian gauge fields: singular spectra and wave confinement

Abstract: We present a geometric construction of a lattice that emulates the action of a gauge field on a fermion. The construction consists of a square lattice made of polymeric sites, where all clustered atoms are identical and represented by potential wells or resonators supporting one bound state. The emulation covers both abelian and non-abelian gauge fields. In the former case, Hofstadter's butterfly is reproduced by means of a chain made of rotating dimers, subject to periodic boundary conditions parallel to the chain. A rigorous map between this model and Harper's Hamiltonian is derived. In the non-abelian case, band mixing and wave confinement are obtained by interband coupling using SU(2) as an internal group, \ie the effects are due to non-commutability of field components. A colored model with SU(3) made of trimers is also studied, finding thereby the appearance of flat bands in special configurations. This work constitutes the first all-geometric emulation of the Peierls substitution, and is valid for many types of waves.