Optical and spectral properties of quantum domain walls in the generalized Wigner lattice

We study the spectral properties of a system of electrons interacting through long-range Coulomb potential on a one-dimensional chain. When the interactions dominate over the electronic bandwidth, the charges arrange in an ordered configuration that minimizes the electrostatic energy, forming Hubbard's generalized Wigner lattice. In such strong-coupling limit, the low-energy excitations are quantum domain walls that behave as fractionalized charges and can be bound in excitonic pairs. Neglecting higher-order excitations, the system properties are well described by an effective Hamiltonian in the subspace with one pair of domain walls, which can be solved exactly. The optical conductivity ? (?) and the spectral function A (k,?) can be calculated analytically and reveal unique features of the unscreened Coulomb interactions that can be directly observed in experiments. © 2007 The American Physical Society.