2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/154693We show that two-photon transport is strongly correlated in one-dimensional waveguide coupled to a two-level system. The exact S-matrix is constructed using a generalized Bethe-Ansatz technique. We show that the scattering eigenstates of this system include a two-photon bound state that passes through the two-level system as a composite single particle. Also, the two-level system can induce effective attractive or repulsive interactions in space for photons. This general procedure can be applied to the Anderson model as well.12 pages. 3 figures. Accepted by Physical Review LettersQuantum Physicstext