Two-photon scattering by a driven three-level emitter in a one-dimensional waveguide and electromagnetically induced transparency.

We study correlated two-photon transport in a (quasi-)one-dimensional photonic waveguide coupled to a three-level Λ-type emitter driven by a classical light field. Two-photon correlation is much stronger in the waveguide for a driven three-level emitter (3LE) than a two-level emitter. The driven 3LE waveguide shows electromagnetically induced transparency (EIT), and we investigate the scaling of EIT for one and two photons. We show that the two transmitted photons are bunched together at any distance separation when energy of the incident photons meets "two-photon resonance" criterion for EIT.