Phase-modulated single-photon router and chiral scattering between two waveguides coupled by a giant three-level atom

We investigate a T-shaped single-photon router constructed by two waveguides connected via a giant Λ-type three-level atom. Under a real-space approach, the analytical expressions of the single-photon transmission and reflection amplitudes are obtained. It is shown that a high transfer-rate routing between two waveguides can be effectively achieved by modulating the phase difference, the accumulated phase and the atom-waveguide coupling strengths, and its frequencies can be tuned with a classical driving field. Interestingly, chiral scattering and a single-photon targeted router with direction selectivity have been realized by the ideally equivalent atom-waveguide interaction. We believe that our results have potential applications in constructing optical quantum devices and designing the single-photon quantum routing using the giant-atom setup.