Phase-tunable single-photon transport in a one-dimensional waveguide with the extra cavity-emitter system

Single-photon scattering properties in a one-dimensional waveguide coupled to the cavity and the two-level atom are investigated theoretically. Two cases are considered: when the one-dimensional waveguide is coupled to the cavity-emitter and when it is coupled to a cavity and two-level atom, respectively, where the cavity and the two-level atom are also coupled. In our system, the phase of the emitter-cavity-waveguide coupling strength, which cannot be eliminated by any gauge transformation, functions as a sensitive controller for the scattering behavior. The results show that the phase of the system not only can be controlled by the single-photon perfect transmission and the perfect reflection but also can adjust the position of perfect transmission and also make irregular transmission spectrum regular. We further show that our approach is experimentally feasible in currently available superconducting quantum circuits.