Phase Control of Single‐Photon States in 1D Coupled‐Resonator Waveguide

Abstract A system consisting of a two‐level system (TLS) coupled to the modes of two adjacent resonators in 1D coupled‐resonator waveguide (CRW) is studied. The single‐photon energy spectrum, transmission spectrum, and the spontaneous emission process of the TLS are considered. The focus is on the influence of the phase difference of the coupling strength. It is found that the phase difference controls the number of the bound states outside the continuous, deciding whether the occupation of the TLS's excited state at long times is residual oscillatory or non‐zero constant with one excitation initial in the TLS and the CRW in the vacuum state. The transport behavior of a single photon within a continuous spectrum is also investigated and discovered that the phase difference controls the crossover between reciprocal and nonreciprocal photon transmission when the dissipation of the TLS is present as well as the position of the transmission dip. These results provide new insights for applications in quantum information processing and quantum optics.