We investigate single-photon scattering properties in a one-dimensional waveguide coupled to a quantum emitter's chain with dipole-dipole interaction (DDI). The photon transport is extremely sensitive to the location of the evanescently coupled atoms. The analytical expressions of reflection and transmission amplitudes for the chain containing two emitters with DDI are deduced by using a real-space Hamiltonian. Two cases, where the two emitters symmetrically or asymmetrically couple to the waveguide, are discussed in detail. It shows that the reflection and transmission typical spectra split into two peaks due to the DDI. The Fano minimum in the spectra can be used to estimate the strength of the DDI. Furthermore, the DDI makes spectra strongly asymmetric and creates a transmission window in the region where there was zero transmission. The scattering spectra for the chain consisting of multiple emitters are also given. Our key finding is that DDI can broaden the frequency bandwidth for high reflection when the chain consists of many emitters.

We investigate theoretically a surface plasmon transport in the metal nanowire coupling to a pair of quantum dots. The Fano-type transmission spectrum is analyzed. The phase shift and group velocity delay of the transmitted surface plasmon are explored. The electromagnetically-induced-transparency-type transmission spectrum is also discussed.

We investigate single photon transport in two waveguides coupled to a two-level quantum emitter (QE). With the deduced analytical scattering amplitudes, we show that under condition of the chiral coupling between the QE and the photon in the two waveguides, the QE can play the role of ideal quantum router to redirect a single photon incident from one waveguide into the other waveguide with a probability of 100% in the ideal condition. The influences of cross coupling between two waveguides and dissipations on the routing are also shown.

The single-photon routing properties in the system composed of two waveguides and two coupled cavities interacting with a two-level system are investigated theoretically. The phases of the coupling strengths are considered. The analytical expressions for the single-photon routing probabilities are obtained. The study shows that single-photon routing in a single waveguide or between two waveguides can be switched on or off by modulating the phase difference between the coupling constants. The analytical results also exhibit that the coupling between the two nanocavities plays an important role in the phase-dependent single-photon routing. We also show numerically the influence of the dissipation of cavities and atoms on routing properties. Our results may be useful in controlling and manipulating light-matter interactions based on waveguides at the single-photon level.

Single-photon scattering properties in a coupled-resonator waveguide (CRW) coupled to a nanocavity embedded with a two-level system are investigated theoretically. Two cases are considered: when the nanocavity is locally coupled to one resonator and when it is nonlocally coupled to two resonators of the CRW. The transmission and reflection amplitudes are obtained for the two cases, respectively. The results show that the position of perfect transmission remains unchanged, while the position of perfect reflection is shifted due to the nonlocal coupling. An asymmetric Fano resonance appears in the transmission spectrum and can be controlled by adjusting the coupling strengths in the nonlocal coupling case. The effects of the coupling strengths and dissipation on the transport properties are also analyzed for the two cases.

We investigate coherent controlling single-photon nonreciprocal propagation in a pair of waveguides chirally coupled to an atom by using a classical optical field. The results show that for a nonresonant photon, the perfect single-photon nonreciprocal propagation can be realized by adjusting the Rabi frequency and detuning. Furthermore, the nonreciprocal propagation is switchable by using the classic field. The calculated results also show that the system can be used as a frequency filter to filter out some special frequencies for single-photon nonreciprocal propagation. The influences of nonperfect chiral coupling and dissipations on the nonreciprocal propagation are also shown.