We investigate quantum routing in a multi-T-shaped waveguide coupled to driven cyclic three-level systems. Exact expressions of the scattering coefficients for the double-T and triple-T waveguides are obtained by employing the discrete-coordinate scattering and the transfer matrix approach, respectively. Our results show that high transfer-rate routing of single photons from the input infinite channel to the other channels can be effectively implemented in the extended multi-T configuration, in contrast with the single-T waveguide with the transfer of no more than 0.5. The proposed router may be utilized as a scalable quantum device to control single-photon routing.

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Based on density functional theory calculations and non-equilibrium Green's function method, we study the photovoltaic effect of monolayer MoSe2-WS2 lateral heterojunction under vertical irradiation. Combined with the differential charge density, it predicts the stability of the MoSe2-WS2 heterojunction and the high possibility of charge transfer from MoSe2 to WS2. As a result, such MoSe2-WS2 lateral heterojunction breaks the spatial inversion symmetry thus leading to a photocurrent. The resultant photocurrent increases from close to zero to a maximum value in the range of photon energy of 1.7 eV to 2.8 eV. The photocurrent response fits the cosine function with respect to the polarization angle. The peak photocurrent is obtained when the photon energy is 2.8 eV, and can be attributable to the large density state peaks near -1.3 eV in the valence band and 1.5 eV in the conduction band. Meanwhile, the single-layer MoSe2-WS2 lateral heterojunction exhibits higher polarization sensitivity that is characterized by an extinction ratio of up to 9.6. These results suggest possible applications of the single-layer MoSe2-WS2 lateral heterojunction in next generation optoelectronic devices.

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Fano-like quantum routing of single photons in a system with two waveguides coupled to two collocated atoms is investigated theoretically. Using a full quantum theory in real space, photonic scattering amplitudes along four ports of the waveguide network are analytically obtained. It is shown that, by adjusting the atomic dipole-dipole interaction, an evident Fano-line shape emerges in the scattering spectra of the single-dot configuration system. Moreover, Fano resonance can also be achieved by varying the atom-waveguide coupling strength and atomic detuning, in the presence of the atomic dipole-dipole interaction. Therefore, the atomic dipole-dipole interaction may be utilized as a possible way to control spectral Fano-like resonance. The feasibility with the experimental waveguide channels is also discussed.