Coherent Control Of The Quantum Routing In The Waveguides

The scalable quantum information processing in the fields of quantum communication and quantum computation is achieved based on quantum networks.A quantum network is composed of the quantum nodes and quantum channels.Quantum nodes coherently connect different channels,in which the routers control transport of signals in the different channels.With the theoretical development and the progress of experimental technologies,coherently controlling the photon transport to improve the high quantum routing capability of the quantum routers in the quantum networks has become a current research hotspot.In the paper we have designed optimally the quantum routers in a waveguide system,whose routing properties have also been investigated in detail by adopting a full quantum theory in real space.Our results show that several possible effective ways to control the photon and surfaceplasmon routing of the system are achieved.The main contents of the paper are as follows:(1)Quantum routing in a single-dot configuration with two parallel linear waveguides coupled to two collocated atoms is investigated theoretically.By adjusting the atomic detuning,atomic dipole-dipole interaction,and atom-waveguide coupling strength,Fano-like quantum routing can be designed.Therefore,the atomic dipole-dipole interaction in the proposed system may be utilized as a way to control Fano-like resonance.(2)Single-photon in a system with two parallel linear waveguides coupled to two whispering gallery resonator cavities is investigated theoretically.Routing capability from input waveguide to another one can exceed 0.5 in the resonance point of scattering spectra due to its special construction,which can be achieved with only one resonator.By adjusting the distance of two whispering gallery resonator cavities and coupling strength between two whispering gallery resonator cavities and waveguides,the transfer rate in the scattering spectra can also reach certain sufficiently high values in the non-resonance case.Therefore,the proposed system may provide a potential application in improving the high quantum routing rate.(3)According to the progress of experimental technologies,the quantum dot with azimuthal angle can be placed determinately in the cylindrical nanowire.The effect of quantum dots with azimuthal angles on transport properties of surface plasmons in a nonlinear metal naowire is investigated theoretically.Exact expressions of the scattering amplitudes in the system of two and three dots are obtained by adopting a full quantum theory in real space and the transfer matrix approach,respectively.Fano-like resonance and the periodic maximum spectra are exhibited by adjusting azimuthal angle difference of quantum dots.Moreover,a plasmonic switch can also be designed.Therefore,the azimuthal angle of quantum dots may be utilized as a new handle to control the surface plasmon transport.(4)The influence of the nanowires nonlinear dispersion on quantum routing of single surface plasmons between two metal nanowires with two quantum dots is investigated theoretically.By properly designing the inter-dot distance and dot-plasmon coupling strength,the transfer rate between two nanowires can reach sufficiently high values.The nonlinear dispersion leads to Fanolike resonances in the scattering spectra.Therefore,the proposed double-dot configuration could be utilized as a robust with the high routing rate between two nanowires.The quantum routing system designed in the paper provides a useful reference for the design of the optical signal router in the quantum level.