Control Of Single-photon Nonreciprocal Transmission In Coupled Waveguides

With the rapid development of quantum communication,the related research in the field of quantum network has gradually become one of the important development directions of modern quantum technology.As a reliable platform for quantum communication,quantum network uses photons with stable coherence and low dissipation as transmission carrier to transmit in quantum channels connected by quantum network nodes,which can form fast and secure communication.Nonreciprocal light propagation refers to the different scattering properties of photons propagating in the forward and backward direction.Nonreciprocal optical components play an important role in constructing quantum networks.One can protect optical devices,such as laser emitters,from being damaged by reflected light;Secondly,the nonreciprocal functions generated by the device can be utilized,such as in the one-way propagation of optical isolators and diodes.The strange phenomena at exceptional points in nonreciprocal transmission,such as unidirectional reflectionlessness and coherent perfect absorption,have potential applications in optical devices.In this paper,we design and discuss the quantum waveguide system to realize the nonreciprocal transmission.By adjusting the physical parameters of the system to achieve ideal nonreciprocal transmission,and optimizing and expanding the model,one gets several effective ways to realize the nonreciprocal transmission conveniently.The main contents are as follows:(1)A multi-band single-photon unidirectional reflectionlessness scheme is proposed in a whispering-gallery-mode resonator coupled waveguide system.By adjusting the coupling between the clockwise and counterclockwise modes of the whispering-gallery-mode resonator,unidirectional multi-band reflectionlessness of the single photon in the waveguide system can be generated,which provides a useful reference for the design of optical quantum devices such as optical isolators and diodes.(2)A tunable single-photon nonreciprocal transport scheme in a whispering-gallery-mode resonator coupled waveguide system is proposed.The quantum entanglement,transmission and group delay in the waveguide can be achieved by adjusting the rotation angular velocity of the whispering-gallery-mode resonator,which provides a convenient way for the design of controllable nonreciprocal optical quantum devices.(3)A scheme of single-photon nonreciprocal transmission in bit-cavity coupled waveguide system is proposed.The multi-band nonreciprocal transmission of single photon in waveguide system is realized by adjusting the coupling intensity of single-mode cavity and quantum bit,which provides an effective method for the design of nonreciprocal optical quantum devices.(4)A scheme of tunable single photon filtering in the coupled waveguide system of a driven three-level emitter is proposed.By adjusting the intensity of the outer driving field of the three-level emitter,the frequency selection function of the photon signal in the drop waveguide is realized,which provides an easy way to control the design of the tunable optical quantum filter.