Single Photon Quantum Router Between Infinite And Semi-infinite Coupled Resonator Waveguides

Quantum state is the basic carrier in quantum information.So the coherent control of single quantum states is a necessary condition for quantum informa-tion processing and quantum computing realization.In multitudinous physical implementation systems,cavity QED system are one of the best candidates for the implementation of quantum state system.In study of the traditional cavity QED,photons are limited to localized modes.Although the existence of cavities greatly enhances the coupling between photons and atoms.But it’s not easy to space expanding.And then it’s unable to form the coupling of the remote systems.Using advantages of the strong coupling of cavity QED,waveguide quantum electrodynamics(waveguide QED)can guide photons from a particular direction to the given goal,being the ideal realization of quantum networks and distributed quantum computing system.The advantages of expansibility of waveguide QED system can be used for studying the single photon coherent manipulation.It can also be applied to the structure of the quantum networks.Quantum networks consists of quantum channels and nodes.The quantum channel can be made by waveguides on a chip.Quantum node is two or more waveguides’ junction where placed a quantum bit.In quantum nodes,quantum bits can also be replaced by quantum emitters,which can be used for conversion,processing and storage of quantum informa-tion.In the quantum channel made of waveguides,photons flying as quantum bits(qubits),transmit in the waveguide.Quantum router has similar function to classical router.It can transport a single photon which carrying quantum informa-tion from one quantum channel to a spatial location of another quantum channel,distributing quantum entanglements in the entire network.So as to realize the function of the single photon router.The study of single photon quantum router is very important for the realization of all optical quantum networks.Recently,work of the single photon router realized by coupling between the endpoint of semi-infinite CRW and the zeroth cavity of infinite CRW via atoms aroused people’s great concern.But the researchers found that the maximum transfer probability incidenting from the infinite CRW is only 0.5.In order to improve the transfer probability incidenting from the infinite CRW and improve the transport properties,we try to change the waveguide structure and the atomic energy level,only considering band overlapping between two CRWs,expecting to fully transfer quantum information from the infinite CRW to the finite CRW.This thesis is based on the previous research work of our team,using cou-pling between coupled resonator waveguides(CRWs)system and single atoms to achieve single photon quantum router,providing theoretical basis for the future development of quantum information technology.In this article,we mainly study the model that the Nth cavity of the semi-infinite CRW coherent coupling with the zeroth cavity of infinite CRW via atoms.It is a T bulge type waveguide array,It can realize the function of single photon quantum routing.The structure of the full text is as follows:The first chapter,we introduced the research progresses of single photon quan-tum device and its coherent control.The second chapter,from the perspective of the quantization of the light field of quantum optics,we illustrate the Fabry-Perots cavity and the quantized electromagnetic field,cavity QED,waveguide QED and CRW system.The third chapter,when considering a two-level atom,single photons inci-denting from infinite CRW(semi-infinite CRW),we found that:photons almost all transmit when the frequency of the photon and the atomic transition frequency are large detuning.When the both frequencies resonate and coupling strength between two waveguides and the atom is equal,transfer probability achieve its maximum 0.5(1).Incidenting photons of many different frequencies can almost all transmit when N increases.When N take a particular value(sin(kN)= 0),the coupling between the semi-infinite waveguide and the atom is inhibited.The fourth chapter,we take in consideration for a cascade three-level system.The coupling strength between the atomic energy level transition and two waveg-uides is equal.Next we adjust the atomic transition state to the excited state transition and photon coupling strength gc.We find that the transfer rate of the photons incidenting from infinite(semi-infinite)waveguide into the other waveguide achieve its maximum 0.5(1).When gc is equal to zero,the model degradates to the two-level situation.In the last chapter,we summarize the full text,and put forward some prospect-s for future work.