Research On Quantum Teleportation And Preparation Of Non-Gaussian Quantum States Based On Linear Devices

Unitary operator is an indispensable tool in quantum fundamental theory and quantum optics,which plays an irreplaceable role in the preparation of quantum states and quantum teleportation.In recent years,many methods have been proposed for the preparation of quantum states with high non-classical and high entanglement properties,including quantum catalysis,quantum scissors,and photon addition/subtraction and other non-Gaussian operation.In addition,quantum states with high entanglement and high non-classical properties are used to optimize the fidelity of quantum teleportation and improve the precision of quantum measurement.Based on these advantages,this thesis proposes the normally ordering forms and compact exponential forms of common quantum states under the coherent state representation.Then,new methods are investigated using the entangled source generated by the beam splitter for calculating the fidelity of quantum teleportation.Ultimately,a new scheme is proposed to prepare the non-Gaussian quantum states with the help of the non-Gaussian operation,and the application of non-Gaussian states in quantum teleportation is investigated.The specific research work in this thesis can be summarized as follow:Firstly,based on the coherent state representation,the technique of integration within operator product(IWOP)technique is used to calculate the normally ordering forms and compact exponential forms of the beam splitter operator?the single(two)mode squeezing operators and the two cascaded beam splitter operators.Secondly,at present,the most common method of calculating the fidelity of quantum teleportation is characteristic function,which lead to the scheme of calculating fidelity is more complicated.In order to study the quantum teleportation process more conveniently,we consider that new methods for calculating the fidelity of quantum teleportation based on the entangled source generated by the beam splitter,which mainly includes the Q function representation,P function representation,and Wigner function representation of fidelity.As an application,the fidelity effect of transmitting coherent states is also considered in quantum teleportation using the entangled source produced by inputting two single-mode squeezing vacuum states into the beam splitter.The results show that the entangled source generated by the symmetric beam splitter has a better fidelity of the transmission coherent state.In addition,we also consider the fidelity of transmitting coherent states using the entanglement source generated by inputting coherent superposition states and vacuum states in the beam splitter,which shows the same results as the above example.Finally,a new non-Gaussian quantum state—photon subtraction and addition coherent superposition two-mode squeezed coherent state(SP-TMSCs)is proposed by acting photon addition/subtraction coherent superposition operation(?)on two-mode squeezed coherent state(TMSCs).Then,the non-classical properties of the SP-TMSCs are investigated based on the Mandle Q parameter,which can be reflected by the sub-Poisson distribution of the light field,the anti-bunching effect,and the negative properties of Wigner function.The results show that there is an obvious non-classical effect existence when the squeezing parameters and the coherent state amplitude is relatively small.In addition,the entanglement property of the SP-TMSCs are analyzed by using EPR correlation.The study found that the coherent superposition operation can improve effectively EPR correlation better than both photon subtraction and photon addition operations for two-mode operation in the range of small squeezing parameter,and the EPR correlation is also enhanced significantly with the increase of coherent state amplitude.As applications,the SP-TMSCs are used as entangled source to teleport coherent states in quantum teleportation,and it is shown that the effect of increasing fidelity is similar to the case of EPR correlation.