Preparation And Application Of Non-Gaussian States Based On Catalytic Quantum Scissors

The generation of quantum states is the premise of quantum information transmission.The preparation of non-Gaussian quantum states plays an important role in quantum information processing.The research on its non-classical properties and the improvement of entanglement properties have received continuous attention.In this thesis,based on the quantum scissor device proposed by Pegg,Phillips and Barnett,two kinds of non-Gaussian quantum states are prepared.The quantum scissor is explored to understand its physical essence.Some relevant non-classical and quantum entanglement methods in quantum mechanics are used to fully analyze the non-classical properties and entanglement properties of the prepared non-Gaussian states.The specific research plans of this thesis are as follows:The thesis based on the quantum scissor device proposed by Pegg et al,we propose a scheme of the generation of non-Gaussian quantum state.When considering the quantum photon catalysis of single-photon input and single-photon detection,the equivalent operator of this catalytic quantum scissor is given in order to understand the physical nature of quantum scissor.When the coherent state is taken as the input state,for an asymmetric beam splitter,the output state can be truncated to zero photon,single photon and two photon components;for a symmetric beam splitter,the output state is only truncated to zero photon and two photon components.The non-classicality of the prepared non-Gaussian quantum state is discussed by the average photon number,signal-to-noise ratio,squeezing effect and Wigner function.These results show that the generated output state will present strong non-classicality if we modulate the amplitude of the coherent state and transmissivity of beam splitter.Based on the quantum scissor operation applied to the two-mode squeezed vacuum state(TMSVS),the output quantum state can be truncated into a superposition of a two mode vacuum state,a two mode single photon state,and a two mode two photon state.In addition,by adjusting the transmittance of the beam splitter,the composition of the output quantum state will change.On top of that,the entanglement properties of the generated output state are further investigated in terms of the entanglement entropy,the Einstein-Podolsky-Rosen(EPR)correlation and the squeezing effect,and its entanglement can be improved in the regions of weak squeezing and low(high)transmittance.It is worth noting that the enhanced region of the EPR correlation for the output state is almost a sub-region of the entanglement entry or squeezing effect,which indicates that the EPR correlation is the most rigorous standard to analyze whether quantum state entanglement is improved or not.The research results of this thesis are expected to provide theoretical reference for the realization of long distance quantum secure communication.