Research On The Effects Of Vacuum State On The Statistics Of Nonclassical States And The Entanglement Characteristics

In this paper,a new class of nonclassical quantum states with a certain universal significance is constructed by adding the vacuum state to the elliptical state.Through the study of the non-classical effects,such as the orthogonal squeezing degree,the negative value of the Wigner distribution function and the sub-Poisson photon statistics of the constructed new states,the dependence of the non-classical characteristics on the superimposed vacuum states is given.The general law of the influence of the vacuum state on the non-classical state statistics is analyzed.Based on the entanglement degree of von Neumann entropy,the entanglement characteristics of the two-mode superposition state constructed by the elliptical state and the vacuum state are calculated and studied.The result shows:1.Compression effect of superposition of the elliptical state and vacuum states.By superimposing different numbers of vacuum states in the new states,it is found that the quadrature X1 and X2 of the constructed parity states clearly exhibit quantum interference characteristics such as compression structures,compression regions,and compression peaks that are completely different from the elliptical states.The compression region of the quadrature component X1 of the even state when?=5 and on the line b=±0.29 and the compression region of the quadrature component X2 of the odd state when ?=1 and on the line b=0 are infinitely compressed along a direction.And the compressed structure shows good symmetry.When ?=1,the orthogonal compression depth of the quadrature component X2 of the even state is-0.97,almost reaching the maximum compression degree of-1.The results show that the orthogonal component X1 and X2 of the parity state are very sensitive to the increase and decrease of the vacuum state and show a strong dependence on the vacuum state coefficient.And the effect of increasing or decreasing vacuum state on the compression effect of non-classical state is completely different from the effect of amplitude,phase and the number of superimposed coherent states.Choosing the appropriate vacuum state superposition coefficient can find the non-classical state with the largest squeezing state and the superposition state with the most quantum interference.2.Wigner distribution and sub-Poisson photon statistics of superposition of the elliptical state and vacuum states.As the increasing of the number of superimposed vacuum states,the interference structure becomes more complicated.It is no longer possible to distinguish the peaks of the Winger distribution of each individual coherent state in the superposition state.The negative value of the non-classical index Wigner distribution function shows a strong dependence on the vacuum state.It turns out that the interference structure between two adjacent coherent states weakens,and the interference strengthens in the two directions p=0 and x=0.The central main interference peak gradually increases with the increasing of the vacuum state coefficient.Therefore,we can control the distribution of the Winger function by controlling the superposition coefficient of the vacuum state to manipulate the non-classical nature of the non-classical state.In addition,the addition of the vacuum state makes the sub-Poisson photon statistics of the new state still exhibit the photon statistics of the elliptical state.3.Entangled coherent state.Having motivated by the strongly nonclassical properties of the constructed new states,a class of two-mode superposition states,namely entangled coherent states are constructed,that is,?N?Ck|?k>and ?|0>.The entanglement degree of von Neumann entropy of the constructed new state is calculated.The laws of entanglement characteristics depending on various parameters is given,and find conditions that satisfy the maximum entanglement and can be used as an excellent source for quantum teleportation.