The Research Of Properties And Dissipation For Optical Quantum States

In the process of quantum information, the carrier of quantum information is quantum state. The operating of quantum state is one of the key technologies. Therefore, the quantum state preparation of nonclassical optical field is the important basis and prerequisite condition for quantum information research. The preparation of quantum state and its property research (antibunching effect, subpossion distribution, squeezed effect and negative of Wigner function) are important.Because the quantum state preparation of optical field is the prerequisite condition for quantum information research. In the third chapte, according to the classical optical field quantum state, the photon-added and photon-subtracted displaced Fork states are generated theoretically for the first time by applying the inverse operator of annihilation and generator operators on the displaced Fork states. In addition, the photon-added squeezed vacuum state is generated by using generator operator on the squeezed vacuum state and the preparation in experiment is described as well.The optical field quantum state of quantum information research is the nonclassical optical field quantum. the nonclassical optical field quantum can be responsed by their nonclassical properties. According to the second-order correlation function, Q factor, squeezed effect and Wigner function, the theoretical research of of properties are carried on for the photon-added and photon-subtracted displaced Fork states, signle photon-added squeezed vacuum state, and Fock state and its superposition states in the fourth chapter. The results are shown that the photon-added and photon-subtracted displaced Fork states have antibunching effect and subpoisson distribution in the small region of |α|2; Single photon-added squeezed vacuum state has clearly antibunching effect and squeezed effect, which denote that these optical field quantum states are the non-classical quantum states. The Wigner functions of these optical field quantum states all have clearly distribution of negative value in the phase space. The wave packages of |1>,|2> and |3> are non-gaussian package and these Wigner functions change to be more complexity with the increment of photon. In the center of phase space, the peak value of Wigner function is related to the parity of n:the peak value of Wigner function is downward with the odd of n, the peak value of Wigner function is upward with the even of n. The Wigner function of the superposition of Fock states have obviously the negative value peak and the upward peak, which show the superposition property of two quantum states. The Wigner function of signle photon-added squeezed vacuum state is similar to the Wigner function of |1>, but the phase space of negative value is shrink. In conclusion, these quantum states have obviously nonclassical property, and are the nonclassical optical field quantum state..The influence between the disposal of quantum information and the environment can not be prevented completely. Thus, the research of the decoherent and the disappearance of the nonclassical property of quantum state has very important significance in the process of quantum information. The Fock state, the superposition of Fock states and photon-added squeezed vacuum states have important practical value in the quamtum information research. However, there is rarely no report about the research of their dissipation. In the fifth chapter, according to the definition of Wigner function and the master equation theory, and the entangled state representation and the relation of Laguerre polynomials and Hermite polynomials, taking the Fock states and their superposition states, the photon-added squeezed vacuum state, the analytical expression of the time evolution Wigner function of these quantum states are obtained. The time evolution characteristics of Wigner functions of these quantum states with different parameters is systematically calculated and discussed. In initial stage, the Wigner functions of these quamtum states have obvious nonclassical property, and the negative value of their Wigner function has apparent and different projective region in the phase space on the condition of dissipation. For the Wigner function of |1>, the projective region of the negative value is a circular surface. For the Wigner function of |2>, it is a solid annulus surface. For the Wigner function of |3>, it is a combination of a centered circular surface and a solid annulus surface. For the Wigner function of |1> and |2>, the projective region of the negative value are two half-moon surfaces. As for the Wigner function of the single photon-added squeezed vacuum states, it is a circular surface. The negative values of the Wigner function of these optical field quantum states will shrink to the positive direction with the time evolution. The projective region of its negative value will decrease simultaneously. If the evolution time is long enough, the negative value of their Wigner function will disappear and the corresponding projective region will also disappear in the phase space. Finally, the original nonclassical optical field quantum states change into the pure state of vacuum. On the condition of the dissipation and the driving, the negative value will approach to positive value until the negative value disappear with the increment of driving coefficient when the dissipation coefficient and dissipation time are determined. The corresponding projective region will shrink and vanish at last. Then the nonclassical optical field quantum states change into the classical quantum states. When the dissipation coefficient and the driving coefficient are given different values, the evolution time is also different for the same optical field quantum states. When the dissipation coefficient is larger than the driving coefficient, it needs relative more time in the process which the nonclassical property of Wigner function of optical field quantum states change to be disappeared. On the contrary, the evolution time is relative short. Therefore, the evolution of these quantum states can be control by the value of g-k in terms of theory. For using the nonclassical property of these quantum states in quantum information, these results offer the foundation of theory.