【作者】 黄素梅；

【导师】 李洪才；

【作者基本信息】 福建师范大学 ， 理论物理， 2004， 硕士

【摘要】 压缩是量子光场的一种非经典效应。由于压缩态光场中某正交分量的量子噪声低于相干态光场中相应分量的量子涨落，若用此分量传递信息，则可得到比相干态光场更高的保真度，所以压缩态光场在弱信号探测、低噪声光通讯等方面具有广泛的应用前景。因此。压缩态光场引起人们极大的关注。 另外，在量子光学中，光强比例于光子数，那么相位是什么?能不能也定义一个与经典电磁场相位相应的相位算符?如何定义?等等。这些自然是很有趣的问题。 本论文：首先，研究了叠加相干态的方差压缩与熵压缩，讨论了方差压缩、熵压缩与相干参数的幅角δ的关系，并对两者进行比较。从而证明了熵压缩实现了光场压缩效应的高灵敏量度。其次，研究了真空态与相干态的叠加态振幅平方压缩，讨论了叠加参数p、相干参数(R，θ)对真空态与相干态的叠加态振幅平方压缩的影响。最后，详细地分析了Dirac相位算符、S—G相位算符、P—B相位算符，并对它们的一些性质作出比较，系统地论述它们的优点和不足之处。更多还原

【Abstract】 Squeezing is a non-classical effect of quantum field. The quantum noise of one of the quadrature components of the squeezed state is less than the noise corresponding to the coherent state, if the squeezed state is used to transmit information,we shall receive higher fidelity than the coherent state.So the squeezed state will have extensive applications in the detection of weak signal in the modern low-noise optical communication systems ,and so on.They draw an increasing amount of attention.Moreover,in quantum optics, the intensity of light is direct proportion to photon numbers,then what is phase?Can we define a phase operator that is corresponding to the phase of classical radiation field?How should it be defined?etc..All these are naturally interesting problems.In this thesis, first, quadrature squeezing and entropic squeezing of superposition coherent states are studied.The relations between quadrature squeezing or entropic squeezing and angle 8 of coherent parameter are discussed and compared.The results show the entropic squeezing is a high sensitive measure for the squeezing effect of the field.Second,amplitude-squared squeezing for the superposition state of the vacuum state and the coherent state is studied.The effects of superposition parameter and coherent parameters on the amplitude-squared squeezing are discussed.Finally,Dirac phase operator, S-G phase operator and P-B phase operator are analyzed in detail. Some properties of these operators are compared. Meanwhile, strong and weak points of these operators are showed more systematically.更多还原