Atomic Spatial Decoherence In A Squeezed Cavity Field

Concerning the difference and relationship between the quantum world and the classical world, researchers put forward lots of explanations. The most famous one is the theory of the quantum decoherence, which is due to the coupling with the environment. That is to say, coherences act an important role in quantum-classical transition. Therefore, a perfect knowledge of the decoherence is very significant for the understanding of the process of the quantum-classical transition.This paper introduces theoretical and experimental researches on the theory of decoherence briefly. Based on these theories, we study the localization dynamical process for a moving two level atom coupling with a single mode cavity field initially in a squeezed coherent state. The reduced density matrix for the atomic spatial degrees of freedom is given where the behavior is described by a decoherence factor. We obtain relationships between the decoherence factor and some parameters by mathematical tool. Our results show that the spatial decoherence factor of the atom is mainly determined by the coherent parameter b and the squeezed parameter g. It shows that both the coherent parameter b and the squeezed parameter g have influence on the decoherence factor. The coherent parameter b mainly affects the frequency of the oscillation. With the increasing of the value of b, the frequency of oscillation decreases. While the squeezed parameter g contributes to the amplitude of the oscillation. The oscillation decreases evidently with the value of squeezed parameter g increasing. Besides, we find that the oscillation of the decoherence factor changes more rapidly with the coordinate of the wave packet center x increasing. It coincides with the reality of macroscopic limitation well.