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arXiv quant-ph/9904058quant-ph
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薛定谔猫原子的Wigner函数、压缩特性和慢退相干

Wigner functions, squeezing properties and slow decoherence of atomic Schrodinger cats

M. G. Benedict, A. Czirjak

摘要:

我们考虑了二能级原子系综中的一类态:两个不同原子相干态的叠加,它可以被视为量子光学中通常称为薛定谔猫态的原子类似物。根据组分间的关系,我们定义了极性猫态和非极性猫态。借助于球维格纳函数,这些性质进行了研究。我们发现,非极性猫态一般表现出压缩,其措施取决于猫的组件的分离,也对组成原子的数量。通过求解极性猫态在外界环境中的主方程,我们确定了退相干、耗散的特征时间以及一个新参数--态的非经典性的特征时间。后者是通过维格纳函数的帮助引入的,维格纳函数也用于可视化该过程。特征时间对猫原子数和环境温度的依赖性表明,极性猫态的退相干是令人惊讶的缓慢。

英文摘要:

We consider a class of states in an ensemble of two-level atoms: a superposition of two distinct atomic coherent states, which can be regarded as atomic analogues of the states usually called Schrodinger cat states in quantum optics. According to the relation of the constituents we define polar and nonpolar cat states. The properties of these are investigated by the aid of the spherical Wigner function. We show that nonpolar cat states generally exhibit squeezing, the measure of which depends on the separation of the components of the cat, and also on the number of the constituent atoms. By solving the master equation for the polar cat state embedded in an external environment, we determine the characteristic times of decoherence, dissipation and also the characteristic time of a new parameter, the non-classicality of the state. This latter one is introduced by the help of the Wigner function, which is used also to visualize the process. The dependence of the characteristic times on the number of atoms of the cat and on the temperature of the environment shows that the decoherence of polar cat states is surprisingly slow.

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