中文摘要：

分类 four-qubit 状态的量纠纷的一套贝尔不平等被介绍。这些不平等每观察员包含二个仅仅测量背景并且能描绘充分可分离、双性人可分离、 tri 可分离的量状态。另外，为 four-qubit 系统的贝尔操作符的二次的不平等被导出。

英文摘要：

A set of Bell inequalities classifying the quantum entanglement of four-qubit states is presented. These inequalities involve only two measurement settings per observer and can characterize fully separable, bi-separable and tri-separable quantum states. In addition, a quadratic inequality of the Bell operators for four-qubit systems is derived.