标题： 关于两个最大纠缠的耦合 显示英文标题

标题： On two maximally entangled couples

摘要： 在一篇开创性的文章中，Higuchi 和 Sudbery 表明纯四量子态不能在每个二分划分上都达到最大纠缠。 这些态现在被称为绝对最大纠缠（AME）态。 在这里，我们给出一系列旧的和新的证明，证明不存在四量子 AME 态。 这些证明基于不变量理论、编码理论的方法以及线性代数的基本性质，如泡利对易关系。 显示英文摘要

摘要： In a seminal article, Higuchi and Sudbery showed that a pure four-qubit state can not be maximally entangled across every bipartition. Such states are now known as absolutely maximally entangled (AME) states. Here we give a series of old and new proofs of the fact that no four-qubit AME state exists. These are based on invariant theory, methods from coding theory, and basic properties from linear algebra such as the Pauli commutation relations.