标题： 两个量子态之间的SLOCC可转换性 显示英文标题

标题： SLOCC Convertibility between Two-Qubit States

摘要： 在本文中，我们对与$U\otimes{U}\otimes{V}\otimes{V}$交换的四量子态进行分类，其中$U$和$V$是泡利群中的任意成员。我们以有限数量的纠缠探测器来表征该类别的可分离态。等价地，我们表征了保持贝尔对角的两量子态、完全正映射，这些映射是可分离的。这些可分离的完全正映射对应于可以借助经典通信辅助的随机局部操作（SLOCC）实现的协议。这使我们能够推导出贝尔对角态的完整的SLOCC单调量，从而提供通过SLOCC将一个两量子态转换为另一个的充分必要条件。 显示英文摘要

摘要： In this paper we classify the four-qubit states that commute with $U\otimes{U}\otimes{V}\otimes{V}$, where $U$ and $V$ are arbitrary members of the Pauli group. We characterize the set of separable states for this class, in terms of a finite number of entanglement witnesses. Equivalently, we characterize the two-qubit, Bell-diagonal-preserving, completely positive maps that are separable. These separable completely positive maps correspond to protocols that can be implemented with stochastic local operations assisted by classical communication (SLOCC). This allows us to derive a complete set of SLOCC monotones for Bell-diagonal states, which, in turn, provides the necessary and sufficient conditions for converting one two-qubit state to another by SLOCC.