Any 2 ⊗ n subspace is locally distinguishable
Any 2 ⊗ n subspace is locally distinguishable
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DOI：
10.1103/physreva.84.012304
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发表时间：
2011-07-05
影响因子：
2.9
通讯作者：
Ying, Mingsheng
中科院分区：
文献类型：
--
作者：
Yu, Nengkun;Duan, Runyao;Ying, Mingsheng
多部希尔伯特空间的子空间称为局部不可区分的，如果这个子空间的任何标准正交基不能通过局部运算和经典通信完全区分。以前证明了任何m圈乘n的二部系统（m > 2，n > 2）都有一个局部不可区分的子空间。然而，自2005年以来，是否存在具有量子比特子系统的局部不可区分二部子空间一直是一个悬而未决的问题。我们解决这个问题的消极表明，任何2圈倍n二部子空间包含一个基础，是当地可区分的。作为一个有趣的应用，我们表明，任何量子信道与两个克劳斯运营商具有最佳的环境辅助经典容量。
A subspace of a multipartite Hilbert space is said to be locally indistinguishable if any orthonormal basis of this subspace cannot be perfectly distinguished by local operations and classical communication. Previously it was shown that any m circle times n bipartite system with m > 2 and n > 2 has a locally indistinguishable subspace. However, it has been an open problem since 2005 whether there is a locally indistinguishable bipartite subspace with a qubit subsystem. We settle this problem in negative by showing that any 2 circle times n bipartite subspace contains a basis that is locally distinguishable. As an interesting application, we show that any quantum channel with two Kraus operators has optimal environment-assisted classical capacity.