Conditional quantum one-time pad
Conditional quantum one-time pad
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DOI：
10.1103/physrevlett.124.050503
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发表时间：
2017-03
影响因子：
8.6
通讯作者：
Kunal Sharma-;Eyuri Wakakuwa;M. Wilde
中科院分区：
文献类型：
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作者：
Kunal Sharma-;Eyuri Wakakuwa;M. Wilde
假设爱丽丝和鲍勃位于遥远的实验室，这两个实验室通过理想的量子通道相连。进一步假设它们共享一个量子态ρ_{ABE}的多个副本，使得Alice拥有A系统，Bob拥有BE系统。在我们的模型中，Bob的实验室有一个可识别的不安全部分：名为Eve的第三方已经渗透到Bob的实验室并控制了E系统。爱丽丝知道这一点，希望使用他们的共享态和理想的量子通道来传递信息，这样鲍勃就可以访问他的整个实验室(BE系统)，而伊芙只能访问鲍勃实验室的一个部分(E系统)，并且是连接爱丽丝和鲍勃的理想量子通道，所以无法了解爱丽丝传输的信息。我们称这个任务为条件一次一密，在这封信中，我们证明了这个任务的最优秘密通信速率等于它们共享状态的条件量子互信息I(A；B|E)。因此，我们通过状态重分布、条件擦除或状态解构，赋予条件量子互信息不同于前人工作的操作意义。我们还从几个方面推广了该模型和方法，其中之一是秘密共享任务，即Alice的消息应该对只拥有AB或AE系统的人是安全的，但应该是可以被拥有所有系统A、B和E的人破译的。
Suppose that Alice and Bob are located in distant laboratories, which are connected by an ideal quantum channel. Suppose further that they share many copies of a quantum state ρ_{ABE}, such that Alice possesses the A systems and Bob the BE systems. In our model, there is an identifiable part of Bob's laboratory that is insecure: a third party named Eve has infiltrated Bob's laboratory and gained control of the E systems. Alice, knowing this, would like use their shared state and the ideal quantum channel to communicate a message in such a way that Bob, who has access to the whole of his laboratory (BE systems), can decode it, while Eve, who has access only to a sector of Bob's laboratory (E systems) and the ideal quantum channel connecting Alice to Bob, cannot learn anything about Alice's transmitted message. We call this task the conditional one-time pad, and in this Letter, we prove that the optimal rate of secret communication for this task is equal to the conditional quantum mutual information I(A;B|E) of their shared state. We thus give the conditional quantum mutual information an operational meaning that is different from those given in prior works, via state redistribution, conditional erasure, or state deconstruction. We also generalize the model and method in several ways, one of which is a secret-sharing task, i.e., the case in which Alice's message should be secure from someone possessing only the AB or AE systems, but should be decodable by someone possessing all systems A, B, and E.