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arXiv quant-ph/0409047quant-ph
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检测量子密钥分发协议中的两方量子关联

Detecting two-party quantum correlations in quantum key distribution protocols

Marcos Curty, Otfried Gühne, Maciej Lewenstein, Norbert Lütkenhaus

摘要:

安全的量子密钥分发(QKD)的一个必要前提是发送方和接收方能够证明在它们之间有效分发的一个量子态中存在纠缠。为了提供这种纠缠证明,可以使用可以从可用的测量结果构造的一类纠缠见证(EW)算子。这类EW可以用来提供一个必要和充分条件,即使在一个量子态不能完全重建的量子关联存在。最近,我们得到了两个著名的基于纠缠的方案,即六态和四态纠缠方案的最优纠缠波集[M。Curty等人,物理修订信函92,217903(2004)]。在这里,我们完成这些结果,现在特别显示的情况下的分析准备和测量(P&M)计划。为此,我们研究了四态和二态P&M方案的信号状态和检测方法。对于这些协议中的每一个,我们得到一个减少的EW集。更重要的是,每一组EW都可以用来推导出一个充分必要条件,以证明这些协议中存在量子关联。

英文摘要:

A necessary precondition for secure quantum key distribution (QKD) is that sender and receiver can prove the presence of entanglement in a quantum state that is effectively distributed between them. In order to deliver this entanglement proof one can use the class of entanglement witness (EW) operators that can be constructed from the available measurements results. This class of EWs can be used to provide a necessary and sufficient condition for the existence of quantum correlations even when a quantum state cannot be completely reconstructed. The set of optimal EWs for two well-known entanglement based (EB) schemes, the 6-state and the 4-state EB protocols, has been obtained recently [M. Curty et al., Phys. Rev. Lett. 92, 217903 (2004)]. Here we complete these results, now showing specifically the analysis for the case of prepare&measure (P&M) schemes. For this, we investigate the signal states and detection methods of the 4-state and the 2-state P&M schemes. For each of these protocols we obtain a reduced set of EWs. More importantly, each set of EWs can be used to derive a necessary and sufficient condition to prove that quantum correlations are present in these protocols.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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