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arXiv quant-ph/0702022quant-ph
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两个密度矩阵的最优无模糊状态判别:第二类精确解

Optimal unambiguous state discrimination of two density matrices: A second class of exact solutions

Philippe Raynal, Norbert Lütkenhaus

摘要:

本文研究了两个混合量子态的非对称态分辨。我们研究的排名和频谱的最佳USD测量的元素。这自然会导致部分第四归约定理。这个定理表明,或者失效概率等于其根据保真度给出的总体下界,或者可以从原始希尔伯特空间中分裂出一个二维子空间。然后,我们使用这个部分约化定理,推导出任何两个同等可能的几何均匀(GU)状态$ρ_0$和$ρ_1=Uρ_0 U^\dagger$,$U^2={\openone}$,在四维希尔伯特空间的最佳解决方案。这代表了USD问题的第二类解析解,这些解析解不能被简化为一些纯状态的情况。我们应用我们的结果来回答两个问题,是相关的Bennett和Bennard 1984年的量子密钥分发协议的实施,使用弱相干态。

英文摘要:

We consider the Unambiguous State Discrimination (USD) of two mixed quantum states. We study the rank and the spectrum of the elements of an optimal USD measurement. This naturally leads to a partial fourth reduction theorem. This theorem shows that either the failure probability equals its overall lower bound given in term of the fidelity or a two-dimensional subspace can be split off from the original Hilbert space. We then use this partial reduction theorem to derive the optimal solution for any two equally probable Geometrically Uniform (GU) states $ρ_0$ and $ρ_1=Uρ_0 U^\dagger$, $U^2={\openone}$, in a four-dimensional Hilbert space. This represents a second class of analytical solutions for USD problems that cannot be reduced to some pure state cases. We apply our result to answer two questions that are relevant in implementations of the Bennett and Brassard 1984 quantum key distribution protocol using weak coherent states.

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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