Diagonal quantum discord
Diagonal quantum discord
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DOI：
10.1088/1751-8121/ab0774
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发表时间：
2017-08
期刊：
影响因子：
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通讯作者：
Zi-Wen Liu;Ryuji Takagi;S. Lloyd
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文献类型：
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作者：
Zi-Wen Liu;Ryuji Takagi;S. Lloyd
量子不和谐通过比较量子互信息与量子测量可获得的最大互信息量来测量量子相关性。本文分析了对角不协调的性质，对角不协调是一种简化版的不协调，它将量子互信息与对应于局部密度矩阵特征态的测量所揭示的互信息进行比较。与优化后的不和谐相比，对角不和谐很容易计算；它还发现了热力学和资源理论的联系。这里我们进一步证明，对于非简并的局部密度矩阵的一般情况，对角不谐表现出理想的性质作为一个较好的不谐测度。我们采用资源破坏图理论（Liu Z-W et al . 2017 Phys.）。Rev. Lett. 118 060502)证明了在局部不和谐非产生量子信道d > 2的操作下对角不和谐是单调不增加的，并提供数值证据证明这种单调性对于量子比特信道也是成立的。我们还证明了它是连续的，并推导出了一个类fannes连续界。我们的结果适用于由对角不谐推广的各种简单不谐测度。
Quantum discord measures quantum correlation by comparing the quantum mutual information with the maximal amount of mutual information accessible to a quantum measurement. This paper analyzes the properties of diagonal discord, a simplified version of discord that compares quantum mutual information with the mutual information revealed by a measurement that correspond to the eigenstates of the local density matrices. In contrast to the optimized discord, diagonal discord is easily computable; it also finds connections to thermodynamics and resource theory. Here we further show that, for the generic case of non-degenerate local density matrices, diagonal discord exhibits desirable properties as a preferable discord measure. We employ the theory of resource destroying maps (Liu Z-W et al 2017 Phys. Rev. Lett. 118 060502) to prove that diagonal discord is monotonically nonincreasing under the operation of local discord nongenerating qudit channels, d > 2, and provide numerical evidence that such monotonicity holds for qubit channels as well. We also show that it is continuous, and derive a Fannes-like continuity bound. Our results hold for a variety of simple discord measures generalized from diagonal discord.