文章基本信息

标题：Quantum Discord for d⊗2 Systems
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作者：Zhihao Ma ; Zhihua Chen ; Felipe Fernandes Fanchini 等
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2015
卷号：5
DOI：10.1038/srep10262
出版社：Springer Nature
摘要：We present an analytical solution for classical correlation, defined in terms of linear entropy, in an arbitrary system when the second subsystem is measured. We show that the optimal measurements used in the maximization of the classical correlation in terms of linear entropy, when used to calculate the quantum discord in terms of von Neumann entropy, result in a tight upper bound for arbitrary systems. This bound agrees with all known analytical results about quantum discord in terms of von Neumann entropy and, when comparing it with the numerical results for 10⁶ two-qubit random density matrices, we obtain an average deviation of order 10⁻⁴. Furthermore, our results give a way to calculate the quantum discord for arbitrary n -qubit GHZ and W states evolving under the action of the amplitude damping noisy channel.