Remedying the local ancilla problem with geometric discord
Remedying the local ancilla problem with geometric discord
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DOI：
10.1103/physreva.87.062303
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发表时间：
2013-06-04
影响因子：
2.9
通讯作者：
Luo, Shunlong
中科院分区：
文献类型：
--
作者：
Chang, Lina;Luo, Shunlong
几何不和谐，介绍了Dakic，Vedral和Brukner [物理学评论快报。105，190502（2010）]是具有广泛应用的量子相关性的重要品质因数。然而，它有一个奇怪的缺点，因为它可能会通过简单地添加一个本地附属物而可逆地改变，正如Piani最近批评的那样[Phys.Rev.A86，034101（2012）]。这使人对几何不协调的信息内容和用法产生怀疑。在这项工作中，我们表明，这个问题与几何不和谐可以简单地从密度算子的平方根，而不是密度算子本身，在定义的不和谐。此外，大多数其他基本属性和分析方面的原始几何不协调可以结转到这个修改后的不协调。由于平方根的性质，这让人想起量子理论中无处不在的概率幅度，修改后的不和谐似乎以更内在和信息的方式捕获量子相关性。
The geometric discord, as introduced by Dakic, Vedral, and Brukner [Phys. Rev. Lett. 105, 190502 (2010)], is a significant figure of merit for quantum correlations with wide applications. However, it has a curious drawback in that it may change reversibly by trivially adding a local ancilla, as recently criticized by Piani [Phys. Rev. A 86, 034101 (2012)]. This casts doubt on the information content and usage of geometric discord. In this work, we show that this problem with geometric discord can be remedied simply by starting from the square root of a density operator, rather than the density operator itself, in defining the discord. Moreover, most other basic properties and analytical aspects of the original geometric discord can be carried over to this modified discord. Due to the square-root character, which is reminiscent of probability amplitudes ubiquitous in quantum theory, the modified discord seems to capture quantum correlations in a more intrinsic and informational fashion.