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arXiv 1111.3643quant-phcond-mat.stat-mechmath-phmath.MP
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纠缠的可计算度量与其他量子关联之间的相互作用

Interplay between computable measures of entanglement and other quantum correlations

Davide Girolami, Gerardo Adesso

摘要:

复合量子系统可以处于一般状态,其特征不仅在于纠缠,而且还在于更一般的量子关联。这两个非古典特征之间的相互作用仍然没有完全理解。在这项工作中,我们研究了这个问题,重点是可计算和可观察的措施,这种相关性:纠缠量化的负N,而一般的量子相关性测量的(归一化)几何量子discord D_G。对于双量子比特系统,我们发现在纯态上,几何不协调退化为负平方,而对于任意混合态,关系式$D_G \geq N^2$成立。后者的结果被严格地推广到两个qudit系统的纯态,Werner态和各向同性态的任意d,并提供了数值证据,其有效性的任意状态的qubit和qutrit以及。我们的研究结果建立了一个有趣的层次结构,我们猜想是普遍的,两个相关的和实验友好的非古典指标之间。这与一般量子关联至少应该包含并且通常超过复合量子系统的混合态上的纠缠的直觉相联系。

英文摘要:

Composite quantum systems can be in generic states characterized not only by entanglement, but also by more general quantum correlations. The interplay between these two signatures of nonclassicality is still not completely understood. In this work we investigate this issue focusing on computable and observable measures of such correlations: entanglement is quantified by the negativity N, while general quantum correlations are measured by the (normalized) geometric quantum discord D_G. For two-qubit systems, we find that the geometric discord reduces to the squared negativity on pure states, while the relationship $D_G \geq N^2$ holds for arbitrary mixed states. The latter result is rigorously extended to pure, Werner and isotropic states of two-qudit systems for arbitrary d, and numerical evidence of its validity for arbitrary states of a qubit and a qutrit is provided as well. Our results establish an interesting hierarchy, that we conjecture to be universal, between two relevant and experimentally friendly nonclassicality indicators. This ties in with the intuition that general quantum correlations should at least contain and in general exceed entanglement on mixed states of composite quantum systems.

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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