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arXiv 0812.0906quant-ph
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一个熵不等式

An Entropy Inequality

Meik Hellmund, Armin Uhlmann

摘要:

设$S(ρ)=- Tr (ρ\logρ)$为$N$维量子态$ρ$的冯诺伊曼熵,$e_2(ρ)$为$ρ$的本征值的第二基本对称多项式.证明了不等式$S(ρ) \le c(N) \sqrt{e_2(ρ)} $,其中$c(N)=\log(N) \sqrt{\frac{2N}{N-1}}$ .这推广了Fuchs和Graaf \cite{fuchsgraaf}针对一个量子比特的情况给出的不等式,即,N=2。当且仅当$ρ$是纯态或最大混合态时,等式才成立。这个不等式为量子信息理论中感兴趣的量提供了新的界限,例如最小输出熵和形成纠缠的上限以及Holevo信道容量的下限。

英文摘要:

Let $S(ρ)=- Tr (ρ\logρ)$ be the von Neumann entropy of an $N$-dimensional quantum state $ρ$ and $e_2(ρ)$ the second elementary symmetric polynomial of the eigenvalues of $ρ$. We prove the inequality $S(ρ) \le c(N) \sqrt{e_2(ρ)} $ where $c(N)=\log(N) \sqrt{\frac{2N}{N-1}}$. This generalizes an inequality given by Fuchs and Graaf \cite{fuchsgraaf} for the case of one qubit, i.e., N=2. Equality is achieved if and only if $ρ$ is either a pure or the maximally mixed state. This inequality delivers new bounds for quantities of interest in quantum information theory, such as upper bounds for the minimum output entropy and the entanglement of formation as well as a lower bound for the Holevo channel capacity.

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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