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arXiv 0812.2378quant-ph
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量子态的最小误差判别:新的界和比较

Minimum-error discrimination of quantum states: New bounds and comparison

Daowen Qiu, Lvjun Li

摘要:

对两个量子态进行模糊判别的最小误差概率是1976年提出的著名的{ \it Helstrom极限}。从那时起,它一直被认为是一个棘手的问题,以获得最小的错误概率模糊判别任意$m$量子态。在本文中,我们得到了一个新的下界的最小错误概率的歧义歧视,并比较此界与其他六个界在文献中。此外,我们表明,模糊和明确的歧视之间的界限并不延伸到合奏两个以上的国家。具体而言,主要技术贡献如下:(1)给出了在给定先验概率的情况下,任意$m$混合量子态的模糊判别的最小错误概率的一个新下界,并给出了该下界可达的充分必要条件. (2)我们比较了这个新的下界与文献中的其他六个界限,在某些情况下,这个界限是最优的。(3)已知若$m=2$,则任意给定的$m$混合量子态之间的最优无定论判别概率$Q_{U}$和最小错误判别概率$Q_{E}$具有关系式$Q_{U}\geq 2Q_{E}$ .在本文中,我们表明,然而,如果$m>2$,关系$Q_{U}\geq 2Q_{E}$可能不会再次举行一般,并可能没有$Q_{U}/Q_{E}$的上确界为两个以上的国家,这也可能反映了一个本质的区别区分两个国家和多个国家。(4)构建了一些示例。

英文摘要:

The minimum-error probability of ambiguous discrimination for two quantum states is the well-known {\it Helstrom limit} presented in 1976. Since then, it has been thought of as an intractable problem to obtain the minimum-error probability for ambiguously discriminating arbitrary $m$ quantum states. In this paper, we obtain a new lower bound on the minimum-error probability for ambiguous discrimination and compare this bound with six other bounds in the literature. Moreover, we show that the bound between ambiguous and unambiguous discrimination does not extend to ensembles of more than two states. Specifically, the main technical contributions are described as follows: (1) We derive a new lower bound on the minimum-error probability for ambiguous discrimination among arbitrary $m$ mixed quantum states with given prior probabilities, and we present a necessary and sufficient condition to show that this lower bound is attainable. (2) We compare this new lower bound with six other bounds in the literature in detail, and, in some cases, this bound is optimal. (3) It is known that if $m=2$, the optimal inconclusive probability of unambiguous discrimination $Q_{U}$ and the minimum-error probability of ambiguous discrimination $Q_{E}$ between arbitrary given $m$ mixed quantum states have the relationship $Q_{U}\geq 2Q_{E}$. In this paper, we show that, however, if $m>2$, the relationship $Q_{U}\geq 2Q_{E}$ may not hold again in general, and there may be no supremum of $Q_{U}/Q_{E}$ for more than two states, which may also reflect an essential difference between discrimination for two-states and multi-states. (4) A number of examples are constructed.

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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