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arXiv 1509.03334quant-ph
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有限测量精度下探测大量子费舍尔信息

Detecting large quantum Fisher information with finite measurement precision

Florian Fröwis, Pavel Sekatski, Wolfgang Dür

摘要:

我们提出了一个实验可行的方案来确定量子费舍尔信息(QFI)的下界,它可以保证多体纠缠或量子精密测量的有用性。该方案是基于一个小的幺正旋转之前和之后的状态的测量统计比较。我们认为,在一般情况下,有限的集体观测分辨率防止检测大QFI。这可以通过在测量之前执行附加操作来克服。我们说明了这个协议的权力,目前的自旋压缩实验,其中用于制备初始自旋压缩状态的相同操作提高了两个数量级的QFI上的下限。我们还建立了一个连接到Leggett-Garg不等式。我们展示了如何模拟我们的协议的不等式的一个变种,并证明了一个大的QFI是必要的,他们违反粗粒度的检测器。

英文摘要:

We propose an experimentally accessible scheme to determine lower bounds on the quantum Fisher information (QFI), which ascertains multipartite entanglement or usefulness for quantum metrology. The scheme is based on comparing the measurement statistics of a state before and after a small unitary rotation. We argue that, in general, limited resolution of collective observables prevents the detection of large QFI. This can be overcome by performing an additional operation prior to the measurement. We illustrate the power of this protocol for present-day spin-squeezing experiments, where the same operation used for the preparation of the initial spin-squeezed state improves the lower bound on the QFI by two orders of magnitude. We also establish a connection to Leggett-Garg inequalities. We show how to simulate a variant of the inequalities with our protocol and demonstrate that a large QFI is necessary for their violation with coarse-grained detectors.

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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