Imperfect measurement settings: Implications for quantum state tomography and entanglement witnesses
Imperfect measurement settings: Implications for quantum state tomography and entanglement witnesses
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DOI：
10.1103/physreva.86.062325
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发表时间：
2012-03
影响因子：
2.9
通讯作者：
D. Rosset;Raphael Ferretti-Schobitz;J. Bancal;N. Gisin;Yeong-Cherng Liang
中科院分区：
文献类型：
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作者：
D. Rosset;Raphael Ferretti-Schobitz;J. Bancal;N. Gisin;Yeong-Cherng Liang
可靠且特性良好的量子资源是量子信息处理中不可或缺的要素。通常，在这些资源的现实表征中，设备具有内在的不确定性，这些不确定性可以以系统误差的形式表现出来。虽然系统误差通常是通过仔细校准来解释的，但文献中很大程度上忽视了剩余缺陷对量子资源表征的影响。在本文中，我们研究了由于测量基准的不完美对准而产生的系统误差的影响——可以想象，由于测量设备的可控性有限，可能会发生这种误差。我们表明，使用量子态断层扫描或纠缠见证对量子资源进行表征可能会因一定程度的不精确性而受到破坏，这在实验室中并不罕见。奇怪的是，对于量子态断层扫描，我们发现纠缠有助于降低对此类错误的敏感性。我们还简要讨论了如何修改给定的纠缠见证以纳入此类错误的影响。
Reliable and well-characterized quantum resources are indispensable ingredients in quantum information processing. Typically, in a realistic characterization of these resources, apparatuses come with intrinsic uncertainties that can manifest themselves in the form of systematic errors. While systematic errors are generally accounted for through careful calibration, the effect of remaining imperfections on the characterization of quantum resources has been largely overlooked in the literature. In this paper, we investigate the effect of systematic errors that arise from imperfect alignment of measurement bases—an error that can conceivably take place due to the limited controllability of measurement devices. We show that characterization of quantum resources using quantum state tomography or entanglement witnesses can be undermined with an amount of such imprecision that is not uncommon in laboratories. Curiously, for quantum state tomography, we find that having entanglement can help to reduce the susceptibility to this kind of error. We also briefly discuss how a given entanglement witness can be modified to incorporate the effect of such errors.