论文标题
通过反馈赔偿的反馈补偿直接评估测量不确定性
Direct evaluation of measurement uncertainties by feedback compensation of decoherence
论文作者
论文摘要
很难评估量子测量的精度，因为无法对同一物理系统进行第二次参考测量，以将测量结果与测量数量的更准确值进行比较。在这里，我表明，当使用测量结果用于补偿通过与系统仔细控制的探针量相互作用来补偿少量的矫正量时，可以直接评估测量不确定性。由于目标可观察到的原始不确定性导致探针量子的相移波动，因此可以使用有关目标可观察到的任何其他信息来通过将条件相位移动应用于参考值来补偿一部分腐蚀性。这种负反馈的大小对应于对目标可观察到的估计值，而无偿的分解定义了该估计值的不确定性。分析的结果表明，估计值的不确定性由Ozawa在Phys中引入的不确定性给出。 Rev. A 67，042105（2003）和最佳估计值由与不同测量结果相关的弱值给出。因此，反馈补偿的反馈补偿证明了错误的定义和估计将输入状态的初始信息与每个测量结果提供的其他信息结合在一起的经验有效性。
It is difficult to evaluate the precision of quantum measurements because it is not possible to conduct a second reference measurement on the same physical system to compare the measurement outcome with a more accurate value of the measured quantity. Here, I show that a direct evaluation of measurement uncertainties is possible when the measurement outcomes are used to compensate the small amount of decoherence induced in a probe qubit by carefully controlled interactions with the system. Since the original uncertainty of the target observable causes fluctuating phase shifts in the probe qubit, any additional information obtained about the target observable can be used to compensate a part of the decoherence by applying a conditional phase shift to the reference qubit. The magnitude of this negative feedback corresponds to an estimate of the target observable, and the uncompensated decoherence defines the uncertainty of that estimate. The results of the analysis show that the uncertainties of the estimates are given by the uncertainties introduced by Ozawa in Phys. Rev. A 67, 042105 (2003) and the optimal estimates are given by the weak values associated with the different measurement outcomes. Feedback compensation of decoherence therefore demonstrates the empirical validity of definitions of errors and estimates that combine the initial information of the input state with the additional information provided by each measurement outcome.
