Quantum Estimation by Local Observables
Quantum Estimation by Local Observables
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DOI：
10.1103/physreva.70.022327
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发表时间：
2004-01
影响因子：
2.9
通讯作者：
M. Hotta;M. Ozawa
中科院分区：
文献类型：
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作者：
M. Hotta;M. Ozawa
量子估计理论提供了各种估计问题的未知参数的状态下的系统的最佳观察。然而，该理论是在假设每个可观察对象都可供实验者使用的前提下发展起来的。在这里，我们将理论推广到实验者只能使用局部可达观测量的问题。对于这样的问题，我们建立了一个Cramer-Rao型不等式，通过获得一个明确的形式的Fisher信息作为一个倒数下界估计的均方误差的局部可达的可观。此外，我们探讨了各种局部量子估计问题的复合系统，其中非平凡的组合需要获得的Fisher信息。
Quantum estimation theory provides optimal observations for various estimation problems for unknown parameters in the state of the system under investigation. However, the theory has been developed under the assumption that every observable is available for experimenters. Here, we generalize the theory to problems in which the experimenter can use only locally accessible observables. For such problems, we establish a Cramer-Rao-type inequality by obtaining an explicit form of the Fisher information as a reciprocal lower bound for the mean-square errors of estimations by locally accessible observables. Furthermore, we explore various local quantum estimation problems for composite systems, where nontrivial combinatorics is needed for obtaining the Fisher information.