N-body-extended channel estimation for low-noise parameters
N-body-extended channel estimation for low-noise parameters
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DOI：
10.1088/0305-4470/39/46/015
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发表时间：
2006-09
期刊：
影响因子：
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通讯作者：
Masahiro Hotta;Tokishiro Karasawa;M. Ozawa
中科院分区：
文献类型：
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作者：
Masahiro Hotta;Tokishiro Karasawa;M. Ozawa
最近提出并详细分析了低噪声信道的概念，以便描述由环境驱动的噪声过程（Hotta M，Karasawa T和Ozawa M 2005 Phys.Rev.A72 052334）。本文还提出了信道低噪声参数的估计理论。在本文中，我们解决了低噪声参数估计问题的N体扩展的耗散低噪声信道。我们微扰计算输出状态的Fisher信息，以评估参数估计的均方误差的下限。我们表明，在所有的输入状态的Fisher信息的最大值可以通过一个因式分解的输入状态的低噪声参数的领先顺序。因此，为了实现最优估计，N个子系统不必纠缠，只要真实的低噪声参数足够小并且信道是适当耗散的。
The notion of low-noise channels was recently proposed and analysed in detail in order to describe noise-processes driven by the environment (Hotta M, Karasawa T and Ozawa M 2005 Phys. Rev. A 72 052334). An estimation theory of low-noise parameters of channels has also been developed. In this paper, we address the low-noise parameter estimation problem for the N-body extension of the dissipative low-noise channels. We perturbatively calculate the Fisher information of the output states in order to evaluate the lower bound of the mean-square error of the parameter estimation. We show that the maximum of the Fisher information over all input states can be attained by a factorized input state in the leading order of the low-noise parameter. Thus, to achieve optimal estimation, it is not necessary for there to be entanglement of the N subsystems, as long as the true low-noise parameter is sufficiently small and the channel is properly dissipative.