量子Fisher信息流及其应用

The Flow of Quantum Fisher Information and Its Application

量子Fisher信息作为精密测量领域中的重要概念,其倒数给出被测参数可达精度的上限。本文利用右对数导数给出开放量子系统量子Fisher信息流的表达式,并将其应用于与非马尔可夫环境相互作用的二能级系统,讨论了利用右对数导数给出的量子Fisher信息流的正负性与非马尔可夫过程之间的关系。此外,系统在演化的过程中,量子Fisher信息流存在奇异性,该奇异性与量子Fisher信息的奇异性同时出现,它们均来源于密度矩阵某一趋于零的本征值。

Quantum Fisher information is a key conception of precision measurement,which determines the precision of the established parameter.In this paper,we give an expression for the quantum Fisher information flow utilizing right logarithmic derivative for open quantum systems and apply it to a two-level system coupled to a non-Markovian environment characterized by Lorentzian spectral density.Discussion of the relation between the sign of quantum Fisher information flow and the non-Markovianity has been made.In addition,we find the quantum Fisher information flow and the quantum Fisher information show similar behavior.The reason behind this similarity is the null eigenvalue of the density matrix.