All path-symmetric pure states achieve their maximal phase sensitivity in conventional two-path interferometry
All path-symmetric pure states achieve their maximal phase sensitivity in conventional two-path interferometry
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DOI：
10.1103/physreva.79.033822
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发表时间：
2009-03-01
影响因子：
2.9
通讯作者：
Hofmann, Holger F.
中科院分区：
文献类型：
--
作者：
Hofmann, Holger F.
结果表明，在传统的双路径干涉仪的相位估计实现量子克拉美-罗界的条件是，该状态是对称的两个路径的（非物理）交换。由于路径对称性在相移下是守恒的，因此可以在任意偏置相位处实现最大相位灵敏度，这表明路径对称态可以在完全未知相位的贝叶斯估计中实现其量子Cramer-Rao界。
It is shown that the condition for achieving the quantum Cramer-Rao bound of phase estimation in conventional two-path interferometers is that the state is symmetric with regard to an (unphysical) exchange of the two paths. Since path symmetry is conserved under phase shifts, the maximal phase sensitivity can be achieved at arbitrary bias phases, indicating that path-symmetric states can achieve their quantum Cramer-Rao bound in Bayesian estimates of a completely unknown phase.