Guo Li-Li, Yu Ya-Fei, Zhang Zhi-Ming
Opt Express. 2018 Oct 29;26(22):29099-29109. doi: 10.1364/OE.26.029099.
We study the phase sensitivity of an SU(1,1) interferometer from two aspects, i.e., the phase estimation determined by the error propagation formula and that by the quantum Cramér-Rao bound (QCRB). The results show that the phase sensitivity by using the intensity detection reaches the sub-shot-noise limit with a coherent state and an m-photon-added squeezed vacuum state (m-PA-SVS) as inputs. The phase sensitivity gradually approaches the Heisenberg limit for increasing m, and the ultimate phase precision improves with the increase of m. In addition, the QCRB can be saturated by the intensity detection with inputting the m-PA-SVS.
我们从两个方面研究了SU(1,1)干涉仪的相位灵敏度，即由误差传播公式确定的相位估计和由量子克拉美-罗界（QCRB）确定的相位估计。结果表明，以相干态和m光子附加压缩真空态（m-PA-SVS）作为输入，利用强度检测的相位灵敏度达到了亚散粒噪声极限。随着m的增加，相位灵敏度逐渐接近海森堡极限，最终相位精度随着m的增加而提高。此外，通过输入m-PA-SVS进行强度检测可以使QCRB饱和。
