Title: Phase estimation of phase shifts in two arms for an SU(1,1) interferometer with coherent and squeezed vacuum states Show Chinese title

Title: 具有相干和压缩真空态的SU(1,1)干涉仪两臂相移的相位估计

Abstract: We theoretically present the quantum Cram\'{e}r-Rao bounds (QCRB) of an SU(1,1) interferometer for Gaussian states input with and without the internal photonic losses. The phase shifts in the single arm and in the double arms are studied and the corresponding analytical expressions of quantum Fisher information with Gaussian input states are presented. Different from the traditional Mach-Zehnder interferometer, the QCRB of single arm case is slightly higher or lower than that of double arms case depending on the input states. With a fixed mean photon number and for pure Gaussian state input, the optimal sensitivity is achieved with a squeezed vacuum input in one mode and the vacuum input in the other. We compare the QCRB with the standard quantum limit and Heisenberg limit. In the case of small internal losses the QCRB can beat the standard quantum limit. Show Chinese abstract

Abstract: 我们从理论上给出了具有内部光子损耗和无内部光子损耗高斯态输入的 SU(1,1) 干涉仪的量子克拉美-罗下界（QCRB）。研究了单臂和双臂中的相位变化，并给出了高斯输入态对应的量子费雪信息的解析表达式。不同于传统的马赫-曾德尔干涉仪，单臂情况下的 QCRB 比双臂情况下的稍高或稍低，具体取决于输入态。对于固定平均光子数且纯高斯态输入的情况下，在一个模式中使用压缩真空输入而在另一个模式中使用真空输入可以实现最优灵敏度。我们将 QCRB 与标准量子极限和海森堡极限进行了比较。在内部损耗较小的情况下，QCRB 可以超越标准量子极限。