XU YU,1 XIANG ZHAO,1,2 LUYI SHEN,1,3 YANYAN SHAO,4 JING LIU,4,5 AND XIAOGUANG WANG1,6
1 Zhejiang Institute of Modern Physics, Department of Physics, Zhejiang University, Hangzhou 310027, China
2 Department of Physics, ETH Zurich, 8049 Zurich, Switzerland
3 Department of Engineer, Ecole Polytechnique, France
4 MOE Key Laboratory of Fundamental Physical Quantities Measurement, Hubei Key Laboratory of Gravitation and Quantum Physics, School of Physics, Huazhong University of Science and Technology,Wuhan 430074, China
5 liujingphys@hust.edu.cn
6 xgwang@zimp.zju.edu.cn
Abstract: Mach-Zehnder interferometer is a common device in quantum phase estimation and the photon losses in it are an important issue for achieving a high phase accuracy. Here we thoroughly discuss the precision limit of the phase in the Mach-Zehnder interferometer with a coherent state and a superposition of coherent states as input states. By providing a general analytical expression of quantum Fisher information, the phase-matching condition and optimal initial parity are given. Especially, in the photon loss scenario, the sensitivity behaviors are analyzed and specific strategies are provided to restore the phase accuracies for symmetric and asymmetric losses.
https://doi.org/10.1364/OE.26.016292
