https://doi.org/10.1140/epjqt/s40507-021-00110-1
Research
Phase sensitivity of an 
interferometer via product detection
1
School of Control and Computer Engineering, North China Electric Power University, 102206, Beijing, China
2
CAS Key Laboratory of Quantum Information, University of Science and Technology of China, 230026, Hefei, China
3
Shanghai Aerospace Control Technology Institute, 201109, Shanghai, China
4
Shanghai Key Laboratory of Aerospace Intelligent Control Technology, 201109, Shanghai, China
5
College of Mathematical and Physical sciences, Qingdao University of Science and Technology, Songling Road 99, 266061, Qingdao, China
6
Microsystems and Terahertz Research Center, China Academy of Engineering Physics, 610200, Chengdu, China
7
Institute of Electronic Engineering, China Academy of Engineering Physics, 621999, Mianyang, China
Received:
13
December
2020
Accepted:
2
August
2021
Published online:
17
August
2021
We theoretically analyze the phase sensitivity of an interferometer with various input states by product detection in this paper. This interferometer consists of two parametric amplifiers that play the role of beam splitters in a traditional Mach–Zehnder interferometer. The product of the amplitude quadrature of one output mode and the momentum quadrature of the other output mode is measured via balanced homodyne detection. We show that product detection has the same phase sensitivity as parity detection for most cases, and it is even better in the case with two coherent states at the input ports. The phase sensitivity is also compared with the Heisenberg limit and the quantum Cramér–Rao bound of the interferometer. This detection scheme can be easily implemented with current homodyne technology, which makes it highly feasible. It can be widely applied in the field of quantum metrology.
Key words: Phase sensitivity / SU(1, 1) interferometer / Product detection
© The Author(s) 2021
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