Abstract
We theoretically analyze the phase sensitivity of an operatorname{SU}(1,1) 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 operatorname{SU}(1,1) 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.
Highlights
Quantum parameter estimation has recently drawn considerable attention for its fundamental and technological applications [1,2,3,4,5,6,7,8,9,10,11,12]
3 Discussion 3.1 Comparison between various detections We have studied the behavior of the phase sensitivity of an SU(1, 1) interferometer with various input states via product detection
In the case with one coherent state as the input (see Fig. 7(a)), product detection achieved the same phase sensitivity as parity detection, and it was slightly better than homodyne detection and intensity detection
Summary
Quantum parameter estimation has recently drawn considerable attention for its fundamental and technological applications [1,2,3,4,5,6,7,8,9,10,11,12]. It has been pointed out that an SU(1, 1) interferometer with coherent and squeezed vacuum states as inputs can approach the HL with both homodyne and parity detection. Another kind of scheme, product detection, which was first proposed in Ref. The phase sensitivity is improved by a factor of 1/ cosh 2r compared to the case of vacuum inputs, which comes from noise reduction of the squeezed vacuum states. In this case, the phase sensitivity cannot saturate the QCRB
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