Absolute sensitivity is measured for the phase measurement in an SU(1,1) type interferometer, and the results are compared to that of a Mach–Zehnder interferometer operated under the condition of the same intra-interferometer intensity. The interferometer is phase locked to a point with the largest quantum noise cancellation, and a simulated phase modulation is added in one arm of the SU(1,1) interferometer. Both the signal and noise level are estimated at the same frequency range, and we obtained 3 dB improvement in sensitivity for the SU(1,1) interferometer over the Mach–Zehnder interferometer. Our results demonstrate a direct phase estimation and may pave the way for practical applications of a nonlinear interferometer.

中文翻译：

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SU（1,1）型干涉仪中相位测量的绝对灵敏度

在SU（1,1）型干涉仪中测量绝对灵敏度以进行相位测量，并将结果与​​在相同干涉仪内强度条件下工作的Mach-Zehnder干涉仪的灵敏度进行比较。干涉仪被锁相到具有最大量子噪声消除的点，并且在SU（1,1）干涉仪的一个臂中添加了模拟的相位调制。信号和噪声电平都在相同的频率范围内估算，与Mach–Zehnder干涉仪相比，SU（1,1）干涉仪的灵敏度提高了3 dB。我们的结果证明了直接的相位估计，可能为非线性干涉仪的实际应用铺平道路。