We investigate the dependence of the measured squeezing level on the local oscillator (LO) intensity noise. The theoretical results indicate that it produces a large measurement error with the increase of the LO intensity noise, but the measurement error has immunity to the product P of the common mode rejection ratio (CMRR) with the LO intensity noise. According to the investigation results and the LO intensity noise, we employ a detector with the CMRR of 67 dB to detect the quantum noise at audio frequencies, the product P of the CMRR with the LO intensity noise is 20 dB below the shot noise limit (SNL), which can induce the measurement error of 0.1 dB for 10 dB of squeezing. Finally, the squeezing level measured at 15.2 kHz is 9.9 ± 0.2 dB. The influence of the intensity noise of the LO, and the electronic noise of the detector is subtracted, the inferred squeezing level is approximately 10.2 ± 0.2 dB. It is extremely important to quantify the requirements of the CMRR of the detector for measuring the squeezing at audio frequency and inferring the real squeezing level.

中文翻译：

---

测得的音频频带压缩水平与本地振荡器强度噪声的关系

我们调查在本地振荡器（LO）强度噪声上测量的压缩水平的依赖性。理论结果表明，随着LO强度噪声的增加，它会产生较大的测量误差，但测量误差对共模抑制比（CMRR）与LO强度噪声的乘积P具有抗扰性。根据调查结果和LO强度噪声，我们使用CMRR为67 dB的检测器来检测音频频率下的量子噪声，乘积PLO强度噪声引起的CMRR低于散粒噪声极限（SNL）20 dB，这会导致10 dB的压缩产生0.1 dB的测量误差。最后，在15.2 kHz处测得的压缩电平为9.9±0.2 dB。减去LO的强度噪声和检测器的电子噪声的影响，推断的压缩电平约为10.2±0.2 dB。量化检测器的CMRR要求非常重要，以便测量音频的压缩并推断出实际的压缩水平。