Naoki, Vicky

In the recent noise budget in alog68912, the frequency noise seems very close to the measured DARM at high frequency. The frequency noise is 1e-20 m/rtHz at 1 kHz and the measured no sqz DARM is 3.2e-20 m/rtHz at 1 kHz in here. The ratio of the frequency noise and the measured no sqz DARM at 1 kHz is 0.31, which corresponds to the effective loss of (0.31)^2~10% due to the frequency noise. 

We calculated the expected squeezing level and the effective total loss as a function of the ratio of the classical noise and the measured no sqz DARM in ASD (attached figure). We assumed that the injection loss is 7%, the readout loss is 20%, and the generated squeezing is 14dB. The phase noise is ignored in the calculation. When the ratio of the classical noise and the measured no sqz DARM is 0.3 as the current noise budget, the expected squeezing level is limited to 4.5dB. If we don't have any classical noise nor other additional loss, we should have ~5.5dB of squeezing. So the classical noise would be one of the main limitation of our squeezing level.