[Yuhang, Chien-Ming, EleonoraP]

After the improvement of homodyne suggested by Chien-Ming, we measured squeezing again.

This time, we could see only two peaks for homodyne shot noise limited down to 10Hz when LO incident. The 34Hz peak is related to some unknown device(maybe air-conditioner). The characterization of this 34Hz peak is done by Federico and Irene. While another peak is a 50Hz power line. (We didn't perform a low-frequency high-resolution measurement, we may see some peaks at low frequency in that case. We will do it soon.)

For SQZ, we could see the noise floor(5.5dB SQZ) down to 10Hz with several narrow peaks. But notice that now there is still 2.4mV DC signal(for SQZ path) not balanced on homodyne. We could possibly improve CMRR for SQZ path soon.

For anti-SQZ, we could see 13.25dB. And it is also very flat.

The result is shown in the attached figure. We didn't pay attention to the measurement bandwidth of anti-SQZ and LO-shot noise. But we may do it again after the refinement of BAB balance.