Aritomi and Yuhang

Today we measured the visibility in a more precise way. Because we use PD and we could fix it and measure it for a longer time. Then we take the mean value of two beams power.

After the improvement of BAB to AMC matching, we did this and the result is shown in the attached figure.

Then we tried to measure squeezing. However, we could measure only roughly 3dB of squeezing. And then we checked the visibility. It is only about 88% at the time of measurement. So in principle, we should see more squeezing. But unfortunately, we have again the misalignment of the homodyne. Then I checked these two beams with AMC. I found out both of BAB and LO were misaligned.

We will measure again after the alignment of homodyne. We still don't know why this alignment can be so easy to be misaligned! We had visibility of 99% before all the measurement and then we found 88% after a not decent measurement. This happens within 5 hours!