Some analysis on theoretical estimation of the squeezing phase noise and optical loss.
The amount of squeezing and anti-squeezing levels depends on 3 main factors:
- Non-linear gain (NLG)
- Phase noise
- Optical loss (Efficiency)
Generally, more squeezing (which is our goal) can be achieved with higher NLG, lower phase noise and lower optical loss. However, the 3 factors have different impacts on squeezing and anti-squeezing.
Given a certain practical amount of optical loss, the asqz level is largely decided by the NLG, but less sensitive to the phase noise, whereas the sqz level depends more on the phase noise amount. A high optical loss (low efficiency) ruins both of the sqz and asqz.
Therefore, given several sqz-asqz value pairs under different NLG's, we can estimate the amount of optical loss and phase noise in the experiment. This can also imply any of bias in our NLG measurements.
Summary of results from Nutsinee's measurements:
| NLG | SQZ (dB) | aSQZ (dB) | alog |
| 3 | 3.69 | 6.31 | 43764 |
| 3.6 | 3.97 | 7.56 | 43782 |
The 1st and 2nd plots show the phase noise and efficiency estimation for each group of measurement.
50mrad phase noise and 70% efficiency gives a well-fitting to these data, and based on these value the 3rd plot shows the sqz/asqz level vs. NLG.
Several reviews in the to-do-list for justify this estimation:
- NLG Measurements review
- Optical loss budget for squeezing (~11% loss from current budget by Terry)
- Phase noise measurements (and calculation from CLF?)
