Andrei, Sheila
This morning we are taking the commissioning time to get a sqz data set similar to 77133 with longer averaging time and no other changes to the IFO happening in parrallel.
- NLG maximium seed is 0.2146
- unamplified seed (pump blocked) is 0.0127
- dark offset (seed and pump blocked) -2.55e-5
- NLG = 16.9
Data times:
- No SQZ- 15:59:30-16:19:00 UTC (1399219188 -1399220361) there was a large glitch right at the end of the time (ref 0)
- ran scan SQZ alignment, results are here: 240508092035 everything went well except COMM P which seems to not have found the maximum. We manually moved ZM4 + ZM6 down in pitch and restarted SCAN SQZ alignment.
- FDS 16:36:48- 16:46:48 (1399221426) RF6 phase 175.81 (ref1)
- FDS -10deg 16:47:14- 17:02:57 RF6 phase 165.79 (ref2) big glitch at 16:52:57
- FDS + 10 deg 17:03:14-17:13:14 UTC RF6 phase 185.84 (ref 3)
- +mid sqz FDS 17:14:01-17:28:45 RF6 phase 206.83 (ref4) big glitch at 17:18-17:19
- FDAS 17:33:37-17:44:50 RF6 phase 106.19 (CLF servo sign -) ref 5 (glitch at end so we stoped the time a few seconds early. glitch at 17:42:45
- -mid sqz FDS 17:46:36-17:56:36 RF6 phase 104.84 ref6
- - mid FIS 17:58:28-18:08:28 RF6 phase 104.84 small glitch 18:02:30 ref 7
- FIS 18:08:49-18:18:49 RF6 phase 175.81 ref 8
- +mid FIS 18:19:00-18:35:00 RF6 phase 206.83 big glitch 18:24 ref 9
- FIAS (106.19 CLF servo sign -) 18:35:45-18:45:45 ref 10
- no sqz repeat 18:47:00-18:57:00 ref11
- FDS -10 deg 19:00:30-19:10:35 RF6 165.79 ref 12 (repeating because we didn't get enough time the first time)
After this data collection, we ran SCAN_SQZANG, which resulted in a demod phase of 184.35
In the attached screenshots the units are different in the top and bottom plots, I filed a dtt bug because the plot disappears if I try to change the units on the bottom plot: 403
Late post of the subtracted quantum noises (FIS (+FDAS) and FDS).
While differences in dB look big on those plots, see these comparisons of just the quantum noise models relative to the total noise (FIS and FDS) -- below 100 Hz, these are really marginal / small differences in the quantum noise, which by 100 Hz is order 2-5 times below total DARM noise. So inferring low-frequency (<100 Hz) quantum noise paramters does require quiet glitch-free (rejected) long averaging times to nail down. So, this helps appreciate why figuring out low-freq quantum noise models is kinda tricky, given we can only measure the total noise in different sqz configurations. So far this analysis code is here.
Note due to the glitch in the no-sqz time, median averaging is required, or else we need to truncate to before the glitch (e.g. 400 seconds vs the full 600). Updating the noise budget environment to run median averaging, which requires the updated (but not fully updated) version of scipy, is underway so noise budget code can use median averaging.
I think several things related to quantum noise budgeting have changed since this sqz dataset in May 2024 (i.e. post-vent, including srcl detuning & fc detuning lho79929 amongst many other things) - so likely another sqz dataset in this vein is needed for more accurate quantum noise budgeting in O4b.
The parameters here in the figure titles are what was used to produce the quantum noise trace. It is rather "simple" at this stage, it does not yet include mode-mismatch, etc. The models do not match measurements well below 40-60 Hz, in part because noisy measurements (note the short 10-min measurement times).
Notably anti-squeezing does not match models well below 80 Hz, see anti-sqz vs. models after subtracting classical noise here. Including mode-mismatches may be able to resolve some of the discrepancies, but so far kinda unclear.
