This graph courtesy of LIGO.
Dominant Sources of Noise
- seismic noise
- mechanical vibrations carried through the earth
- transmitted into interferometer via infrastructure
- caused by plate tectonics, ocean tides, logging, cars, ....
- thermal noise
- molecular motion associated with non-zero temperature
- most problematic in the suspension system.
- photon shot noise
- statistical fluctuations in number of photons measuring mirror position
- can be reduced by increasing laser power