Space based gravitational wave detectors are plagued with a parasitic coupling between the jitter of the laser beams relative to one another and the optical path length read out of the interferometer. This noise source was not limiting on ground based GW detectors since the state of the art stabilisation technologies developed for LVK observatories allow to have extremely stable test masses,...
The Einstein Telescope (ET) is a next-generation observatory for gravitational waves. It will push sensitivity beyond current detectors. One major challenge is quantum noise. This limits the detector at both low and high frequencies. The baseline design uses frequency-dependent squeezing to reduce this noise. It includes two filter cavities (FCs) for the low-frequency interferometers and one...
Fabry-Perot cavities are used in present GW interferometers for the frequency-dependent squeezing technique, which reduces quantum noise across the entire observation frequency range. However, they may not offer sufficient control over the squeezing properties required for next-generation detectors, in particular the Einstein Telescope. To this end, different filtering system configurations...
