Determine low-frequency technical noise in a LIGO-scale polarimeter

Determine the dominant technical noise sources at low frequencies in a LIGO-scale optical polarimeter designed to measure axial-vector dark-matter-induced polarization rotation, and quantify their impact on the projected sensitivity below approximately 1 Hz.

Background

The paper argues that a long-baseline, high-finesse interferometer such as LIGO could substantially improve searches for axial-vector dark matter through polarization rotation. However, the extrapolation assumes shot-noise-limited operation and does not establish whether mirror birefringence, coating fluctuations, or other technical effects dominate at the relevant low frequencies.

References

For a LIGO-scale polarimeter it is not clear what the dominant technical noise sources would be at low frequencies; for instance, LIGO's mirrors are made of fused silica to avoid birefringence noise.

— Ultralight Axial Dark Matter  (2609.10671 - Hook et al., 9 Sep 2026) in Section 3.1, paragraph “Laboratory Polarimetry”