Constraints on scalar field dark matter from co-located Michelson interferometers

Understand

Low-mass (sub-eV) scalar field dark matter may induce apparent oscillations of fundamental constants, resulting in corresponding oscillations of the size and the index of refraction of solids.

• Laser interferometers are highly sensitive to changes in the size and index of refraction of the main beamsplitter.
• Using cross-correlated data of the Fermilab Holometer instrument, which consists of twin co-located 40-m arm length power-recycled interferometers, we investigate the possible existence of scalar field dark matter candidates in the mass range between 1.6$\cdot$10$^{-12}$ eV and 1.0$\cdot$10$^{-7}$ eV.
• We set new upper limits for the coupling parameters of scalar field dark matter, improving on limits from previous direct searches by up to three orders of magnitude.