Decoherence as a way to measure extremely soft collisions with dark matter

Understand

A new frontier in the search for dark matter (DM) is based on the idea of detecting the decoherence caused by DM scattering against a mesoscopic superposition of normal matter.

• Such superpositions are uniquely sensitive to very small momentum transfers from new particles and forces, especially DM with a mass below 100 MeV.
• Here we investigate what sorts of dark sectors are inaccessible with existing methods but would induce noticeable decoherence in the next generation of matter interferometers.
• We show that very soft, but medium range (0.1 nm - 1 $\mu$m) elastic interactions between nuclei and DM are particularly suitable.