  Dark sectors lying beyond the Standard Model and containing sub-GeV particles
which are bilinearly coupled to nucleons would induce quantum forces of the
Casimir-Polder type in ordinary matter. Such new forces can be tested by a
variety of experiments over many orders of magnitude. We provide a generic
interpretation of these experimental searches and apply it to a sample of
forces from dark scalars behaving as $1/r^3$, $1/r^5$, $1/r^7$ at short range.
The landscape of constraints on such quantum forces differs from the one of
modified gravity with Yukawa interactions, and features in particular strong
short-distance bounds from molecular spectroscopy and neutron scattering.
