  We study the process of dark matter particles scattering off $^{3,4}$He with
nuclear wave functions computed using an ab initio many-body framework. We
employ realistic nuclear interactions from chiral effective field theory at
next-to-next-to-leading order (NNLO) and develop an ab initio scheme to compute
a general set of different nuclear response functions. In particular, we then
perform an accompanying uncertainty quantification on these quantities and
study error propagation to physical observables. We find a rich structure of
allowed nuclear responses with significant uncertainties for certain
spin-dependent interactions. The approach and results that are presented in
this Paper establish a new framework for nuclear structure calculations and
uncertainty quantification in the context of direct and (certain) indirect
searches for dark matter.
