  We present stability and structure of two- and three-alpha systems embedded
in dilute cold neutron matter. By solving a few-alpha Schr\"{o}dinger equation
with quasiparticle properties, i.e., effective mass and induced two- and
three-alpha interactions, which are evaluated in terms of Fermi polarons, it is
shown that $^8 \mathrm{Be}$ and the Hoyle state become bound at densities of
about $10^{-4}$ and $10^{-3}$ of the saturation density, respectively. It is
also seen that, under cold neutron matter environment, both systems become
smaller than the corresponding systems in vacuum. Our results would affect
astrophysical models for stellar collapse and neutron star mergers, as well as
relevant reaction rates for nucleosynthesis.
