  In this paper we construct bosonic short range entangled (SRE) states in all
spatial dimensions by coupling a $Z_2$ gauge field to fermionic SRE states with
the same symmetries, and driving the $Z_2$ gauge field to its confined phase.
We demonstrate that this approach allows us to construct many examples of
bosonic SRE states, and we demonstrate that the previous descriptions of
bosonic SRE states such as the semiclassical nonlinear sigma model field theory
and the Chern-Simons field theory can all be derived using the fermionic SRE
states.
