We propose a scheme to create a metastable state of paired bosonic atoms in
an optical lattice. The most salient features of this state are that the
wavefunction of each pair is a Bell state and that the pair size spans half the
lattice, similar to fermionic Cooper pairs. This mesoscopic state can be
created with a dynamical process that involves crossing a quantum phase
transition and which is supported by the symmetries of the physical system. We
characterize the final state by means of a measurable two-particle correlator
that detects both the presence of the pairs and their size