  We analyse the possibility to create two-mode spin squeezed states of two
separate spin ensembles by inverting the spins in one ensemble and allowing
spin exchange between the ensembles via a near resonant cavity field. We
investigate the dynamics of the system using a combination of numerical and
analytic calculations, and we obtain squeezing for a wide range of parameters.
We also investigate the transfer of the squeezing properties to the cavity
field and to an output mode from the cavity. Finally, we investigate how the
squeezing is affected by effects of inhomogeneities which would be present in
solid state implementations of the spin ensembles.
