  We describe a general technique that allows for an ideal transfer of quantum
correlations between light fields and metastable states of matter. The
technique is based on trapping quantum states of photons in coherently driven
atomic media, in which the group velocity is adiabatically reduced to zero. We
discuss possible applications such as quantum state memories, generation of
squeezed atomic states, preparation of entangled atomic ensembles and quantum
information processing.
