  Rare earth ions have exceptionally long coherence times, making them an
excellent candidate for quantum information processing. A key part of this
processing is quantum state transfer. We show that perfect state transfer can
be achieved by time reversing the intermediate quantum channel, and suggest
using a gradient echo memory (GEM) to perform this time reversal. We propose an
experiment with rare earth ions to verify these predictions, where an emitter
and receiver crystal are connected with an optical channel passed through a
GEM. We investigate the affect experimental imperfections and collective
dynamics have on the state transfer process. We demonstrate superrandiant
effects can enhance coupling into the optical channel and improve the transfer
fidelity. We lastly discuss how our results apply to state transfer of
entangled states.
