  We formulate a theory of slow polaritons in atomic gases and apply it to the
slowing down, storing, and redirecting of laser pulses in an EIT medium. The
normal modes of the coupled matter and radiation are determined through a full
diagonalization of the dissipationless Hamiltonian. Away from the EIT resonance
where the polaritons acquire an excited-state contribution, lifetimes are
introduced as a secondary step. With detuning included various four-wave mixing
possibilities are analyzed. We investigate specifically the possibility of
reverting a stopped polariton by reversing the control beam.
