  Here we demonstrate generating and storing entanglement in a solid state
spin-wave quantum memory with on-demand read out using the process of rephased
amplified spontaneous emission (RASE). Amplified spontaneous emission (ASE),
resulting from an inverted ensemble of Pr$^{3+}$ ions doped into a Y$_2$SiO$_5$
crystal, generates entanglement between collective states of the praseodymium
ensemble and the output light. The ensemble is then rephased using a four-level
photon echo technique. Entanglement between the ASE and its echo is confirmed
and the inseparability violation preserved when the RASE is stored as a
spin-wave for up to 5 $\mu$s. RASE is shown to be temporally multimode with
almost perfect distinguishability between two temporal modes demonstrated.
These results pave the way for the use of multimode solid state quantum
memories in scalable quantum networks.
