  A very promising recent trend in applied quantum physics is to combine the
advantageous features of different quantum systems into what is called "hybrid
quantum technology". One of the key elements in this new field will have to be
a quantum memory enabling to store quanta over extended periods of time.
Systems that may fulfill the demands of such applications are comb-shaped spin
ensembles coupled to a cavity. Due to the decoherence induced by the
inhomogeneous ensemble broadening, the storage time of these quantum memories
is, however, still rather limited. Here we demonstrate how to overcome this
problem by burning well-placed holes into the spectral spin density leading to
spectacular performance in the multimode regime. Specifically, we show how an
initial excitation of the ensemble leads to the emission of more than a hundred
well-separated photon pulses with a decay rate significantly below the
fundamental limit of the recently proposed "cavity protection effect".
