  We address ultracold $N$-atom degenerate cascade systems and show that
stationary subradiant states, already observed in the semiclassical regime,
also exist in a fully quantum regime and for a small number of atoms. We
explicitly evaluate the amount of stationary entanglement for the two-atom
configuration and show full inseparability for the three-atom case. We also
show that a continuous variable description of the systems is not suitable to
detect entanglement due to the nonGaussianity of subradiant states.

Quantum Physics