  One-dimensional (1D) subwavelength atom arrays display multiply excited
subradiant eigenstates which are reminiscent of free fermions. So far, these
states have been associated with subradiant states with decay rates $\propto
N^{-3}$, with N the number of atoms, which fundamentally prevents detection of
their fermionic features by optical means. In this Letter, we show that
free-fermion states generally appear whenever the band of singly excited states
has a quadratic dispersion relation at the band edge and, hence, may also be
obtained with radiant and even superradiant states. 1D arrays have free-fermion
multiply excited eigenstates that are typically either subradiant or
(super)radiant, and we show that a simple transformation acts between the two
families. Based on this correspondence, we propose different means for their
preparation and analyze their experimental signature in optical detection.

Quantum Physics