  Strongly interacting fermionic atoms are shown to develop $\eta$-pairing
superfluid correlations in a nonequilibrium steady state in the presence of
spontaneous emission of light from atoms. On the basis of the Hubbard model
subject to spontaneous decay between internal spin states, we show that
prohibition of radiative decay due to the Pauli exclusion principle and
destructive interference between doublon-decay processes lead to nonequilibrium
$\eta$ pairing. Because of the non-thermal nature of the steady state, pair
correlations arise even from a completely uncorrelated infinite-temperature
initial state, allowing coherent atom pairs to be formed at high temperatures.
Experimental implementation with fermionic atoms in an optical lattice is
discussed.
