  In the superradiance phenomenon, a collection of non-interacting atoms
exhibits collective dissipation due to interaction with a common radiation
field, resulting in a non-monotonic decay profile. This work shows that
dissipative dipolar-coupled systems exhibit an identical collective dissipation
aided by the nonsecular part of the dipolar coupling. We consider a simplified
dipolar network where the dipolar interaction between the spin-pairs is assumed
to be identical. Hence the dynamics remain confined in the block diagonal
Hilbert spaces. For a suitable choice of the initial condition, the resulting
dynamics require dealing with a smaller subspace which helps extend the
analysis to a larger spin network. To include the nonsecular dipolar
relaxation, we use a fluctuation-regulated quantum master equation. We note
that a successful observation of superradiance in this system requires a weak
system-bath coupling. Moreover, we find that for an ensemble of N spins, the
maximum intensity of the radiation exhibits a nearly quadratic scaling (N^2),
and the dipolar relaxation time follows an inverse square proportionality
(1/N^2); these two observations help characterize the emergence of
superradiance. Our results agree well with the standard results of pure spin
superradiance observed experimentally in various systems.
