Resonant dipole-dipole interaction modifies the energy and decay rate of
electronic excitations for finite one dimensional chains of ultracold atoms in
an optical lattice. We show that collective excited states of the atomic chain
can be divided into dark and bright modes, where a superradiant mode with an
enhanced collective effective dipole dominates the optical scattering. Studying
the generic case of two chain segments of different length and position
exhibits an interaction blockade and spatially structured light emission.
Ultimately, an extended system of several interfering segments models a long
chain with randomly distributed defects of vacant sites. The corresponding
emission pattern provides a sensitive tool to study structural and dynamical
properties of the system.Comment: 8 pages, 12 figure
