  We investigate numerically the role of near-field dipole-dipole interactions
on the late emission dynamics of large disordered cold atomic samples driven by
a weak field. Previous experimental and numerical studies of subradiance in
macroscopic samples have focused on low-density samples of pure two-level
atoms, without internal structure, which corresponds to a scalar representation
of the light. The cooperative nature of the late emission of light is then
governed by the resonant optical depth. Here, by considering the vectorial
nature of the light, we show the detrimental role of the near-field terms on
cooperativity in higher-density samples. The observed reduction in the
subradiant lifetimes is interpreted as a signature of the inhomogeneous
broadening due to the near-field contributions, in analogy with the Van der
Waals dephasing phenomenon for superradiance.
