  We consider the interaction of atoms with the quantized electromagnetic field
in the presence of materials with negative index of refraction. Spontaneous
emission of an atom embedded in a negative index material is discussed. It is
shown furthermore that the possibility of a vanishing optical path length
between two spatially separated points provided by these materials can lead to
complete suppression of spontaneous emission of an atom in front of a perfect
mirror even if the distance between atom and mirror is large compared to the
transition wavelength. Two atoms put in the focal points of a lens formed by a
parallel slab of ideal negative index material are shown to exhibit perfect
sub- and superradiance. The maximum length scale in both cases is limited only
by the propagation distance within the free-space radiative decay time.
Limitations of the predicted effects arising from absorption, finite
transversal extension and dispersion of the material are analyzed.
