  We study the quantum dynamics of N coherently driven two-level atoms coupled
to an optical resonator. In the strong coupling regime the cavity field
generated by atomic scattering interferes destructively with the pump on the
atoms. This suppresses atomic excitation and even for strong driving fields
prevents atomic saturation, while the stationary intracavity field amplitude is
almost independent of the atom number. The magnitude of the interference effect
depends on the detuning between laser and cavity field and on the relative
atomic positions and is strongest for a wavelength spaced lattice of atoms
placed at the antinodes of the cavity mode. In this case three dimensional
intensity minima are created in the vicinity of each atom. In this regime
spontaneous emission is suppressed and the dominant loss channel is cavity
decay. Even for a cavity linewidth larger than the atomic natural width, one
regains strong interference through the cooperative action of a sufficiently
large number of atoms. These results give a new key to understand recent
experiments on collective cavity cooling and may allow to implement fast
tailored atom-atom interactions as well as nonperturbative particle detection
with very small energy transfer.
