Collective effects in the dynamics of driven atoms in a high-Q resonator

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.