DIPOLE-DIPOLE INTERACTION IN OPTICAL CAVITIES

At the most fundamental level of quantum electrodynamics, there is no such thing as two-body interactions between atoms. The potentials that describe these interactions are effective potentials resulting from a series of approximations whose validity depends on the precise situat ion at hand. Considering a one-dimensional geometry for simplicity, we discuss under which conditions the familiar form of the near-resonant dipole-dipole interaction is valid, paying particular attention to th e effects of interatomic propagation of light, and to what extent it c an be modified in the tailored electromagnetic environments provided b y optical resonators. We find that once the atoms have established tha t they are inside a resonator, the dipole-dipole potential may or may not remain a useful concept, depending upon the strength of the atom-f ield interaction. In the weak-coupling regime, one finds a two-body di pole-dipole interaction that can be enhanced or inhibited by varying t he atom-field detuning. In the strong-coupling regime, by contrast, th e two-body dipole-dipole potential ceases to be meaningful. [S1050-294 7(97)05612-6].