We have observed interference fringes, like those in Young’s classic experiment, in the laser light
scattered by two trapped atoms. The interference fringes are present only in one polarization of
the scattered light. The polarization dependence is related to the complementarity principle, which
forbids the simultaneous observation of wave-like and particle-like aspects of light. The interference
fringes are due to processes in which a single photon scatters from two atoms. We describe methods
which might be used to observe other interference eects due to two photons scattering from two
atoms.