Two-ion interference: Bragg scattering and superradiance

Bragg scattering and superradiance, always considered independently, are examined jointly for the case of two trapped ions. The two phenomena are seen to be different representations of the same basic two-ion interference resulting from a common coherent optical preparation. Solutions of a master equation for two four-level atoms show that fringes (spatial interference) and a variation of the spontaneous emission lifetime with ion-ion distance (temporal interference) can occur either simultaneously or separately. Unlike a classical calculation, not all scatterings result in interference, a quantum effect not considered in interpreting recent experiments.