Interference without interference: Directional properties of spontaneous emission

A fully quantum-mechanical description of the spontaneous emission from an excited two-level atom placed in front of the two slit interferometer is gi ven. Global modes of the electromagnetic field in a two slit system are der ived within the Kirchhoff-Huygens diffraction approximation, serving as a b ase for the field quantization. The standard Fermi's golden rule, supplemen ted by a factor coming from the nontrivial mode structure caused by the pre sence of the two slit interferometer, is used to show that interference res ults from the position dependent coupling between the atom and different fi eld modes of the system.