  We demonstrate how the anisotropy of the vacuum of the electromagnetic field
can lead to quantum interferences among the decay channels of close lying
states. Our key result is that interferences are given by the {\em scalar}
formed from the antinormally ordered electric field correlation tensor for the
anisotropic vacuum and the dipole matirx elements for the two transitions. We
present results for emission between two conducting plates as well as for a two
photon process involving fluorescence produced under coherent cw excitation
