Quantum interference in spontaneous emission of an atom embedded in a double-band photonic crystal

Quantum interferences in spontaneous emission spectrum from a V-type three-level and a double V-type four-level atom embedded in a double-band photonic band-gap material have been investigated. We demonstrate that there is not only a black dark line, but also a narrow spontaneous line in the spectrum. The dark line results from a destructive interference or singularities of the density of states of the radiation field. The narrow spectral line arises from a population transfer under joint constructive interferences. The spontaneous emission spectrum is compared to the cases of single-band and double-band photonic band-gap reservoirs.