Quantum beat phenomenon due to polariton in III–V and IV–IV semiconductors doped with quantum dot

The quantum beat phenomenon due to polaritons has been studied in III–V and IV–IV band gap materials doped with a four-level atom. There is a band gap in the polariton spectrum in these semiconductors due to the coupling of photons and optical phonons. The atom is prepared in such way that it is in top two excited states and emits spontaneously two polaritons with different resonance frequencies. It is found that when the two polariton resonance frequencies lie outside the band gap the quantum beat phenomenon can be observed. On the other hand, when both or one of the resonance frequencies lie within the energy gap no quantum beat phenomenon is observed.