Polariton spontaneous emission superradiance and polariton-impurity states in III–V semiconductors

Abstract

In this paper, we study the polariton energy dispersion of two different types of two-level atoms placed within a III–V semiconductor which has a polariton gap due to photon coupling to optical phonons. We employ the spherical harmonic representation to derive the model Hamiltonian within the framework of the dipole resonance approximation. Two polariton impurity states lying within the polariton gap are found. The spontaneous emission rate of a system with two identical two-level atoms placed within a III–V semiconductor is also studied as a function of interatomic distance when the atomic resonance frequency lies in the polariton continuous spectra. It is found that when the interatomic separation between the atoms is small, the polariton-atom system in the symmetric state can radiate a polariton with a probability that is twice that of the independent or single atom case (i.e. superradiance). On the other hand, when the polariton-atom system in the antisymmetric state, the system is prevented from radiating a polariton (i.e. subradiance). Numerical calculations are performed for polariton-impurity states and polariton spontaneous decay rate of the polariton-atom system for GaAs semiconductor.