حسین فالی نژاد

The aim of the present work is to determine the spontaneous emission rate of an atom between two semi infinite dielectric medium. Using Fermi Golden Rule for spontaneous emission rate between two eigenstate of an atom offers correlation function in terms of the electric field. In statistical mechanics by applying a fluctuation- dissipation-theorem and kubo formula in the form of the Fermi Golden Rule, according to the imaginary parts relationship vector potential Green Functions is obtained. Finally, the spontaneous emission rate is calculated by using the Green function of a system containing one atom in between two semi infinite slabs. The result is presented in a diagram by considering the Lorentz model for the dielectric function. It is observed that, if the distance from the slabs is about one wavelength, the fluctuation is almost disappeared and the spontaneous emission rate of the atom approach to vacuum spontaneous emission rate. In this method, the explicit form of electric field operator is not required. Thus calculations becomes simpler