حسین شیرکانی

The aim of this thesis is to determine the force between an atom and a conductive wall. in the quadratic stark shift formula of an atomic energy level,the classical electric field is replaced by the electric field operator and then the expectation is taken in the vacuum state of the electromagnetic field.Using Fluctuation-dissipation theorem in statistical mechanics, the electric field correlation function can be related to the imaginary part of the vector potential Green function. For the system of a conductive wall in vacuum, The Green function is computed and then the atomic energy level shift or in other words, the interaction energy between the atom and the conductive wall is evaluated. Finally, by using the calculated interaction energy, the force exerted on the atom is computed in terms of the distance from the wall and the atomic Polarizability.