Theory of dispersion in relation to light shifts

Abstract

A quantum mechanical system consisting of one photon interacting with N atoms not far from resonance is considered and an (approximately) stationary solution found for the eigenstates and energy of the interacting system. It is shown that the interaction energy (light shift) is simply related to the atomic polarizability. A consideration of the expectation value of the operator representing the first-order correlation function of an optical field yields a quantum-mechanical interpretation of refractive index.