Atoms and Light: Quantum Theory

Some of the most basic aspects of the interaction of atoms with light are considered, with emphasis on distinctly quantum-electrodynamical effects. Absorption and stimulated emission are associated with interference between incident and scattered fields. The JaynesCummings model, collapses and revivals, and dressed states are discussed along with related experimental studies in cavity quantum electrodynamics. Entangled states are associated with the interference of probability amplitudes for indistinguishable processes. The no-cloning theorem is reviewed. Von Neumann’s proof concerning hidden variable theories is examined and used to introduce Bell’s theorem and its proof. Resonance fluorescence spectra and photon anti-bunching correlations are calculated and compared with experiment. Photon polarization correlations in atomic cascades are calculated from the perspectives of both source fields and entanglement, and experimental studies of these correlations and Bell inequalities are reviewed.