Field quantization

Abstract

Field or second quantization is carried through for electromagnetism, giving creation and annihilation operators for photons. Vacuum energy arises from field fluctuations, which causes the Casimir force and the Lamb shift of spectral lines. The connection between absorption, spontaneous emission and the stimulated emission of radiation is shown to emerge naturally. This yields Einstein’s equations for radiation in thermal equilibrium. The prerequisites for lasing, the operation and the properties of lasers are described. Fully coherent (Laser) states are expressed in terms of Fock states. The first and second order coherence of lasers and thermal sources are worked out. The Hanbury Brown and Twiss experiment is described and the application of the principle to determining stellar sizes and interaction regions in particle collisions from meson correlations are described.