Quantum Electrodynamic Effects in Few-Electron Atomic Systems

Abstract

Publisher Summary The generally good agreement between theory and experiment has provided an important check on the computational techniques of quantum electrodynamics in the presence of strong fields. Equally important confirmations of quantum electrodynamics in the low-energy regime provided by atomic physics have been obtained from studies of the anomalous magnetic moments of the electron and muon and of the properties of positronium and muonium. The study of quantum electrodynamic effects in one-electron systems has now reached a high state of refinement, both theoretically and experimentally. This chapter briefly summarizes the material contained in the older reviews and then discusses the progress that has been made since 1977, in detail. The Lamb shift of light muonic atoms is dominated by the “vacuum-polarization” term, and approximate numerical values using nonrelativistic wave functions are given here. The chapter provides a discussion on two-electron systems. High-precision calculations for two-electron atoms and ions are complicated by the necessity of simultaneously taking into account relativistic, QED, and electron-correlation effects. There is no unique way of specifying an exact relativistic two-electron Hamiltonian analogous to the Dirac Hamiltonian without at the same time including QED effects to all orders. The analysis of QED effects in atomic systems containing more than two electrons is obscured by the lack of high-precision nonrelativistic eigenvalues and relativistic corrections available for two-electron systems. It therefore becomes more difficult to make a reliable subtraction of these contributions from the observed transition frequencies to reveal the specifically QED effects such as the Lamb shift.