Near field in quantum electrodynamics: Green functions, Lorentz condition, "nonlocality in the small", frustrated total reflection

Abstract

Investigation of near field of QED requires the refuse from an averaging of the Lorentz condition that smooths out some field peculiarities. Instead of it Schwinger decomposition of the 4-potential with the Bogoliubov method of interaction switching in time and in space regions is considered. At such approach near field is describable by the part of covariant Green function of QED, the fast-damping Schwinger function formed by longitudinal and scalar components of Aμ none restricted by light cone. This description reveals possibility of superluminal phenomena within the near field zone as a "nonlocality in the small". Some specification of Bogoliubov method allows, as examples, descriptions of near fields of point-like charge and at FTIR phenomena. Precisely such possibilities of nonlocal interactions are revealed in the common QED expressions for the Van-der-Waals and Casimir interactions and in the F\"{o}rster law. Key words: Lorentz condition, near field, propagators, superluminal, FTIR. PACS: 03.30.+p, 12.20.-m, 13.40.-f, 68.37.Uv.