Electrodynamics of the strong-field approximation and deficiencies of the tunneling model

TL;DR

This paper critiques the use of the tunneling model in strong-field laser physics, emphasizing the fundamental differences between oscillatory electric fields and propagating laser fields, and advocates for proper electrodynamic treatment.

Contribution

It highlights the deficiencies of the tunneling model and advocates for electrodynamic methods tailored to propagating laser fields, clarifying misconceptions in the field.

Findings

Oscillatory electric fields and laser fields are fundamentally different.

Many phenomena attributed to tunneling are better explained by electrodynamics.

Misuse of terminology like KFR and SFA causes conceptual confusion.

Abstract

The strong-field laser physics enterprise is investing important resources in the study of the effects of oscillatory electric fields on matter using the tunneling concept, whereas laser fields are vector fields that do not support the tunneling model. Oscillatory electric fields and propagating plane-wave laser fields are different electrodynamic phenomena, and similarities in their effects diminish as field intensity increases. Major differences are known in the case of very low frequencies where oscillatory electric fields act adiabatically as the frequency declines, in contrast to extreme relativistic effects of strong laser fields. Many supposed new phenomena, such as ATI (Above-Threshold Ionization), channel closing, and stabilization were studied in terms of propagating fields before they came to the attention of the atomic physics community. This illustrates the efficiency of using proper electrodynamic methods for the treatment of laser effects. Problems arising from the conflation of the effects of oscillatory electric fields and propagating fields are exacerbated by using ill-defined nomenclature, such as KFR and SFA, that has been used indiscriminately to apply both to oscillatory electric fields and to propagating fields. Research resources can be applied with much-improved efficiency if proper electrodynamic treatment of laser fields is employed.