Schwinger effect in inhomogeneous electric fields

TL;DR

This paper investigates the Schwinger effect in inhomogeneous electric fields using the equal-time Wigner formalism, deriving analytic solutions and performing ab initio simulations to understand pair creation in realistic laser pulse scenarios.

Contribution

It provides new analytic expressions for the Wigner function in time-dependent fields and performs the first ab initio simulation of the effect in space- and time-dependent electric fields.

Findings

Analytic solutions for the Wigner function in static and pulsed fields.

Simulation of pair creation dynamics in realistic laser pulse models.

Calculation of observables like charge density and particle number over time.

Abstract

The vacuum of quantum electrodynamics is unstable against the formation of many-body states in the presence of an external electric field, manifesting itself as the creation of electron-positron pairs (Schwinger effect). This effect has been a long-standing but still unobserved prediction as the generation of the required field strengths has not been feasible so far. However, due to the advent of a new generation of high-intensity laser systems such as the European XFEL or the Extreme Light Infrastructure (ELI), this effect might eventually become observable within the next decades. Based on the equal-time Wigner formalism, various aspects of the Schwinger effect in electric fields showing both temporal and spatial variations are investigated. Regarding the Schwinger effect in time-dependent electric fields, analytic expressions for the equal-time Wigner function in the presence of a static as well as a pulsed electric field are derived. Moreover, the pair creation process in the presence of a pulsed electric field with sub-cycle structure, which acts as a model for a realistic laser pulse, is examined. Finally, an ab initio simulation of the Schwinger effect in a simple space- and time-dependent electric field is performed for the first time, allowing for the calculation of the time evolution of various observables like the charge density, the particle number density or the number of created particles.