Lifting shell structures in the dynamically assisted Schwinger effect in periodic fields

TL;DR

This paper investigates how superimposing two periodic electric fields enhances the Schwinger pair creation effect, revealing lifted shell structures and resonance amplification effects in phase space.

Contribution

It demonstrates that a weak high-frequency field can significantly enhance pair creation and lift shell structures caused by a strong low-frequency field in a finite-time setting.

Findings

Strong enhancement of pair creation by orders of magnitude.

Lifted shell structures in phase space due to high-frequency field.

Resonance amplification leading to residual shell structures.

Abstract

The dynamically assisted pair creation (Schwinger effect) is considered for the superposition of two periodic electric fields acting a finite time interval. We find a strong enhancement by orders of magnitude caused by a weak field with a frequency being a multitude of the strong-field frequency. The strong low-frequency field leads to shell structures which are lifted by the weaker high-frequency field. The resonance type amplification refers to a new, monotonously increasing mode, often hidden in some strong oscillatory transient background which disappears during the smoothly switching off the background fields, thus leaving a pronounced residual shell structure in phase space.