Diffraction at a time grating in electron-positron pair creation from vacuum

TL;DR

This paper investigates electron-positron pair creation from vacuum under time-dependent electric fields, revealing interference patterns and coherence effects beyond traditional WKB theory through quantum-field theoretical analysis.

Contribution

It introduces a quantum-field theoretical framework to analyze interference structures in pair creation, extending understanding beyond WKB approximations and exploring coherence conditions.

Findings

Interference patterns in pair production probability distributions.

Coherence peaks are limited by nonadiabatic phase transitions.

Conditions for loss of nearly perfect coherence are identified.

Abstract

The Sauter-Schwinger process of electron-positron pair creation from vacuum, driven by a sequence of time-dependent electric-field pulses, is studied in the framework of quantum-field theoretical approach. As demonstrated by our numerical results, the probability distributions of produced pairs exhibit intra- and inter-pulse interference structures. We show that such structures can be observed beyond the regime of applicability of the WKB theory, which was the focus of earlier investigations. Going beyond these developments, we perform the analysis of the time-evolution operator for an arbitrary eigenmode of the fermionic field. This shows that a perfect coherent enhancement of the inter-pulse peaks can never be reached. A nearly perfect coherence, on the other hand, is due to nonadiabatic transitions at avoided crossings of the phases defining the unitary time evolution. This analysis allows us to determine the conditions under which the nearly perfect coherence is lost.