Quantum Limitation to the Coherent Emission of Accelerated Charges

TL;DR

This paper investigates how quantum effects influence the coherence of electromagnetic emission from accelerated charges, revealing that quantum recoil can diminish classical coherence predictions even at low nonlinearity.

Contribution

It introduces a quantum parameter linking recoil and wave packet width, showing quantum effects can reduce classical coherence in strong-field QED.

Findings

Quantum recoil affects coherence in electromagnetic emission.

Classical coherence predictions are diminished by quantum effects.

A new quantum parameter governs the coherence behavior.

Abstract

Accelerated charges emit electromagnetic radiation. According to classical electrodynamics if the charges move along sufficiently close trajectories they emit coherently, i.e., their emitted energy scales quadratically with their number rather than linearly. By investigating the emission by a two-electron wave packet in the presence of an electromagnetic plane wave within strong-field QED, we show that quantum effects deteriorate the coherence predicted by classical electrodynamics even if the typical quantum nonlinearity parameter of the system is much smaller than unity. We explain this result by observing that coherence effects are also controlled by a new quantum parameter which relates the recoil undergone by the electron with the width of its wave packet in momentum space.