Quantum Limitation to the Coherent Emission of Accelerated Charges

Understand

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.