Dynamical stabilization by vacuum fluctuations in a cavity: Resonant electron scattering in the ultrastrong light-matter coupling regime

TL;DR

This paper presents a theory showing how vacuum fluctuations in a cavity can stabilize polariton states and enable resonant electron scattering, potentially leading to new sources of nonclassical light.

Contribution

It introduces a novel theoretical framework for electron-cavity interactions in the ultrastrong coupling regime, highlighting vacuum fluctuation effects on electron scattering.

Findings

Vacuum fluctuations stabilize polariton states in a cavity.

Resonant electron scattering emits cavity photons.

Potential for free-electron sources of nonclassical light.

Abstract

We developed a theory of electron scattering by a short-range repulsive potential in a cavity. In the regime of ultrastrong electron coupling to the cavity electromagnetic field, the vacuum fluctuations of the field result in the dynamical stabilization of a quasistationary polariton state confined in the core of the repulsive potential. When the energy of a free electron coincides with the energy of the confined state, the extremely efficient resonant nonelastic scattering of the electron accompanied by emission of a cavity photon appears. This effect is discussed as a basis for possible free-electron sources of nonclassical light.