Gouy Phase-Related Effects in the Free-Space Optical Modulation of Free Electrons

TL;DR

This paper theoretically explores how Gouy phase effects in counter-propagating Gaussian beams can be used to efficiently modulate free-electron wave functions, enabling advanced quantum applications with tailored electron states.

Contribution

It introduces a theoretical framework showing Gouy phase's role in free-electron modulation and proposes practical methods for generating specific electron states.

Findings

Gouy phase influences free-electron wave function modulation.

Counter-propagating Gaussian beams can produce comb-like electron spectra.

Feasibility of using chirped femtosecond pulses for experimental demonstration.

Abstract

Modulating the free-electron wave function with light brings new opportunities to create attosecond electron pulse trains, to probe the quantum coherence of systems with significantly improved spatial resolution, and to generate classical and non-classical states of light with wide tunability. It is therefore crucial to efficiently generate free-electron wave functions that are suitable for these applications. In this study, we theoretically investigate an efficient free-space optical modulation of free electrons with two counter-propagating Gaussian beams. We find that the Gaussian beams' Gouy phase not only plays a crucial role in the interaction, but also enables straight-forward generation of valuable free-electron states, including comb-shape spectra with similar amplitudes, and states with high degree of coherence. We also discuss the feasibility of demonstrating these Gouy phase-related effects with chirped femto-second laser pulses. Our study establishes a theoretical foundation and physical intuition about the role of the Gouy phase. It can provide guidance to efficiently shape the free-electron wave function for a wide range of quantum applications.