A general framework for interactions between electron beams and quantum optical systems

TL;DR

This paper introduces a comprehensive theoretical framework for modeling the interactions between free-electron beams and quantum optical systems, enabling advanced quantum control and measurement techniques at the nanoscale.

Contribution

It extends quantum optics to include free-electron beams in arbitrary environments, revealing environment-induced amplification of electron-photon coupling and facilitating new quantum protocols.

Findings

Electromagnetic environments can significantly enhance electron-bound system interactions.

The framework recovers known results and predicts new regimes of strong coupling.

Potential applications include quantum control, imaging, and spectroscopy at the nanoscale.

Abstract

We provide a theoretical framework to describe the dynamics of a free-electron beam interacting with quantized bound systems in arbitrary electromagnetic environments. This expands the quantum optics toolbox to incorporate free-electron beams for applications in highly tunable quantum control, imaging, and spectroscopy at the nanoscale. The framework recovers previously studied results and shows that electromagnetic environments can amplify the intrinsically weak coupling between a free-electron and a bound electron to reach previously inaccessible interaction regimes. We leverage this enhanced coupling for experimentally feasible protocols in coherent qubit control and towards the nondestructive readout and projective control of the electron beam's quantum-number statistics. Our framework is broadly applicable to microwave-frequency qubits, optical nanophotonics, cavity quantum electrodynamics, and emerging platforms at the interface of electron microscopy and quantum information.