Shaping Quantum Photonic States Using Free Electrons

TL;DR

This paper investigates how free electrons interacting with optical cavities can be used to generate and control various quantum states of light, potentially enabling new quantum photonic technologies.

Contribution

It introduces a theoretical framework for shaping quantum states of light through electron-photon interactions, including methods for generating displaced and Fock states.

Findings

Electron energy combs enable photon displacement operations.

Repeated electron-cavity interactions can produce specific Fock states.

Theoretical models for single and multiple electron interactions with cavities.

Abstract

It is a long-standing goal to generate robust deterministic states of light with unique quantum properties, such as squeezing, sub-Poissonian statistics and entanglement. It is of interest to consider whether such quantum states of light could be generated by exploiting interactions with free electrons, going beyond their already ubiquitous use in generating classical light. This question is motivated by developments in electron microscopy, which present a new platform for manipulating photons through their interaction with quantum free electrons. Here, we explore the shaping of photon statistics using the quantum interactions of free electrons with photons in optical cavities. We find a variety of quantum states of light that can be generated by a judicious choice of the input light and electron states. For example, we show how shaping an electron into an energy comb can provide an implementation of a photon displacement operation, allowing, for instance, the generation of displaced Fock and displaced squeezed states. We also show how one can generate a desired Fock state by repeated interactions of electrons with a cavity, followed by measurements. We develop the underlying theory of the interaction of both a single and many consecutive electrons with a common cavity mode. Looking forward, by exploiting the degrees of freedom of arbitrary electron-photon quantum states, we may achieve complete control over the statistics and correlations of output photonic states, leading to the generation of novel quantum states of light.