Jaynes-Cummings interaction between low-energy free electrons and cavity photons

The Jaynes-Cummings Hamiltonian is at the core of cavity quantum electrodynamics; however, it relies on bound-electron emitters fundamentally limited by the binding Coulomb potential. In this work, we propose theoretically a new approach to realizing the Jaynes-Cummings model using low-energy free electrons coupled to dielectric microcavities and exemplify several quantum technologies made possible by this ap-proach. Using quantum recoil, a large detuning inhibits the emission of multiple consecutive photons, effective-ly transforming the free electron into a few-level system coupled to the cavity mode. We show that this approach can be used for generation of single photons, photon pairs, and even a quantum SWAP gate between a photon and a free electron, with unity efficiency and high fidelity. Tunable by their kinetic energy, quantum free elec-trons are inherently versatile emitters with an engineerable emission wavelength. Hence, they pave the way toward new possibilities for quantum interconnects between photonic platforms at disparate spectral regimes.

Automated summary

This work proposes a new approach to realize the Jaynes-Cummings model using low-energy free electrons coupled to dielectric microcavities and demonstrates several quantum technologies enabled by this method. By utilizing quantum recoil, the emission of multiple consecutive photons can be inhibited through a large detuning, effectively converting the free electron into a few-level system coupled to the cavity mode. The approach enables the generation of single photons, photon pairs, and even a quantum SWAP gate between a photon and a free electron with unity efficiency and high fidelity. The quantum free electrons, tunable by their kinetic energy, serve as versatile emitters with engineerable emission wavelengths, paving the way for quantum interconnects between photonic platforms at different spectral regimes.