Generating correlated pairs of free electrons and waveguide photons

In this talk, we establish chip-based integrated silicon nitride photonics as a platform for experiments on the interactions between free electrons and light. Placing the fibre-coupled microresonators in a transmission electron microscope, we observe a quantised loss of energy for electrons passing the waveguide in an aloof geometry and inelastically scattering off the initially empty cavity modes while generating photons. Coincidence measurements performed on both particles reveal the common origin of these correlated electron-photon pairs, while post-selection allows for enhanced imaging of the resonator’s optical modes and promises applications as a high-fidelity heralded photon Fock state source.