Generation of nonclassical photon states via free electron scattering

Nonclassical states of light, such as photon number states, are crucial in multiple regions of quantum technology. However, many states are still difficult to achieve. A potential new source of quantum states is free electron scattering. Especially coherent, parametric cathodoluminescence preserves the quantum phase between free electrons and light and enables wavelength tuning. Here, we demonstrate the generation of nonclassical multiphoton states via coherent cathodoluminescence, correlating electrons and photons in time and energy. We characterize the electron-heralded photons, observing the correlation between the electron energy loss and generated photon number and measuring an antibunching behavior in the electron-heralded optical intensity correlation. In the future, this combination of cathodoluminescence and correlation detection may form a versatile source of complex quantum photon states.