A team of Swiss and German researchers have demonstrated the generation of electron-photon pair states using integrated photonic circuits on a chip.
The new technique developed by the researchers could enable quantum-enhanced electron microscopy and can add free electrons to the quantum tech toolbox. The study demonstrates a new technique for generating free electron/cavity-photon pairs using photonics chips integrated in an electronic microscope.
A beam of electron microscope passes a built-in photonic chip which has a micro-ring resonator and optical fiber output ports. The team used photonic structure fabricated at EPFL for TEM experiments. When an electron interacts with the vacuum field of the ring resonator, it evolves into an electron-photon pair state.
Obeying the laws of energy and momentum conservation, the electron loses the energy quantum of a photon when one photon is generated. With a newly developed measurement method, the researchers were able to detect both the electron energy and the number of photons generated simultaneously. The findings revealed the underlying electron-photon pair states.
Apart from the observation, these findings implement a novel concept of generating a single electron or photon. The measurement of the pair state enables the ready particle sources, where the detection of one particle indicates the generation of the other. This is one of the necessities for many applications in quantum technology and emerging toolboxes.
“The method opens up fascinating new possibilities in electron microscopy. In the field of quantum optics, entangled photon pairs already improve imaging. With our work, such concepts can now be explored with electrons,” said Max Planck Director Claus Ropers.
One particular challenge for the future quantum technology is how to interface various physical systems. This research work contributes to the emerging field of free-electron quantum optics. It demonstrates a powerful experimental platform for photon-gated electron spectroscopy and imaging.