Photons are essential in various current research fields and technologies, such as quantum state engineering, which is the foundation of all quantum photonic technologies. Metasurfaces are gaining attention as photon pair sources for quantum research. They can simultaneously transform photons in multiple degrees of freedom, including polarization, frequency, and path.
Researchers have now taken another step toward the quantum research goal. They demonstrated for the first time how metasurfaces generate pairs of photons with different wavelengths. It is possible to pair photons of one wavelength with photons of two or more different wavelengths simultaneously. It allows for the creation of multiple links between photons of different colors. Furthermore, resonances of the metasurface increase the photon emission rate by several orders of magnitude when compared to uniform sources of the same thickness.
Metasurfaces will be crucial in future quantum research. Metasurfaces are causing a paradigm shift in quantum optics by combining ultra-small quantum light sources with far-reaching quantum state engineering possibilities.
The characteristics can help create very large, complicated quantum states required for quantum computation in future quantum research. Metasurfaces have a slim profile and multifunctional operation. It enables the development of more advanced compact devices that combine quantum state generation, transformation, and detection. The sources of quantum photons are getting tinier and tinier, while their possibilities are getting broader and broader.