Researchers at Stevens Institute of Technology have coaxed photons into interacting with one another with unprecedented efficiency which is a key advance toward realizing long-awaited quantum optics technologies for computing, communication and remote sensing. The new method works at very low energy levels, suggesting that it could be optimized to work at the level of individual photons.
The team fired a laser beam into a racetrack-shaped micro-cavity carved into a sliver of crystal. As the laser light bounces around the racetrack, its confined photons interact with one another, producing a harmonic resonance that causes some of the circulating light to change wavelength. They boosted its efficiency by using a chip made from lithium niobate on insulator, a material that has a unique way of interacting with light. This hard-to-process material was etched with an ion-milling tool, essentially a nano-sandblaster, with nanometer precision. (Stevens Institute of Technology)