Researchers at the University of Manitoba and Lanzhou University in China have successfully demonstrated nonreciprocal control of light speed using a cavity magnonics device. This breakthrough has significant implications for advanced technologies, including high-speed communication systems and quantum information processing devices.
Current methods for manipulating light speed, such as electromagnetically induced transparency (EIT) effects, only allow reciprocal control of group velocity, meaning the speed at which a light beam travels through a medium remains constant regardless of direction. However, nonreciprocal control of light speed could be equally valuable, particularly in developing devices that can direct signals to desired directions at desired speeds.
The researchers employed magnonics-based methods outlined in a paper published in Physical Review Letters to achieve nonreciprocal signal transmission with substantial isolation ratio and flexible controllability. They constructed a hybridized system using microwave photons and magnons in magnetic yttrium iron garnet (YIG) spheres, harnessing the intrinsic chirality of these materials to induce nonreciprocity.
The team sent a microwave pulse into the coupled cavity magnonics system from two directions and found striking delay and advance effects, demonstrating nonreciprocal control of light speed. This method has broad implications for various fields, including signal communications, neuromorphic computing, and quantum circuits.
While the current effect is relatively modest, researchers are working to further improve their methodology, with plans to introduce new techniques to enhance the delay and advance effects. The breakthrough could soon enable the development of cutting-edge technologies that were previously unimaginable.
Source: https://phys.org/news/2025-06-nonreciprocal-cavity-magnonics-device.html