2D magnetic semiconductor bridges microwaves and light in 300MHz quantum push

A layered magnetic semiconductor could help solve one of the toughest problems in quantum networking. Researchers want to move information between microwave hardware and optical systems. Physicists at The City College of New York have demonstrated microwave-to-optical conversion using chromium sulfide bromide, or CrSBr. Their experiment shows how magnetic waves inside the material can imprint microwave signals onto laser light. The result could support future interfaces between quantum processors and long-distance optical networks. New route to conversion Many quantum processors work with microwave-frequency signals. Optical fiber, however, provides a practical path for moving information across long distances. That mismatch creates a major engineering hurdle for connected quantum systems. A transducer must shift information between frequencies without destroying the signal. The CCNY team used CrSBr to perform that conversion. The material contains magnetic moments that respond collectively when researchers apply a microwave signal. Those collective motions create quasiparticles called magnons. The magnetic waves then interact with excitons inside the semiconductor. Excitons form when an electron becomes bound to a hole. They also interact strongly with light near specific optical resonances. That interaction lets the microwave-driven magnetic motion influence reflected laser light. The optical signal then follows the original microwave excitation coherently. Crsbr opens design options The researchers measured conversion across a microwave bandwidth of roughly 300 megahertz. They also changed the operating frequency by applying an external magnetic field. One detail makes the demonstration particularly notable from an engineering perspective. The team achieved the effect using a bulk crystal without resonators. Optical and microwave resonators can strengthen interactions in frequency-conversion systems. Removing those components could offer greater flexibility during early device development. CrSBr also has a layered structure that could help engineers shrink future devices. Researchers can reduce the material to only a few layers while preserving its magnetic and optical behavior. Pratap Chandra Adak, a postdoctoral researcher in Vinod M. Menon’s group, led the study. He said the material’s structure creates opportunities for stronger interactions and tighter integration. The Laboratory for Nano and Micro Photonics at CCNY conducted the work under Menon’s leadership. Quantum networking still ahead The experiment demonstrates the physical conversion mechanism, but it does not yet transfer individual quantum states. That distinction matters because quantum communication demands extremely high efficiency. The conversion process must also introduce very little additional noise. The researchers identified several ways to improve the system. Thinner CrSBr layers could increase interactions within smaller devices. Microwave resonators and high-quality optical cavities could provide another path toward stronger conversion. The team also pointed to exciton-polaritons as a possible way to manage optical losses. Menon said CrSBr combines strong optical interactions with microwave-frequency magnetism in one crystal. Expanding research into layered magnetic materials could reveal other combinations suited to opto-magnonic devices. The next engineering challenge will be turning the laboratory demonstration into an efficient quantum interface. That step could determine how useful this material becomes for future quantum networks. The study is published in the journal Nature Materials. Get the latest in engineering, tech, space & science - delivered daily to your inbox.Aamir is a seasoned tech journalist with experience at Exhibit Magazine, Republic World, and PR Newswire. With a deep love for all things tech and science, he has spent years decoding the latest innovations and exploring how they shape industries, lifestyles, and the future of humanity.