CCNY physicists convert microwave signals to light in CrSBr crystal

Physicists at The City College of New York demonstrated microwave-to-optical transduction using magnon-exciton coupling in chromium sulfide bromide, according to a Nature Materials paper led by Vinod M. Menon's Laboratory for Nano and Micro Photonics. Microwave-driven magnons in the layered magnetic semiconductor shift exciton energies, so reflected laser light carries a coherent optical signal that tracks the microwave drive. The conversion operated across about 300 megahertz and could be tuned with a magnetic field. The team observed the effect in a bulk crystal without an optical or microwave resonator. Researchers present CrSBr as a materials platform for future interfaces between microwave quantum processors and optical fiber. Transferring individual quantum states will require substantial efficiency gains and careful control of added noise.