Quantum light controlled by a magnet: a new dial for the computers of the future

Deep in a lab in Regensburg, Germany, physicists built something that sounds like science fiction: a quantum state of matter and light — an exciton-polariton condensate — living inside a layered crystal of chromium sulfide bromide, a magnetic semiconductor. Dr. Heng Zhang, Professor Rupert Huber, and colleagues from the University of Regensburg, Technical University of Munich, and Prague showed that when the condensate forms, the emitted light suddenly brightens more than a hundredfold and locks into step. Then came the real trick: by applying a magnetic field, they could shift the energy of that emitted light — ten times more strongly than previous electrical approaches. Published in Nature Materials, the work creates a new interface between quantum states and magnetism, pointing toward quantum memories and converters that turn microwave signals into light.