Scientists can now flip the direction of light-like particles with a tiny magnetic nudge, enabling ultra-fast optical computers.
April 15, 2026
Original Paper
Magnetic switching of self-hybridized exciton-polaritons in CrSBr photonic crystal slabs
arXiv · 2604.11750
The Takeaway
Exciton-polaritons are 'hybrid' particles that are half-light and half-matter, and they move incredibly fast. This paper shows that by using a tiny magnetic field (about 40 mT, or about as much as a strong refrigerator magnet), researchers can completely reverse the direction these particles move. This is a massive 'Holy Grail' for computing because it means we can use magnets to control light signals directly on a chip. It’s the basis for a new kind of 'optical transistor' that could be thousands of times faster than the ones in your current phone. It turns a tiny magnetic flick into a high-speed data switch.
From the abstract
Layered van der Waals antiferromagnet CrSBr supports strong light--matter coupling and formation of magnetically tunable exciton-polaritons, yet active magnetic control over polariton propagation direction has remained elusive. Here, we investigate self-hybridized exciton-polaritons in photonic crystal slabs fabricated from CrSBr flakes and their evolution across the antiferromagnetic-to-ferromagnetic spin-flip transition induced by moderate in-plane magnetic fields. Using angle-resolved reflect