Researchers at the University of Regensburg and the University of Michigan have shown that chromium sulfide bromide, a quantum “miracle material,” can support magnetic switching. This discovery could have applications in quantum computing and sensing.
Excitons are sometimes effectively confined to a single line within chromium sulfide bromide. The new research offers a detailed theoretical and experimental explanation of how this confinement is linked to the material’s magnetic order.
Chromium sulfide bromide is unique because it can encode information in various ways: electric charge, photons (light), magnetism (electron spins), and phonons (vibrations). Its layers become magnetized at low temperatures, confining excitons (quantum particles) to single lines. This confinement helps quantum information last longer by reducing collisions between excitons.
Mackillo Kira, a U-M professor of electrical and computer engineering, said, “The long-term vision is that you could potentially build quantum machines or devices that use these three or even all four of these properties: photons to transfer information, electrons to process information through their interactions, magnetism to store information, and phonons to modulate and transduce information to new frequencies.”
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The research team studied excitons in chromium sulfide bromide by using pulses of infrared light, each lasting just 20 quadrillionths of a second. They then used another, less energetic infrared laser to push the excitons into slightly higher energy states. Through this process, they discovered two variations of excitons with different energies, whereas normally, they would have identical energies. This splitting of energy states is called fine structure.
The team examined how the material changes in space by sending less energetic pulses along two directions. This revealed excitons that could be confined to a line or expanded in three dimensions, depending on the magnetic state. These configurations can be adjusted using external magnetic fields or temperature changes.
Matthias Florian, a U-M research investigator in electrical and computer engineering and co-first author with Marlene Liebich, a Ph.D. candidate in physics at the University of Regensburg, said, “Since the electronic, photonic, and spin degrees of freedom are strongly intertwined, switching between a magnetized and a nonmagnetized state could serve as an extremely fast way to convert photon and spin-based quantum information.”
The researchers aim to explore whether excitons can be converted to magnetic excitations. This would provide a way to transfer quantum information between photons, excitons, and spins, which could be a game-changer for future electronics and information technology.
Journal Reference:
- Liebich, M., Florian, M., Nilforoushan, N. et al. Controlling Coulomb correlations and fine structure of quasi-one-dimensional excitons by magnetic order. Nat. Mater. (2025). DOI: 10.1038/s41563-025-02120-1
