A magnetic switch traps quantum storage media in one dimension. (Image credit: Brad Baxley, Part to Whole. For use in reporting this research, DOI: 10.1038/s41563-025-02120-1)
Researchers have figured out how to use a quantum material to harness the power of magnetism to store quantum information – thanks to its ability to support magnetic switching (when magnetic polarization reverses direction). They say this could lead to more efficient quantum computing and sensors by significantly increasing the lifetime of quantum states.
Chromium bromide sulfide is a unique material that resembles filo dough (thin, folded layers of dough) due to its structure consisting of only a few atomic layers. Scientists consider it extremely promising for quantum devices because many of its properties can be used for different ways of storing information. It can be used to store data through electrical charge, like photons (like light), through magnetism (due to electron spin), and even through phonons, like sound vibrations. One of the many ways in which chromium bromide sulfide can serve as an information store is through excitons, quasiparticles that form when an electron and its hole combine. When a photon moves from its ground energy state, it essentially leaves behind the hole where it was located. Even though they are separated, the photon and hole remain paired and form an exciton.
Previous studies have shown that these excitons can sometimes form in a linear configuration in the material. However, these excitons also exhibit unusual magnetic properties.
At temperatures below 132 degrees Kelvin (-222 degrees Fahrenheit or -141 degrees Celsius), the layers of material become magnetized, the electrons align, and the direction of the magnetic field changes for each layer.
As the temperature of chromium sulfide bromide increases above 132 K, the material loses its magnetization as the electrons begin to move in random directions. In this unmagnetized state, excitons are no longer held and spread across several layers of the material.
However, when the chromium sulfide bromide is only one atom thick, the excitons are confined to one dimension. When applied in a quantum device, this confinement could allow the quantum information in the excitons to persist much longer than would otherwise be the case, since the excitons are less susceptible to collisions and loss of information due to decoherence (loss of quantum information due to interference).
Quantum information in one dimension
In a new study published February 19 in the journal Nature Materials, the scientists reported creating excitons in chromium bromide sulfide by firing pulses of infrared light in 20 bursts, each lasting just 20 quadrillionths of a second (20 x 10-15). They then used a second infrared laser to excite the excitons into a higher energy state, and found that they had created two different variations of excitons, even though they would otherwise have had identical energy states.
When less energetic pulses were fired from different axes, the researchers found that direction-dependent excitons could be confined to a single line or extended into three dimensions. The transition from one-dimensional to three-dimensional excitons explained how long excitons could exist without colliding with each other.
“Magnetic order is a new regulator for the formation of excitons and their interactions. This could be a turning point for future electronics and information technology,” said study co-author Rupert Huber, professor of experimental and applied physics at the University of Regensburg, Germany.
One key area the research team plans to pursue is to explore whether these excitons can be converted into magnetic excitations in the electron spin of the material. If they can do this, it could be a useful way to convert quantum information between different subatomic particles (photons, excitons, and electrons).
Switching between magnetized
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