Quantum Switch: How Magnetism Harnesses Excitons for Information Revolution

Chromium sulfide bromide (CrSBr) stands out among materials studied by scientists due to its exceptional ability to manage quantum data in manners unmatched by any other compound. This may be the sole known substance capable of storing information through light, electrical charges, vibration akin to sound waves, and magnetic fields. However, this discovery is just scratching the surface; recent research unveils yet another remarkable feature of this extraordinary material.

Researchers have found that CrSBr exhibits unusual magnetic characteristics enabling it to efficiently capture and manage excitons. As explained by the study authors, "An 'exciton' occurs when an electron transitions from its 'ground' energy level within the semiconductor to a higher energy level, thereby creating a 'hole'. This pair consisting of the electron and the hole constitutes an exciton."

The study indicates that the magnetic state of chromium sulfide bromide can be toggled on or off by adjusting the temperature. This alteration in magnetism has an impact. how the excitons inside the material behave.

"The magnetic order presents a novel control parameter for manipulating excitons and their interactions. This might revolutionize the field of electronics and information technology," stated Rupert Huber, an author of the study and a physics professor at the University of Regensburg in Germany. said .

Harnessing excitons as never before

Excitons play a crucial role as they enable us to grasp the movement of light and energy within materials, which is particularly significant for advancements in technology such as solar panels, LED lights, and quantum computers. In this research, the scientists conducted an intriguing experiment aimed at observing exciton behavior within CrSBr.

They utilized ultrashort laser pulses that lasted merely for 20 quadrillionths of a second (20 x 10). ^-15 seconds) to create excitons Inside CrSBr, they then employed a secondary laser to nudge the excitons subtly into somewhat elevated energy levels.

What they discovered was unexpected: rather than possessing just one energy level, the excitons divided into two separate energy levels, a process referred to as fine structuring. Additionally, it became evident that the behavior of these excitons varied based on their movement direction within the substance.

For example, when exposed to extremely low temperatures (below -222°F or 140 Kelvin), CrSBr exhibits magnetic properties. Consequently, within each individual layer, the minute magnetic orientations of the electrons align themselves; however, these alignments point in contrasting directions between successive layers. This phenomenon is referred to as an antiferromagnetic arrangement. antiferromagnetic state Here, excitons are observed to get confined within a single layer, traveling exclusively in one dimension.

Nevertheless, when the temperature rises above 132 Kelvin, CrSBr ceases to exhibit magnetic properties; instead, warmth causes the electron spins to orient randomly. Under these conditions, excitons escape confinement. Rather than being restricted, they extend across several layers and circulate freely in every direction, demonstrating three-dimensional characteristics.

The capability to capture or let go of excitons depending on temperature (or magnetic fields) functions akin to toggling a magnetic switch. This unveils a robust method for managing the transmission of data within quantum devices.

"Given that the electronic, photonic, and spin aspects are highly interconnected, transitioning between a magnetized and non-magnetized condition might offer an incredibly rapid method for converting photon and spin-driven quantum data," stated Matthias Florian, who is part of the research group.

The next step is information conversion

The study authors now aim to explore whether excitons can serve as a bridge for transferring quantum information between different physical systems. For example, can a message carried by an exciton be passed on to the spin of an electron?

This is important because if scientists can convert quantum information smoothly between photons, excitons, and electron spins, it would make quantum systems significantly more adaptable and unlock new opportunities for developing more sophisticated technologies.

“The long-term vision is, 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,” said Mackillo Kira, one of the study authors.

The study is released in the publication Nature Materials .