Researchers from the University of Regensburg and the University of Michigan have identified a new quantum “miracle material” that could lead to breakthroughs in quantum computing, sensing, and other advanced technologies. The material, chromium sulfide bromide, is capable of magnetic switching—a critical step in the development of future quantum devices. This discovery opens the door for utilizing quantum properties in innovative ways, including encoding information via light (photons), charge, magnetism (electron spins), and vibrations (phonons).
Chromium sulfide bromide has unique properties that allow it to encode quantum information in excitons. An exciton forms when an electron is excited into a higher energy state, leaving behind a hole. The electron and hole then pair up, creating an excitonic state. The new research sheds light on how this material’s magnetic characteristics affect the behavior of excitons, particularly in their confinement to one dimension, a feature that could be crucial for future quantum technologies.
At temperatures below 132 Kelvin (-222°F), the layers of chromium sulfide bromide become magnetized, aligning the spins of the electrons in an antiferromagnetic structure. This means that each layer’s magnetic field flips direction in relation to the next, creating a highly ordered state. Above this temperature, however, the material becomes unmagnetized, with the electron spins pointing in random directions, causing the excitons to expand across multiple layers and move in any direction.
The critical finding here is that when chromium sulfide bromide maintains its antiferromagnetic structure, excitons are confined to a single atomic layer and are further restricted to a single dimension—moving along only one of the two axes within the plane. This confinement helps to preserve quantum information because the excitons are less likely to collide and lose the information they carry. This magnetic order could be the key to building longer-lasting quantum systems.
The research team, led by Rupert Huber at the University of Regensburg, used infrared pulses to excite the chromium sulfide bromide material and induce the formation of excitons. They discovered that these excitons had a surprising fine structure, which means they split into two variations with different energies—a phenomenon that typically wouldn’t happen under normal conditions. This fine structure is crucial because it indicates that the material has the ability to support excitons with different energy states, a feature that could be exploited for advanced quantum information processing.
By applying less energetic infrared pulses along two different axes, the team was able to study the spatial behavior of the excitons. They found that excitons could either be confined to a line or expand into three dimensions, with this configuration being adjustable depending on the magnetic state of the material. This flexibility, controlled by external magnetic fields or temperature changes, could allow for a wide range of quantum experiments and technologies.
The findings also point to a new way of switching between different quantum states. According to Matthias Florian, U-M research investigator and co-author of the study, “Switching between a magnetized and a nonmagnetized state could serve as an extremely fast way to convert photon and spin-based quantum information.” This ability to rapidly switch between states could be a game-changer for quantum computing, as it allows for more efficient conversions of quantum information across different forms (e.g., from photons to spins).
The theoretical framework supporting these findings, developed by Mackillo Kira and his team at the University of Michigan, used quantum many-body calculations to predict the fine-structure splitting in the magnetically ordered material. The team’s calculations also confirmed that the transition from one-dimensional to three-dimensional excitons is responsible for the observed differences in the excitons’ longevity—larger, more mobile excitons have more chances to collide and lose their information.
One of the next big challenges for the researchers is to explore whether excitons, which embody charge separation, can be converted into magnetic excitations in the form of electron spins. If successful, this conversion could provide a powerful way to move quantum information between the different realms of photons, excitons, and spins. This ability to interface between various quantum states could lead to major advancements in quantum information technology and help pave the way for the development of more efficient quantum machines.
In summary, chromium sulfide bromide holds immense potential for the future of quantum computing and other quantum technologies. Its unique ability to manipulate excitons, combined with its magnetic properties, could offer a new pathway for faster, more efficient quantum information processing. As researchers continue to investigate its properties, the material may prove to be a cornerstone in the development of next-generation quantum devices.
By Impact Lab
