Quantum encoding of structured light into in-plane topological spin textures

In the quest to build faster, smaller, and more efficient computers, scientists have long looked to the magnetic properties of materials to store information. Instead of using electric currents to flip bits on a hard drive, which generates heat and requires significant power, researchers are exploring "topological spin textures." These are tiny, stable swirls of magnetic orientation that behave like solid particles, even though they are made of nothing more than the collective alignment of atoms. Because these swirls are robust and difficult to accidentally erase, they are seen as ideal candidates for the next generation of memory devices. The challenge has always been how to create them precisely and with minimal energy. Traditional methods often involve injecting electric currents or applying magnetic fields, but these approaches can be messy, requiring high energy or complex wiring that limits how small the devices can become.

A team of researchers at the University of New South Wales has now proposed a different way to write these magnetic patterns, using light itself as the tool. In a study published in August 2026, they used computer simulations to show that structured light beams, specifically those shaped like spirals, can be used to deterministically create these magnetic swirls in thin magnetic films. The key discovery is that the specific "quantum numbers" of the light beam—its shape, its spin, and how it twists—can be directly translated into the shape and identity of the magnetic pattern left behind. This suggests a future where information is written onto magnetic chips using light pulses, offering a path toward ultrafast, energy-efficient data storage without the need for physical contact or high electrical currents.

The researchers focused on a type of light called a Laguerre-Gaussian vortex. Imagine a beam of light that doesn't just travel in a straight line but carries a twist, like a corkscrew, as it moves forward. This twist gives the light a property known as orbital angular momentum. In their simulations, the team fired pulses of this spiraling light at a very thin film of chiral ferromagnetic material. Chiral materials are those where the magnetic atoms prefer to twist in a specific direction, much like a left-handed or right-handed screw. The light pulse interacts with the magnetic film through a fundamental force called the Zeeman interaction, essentially nudging the magnetic atoms out of their resting position.

The outcome of this interaction depends heavily on the specific properties of the light beam. When the researchers used a light beam with a single twist and circular polarization—where the light's electric field rotates as it travels—they found they could reliably create a single, isolated magnetic swirl. The type of swirl created, whether it was a specific kind of magnetic pair known as a bimeron or its opposite, an antibimeron, was determined by the combination of the light's twist direction and the material's own preferred magnetic direction. If the light's twist matched the material's natural preference, a stable magnetic texture formed. If they opposed each other, the process failed to create the desired pattern. This demonstrated that the light's properties could be used to select exactly which magnetic state to write.

The study also explored what happens when the light beam is more complex. When the researchers used beams with multiple twists, or when they changed the polarization to be linear rather than circular, the results became even more versatile. With linearly polarized light, the number of twists in the light beam directly dictated the number of magnetic twists in the resulting pattern. A beam with two twists created a magnetic texture with a topological charge of two, and a beam with three twists created a charge of three. In these cases, the light acted as a direct blueprint, encoding its own structural complexity into the magnetic film.

When the light pulses were even more complex, carrying multiple twists or having a more intricate radial structure, the simulations showed the formation of clusters. Instead of a single isolated swirl, the light would nucleate groups of magnetic textures that stuck together. The researchers found that by carefully adjusting the intensity of the light pulse and its duration, they could control whether these clusters formed or whether the light simply created separate, isolated swirls. This sensitivity to the light's parameters suggests that the method is not just a one-trick pony but a flexible tool capable of generating a wide variety of magnetic configurations.

One of the most significant findings was the ability to create these patterns without the need for the high electrical currents that usually drive such devices. The simulations showed that the light pulses, lasting only a few picoseconds, were sufficient to drive the magnetic atoms into these new states. The process relied on the precise timing and shape of the light pulse to guide the magnetic atoms into a stable configuration before they relaxed back to their original state. If the light was too weak or the pulse too short, the magnetic atoms would simply return to their uniform state. However, with the right parameters, the light would leave behind a permanent, stable magnetic texture.

The researchers also noted that the size of the light beam mattered. To create a single, clean magnetic swirl, the beam needed to be focused to a size comparable to the swirl itself, roughly 15 nanometers in diameter. This tight focus ensures that the energy is concentrated exactly where it is needed, preventing the formation of messy, uncontrolled patterns. While creating such a tightly focused beam in a real-world experiment would require advanced techniques like near-field optics, the simulations provide a proof of concept that such control is theoretically possible.

This work bridges the gap between the abstract world of quantum optics and the practical needs of spintronics. By showing that the quantum properties of light can be directly mapped onto the magnetic states of a material, the study opens up new possibilities for how we might write data in the future. It suggests that the complex language of light—its spin, its twist, and its shape—can be used to speak directly to the magnetic atoms in a computer chip, telling them exactly how to arrange themselves. This could lead to devices that are not only smaller and faster but also consume far less energy than current technologies, as the writing process would rely on the precise delivery of light rather than the brute force of electrical current.

The study remains a simulation, meaning the results are based on mathematical models of how these materials behave rather than physical experiments in a lab. However, the models used are well-established and rely on known physical laws, giving the findings a high degree of reliability. The researchers explicitly ruled out the idea that standard, non-twisting light beams could create these specific topological textures with the same level of control. They found that without the orbital angular momentum of the vortex beam, the light simply could not induce the necessary magnetic transitions to form the desired patterns.

Ultimately, the paper presents a clear and promising route for topology-selective writing. It demonstrates that by tuning the optical quantum numbers of a light pulse, one can deterministically write specific magnetic states into a material. Whether creating a single swirl, a cluster of swirls, or complex multi-texture configurations, the light acts as a precise pen, writing information into the magnetic fabric of the material. This approach offers a compelling vision for the future of data storage, where the intricate properties of light are harnessed to build the next generation of computing devices.