Skyrmion Helicity Stores Information and Functions as a Qubit in Magnets

Skyrmions, nanoscale magnetic whirls, represent a promising avenue for next-generation information technologies, and researchers are now exploring their potential beyond simple binary data storage. D. Maroulakos from the Doctoral School at the University of Rzeszów, A. Wal from the University of Rzeszów’s Institute of Physics, and A. Ugulava from I. Javakhishvili Tbilisi State University, along with their colleagues, demonstrate that these magnetic textures can encode significantly more information than previously understood. Their work reveals that under certain conditions, skyrmions function not as qubits, the quantum equivalent of bits, but as qudits, which leverage multiple quantum states to increase data capacity dramatically. This discovery, achieved through a detailed theoretical analysis of skyrmion behaviour in frustrated magnets, suggests a pathway towards building more powerful and efficient quantum devices, and the exceptionally high coherence observed in these skyrmion qudits offers exciting possibilities for stable and reliable quantum information processing.

Since the pioneering work of Lohani et al., quantum skyrmions have become recognised for possessing highly unusual properties when compared to their classical counterparts, and, due to their quantum nature, cannot be described by continuous magnetic textures like classical skyrmions. Competing magnetic interactions in frustrated triangular magnets lead to the formation of these quantum skyrmion states, and the system exhibits unique behaviour in the presence of a weak electric field.

Skyrmions Encode and Process Quantum Information

This research explores the potential of using quantum skyrmions as a platform for high-dimensional quantum computing, specifically using qudits, quantum units with more than two levels. It builds on the established field of skyrmionics, which uses magnetic skyrmions for information storage and processing, and pushes it into the realm of quantum information. The central idea is that the topological properties of skyrmions, their stable, localised magnetic textures, can be harnessed to encode and manipulate quantum information, with the helicity, a measure of the twist within a skyrmion, serving as a qudit degree of freedom. The work advocates for moving beyond qubits, which represent information using two states, to qudits, which can represent multiple states to increase the information density and computational power of quantum computers.

A significant challenge is maintaining quantum coherence in skyrmion-based qudits, and the research investigates mechanisms to protect coherence and proposes methods for manipulating skyrmion helicity using external fields or other control parameters. The team developed a robust mathematical framework to describe the quantum dynamics of skyrmion qudits, drawing on concepts from group theory, quantum mechanics, and topology. The proposal to use skyrmion helicity as a qudit variable is a novel and promising approach, leveraging the inherent topological stability of skyrmions to protect quantum information. The development of a comprehensive mathematical framework is a significant contribution, allowing for rigorous analysis of skyrmion qudit dynamics and providing a foundation for designing quantum algorithms. Understanding how chaotic dynamics affect skyrmion qudits can lead to strategies for mitigating decoherence and improving control.

Skyrmion Qudits Exhibit Enhanced Quantum Coherence

Skyrmions in frustrated triangular magnets arise from competing magnetic interactions and exhibit unique quantum properties, differing from their classical counterparts. This research demonstrates that these skyrmions, previously considered potential qubits storing information as two-level systems, can more accurately be described as qudits, capable of storing more complex quantum information. Researchers obtained an exact analytical solution describing the evolution of these quantum skyrmions, revealing that a time-dependent Mathieu-Schrödinger equation governs their behaviour. Notably, the team showed that the coherence of this skyrmion qudit, a measure of its ability to maintain quantum information, is a thousand times greater than that of a skyrmion qubit. This enhanced coherence suggests skyrmion qudits offer improved stability and resilience against environmental noise, making them promising candidates for quantum information technologies.

Skyrmion Qudits Function as Quantum Qudits

Recent research has significantly advanced our understanding of skyrmions, nanoscale magnetic textures with potential applications in novel information technologies. Researchers have now demonstrated that these skyrmions can function not as simple quantum bits, or qubits, but as quantum qudits, a more complex system capable of storing significantly more information. Previous models of skyrmion qubits were limited to scenarios with small energy barriers, but this work presents a general analytical solution valid for any barrier strength. This breakthrough reveals that under certain conditions, the skyrmion’s quantum state transitions from a qubit to a qudit, dramatically increasing its information storage capacity.

While a qubit holds one bit of quantum information, a qudit can have multiple bits depending on its complexity, meaning fewer qudits are needed to store the same amount of data. The team’s calculations demonstrate that the coherence of these skyrmion qudits is a thousand times greater than that of previously considered skyrmion qubits, suggesting a much more robust and reliable system for quantum information processing. This discovery opens new avenues for developing compact and efficient quantum technologies, potentially surpassing the limitations of current qubit-based architectures. The increased information density and improved robustness of skyrmion qudits promise a more powerful and reliable platform for future quantum devices and a deeper understanding of quantum materials.