Magnetic Skyrmions Simulated Efficiently Offer Promise for Spintronics Applications

Variational eigensolver simulations of the two-dimensional spin-1/2 Heisenberg model, incorporating Dzyaloshinskii-Moriya interaction, reveal evidence for stable, zero-temperature magnetic skyrmions. Calculations demonstrate a discontinuity in total energy and magnetization with changing magnetic field, suggesting potential for spintronic applications and information storage.

The pursuit of stable, nanoscale magnetic structures with defined topological properties represents a significant area of materials science, with potential applications ranging from high-density data storage to novel computing architectures. Researchers are increasingly focused on magnetic skyrmions – quasiparticles exhibiting particle-like behaviour and possessing a defined ‘handedness’ or topological charge – due to their potential as robust information carriers. A team from the Jožef Stefan Institute, comprising Matej Komelj, Vinko Sršan, Kristina Žužek, and Sašo Šturm, detail in their work, ‘Quantum computing of magnetic-skyrmion-like patterns in Heisenberg ferromagnets’, a computational investigation into the emergence of these skyrmion-like structures within a simplified model of a magnetic material. They demonstrate the efficacy of a quantum computing approach – specifically, a variational eigensolver implemented on a simulator – in modelling these complex magnetic arrangements, surpassing the limitations of classical computational methods for larger systems.

Skyrmions as Qubits: Investigating Topological Stability for Quantum Computation

This research investigates the potential of magnetic skyrmions as robust qubits for quantum computation, employing a variational eigensolver (VES) to analyse the behaviour of a two-dimensional spin-1/2 Heisenberg model incorporating Dzyaloshinskii-Moriya interaction (DMI). This approach demonstrates improved computational efficiency compared with classical direct diagonalisation for systems exceeding 17 sites, facilitating detailed investigation of magnetic textures and enabling exploration of complex phenomena. The DMI, a relativistic interaction arising from spin-orbit coupling in certain materials, induces the formation of these skyrmionic structures, providing a foundation for their potential use in information storage and processing.

Calculations reveal a distinct discontinuity in total energy, magnetisation, and topological charge as the external magnetic field varies, strongly suggesting the existence of zero-temperature skyrmion-like structures. Their formation is governed by the interplay between exchange coupling and DMI parameters, offering a pathway to manipulate and stabilise these structures for technological applications. Researchers calculate topological numbers, such as the skyrmion number – an integer quantifying the winding of the spin texture – which characterise the stability of these structures and are essential for assessing their suitability as qubits, providing a quantitative measure of their potential. The ARPACK software package was utilised to solve the large-scale eigenvalue problems inherent in these calculations, ensuring accuracy and efficiency.

A key finding centres on a measurable jump in magnetisation upon changes to the applied magnetic field, indicating that the investigated skyrmionic objects possess sufficient stability for applications in spintronics. This stability is crucial for their potential use as information carriers within quantum systems, opening possibilities for novel devices. The study addresses challenges related to symmetry breaking, which can impede the VES algorithm’s convergence, and explores adaptive circuit construction techniques to optimise computational efficiency, ensuring reliable results.

Furthermore, the research leverages open-source software like Tangelo, designed for chemistry workflows on quantum computers, and employs quantum spin projection to simplify the circuits required for simulating skyrmions. This combination of theoretical modelling, numerical simulation, and quantum computing advances understanding of skyrmion behaviour and strengthens the case for their exploitation in future technologies. By integrating these approaches, researchers gain a comprehensive understanding of the underlying physics and potential applications.

This research demonstrates the viability of employing the variational quantum eigensolver (VQE) to investigate the magnetic properties of the two-dimensional spin-1/2 Heisenberg model, incorporating DMI. Simulations, executed on a quantum simulator, prove more efficient than classical methods for systems exceeding 17 sites, establishing a computational advantage and accelerating discovery. The observed efficiency allows researchers to explore larger and more complex systems, pushing the boundaries of computational feasibility.

The study confirms VQE’s capacity to accurately characterise topological properties, specifically the topological charge, which defines skyrmion stability and is essential for assessing their suitability as information carriers in spintronic devices. This ability is crucial for evaluating their potential as qubits, opening new avenues for quantum information processing and accelerating the development of skyrmion-based technologies.

Further investigation focuses on refining the computational methods to address challenges related to symmetry breaking, ensuring the accuracy and reliability of the simulations. Optimising quantum circuit construction, specifically towards shallower circuits, remains a priority to enhance computational efficiency and scalability, paving the way for more complex simulations. Future work will explore the influence of varying DMI and exchange coupling parameters on skyrmion stability and properties, aiming to identify optimal conditions for their manipulation and control.

Expanding the scope to include dynamic simulations will be essential to understand the response of skyrmions to external stimuli and their potential for information processing, providing insights into their behaviour in real-world applications. Investigating the effects of defects and disorder on skyrmion stability represents another crucial avenue for research, addressing the challenges of implementing these structures in realistic devices. Ultimately, these efforts aim to translate the promising theoretical findings into tangible advancements in spintronics and quantum computing, driving innovation in these fields.