Colloquium: Quantum Properties and Functionalities of Magnetic Skyrmions

TL;DR

This paper reviews the quantum properties of magnetic skyrmions, exploring their theoretical foundations, experimental challenges, and potential for quantum computing and topological quantum states.

Contribution

It introduces the quantum aspects of skyrmions, including their quantization, dynamics, and potential for quantum operations, advancing understanding beyond classical descriptions.

Findings

Quantum skyrmions exhibit macroscopic quantum tunneling.

Hybrid architectures can engineer topological superconductivity.

Experimental methods are crucial for observing quantum skyrmion phenomena.

Abstract

Competing magnetic interactions may stabilize smooth magnetization textures that can be characterized by a topological winding number. Such textures, which are spatially localized within a two-dimensional plane, are commonly known as skyrmions. On the classical level, their significance for fundamental science and their potential for applications, ranging from spintronic devices to unconventional computation platforms, have been intensively investigated in recent years. This Colloquium considers quantum effects associated with skyrmion textures: their theoretical origins, the experimental and material challenges associated with their detection, and the promise of exploiting them for quantum operations. Starting with classical skyrmions, we discuss their magnon and electron excitations and show how hybrid architectures offer new platforms for engineering quantum orders, including topological superconductivity. We then focus on the quantization of the skyrmion texture itself and formulate the long-time skyrmion dynamics in terms of collective coordinates. Next, we discuss the quantization of helicity and phenomena of macroscopic quantum tunneling: key concepts that fundamentally distinguish quantum skyrmions from their classical counterparts. Looking ahead, we propose material classes suitable for the realization of skyrmions in quantum spin systems and identify device architectures with the promise of achieving quantum operations. We close by addressing the advances in experimental methods which will be a prerequisite for resolving the quantum aspects of topological spin patterns, sensing their local dynamical response, and achieving their predicted functionalities in magnetic systems.