UC Santa Cruz

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, this Colloquium discusses their magnon and electron excitations and shows how hybrid architectures offer new platforms for engineering quantum orders, including topological superconductivity. The focus then moves to the quantization of the skyrmion texture itself and the formulation of long-time skyrmion dynamics in terms of collective coordinates. Discussed next are the quantization of helicity and phenomena of macroscopic quantum tunneling, key concepts that fundamentally distinguish quantum skyrmions from their classical counterparts. Looking ahead, material classes suitable for the realization of skyrmions in quantum spin systems are proposed and device architectures are identified with the promise of achieving quantum operations. The Colloquium closes by addressing the advances in experimental methods that will be prerequisites for resolving the quantum aspects of topological spin patterns, sensing their local dynamical response, and achieving their predicted functionalities in magnetic systems.