Optical signatures of quantum skyrmions

TL;DR

This paper proposes using Brillouin light scattering to detect quantum skyrmions in frustrated magnets, identifying spectral asymmetries as signatures of their non-classical quantum behavior, which is crucial for quantum computing applications.

Contribution

It introduces a novel optical protocol to distinguish quantum skyrmions from classical ones via BLS spectral asymmetry, advancing experimental detection methods.

Findings

Quantum skyrmions show asymmetric BLS sidebands due to vacuum fluctuations.

Asymmetry is more pronounced at low temperatures and controllable by laser power.

The protocol provides a robust way to identify non-classical spin textures.

Abstract

Magnets have recently emerged as promising candidates for quantum computing, particularly using topologically-protected nanoscale spin textures. While the quantum dynamics of such spin textures has been theoretically studied, direct experimental evidence of their non-classical behavior remains an open challenge. To address this, we propose to employ Brillouin light scattering (BLS) as a method to probe the quantum nature of skyrmions in frustrated magnets. We show that, for a specific geometry, classical skyrmions produce symmetric sidebands in the BLS spectrum, whereas quantum skyrmions exhibit a distinct asymmetry arising from vacuum fluctuations of their rotation. By studying the photon-skyrmion interaction, we calculate the BLS spectrum using a quantum master equation and show that sideband asymmetry serves as a robust witness of energy level quantization. We find that this asymmetry is pronounced at low temperatures, and can be controlled by input laser power. These findings establish a concrete protocol for the optical detection of non-classical features in spin textures, paving the way for exploring their role in quantum applications.