Optical signatures of quantum skyrmions

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.

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