Speaker
Description
Cavity Quantum Electrodynamics (C-QED) is used to manipulate and interrogate qubits or to engineer hybrid light-matter states. However, cavity photons impose severe restrictions on their maximum coupling strength to paramagnetic objects, thus limiting the accessible regimes and the physics that can be explored in C-QED platforms. Beyond light, the solid state offers different quantized bosonic excitations, such as magnons, the quantum of spin waves in magnetic solids. The rich physics of light-matter hybrids is, in principle, also applicable to magnon-matter states, which come with additional advantages such as reduced size and enhanced coupling strengths.
Here we report on magnon-spin interaction between the layered van der Waals antiferromagnet CrSBr [1,2] and paramagnetic ion crystal GdW10 [3], measured via microwave absorption spectroscopy at millikelvin temperatures. The avoided crossing found at low probing power [4] indicates we achieve the strong coupling regime of interaction between both systems, while higher probing power saturates the paramagnet, thus losing the anticrossing. This result opens a path for the use of CrSBr and similar layered materials as magnonic platforms in hybrid quantum systems, both for fundamental physics and device-oriented experiments.
Complementing these results, we performed measurements of microscopic CrSBr flakes integrated on chip, which give us insights into controlling dispersion and thus linewidth of the magnonic modes, bringing us closer to integrating Van der Waals antiferromagnets into functional devices.
[1] Nano Letters 2022 22 (16), 6716-6723
[2] Nano Letters 2024 24 (15), 4319–4329
[3] Physical Review Letters 2012 108, 247213
[4] arXiv:2508.17888