Magnon-Skyrmion Hybrid Quantum Systems: Tailoring Interactions via Magnons

Coherent and dissipative interactions between different quantum systems are essential for the construction of hybrid quantum systems and the investigation of novel quantum phenomena. Here, we propose and analyze a magnon-skyrmion hybrid quantum system, consisting of a micromagnet and nearby magnetic skyrmions. We predict a strong-coupling mechanism between the magnonic mode of the micromagnet and the quantized helicity degree of freedom of the skyrmion. We show that with this hybrid setup it is possible to induce magnon-mediated nonreciprocal interactions and responses between distant skyrmion qubits or between skyrmion qubits and other quantum systems like superconducting qubits. This work provides a quantum platform for the investigation of diverse quantum effects and quantum information processing with magnetic microstructures.

Figure 1

(a) Hybrid quantum system consisting of a YIG sphere (a YIG square or circular dot) and a skyrmion. (b) Energy level structure of skyrmion qubits. (c) Coupling mechanisms of magnons and skyrmion qubits.

Figure 2

Contour maps of the coupling strength ${\lambda }_{\mathrm{KS}}$ versus $R_K$ and $d_K$ are visualized in (a). (b) Coupling strength ${\lambda }_{\mathrm{KS}}$ as a function of $R_K$. (c) Contour maps of the cooperativity $\mathcal{C}$. The dissipation used to calculate the cooperativity is ${\gamma }_K/2\pi ={\gamma }_{\mathrm{sky}}/2\pi =1\mathrm{MHz}$. (d) The enhanced coupling strength by the two-magnon drive ($d_K=10\mathrm{nm}$).

Figure 3

Population conversion dynamics. (a) Only qubit 1 in the excited state and (b) Only qubit 2 in the excited state. $S_1$ and $S_2$ correspond to the population of the first skyrmion and second skyrmion, respectively. The parameters used are ${\mathrm{\Delta }}_{K,1}={\mathrm{\Delta }}_{q,1}={\mathrm{\Omega }}_2={\overline{\lambda }}_{\mathrm{KS}}$ and ${\gamma }_K=10{\overline{\lambda }}_{\mathrm{KS}}$.

Figure 4

Population conversion dynamics for the case of (a) the skyrmion qubit being excited and (b) the SQ being excited. The parameters used are $\eta =1$, ${\varphi }_e=\pi /2$, ${\mathcal{G}}_{\mathrm{SS}}={\overline{\lambda }}_{\mathrm{KS}}$, and ${\gamma }_K=10{\overline{\lambda }}_{\mathrm{KS}}$.