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arXiv · 2106.10450

Approaching to the deep-strong photon-to-magnon coupling

I. A. Golovchanskiy·N. N. Abramov·V. S. Stolyarov·A. A. Golubov·M. Yu. Kupriyanov·V. V. Ryazanov·A. V. Ustinov
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Abstract

In this work, the ultra-strong photon-to-magnon coupling is demonstrated for on-chip multilayered superconductor/ferromagnet/insulator hybrid thin film structures reaching the coupling strength above 6 GHz, the coupling ratio about 0.6, the single-spin coupling strength about 350 Hz, and cooperativity about 10^4. High characteristics of coupling are achieved owing to a radical suppression of the photon phase velocity in electromagnetic resonator. With achieved coupling the spectrum reveals inapplicability of the Dicke model, and evidences contribution of the diamagnetic A^2 interaction term in the Hamiltonian of the system, which satisfies the Thomas-Reiche-Kuhn sum rule. The contribution of the A^2 term denotes validity of the Hopfield quantum model and manifests observation of a different hybrid polariton quasi-particle, namely, the plasmon-magnon polariton.

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I. A. Golovchanskiy, N. N. Abramov, V. S. Stolyarov, A. A. Golubov, M. Yu. Kupriyanov, V. V. Ryazanov, A. V. Ustinov. 2021-06-19. Approaching to the deep-strong photon-to-magnon coupling. https://doi.org/10.1103/physrevapplied.16.034029

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