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arXiv · 1507.03739

High cooperativity coupling between a phosphorus donor spin ensemble and a superconducting microwave resonator

Christoph W. Zollitsch·Kai Mueller·David P. Franke·Sebastian T. B. Goennenwein·Martin S. Brandt·Rudolf Gross·Hans Huebl
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Abstract

We investigate the coupling of an ensemble of phosphorus donors in an isotopically purified $^{28}$Si host lattice interacting with a superconducting coplanar waveguide resonator. The microwave transmission spectrum of the resonator shows a normal mode splitting characteristic for high cooperativity. The evaluated collective coupling strength $g_{\mathrm{eff}}$ is of the same order as the loss rate of the spin system $\gamma$, indicating the onset of strong coupling. We develop a statistical model to describe the influence of temperature on the coupling strength from $50\,\mathrm{mK}$ to $3.5\,\mathrm{K}$ and find a scaling of the coupling strength with the square root of the number of thermally polarized spins.

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Christoph W. Zollitsch, Kai Mueller, David P. Franke, Sebastian T. B. Goennenwein, Martin S. Brandt, Rudolf Gross, Hans Huebl. 2015-07-14. High cooperativity coupling between a phosphorus donor spin ensemble and a superconducting microwave resonator. https://doi.org/10.1063/1.4932658

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