Theory of high-power excitation spectra of rf-SQUID

Olesia Dmytruk; R. H. Rodriguez; Ç. Ö. Girit; Marco Schiró

doi:10.1103/PhysRevB.104.214508

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Theory of high-power excitation spectra of rf-SQUID

Olesia Dmytruk, R. H. Rodriguez, Ç. Ö. Girit, Marco Schiró

DOI 10.1103/PhysRevB.104.214508 · Physical Review B

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Abstract

We discuss the theory of linear and nonlinear spectroscopy of an rf superconducting quantum interference device (rf-SQUID) coupled to a Josephson spectrometer. Recent experimental measurements on this system have shown a strongly nonlinear absorption line shape, whose current peak maximum undergoes a forward-backward bending transition depending on the value of the rf-SQUID phase. We show that this transition can be qualitatively understood by mapping the dynamics of the driven rf-SQUID onto a generalized Duffing oscillator, with tunable drive and nonlinearity, undergoing a bifurcation. Finally we show that in order to quantitatively reproduce the experimental data reported by Griesmar et al. [Phys. Rev. Research 3, 043078 (2021)], it is crucial to include the feedback from the load line, leading to an additional source of nonlinearity.