Kerr nonlinearity in a superconducting Josephson metamaterial
Y. Krupko, V. D. Nguyen, Thomas Weißl, Étienne Dumur, Javier Puertas, Rémy Dassonneville, C. Naud, F. W. J. Hekking, D. M. Basko, Olivier Buisson, Nicolas Roch, Wiebke Guichard · Physical review. B./Physical review. B · 2018
We present a detailed experimental and theoretical analysis of the dispersion and nonlinear Kerr frequency shifts of plasma modes in a one-dimensional Josephson junction chain containing 500 superconducting quantum interfence devices in the regime of weak nonlinearity. The measured low-power dispersion curve agrees perfectly with the theoretical model if we take into account the Kerr renormalization of the bare frequencies and the long-range nature of the island charge screening by a remote ground plane. We measured the self- and cross-Kerr shifts for the frequencies of the eight lowest modes in the chain. We compare the measured Kerr coefficients with theory and find good agreement.