We present a detailed experimental and theoretical analysis of the dispersion and non-linear Kerr frequency shifts of plasma modes in a one-dimensional Josephson junction chain containing 500 SQUIDs 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 renormalisation 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.
@article{arxiv.1807.01499,
title = {Kerr non-linearity in a superconducting Josephson metamaterial},
author = {Yu. Krupko and V. D. Nguyen and T. Weißl and É. Dumur and J. Puertas and C. Naud and F. W. J. Hekking and D. M. Basko and O. Buisson and N. Roch and W. Hasch-Guichard},
journal= {arXiv preprint arXiv:1807.01499},
year = {2018}
}