We calculate the frequency-dependent admittance of a phase-biased Josephson junction spanning a magnetic impurity or a spinful Coulomb-blockaded quantum dot. The local magnetic moment gives rise to Yu-Shiba-Rusinov bound states, which govern the sub-gap absorption as well as the inductive response. We model the system by a superconducting spin-polarized exchange-cotunnel junction and calculate the linear current response to an AC bias voltage, including its dependence on phase bias as well as particle-hole, and source-drain coupling asymmetry. The corresponding inductive admittance is analyzed and compared to results of a zero-bandwidth, as well as an infinite-gap approximation to the superconducting Anderson model. All three approaches capture the interaction-induced 0−π transition, which is reflected as a discontinuity in the adiabatic inductive response.
@article{arxiv.2112.11261,
title = {Inductive microwave response of Yu-Shiba-Rusinov states},
author = {Cecilie Hermansen and Alfredo Levy Yeyati and Jens Paaske},
journal= {arXiv preprint arXiv:2112.11261},
year = {2022}
}