SKM 2021 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 1: Focus Session: Disordered and Granular Superconductors: Fundamentals and Applications in Quantum Technology I

TT 1.5: Talk

Monday, September 27, 2021, 11:30–12:00, H6

Spectroscopy of a single Josephson impurity in a high kinetic inductance array — •Serge Florens¹, Sébastien Léger¹, Théo Sépulcre¹, Denis Basko², Izak Snyman³, and Nicolas Roch¹ — ¹Néel Institute, CNRS, Grenoble, France — ²LPMMC, UGA, Grenoble, France — ³Wits University, Johannesburg, South Africa

Superconducting arrays constitute a promising platform to explore a large class of physical phenomena, from quantum phase transitions to non-linear quantum optics in the microwave domain. We design a fully-tunable model system where a long chain of several thousands linear Josephson elements, acting as a high inductance transmission line, is terminated by a small Josephson junction endowed with a strong non-linearity, acting as a single impurity. From microwave spectroscopic measurements, we extract the phase shift and the inelastic losses induced by the impurity onto the linear modes of the array. In agreement with a microscopic modeling of the circuit, we put into evidence a huge renormalization of the Josephson tunnel energy at the impurity site, and show that the associated enhancement of phase fluctuations provides the dominant dissipation mechanism in the array.