Wiebke Guichard
Université Grenoble-Alpes, France
Title: Weak and strong non-linear effects in Josephson junction chains
Biography
Biography: Wiebke Guichard
Abstract
I will present our microwave transmission measurements on propagation modes in Josephson junction chains containing several hundreds of junctions. After some preliminary measurements we have done a more systematic measurement in an improved measurement set-up that I will present. Some of the chains have been embedded into the microwave strip line, while others have been coupled capacitively to it. The latter configuration enables a study of the internal quality factor of the chain while the first one is more suited to study quantitatively the Kerr effects occurring between different modes in the chain. The experimental dispersion curve of this meta- material fits well the theoretical prediction. We measured the Self- and Cross Kerr effects by two-tone spectroscopy measurements for the first 8 modes of the chain and compare them to theory. Secondly, I will show our recent results on the realization of a fluxonium qubit. I will discuss spectroscopy measurements and measurements of the relaxation and decoherence time of this qubit. At the end I will discuss future experiments with fluxonium type devices.
Figure: A fluxonium qubit fabricated at the Néel Institute Grenoble