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Frequency-to-current conversion with coherent Josephson crystals

Final Report Summary - FREQUJOC (Frequency-to-current conversion with coherent Josephson crystals)

During this project we have worked on the realisation of a frequency-to-current conversion device for future applications in quantum metrology.
We have analysed the dispersion of electromagnetic modes in a Josephson junction chain and we could explain their dispersion relation perfectly with a new model taking into account long range Coulomb interactions. We have as well measured the Kerr effect in these chains, which is by 11 orders of magnitude bigger than in optical system.
Our research on disordered Josephson junction chains resulted in the conclusion that disordered chains do not suppress the dissipation of the electromagnetic modes which are harmful to the coherence of quantum phase-slips. The coherence of quantum phase-slips is an essential condition for the frequency-to-current conversion device. We have as well analysed why a frequency-to-current conversion device is necessarily build up by a long Josephson junction chain: a single Josephson junction in a purely inductive environment cannot serve as a frequency-to-current conversion device.
Due to our research we have developed new ideas for the realisation of a frequency-to-current conversion device which we continue to pursue.