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Jean Eudes Duvauchelle

Effect of a microwave irradiation on the electronic response of Josephson tri-junctions: Evidence for coherent quartet modes

Published on 18 December 2015
Abstract:
I investigated a device where three superconducting (Al) electrodes are connected by a submicron normal metal (Cu) composing a Josephson three-junction. New sub-gap features appear in the differential conductance which correspond to correlated motion of Cooper pairs and are consistent with the prediction of quartets formed by the simultaneous splitting of two Cooper pairs from one of the superconducting reservoirs and the emission of two phase correlated Cooper pairs in the two other electrodes. In order to probe the quantum coherence of such mechanism, I irradiated the structure with a microwave down to very low temperature. My study reveals that the Quartet feature also shows Shapiro-like resonance. This result demonstrates that the Quartet feature is a true quantum mechanism and confirms the Quartet scenario that implies the coherent splitting of two Cooper pairs.

Keywords:
Josephson Junctions, Mesoscopic Physics, Proximity effects Andreev reflection SN and SNS junctions

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