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arXiv · 2405.13642

Direct measurement of a $\sin(2\varphi)$ current phase relation in a graphene superconducting quantum interference device

Simon Messelot·Nicolas Aparicio·Elie de Seze·Eric Eyraud·Johann Coraux·Kenji Watanabe·Takashi Taniguchi·Julien Renard
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Abstract

In a Josephson junction, the current phase relation relates the phase variation of the superconducting order parameter, $\varphi$, between the two superconducting leads connected through a weak link, to the dissipationless current . This relation is the fingerprint of the junction. It is usually dominated by a $\sin(\varphi)$ harmonic, however its precise knowledge is necessary to design superconducting quantum circuits with tailored properties. Here, we directly measure the current phase relation of a superconducting quantum interference device made with gate-tunable graphene Josephson junctions and we show that it can behave as a $\sin(2\varphi)$ Josephson element, free of the traditionally dominant $\sin(\varphi)$ harmonic. Such element will be instrumental for the development of superconducting quantum bits protected from decoherence.

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Simon Messelot, Nicolas Aparicio, Elie de Seze, Eric Eyraud, Johann Coraux, Kenji Watanabe, Takashi Taniguchi, Julien Renard. 2024-05-22. Direct measurement of a $\sin(2\varphi)$ current phase relation in a graphene superconducting quantum interference device. https://doi.org/10.1103/physrevlett.133.106001

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