  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.
