  A Josephson junction of an ultradilute quantum liquid is studied in a
double-well potential. We analyze the dynamics as a function of the interaction
strength and compare the results to the standard bosonic Josephson junction. It
is found that the beyond-mean-field effects alter the dynamics, particularly in
the regime, where the beyond-mean-field corrections dominate over the residual
mean-field interaction. In that case, we observe non-linear dynamics describing
localization revivals instead of regular Josephson oscillations. In the regime
where the ultradilute quantum liquids perform the regular Josephson
oscillations, their frequency is also significantly changed in comparison with
the regular Josephson junction. These results provide experimental
characteristics of the ultradilute quantum liquids that contrast with the
Josephson oscillations of a regular Bose-Einstein condensate.
