Relation between ac Josephson effect and double-well Bose-Einstein-condensate oscillations

In this article we comment on the relation between the ac Josephson effect and the coherent oscillations of a Bose-Einstein condensate confined to a double-well potential. The goal is to elucidate the extent to which the latter is a realization of the former. We detail the correspondence between the two oscillation frequencies, that emerges in the high occupation limit of the double-well potential. We show that in the latter thermodynamic limit the effective one-particle interwell coupling vanishes with the system size, leading to oscillation frequency that depends only on the interwell imbalance, consistent with the ac Josephson effect frequency.