Quasiresonant tunneling of phonons in bosonic superfluid-insulator- superfluid junctions

We investigate the quasiresonant tunneling of phonon excitations across a potential barrier spatially separating two condensates with different macroscopic phases. We confirm that the quasiresonant tunneling occurs through the quasibound state. The quasibound state is induced by a potential well created by the condensate density. We analyze the relation between the phase difference Φ of two condensates and the transmission coefficient T by solving the Bogoliubov-de Gennes equations. As a result, the transmission coefficient T is found to depend strongly on Φ because of the Φ dependence of the quasibound state.