Phase Dependence of Phonon Tunneling in Bosonic Superfluid-Insulator-Superfluid Junctions

TL;DR

This paper investigates how the phase difference between two superfluid condensates affects phonon tunneling, revealing a strong dependence of transmission on phase and identifying a critical phase where perfect transmission ceases.

Contribution

The study provides a detailed analysis of phase-dependent phonon tunneling in superfluid junctions using Bogoliubov equations, highlighting the critical phase for supercurrent maximum.

Findings

Transmission coefficient T varies strongly with phase difference φ.

Perfect low-energy phonon transmission disappears at a critical phase.

Feasibility of experimental observation of phase differences is discussed.

Abstract

We consider the tunneling of phonon excitations across a potential barrier spatially separating two condensates with different macroscopic phases. We analyze the relation between the phase difference $\phi$ of the two condensates and the transmission coefficient {\it T} by solving the Bogoliubov equations. It is found that {\it T} strongly depends on $\phi$, and that the perfect transmission of low-energy excitations disappears when the phase difference reaches the critical value which gives the maximum supercurrent of the condensate. We also discuss the feasibility of observing the phase differences in experiments.