Dynamics of a tunable superfluid junction

TL;DR

This paper investigates the population dynamics of a Bose-Einstein condensate in a double-well potential, revealing a transition from Josephson oscillations to hydrodynamic behavior and identifying multiple oscillation modes.

Contribution

It provides a comprehensive analysis of the crossover from Josephson to hydrodynamic regimes in a tunable superfluid junction, supported by experimental data and numerical simulations.

Findings

Slow Josephson oscillations at high barriers

Hydrodynamic frequency matches simple models at low barriers

Discovery of a second, higher frequency mode

Abstract

We study the population dynamics of a Bose-Einstein condensate in a double-well potential throughout the crossover from Josephson dynamics to hydrodynamics. At barriers higher than the chemical potential, we observe slow oscillations well described by a Josephson model. In the limit of low barriers, the fundamental frequency agrees with a simple hydrodynamic model, but we also observe a second, higher frequency. A full numerical simulation of the Gross-Pitaevskii equation giving the frequencies and amplitudes of the observed modes between these two limits is compared to the data and is used to understand the origin of the higher mode. Implications for trapped matter-wave interferometers are discussed.