Route to turbulence in a trapped Bose-Einstein condensate

TL;DR

This study investigates how oscillatory excitation parameters induce different behaviors, including vortex formation and turbulence, in a trapped Bose-Einstein condensate, supported by experimental observations and Gross-Pitaevskii simulations.

Contribution

It maps the parameter space of excitation amplitude and duration leading to turbulence, vortex states, and granular phases in a BEC, providing a comprehensive phase diagram.

Findings

Vortex number increases with excitation amplitude.

Turbulence occurs at specific excitation parameter combinations.

Granular phase appears when parameters exceed turbulence regime.

Abstract

We have studied a Bose-Einstein condensate of $^{87}Rb$ atoms under an oscillatory excitation. For a fixed frequency of excitation, we have explored how the values of amplitude and time of excitation must be combined in order to produce quantum turbulence in the condensate. Depending on the combination of these parameters different behaviors are observed in the sample. For the lowest values of time and amplitude of excitation, we observe a bending of the main axis of the cloud. Increasing the amplitude of excitation we observe an increasing number of vortices. The vortex state can evolve into the turbulent regime if the parameters of excitation are driven up to a certain set of combinations. If the value of the parameters of these combinations is exceeded, all vorticity disappears and the condensate enters into a different regime which we have identified as the granular phase. Our results are summarized in a diagram of amplitude versus time of excitation in which the different structures can be identified. We also present numerical simulations of the Gross-Pitaevskii equation which support our observations.