Rayleigh-Taylor instability and mushroom-pattern formation in a two-component Bose-Einstein condensate

Kazuki Sasaki,Hiroki Saito,Daisuke Akamatsu,Naoya Suzuki

doi:10.1103/physreva.80.063611

Abstract

The Rayleigh-Taylor instability at the interface in an immiscible two-component Bose-Einstein condensate is investigated using the mean-field and Bogoliubov theories. Rayleigh-Taylor fingers are found to grow from the interface and mushroom patterns are formed. Quantized vortex rings and vortex lines are then generated around the mushrooms. The Rayleigh-Taylor instability and mushroom-pattern formation can be observed in a trapped system.

Highlights

When a layer of a lighter fluid lies under that of a heavier fluid, the translation symmetry on the interface is spontaneously broken and the interface is modulated due to the Rayleigh-Taylor instabilityRTI ͓1–4͔
Quantized vortex rings and vortex lines are generated around the mushrooms
We investigate the RTI and ensuing dynamics in a phase-separated two-component Bose-Einstein condensateBEC

Summary

INTRODUCTION

When a layer of a lighter fluid lies under that of a heavier fluid, the translation symmetry on the interface is spontaneously broken and the interface is modulated due to the Rayleigh-Taylor instabilityRTI ͓1–4͔. There has been a growing interest in the surface and interface properties of BECs. For instance, the Kelvin-Helmholtz instability4,7,8͔, which occurs at the interface between two fluids with a relative velocity, has been observed in a 3He superfluid system9,10͔. When a magnetic field is applied to a magnetic fluida colloidal suspension of fine magnetic particles, the surface is deformed by the Rosensweig instability12͔ and grows into a pattern of crests. Such a surface phenomenon can be theoretically shown to occur at the interface in a two-component BEC with a dipole-dipole interaction13͔. We first consider an ideal flat interface, and numerically show that the interface becomes deformed by the RTI to grow into the well-known mushroom pattern.

Mean-field dynamics

Bogoliubov analysis

DYNAMICS IN A HARMONIC TRAP

CONCLUSIONS