The Rayleigh-Taylor instability in a binary quantum fluid

TL;DR

This paper reports the first observation of the Rayleigh-Taylor instability in a binary quantum fluid, demonstrating mushroom-shaped structures, interface modes, and vortex chains, bridging classical and quantum fluid dynamics.

Contribution

It introduces the experimental realization of RTI in a two-component Bose-Einstein condensate, linking classical fluid instabilities with quantum superfluid behavior.

Findings

Observation of mushroom-like structures during RTI

Spectroscopic measurement of ripplon interface modes

Transformation of velocity fields into vortex chains

Abstract

Instabilities, where small fluctuations seed the formation of large-scale structures, govern dynamics in a variety of fluid systems. The Rayleigh-Taylor instability (RTI), present from tabletop to astronomical scales, is an iconic example characterized by mushroom-shaped incursions appearing when immiscible fluids are forced together. Despite its ubiquity, RTI experiments are challenging; here, we report the observation of the RTI in an immiscible binary superfluid consisting of a two-component Bose-Einstein condensate. We force these components together to initiate the instability, and observe the growth of mushroom-like structures. The interface can also be stabilized, allowing us to spectroscopically measure the "ripplon" interface modes. Lastly, we use matter-wave interferometry to transform the superfluid velocity field at the interface into a vortex chain. These results-in agreement with our theory-demonstrate the close connection between the RTI in classical and quantum fluids.