The Rayleigh-Taylor instability in a binary quantum fluid

Area of Science:

• Quantum fluid dynamics
• Bose-Einstein condensates
• Fluid instabilities

Background:

• Fluid instabilities, such as the Rayleigh-Taylor instability (RTI), are fundamental to structure formation in diverse fluid systems.
• RTI is characterized by mushroom-shaped structures formed when immiscible fluids interact under acceleration.
• Experimental observation of RTI is challenging, particularly in quantum systems.

Purpose of the Study:

• To observe and characterize the Rayleigh-Taylor instability in a binary superfluid system.
• To investigate the behavior of quantum fluids under conditions that induce RTI.
• To explore the relationship between classical and quantum fluid instabilities.

Main Methods:

• Utilized a two-component Bose-Einstein condensate as the immiscible binary superfluid.
• Initiated the instability by forcing the two superfluid components together.
• Employed spectroscopy to measure interface modes and matter-wave interferometry to analyze the superfluid velocity field.

Main Results:

• Successfully observed mushroom-shaped structures characteristic of RTI in the superfluid system.
• Demonstrated the stabilization of the fluid interface and measured 'ripplon' interface modes.
• Transformed the superfluid velocity field into a vortex chain using matter-wave interferometry.

Conclusions:

• The study provides the first observation of RTI in a binary superfluid.
• Results align with theoretical predictions, confirming the close analogy between classical and quantum fluid instabilities.
• Highlights the potential of Bose-Einstein condensates as a platform for studying fundamental fluid dynamics.