Physicists have taken inspiration from Vincent van Gogh’s “The Starry Night” to describe a breakthrough discovery in quantum physics
Researchers at Osaka Metropolitan University and the Korea Advanced Institute of Science and Technology have directly observed a long theorised phenomenon known as the quantum Kelvin–Helmholtz instability (KHI). By doing this, they have managed to uncover structures that have never been seen before, called eccentric fractional skyrmions.
Their swirling, crescent-shaped patterns have a similar resemblance to the spirals and moonlit sky of van Gogh’s masterpiece.
What is the Kelvin-Helmholtz instability?
The Kelvin–Helmholtz instability is a well-known concept in classical fluid dynamics. It occurs at the interface between two fluids moving at different speeds, like wind sweeping across a body of water.
But until now, scientists had only theorised whether this instability could occur in quantum fluids, where matter behaves in unusual ways due to the rules of quantum mechanics.
Bringing KHI into the quantum realm
To explore this, researchers cooled lithium gas to near absolute zero, forming a multi-component Bose–Einstein condensate. A multi-component Bose–Einstein condensate is a type of quantum superfluid where atoms move in perfect coordination. By creating two separate quantum streams moving at different velocities within the condensate, they set the stage for a quantum version of the Kelvin–Helmholtz instability.
At the interface between the two streams, ripples began to form, indicating KHI. But unlike their classical counterparts, these ripples didn’t evolve into chaotic turbulence. Instead, they created an exotic pattern of quantum vortices governed by the subtle rules of quantum physics and topology.
The discovery of eccentric fractional skyrmions
These new vortices were eccentric fractional skyrmions (EFSs), a newly identified form of topological defect. Unlike typical skyrmions, which are symmetrical and centred, EFSs appear crescent-shaped and contain internal singularities, where the usual spin structure breaks down. This makes them both visually striking and scientifically significant.
The researchers were quick to notice the resemblance between the shape of these quantum vortices and the famous crescent moon in “The Starry Night.”
A step forward in quantum physics
Skyrmions have already been studied extensively in magnetic materials for their potential in next-generation technologies like spintronics and quantum memory devices. The discovery of a new, more complex form of skyrmion in a superfluid opens new paths for both practical applications and theoretical exploration.
This breakthrough not only confirms a decades-old prediction but also introduces new questions about the nature of quantum vortices, the structure of multi-component fluids, and the limits of topological classification in physics.
The team aims to improve the precision of their experiments, potentially allowing them to test 19th-century predictions about fluid wave dynamics.
