Water vortices are common in nature. Huge tornadoes can happen when the air is stirred up.

This is also true in the quantum world, but because the vortex is quantized, many identical vortices are forming at once. Such quantized vortices have already been shown to exist in numerous quantum gases.

“This is interesting,” says Francesca Ferlaino from the Department of Experimental Physics at the University of Innsbruck and the Institute of Quantum Optics and Quantum Information at the Austrian Academy of Sciences, “because such vortices are a clear indication of the frictionless flow of a quantum gas – the so-called superfluidity.”

Ferlaino’s team studies strongly magnetic quantum gases. So far, quantum vortices have not been seen in dipolar quantum gases where the atoms are very close to each other. 

So far, quantum vortices have not been seen in dipolar quantum gases where the atoms are very close to each other.

Now, scientists have come up with a new way to stir gas. 

“We use the directionality of our quantum gas of dysprosium, whose atoms behave like many small magnets, to stir the gas,” says Manfred Mark from Francesca Ferlaino’s team.

To do this, the scientists put a magnetic field around their quantum gas in a way that causes magnetostriction to change the pancake-shaped gas into an ellipse.

This simple but powerful idea came from a theoretical proposal made by the Newcastle University theoretical team a few years ago.

The team was led by Nick Parker, and Thomas Bland, the second author of the paper, was a member.

Lauritz Klaus, the paper’s first author, notes that “By rotating the magnetic field, we can rotate the quantum gas. If it spins fast enough, then small vortices form in the quantum gas. This is how the gas tries to balance the angular momentum.” 

At high enough rotational speeds, strange stripes of vortices occur along the magnetic field, which is the gas’s attempt to counteract the angular momentum.

This is a unique thing about dipolar quantum gases, and it has just been seen for the first time at the University of Innsbruck in Austria.

The novel approach, which has just been published in Nature Physics, will be used to examine superfluidity in supersolid states, where quantum matter is both solid and liquid at the same time.

The degree of superfluidity in the recently discovered supersolid states is in fact still a significant unresolved subject, and it has received very little research so far.


Image Credit: Ella Maru Studio scientific-illustrations.com

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