Illustration of the density circulation of a turning dipolar Bose-Einstein-Condensate (dBEC) displaying quantized vortices based on simulation data from the paper. The vortices, visible via their density dips in the dBEC, arrange in stripes due to the long-range and anisotropic character of the dipolar interactions between the atoms. Credit: Ella Maru Studio
In nature, vortices can be found everywhere: Whirling up water can produce swirls. When the environment is stirred up, huge tornadoes can form. This is also the case in the quantum world, other than that many identical vortices are being formed concurrently– the vortex is quantized. In lots of quantum gases, such quantized vortices have already been shown.
” This is intriguing due to the fact that such vortices are a clear indicator of the frictionless flow of a quantum gas– the so-called superfluidity,” states 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.
Ferlaino and her team are looking into quantum gases made from highly magnetic components. For such dipolar quantum gases, in which atoms are extremely linked to each other, quantum vortices might not be demonstrated so far. Researchers have established a brand-new technique: “We utilize the directionality of our quantum gas of dysprosium, whose atoms act like numerous small magnets, to stir the gas,” discusses Manfred Mark from Francesca Ferlainos team.
This is likewise the case in the quantum world, other than that lots of identical vortices are being formed simultaneously– the vortex is quantized. In numerous quantum gases, such quantized vortices have already been shown.
For such dipolar quantum gases, in which atoms are highly connected to each other, quantum vortices might not be shown so far. “If it spins fast enough, then small vortices form in the quantum gas.
To do this, the scientists use an electromagnetic field to their quantum gas in such a method that this at first round, pancake-shaped gas becomes elliptically warped due to magnetostriction. This idea, as easy as it is powerful, originated from a theoretical proposal a few years ago by the Newcastle University theoretical group, led by Nick Parker and of which Thomas Bland, the papers second author, was a member.
” By rotating the magnetic field, we can turn the quantum gas,” discusses Lauritz Klaus, very first author of the current paper. “If it spins fast enough, then little vortices form in the quantum gas. This is how the gas tries to balance the angular momentum.”
At adequately high rotational speeds, strange stripes of vortices form along the magnetic field. These are an unique quality of dipolar quantum gases and have now been observed for the very first time at the University of Innsbruck, Austria.
The brand-new technique, now presented in Nature Physics, will be utilized to study superfluidity in supersolid states in which quantum matter is concurrently solid and liquid. “It is undoubtedly still a major open concern the degree of superfluid character in the freshly found supersolid states, and this concern stays still really little studied today.”
Reference: “Observation of vortices and vortex stripes in a dipolar condensate” 31 October 2022, Nature Physics.DOI: 10.1038/ s41567-022-01793-8.
The work was performed in cooperation with Giacomo Lamporesi from the University of Trento, Italy, and the theorist Russell Bisset from the University of Innsbruck, and was financially supported by the European Research Council ERC, the Austrian Science Fund FWF and the Austrian Academy of Sciences ÖAW, to name a few.