Physicists probing the nature of quantum matter have become tied up in knots – but don’t worry, that’s a good thing. The find could lead to new theories about the particles that make up our universe, and perhaps help develop quantum computers.
Researchers have previously made knots from all kinds of surprising things, including DNA, light and water. Now Mikko Möttönen of Aalto University in Finland and his colleagues have tied up a more exotic material: a type of quantum matter called a Bose-Einstein condensate (BEC).
BECs are an unusual kind of gas in which the atoms have been cooled to near absolute zero, putting them all into a single quantum state. Using a carefully changing magnetic field, Möttönen’s team coaxed a BEC made from rubidium atoms into a complex knot called a Hopf fibration, a tangle of interlocking circles in the shape of a doughnut.
“These knots are inspiring and visually rich,” he says. “After having worked with them, you start to really appreciate their elegance.”
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