Physicists have long predicted the possibility of tying knots in quantum fields. But no one has been able to make or observe a three-dimensional quantum knot—until now.
Inside the lab of David S. Hall ’91, Amherst’s Paula R. and David J. Avenius 1941 Professor of Physics, scientists have found a way to create knotted solitary waves in a quantum-mechanical field. This represents a major step forward in understanding the nature of quantum fluids.
“First we cooled a gas of rubidium atoms down to billionths of a degree above zero,” says Hall, who, with Mikko Möttönen of Aalto University in Finland, led the team that made the discovery.
The cooling process created “a superfluid—a tiny, well-ordered environment,” which the scientists then exposed to a rapid change of a magnetic field, “which tied the knot in less than a thousandth of a second.”