Strange state of matter made into a pancake-shape for first time

A supersolid is an exotic state of matter that behaves like both a solid and a fluid. It was first predicted 60 years ago, but has only recently been created in the lab. 

A pancake-shaped supersolid has been made for the first time. This exotic state of matter behaves as a solid, but also flows like a frictionless fluid. It was first theorised 60 years ago, but was only recently created in the lab.

At temperatures a billionth of a degree Celsius above absolute zero, atoms form exotic phases of matter instead of freezing into solids. Some ultracold metals become perfect conductors of electricity. Ultracold materials that are very magnetic can become supersolids, in which atoms are ordered in a crystal-like grid, but can also flow together without exerting any friction on each other.

Researchers had previously only been able to create very narrow, line-like and oblong, cigar-shaped supersolids. Francesca Ferlaino at the University of Innsbruck in Austria and her colleagues have now created the first one to be shaped like a pancake.

The researchers used approximately 100,000 atoms of the rare-earth element dysprosium to create a supersolid around 0.01 millimetres in diameter. They first put the atoms in a vacuum, then used a carefully calibrated laser to make them lose energy and become ultracold – similar to how blowing on a hot cup of tea cools it down. Specially designed magnets controlled how the atoms interacted with each other, and the magnets and lasers kept them all in place.

In past experiments, the atoms were first cooled into a superfluid, then forced to interact in a particular way, but Ferlaino and her team found this procedure only works for producing long, narrow shapes. To make a bigger, rounder supersolid, they had to work out how to adjust the atoms’ temperature and interactions at the same time, so they could cool them directly into a supersolid state.

Ferlaino says that physicists have known how to make atoms ultracold for years, but theorists had to model and calculate exactly how to coax those atoms into a supersolid state. “There were a lot of questions among physicists about how far we can push towards more and more exotic states,” she says. “We had to find the right [supersolid] recipe.”

The new circular configuration could reveal more about how supersolids behave. Charles Clark at the National Institute of Standards and Technology in Maryland says it may show how a superfluid becoming a supersolid differs from fluid water turning into solid ice.

Ferlaino says her team also wants to spin its supersolid to see if it develops tiny, hurricane-like vortices that have been observed in other quantum fluids.


Post a Comment

Previous Post Next Post