Evidence mounts for an exotic supersolid

Rubidium atoms simultaneously act like a solid and a superfluid

PITTSBURGH — Hallmarks of an exotic state of matter called a supersolid have been spotted in a gas of ultracold rubidium atoms. In the same piece of matter, researchers found signs of the seemingly disparate properties of both solidity and superfluidity, the frictionless flow of atoms.

Reporting March 18 at a meeting of the American Physical Society, Dan Stamper-Kurn described two telltale signs that suggest this weird state of matter may indeed be a supersolid.