By Peter Weiss
Captured within the cavities of a porous glass disk, frozen helium has coalesced into a long-awaited, but never-before-observed, quantum phase of matter, a team of physicists claims. In that extraordinary state, known as a superfluid solid or supersolid, the material is expected to flow like a liquid yet maintain its solid crystal structure, says team leader Moses H.W. Chan of Pennsylvania State University in State College.
Frictionless flow, also known as superfluidity, has previously been observed only in liquids and gases (SN: 10/25/03, p. 262: Available to subscribers at Super Spinner: Seven-atom speck acts like superfluid). “Now, we’re saying that even in a solid we can see it,” Chan says. In the Jan. 15 Nature, he and his Penn State colleague Eun-Seong Kim present evidence for what they suspect is the world’s first supersolid.