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.
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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.