HAVE we made a supersolid - a quantum phase in which a solid starts to flow fluidly? Debate has raged ever since one was reportedly made in 2004, but the latest studies suggest genuine supersolids exist after all.
Atoms in solids are bound in a regular lattice, which normally keeps them rigid. But according to quantum theory, cool some solids close to absolute zero and they become frictionless, flowing supersolids, while retaining their lattice structure.
In 2004, Eunseong Kim, now at the Korea Advanced Institute of Science and Technology in Daejeon, South Korea, and Moses Chan of Pennsylvania State University in University Park cooled and pressurised liquid helium until the atoms were forced into a lattice, and filled a cylinder with this solid. They then placed the cylinder in a machine that caused it to spin one way and then the other; the frequency at which the helium cylinder switched ...
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