High-quality, single-crystal, ultra-cold solid helium exhibits supersolid behavior, suggesting that this frictionless solid flow is not a consequence of defects and grain boundaries in poor-quality, ...

In 2004 researchers reported the first clear evidence for superfluidity in solid helium-4. However, Matthew Chalmers describes recent experimental and theoretical work that has brought the very ...

New experiments are casting doubt on previously reported observations of supersolid helium. In a paper appearing in the current issue of Physical Review Letters (PRL), John Reppy (Cornell University) ...

The long-held, but unproven idea that helium-4 enters into an exotic phase of matter dubbed a "supersolid" when cooled to extremely low temperatures has been challenged in a new article. The long-held ...

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 ...

The flow behaviour of solid helium at very low temperatures has recently generated as much controversy as excitement. An experiment looking directly at the grain boundaries offers fresh insights. The ...