PORTLAND, Ore. -- Superconductors demonstrate that quantum effects--like the perpetual motion of electrons around a loop of supercooled wire--can manifest at the macroscopic level under the right conditions. Likewise, superfluidity--the resistanceless flow of a liquid akin to the resistanceless flow of electrons in superconductors--was recently demonstrated at the National Institute of Standards and Technology (NIST). Now, researchers at the University of Alberta (Canada) claim to be close to demonstrating supersolidity in supercooled helium. When cooled below .25 degrees Kelvin, the solid helium began exhibiting characteristics that indicate the resistanceless flow of a solid. Supersolidity could enable persistent flows on the surface of chips and eventually, perhaps, perpetual motion machines.
This new state of matter--supersolidity--was demonstrated at University of Alberta physicists by professor John Beamish, chair of the Department of Physics, and his doctoral candidate James Day. To achieve the state of supersolidity, the researchers had to supercool liquid helium, then put it under enormous pressure to create a solid. Finally, the solid helium was cooled further to within .25 degrees Kelvin of absolute zero, resulting in a 20 percent increase in its shear modulus--a result indicating that the quantum effects of supersolidity were being expressed.
Supersolidity was first discovered by a Pennsylvania State University in 2004 by a team of physicists led by professor Moses Chan. That research team attempted to directly observe supersolidity in helium by oscillating the supercooled solid and measuring its motion, which appeared to exhibit the characteristics of a Bose-Einstein condensate.
However, Day and Beamish did not try to directly measure the perpetual (or even persistent) motion of the Bose-Einstein condensate form of helium, but, instead, made indirect measurements by shearing it elastically. By determining its shear modulus, Day and Beamish appeared to confirm Chan's team's earlier measurements of torsional oscillation, both of which indicate supersolidity. The results measured by Day and Beamish also appear to confirm the torsional oscillation changes measured by Chan, both of which can be explained by supersolidity in helium.