Picture a nanoscale dance floor full of independently moving particles. When things really start to heat up - or, in this case, cool down - particles partner off, but on opposite sides of the space, 'dancing' in synch as if telepathically.
In the ultra-pure isotope helium-three (3He), this dance starts at a very specific, very low temperature, when it converts into the superfluid phase (where its superfluid component has no viscosity and thus flows without friction) through a mechanism called pairing. Pairs of particles form over huge atomic distances in three dimensions.
"It's something like a dance in space," said Jeevak Parpia, professor of physics in the College of Arts and Sciences (A&S). "The effect of this pairing, called a 'fluctuation,' is to scatter other non-paired partners and disrupt the overall transport of momentum."
These superfluid fluctuation effects were predicted almost 50 years ago, but no one had the instrumentation to see it; now, enabled by a custom thermometer that is accurate at super-low temperatures and sensitive enough to capture this subtle effect, Cornell researchers have observed the phenomenon in experiments - possibly gaining new insight for quantum computing and the physics of the early universe.
"Observation of Suppressed Viscosity in the Normal State of 3He due to Superfluid Fluctuations" published Sept. 20 in Nature Communications. Parpia led the study, and research was primarily conducted by postdoctoral researcher Yefan Tian and doctoral student Rakin Baten. Eric Smith, Ph.D. '72, was an essential team member and Erich Mueller, professor of physics (A&S), provided theoretical support.
