5/27/09
Phil
Ciciora, News Editor
217-333-2177;pciciora@illinois.edu
CHAMPAIGN, Ill. —
A team of researchers at the University of Illinois has demonstrated that,
counter to classical Newtonian mechanics, an entire collection of
superconducting electrons in an ultrathin superconducting wire is able to
“tunnel” as a pack from a state with a higher electrical current to one with a
notably lower current, providing more evidence of the phenomenon of macroscopic
quantum tunneling.
Physics
professors Alexey Bezryadin and Paul Goldbart led the team, with graduate
student Mitrabhanu Sahu performing the bulk of the measurements. Their research
was published on the Web site of the journal Nature Physics on May
17.
Quantum tunneling is the capability of a particle to inhabit regions
of space that would normally be off-limits according to classical mechanics.
This research observes a process called a quantum phase slip, whereby packs of
roughly 100,000 electrons tunnel together from higher electrical current states
to lower ones. The energy locked in the motion of the electrons as they phase
slip is dissipated as heat, causing the nanowires to switch from a
superconducting state to a more highly resistive one.
It’s through this
switching of states that allows the tunneling of the phase slip to be observed,
the researchers say.
