SIGNIFICANT EVENTS - SCIENCE EVENTS
07/06/01
Nature Article from the Packard-Davis Group at Berkeley is the Basis for a JPL Press Release
An article titled "Quantum interference in superfluid 3He" was published in the July 5
issue of Nature. Written by R.W. Simmonds, A. Marchenkov, E. Hoskinson, J.C. Davis
and R.E. Packard of the University of California, Berkeley, the article describes their work
with superfluid 3He and their study of the mass flow properties of this superfluid.
Quantum interference is the phenomenon whereby the wave-particle duality in nature is revealed.
The wave nature of light, which had previously been viewed as corpuscular, was first
demonstrated in 1845 by Thomas Young in his celebrated two-slit interference experiment.
The direct evidence for the quantum wave nature of electrons emerged in 1928 from the
Davisson-Germer interference experiment. In recent years double path interference experiments
have demonstrated the quantum wave nature of beams of neutrons, atoms, and even Bose-Einstein
condensates of laser-cooled atoms. In condensed matter systems, double-path quantum interference
is observed in the superconducting dc-SQUID. The paper by the Berkeley group reports a double-path
quantum interference experiment involving superfluid 3He. Using a toroidal geometry analogous
to a superconducting dc-SQUID, they control a quantum phase shift by using the rotation of the
Earth and find the classic interference pattern with periodicity determined by the quantum of
circulation:
where h is Plank's constant and m3 is the atomic mass of 3He.
This observation of interference in this superfluid system has been announced to the general public in a JPL press release that can be found in our News section. A local radio station KNX intends to air an interview based on the press release. The ABC Radio Network, with 100s of radio stations nationwide, also intends to produce a report on this discovery.
