ScienceDaily (May 29, 2012) —
Invisibility, once the subject of magic
or legend, is slowly becoming reality.
Over the past five years
mathematicians and other scientists
have been working on devices that
enable invisibility cloaks -- perhaps not
yet concealing Harry Potter, but at
least shielding small objects from
detection by microwaves or sound
waves.
A University of Washington
mathematician is part of an
international team working to
understand invisibility and extend its
possible applications. The group has
now devised an amplifier that can
boost light, sound or other waves
while hiding them inside an invisible
container.
"You can isolate and magnify what
you want to see, and make the rest
invisible," said corresponding author
Gunther Uhlmann, a UW mathematics
professor. "You can amplify the waves
tremendously. And although the wave
has been magnified a lot, you still
cannot see what is happening inside
the container."
The findings are published online this
week in the Proceedings of the
National Academy of Sciences.
As a first application, the researchers
propose manipulating matter waves,
which are the mathematical
description of particles in quantum
mechanics. The researchers envision
building a quantum microscope that
could capture quantum waves, the
waves of the nanoworld. A quantum
microscope could, for example, be
used to monitor electronic processes
on computer chips.
The authors dubbed their system
"Schrödinger's hat," referring to the
famed Schrödinger's cat in quantum
mechanics. The name is also a nod to
the ability to create something from
what appears to be nothing.
"In some sense you are doing
something magical, because it looks
like a particle is being created. It's like
pulling something out of your hat,"
Uhlmann said.
Matter waves inside the hat can also
be shrunk, though Uhlmann notes
that concealing very small objects "is
not so interesting."
Uhlmann, who is on leave at the
University of California, Irvine, has
been working on invisibility with fellow
mathematicians Allan Greenleaf at the
University of Rochester, Yaroslav
Kurylev at University College London
in the U.K., and Matti Lassas at the
University of Helsinki in Finland, all of
whom are co-authors on the new
paper.
The team helped develop the original
mathematics to formulate cloaks,
which must be realized using a class
of engineered materials, dubbed
metamaterials, that bend waves so
that it appears as if there was no
object in their path. The international
team in 2007 devised wormholes in
which waves disappear in one place
and pop up somewhere else.
For this paper, they teamed up with
co-author Ulf Leonhardt, a physicist at
the University of St. Andrews in
Scotland and author on one of the
first papers on invisibility.
Recent progress suggests that a
Schrodinger's hat could, in fact, be
built for some types of waves.
"From the experimental point of view,
I think the most exciting thing is how
easy it seems to be to build materials
for acoustic cloaking," Uhlmann said.
Wavelengths for microwave, sound
and quantum matter waves are longer
than light or electromagnetic waves,
making it easier to build the materials
to cloak objects from observation
using these phenomena.
"We hope that it's feasible, but in
science you don't know until you do
it," Uhlmann said. Now that the paper
is published, they hope to find
collaborators to build a prototype.
The research was funded by the
National Science Foundation in the
U.S., the Engineering and Physical
Sciences Research Council and the
Royal Society in the U.K., and the
Academy of Finland.
http://www.sciencedaily.com/releases/2012/05/120529182715.htm