In new state of
matter, echoes of an old symbol
March 16,
2006
Courtesy University of Chicago
and World
Science staff
Physicists say they have
converted three atoms into a new state of matter
whose existence a Russian scientist predicted in
1970.
Borromean rings. The symbol of the
medieval Borromeo family, these rings
were so
intertwined that removing any one caused the entire
structure to fall
apart. Physicists use the term
to describe some atomic nuclei, because if any
one
constituent is removed, the rest of the nucleus
disintegrates. In a new
state of matter, atoms
themselves form into structures of this
nature.
In this state, any two of the
atoms repel each other when close together,
but
when you put three of them together, it turns out that
they attract and
form a new state, said the
University of Chicago's Cheng Chin.
In the
laboratory of Rudolf Grimm at the University of
Innsbruck in Austria,
they reported, they observed
the state in a vacuum chamber at a frigid minus
459.6 degrees Fahrenheit.
That's equivalent to
a billionth of a degree above absolute zero, the
coldest temperature that can exist.
The new
state behaves like a Borromean ring, a symbol of three
interlocking
circles significant in Medieval
Italy, the researchers explained. The
Borromean
concept is also important in some other aspects of
physics, chemistry and
mathematics.
This
ring means that three objects are entangled. If you
pick up any one of
them, the other two will
follow. However, if you cut one of them off, the
other two will fall apart, Chin said. There is
something magic about this
number of three.
The new state is called an Efimov state after
the Russian researcher, Vitaly
Efimov. Chin and 10
other scientists described the finding in the March 16
issue of the research journal Nature.
The
physicists said they coaxed three atoms of cesium, a
soft metal used in
atomic clocks, into the Efimov
state. But in theory the state is possible for
any
sets of three particles at ultracold temperatures,
according to Chin.
If you can create this kind of
state out of any other type of particle, it'll
have exactly the same behavior, he said.
After working on cesium for many years, this
is a dream come true for me,â€
he
added.
The finding may spur new research
programs devoted to understanding the
quantum
mechanical behavior of just a few interacting
particles, Grimm said.
Quantum mechanics, the
study of physical laws governing the smallest things,
is well worked out when it comes to explaining the
interactions of either
two particles, or many,
Chin said. But a good understanding of systems
containing a handful of particles is elusive. That
may change as scientists start to
produce
experiments that simulate systems of three or four
particles, like
those found in atomic nuclei.
Now that the Efimov state has been achieved,
scientists can aspire to
engineer the properties
of matter, Chin said.
Using so-called
nanotechnology, scientists can already combine atoms
in
different ways to form materials with
interesting new properties, but that doesn
t change
the fundamental interactions of these atoms, Chin
said.
The new findings, he added, expand those
horizons. He said the researchers
exerted total
control over the atoms in the experiments, converting
them into
the Efimov state and back at
will.
This so-called quantum control over the
fundamental properties of matter
now seems
feasible. We're not limited to the properties of, say,
aluminum, or
the properties of the copper of these
particles. We are really creating a new
state in
which we can control their properties. But not too
easily: for now,
he added, it seems this can only
be done at temperatures near absolute zero.
The
Borromean rings were added to the coat of arms of the
Borromeo family,
Milanese aristocrats, in the 15th
century. Although there are different
accounts of
what they stood for, one story has it that they
represented marriages
that had inseparably bound
the family with two others.
http://www.world-science.net/othernews/060316_newstatefrm.htm
_
http://www.world-science.net/othernews/060316_newstatefrm.htm
"Truth can never be reached by just listening
to the voice of an authority."
-- Francis
Bacon
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