Coldest lab in Chicago to simulate hot physics of early universe (Forwarded)

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Feb. 15, 2007

Coldest lab in Chicago to simulate hot physics of early universe

Project also to explore futuristic world of quantum computing

Cheng Chin will make a vacuum chamber in his laboratory the coldest place in
Chicago in order to simulate the impossibly hot conditions that followed the
big bang during the earliest moments of the universe.

"It turns out that matter at ultralow and ultrahigh temperatures might have
something in common," said Chin, an Assistant Professor in Physics at the
University of Chicago. Chin's strategy for probing the formative moments of
the early universe may also help boost the capability of quantum computers.
The work is supported by a 2006 Packard Fellowship for Science and
Engineering. As one of 20 new Fellows of the David and Lucile Packard
Foundation, Chin will receive an unrestricted research grant of $625,000
over five years.

Astrophysicists believe that moments after the big bang, subatomic particles
were spread evenly throughout a uniform environment that pervaded the
universe. "After billions of years, our universe is now far from uniform,
with all kinds of complex structu galaxies, planet systems, you and me,"
Chin said. "What is the origin of these complexities and when and how did
they develop?"

One scenario, called quantum fluctuation, describes a random process. Chin
likened it to throwing beans on the floor. Any pattern that forms will arise
entirely by chance. The alternative theory depends on what scientists call
the Kibble-Zurek mechanism in which matter undergoes a quantum phase
transition.

In the physics of everyday life, a phase transition occurs when snow flakes
form out of cooling water vapor on a winter day. In the quantum world of
subatomic particles, matter undergoes more exotic phase transitions under
ultracold or ultrahot conditions. According to the laws of quantum physics,
these transitions display a universal behavior regardless of whether they
occur at absolute zero or under big-bang conditions of many billions of
degrees.

Physicists are unable to recreate the big bang on Earth, but they can watch
how uniformly distributed atoms develop patterns in an ultracold vacuum
chamber. In his laboratory at the Gordon Center for Integrative Science,
Chin will cool the atoms in a two-foot cylindrical vacuum chamber to
billionths of a degree above absolute zero -- minus 459.67 degrees
Fahrenheit.

The cooled atoms will become a superfluid, an exotic state of matter that
differs dramatically from the solids, liquids and gases that dominate
everyday life. As the most uniform medium that technology can produce, the
ultracold atoms in this superfluid will simulate how evenly distributed
matter forms patterns under extreme conditions.

If the Kibble-Zurek process was operating after the big bang, voids and
clumps of matter formed as the universe expanded and cooled over millions
and billions of years, leading to the formation of galaxies interspersed by
vast, nearly empty expanses of intergalactic space. "Cosmological structures
formed in this way will have predictable properties and are not fully
random," Chin said.

Chin controls the atoms in his experimental chamber by trapping them in the
crossing pattern of infrared laser beams. These optical lattices hold
ultracold atoms fast, like eggs in an egg crate, Chin said. In the second
phase of his research program, Chin will attempt to develop these optical
lattices to store and transmit information between large numbers of atoms.

In the world of computation, smaller is better. Quantum computers, if fully
developed, would be far more powerful than conventional computers because
they would use atoms instead of transistors as their basic components.

"There are many more tricks we can play on these atoms than on eggs or on
any tangible object," Chin said. These tricks, or "quantum operations," as
scientists call them, could make it possible to tackle tasks with quantum
computers that would otherwise prove impossible.

In particular, optical lattices can provide a way of maintaining a state of
quantum coherence. In this state, all atoms are moving, spinning and tipping
in perfect synchronicity. "Think about setting a bunch of eggs to spin in
sync. It is not an easy task!" Chin said.

"Quantum computation demands a very high degree of quantum coherence.
Decoherence is essentially the No. 1 mechanism that limits the lifetime and
the performance of a quantum computer. When quantum coherence is lost, you
can only press the reset button and restart the computer," he said.

[NOTE: Images supporting this release are available at
http://www-news.uchicago.edu/release...215.chin.shtml ]