“ This work says that if you have a predisposition to getting cancer, wounding might enhance the chance that it will develop. ” — ANTHONY ORO, PAGE 9
In the News
Physicists made a ring of
atomic current by trapping
sodium atoms (center) in
a pair of crossed laser
beams (small arrows)
and then setting them
spinning with another
pair of lasers (big
arrow).
By Devin Powell
Forget about wires, silicon and electricity. Physicists have developed a new type of circuit that is little more than
a puff of gas dancing in laser beams.
By choreographing the atoms of this
ultracold gas to flow as a current
that can be controlled and switched
on and off, the scientists have taken
a step toward building the world’s
first atomtronic” device.
Atomtronics is a young,
small and mostly theoretical
field based on the idea that
atoms in unusual quantum states of matter may
provide an alternative
to the tried-and-true
electron for making
useful devices. In
2006 Murray
Holland
Ultracold atoms
on spin cycle can
mimic electricity
‘Atomtronics’ could lead to
the creation of new devices
of JILA, a joint institute of the University
of Colorado at Boulder and the National
Institute of Standards and Technology,
developed many of the first blueprints for
atomic versions of traditional electronic
components. He proposed using optical
lattices, egg carton–like structures made
of laser light, to trap individual atoms
and move them around from pocket to
pocket. This approach, he argued, could
be used to make atomtronic wires, batteries, transistors and diodes.
“None of these devices have been
made yet,” Holland says.
At the Joint Quantum Institute in
Gaithersburg, Md., graduate student
Anand Ramanathan and his colleagues
have been working on a completely different approach. They hope to make
atomtronic sensors not by controlling
atoms individually, but by manipulating the flow of hundreds of thousands
STORY ONE
u provide an alternative to the tried-and-truelectron for making lectron for making useful devices. In 2006 Murray Holland
This doughnut of ultracold gas spins
without friction, creating a current of
atoms that could be used to develop
the first “atomtronic” sensors.
of atoms all moving together in an
ultracold state of matter called a Bose-Einstein condensate.
In an upcoming paper in Physical
Review Letters, the team reports creating this condensate by cooling sodium
atoms suspended in magnetic fields.
The researchers trapped the sodium
atoms in a pair of crossed laser beams
and further chilled the atoms to less
than 10 billionths of a degree above
absolute zero. The two beams shaped
the resulting condensate into a flattened doughnut with a radius of about
20 micrometers.
“A lot of care was required in how we
created the trap,” Ramanathan says. “We
had to make it as smooth as possible to
make sure that imperfections played a
minimal role.”
A second pair of lasers transferred
energy to the doughnut to start it rotat-
ing. Because atoms in the condensate
behave as a single, coherent quantum
“superatom,” such a ring doesn’t speed
up or slow down gradually— it jumps
between different speeds, much like a
blender would if it could change settings
instantaneously. The scientists chose
