http://www.wired.com/science/discoveries/magazine/15-11/st_alphageek
WIRED MAGAZINE: ISSUE 15.11
Harvard Physicist Plays Magician With the Speed of Light
By Erin Biba Email 10.23.07 | 12:00 AM
Lene Vestergaard Hau can stop a pulse of light in
midflight, start it up again at 0.13 miles per
hour, and then make it appear in a completely
different location. "It's like a little magic
trick," says Hau, a Harvard physicist. "Of
course, in all magic tricks there's a secret."
And her secret is a 0.1-mm lump of atoms called a
Bose-Einstein condensate, cooled nearly to
absolute zero (-459.67 degrees Fahrenheit) in a
steel container with tiny windows. Normally
well, in a vacuum light goes 186,282 miles per
second. But things are different inside a BEC, a
strange place where millions of atoms move barely in quantum lockstep.
About a decade ago, Hau started playing with BECs
for a physicist, that means shooting lasers at
them. She blew up a few. Eventually, she found
that lasers of the right wavelengths could tune
the optical properties of a BEC, giving Hau an
almost supernatural command over any other light
shined into it. Her first trick was slowing a
pulse of light to a crawl 15 mph as it traveled
through the BEC. Since then, Hau has completely
frozen a pulse and then released it. And recently
she shot a pulse into one BEC and stopped it
turning the BEC into a hologram, a sort of matter
version of the pulse. Then she transferred that
matter waveform into an entirely different BEC
nearby which emitted the original light pulse.
That's just freaky. Hey, Einstein may have set
that initial speed limit of light, but he only
theorized about BECs. "It's not breaking
relativity," Hau says. "But I'm sure he would have been rather surprised."
--
((Udhay Shankar N)) ((udhay @ pobox.com)) ((www.digeratus.com))
