[tt] [silk] A trick of the light

[Eugen Leitl]

----- Forwarded message from Udhay Shankar N <udhay at pobox.com> -----

From: Udhay Shankar N <udhay at pobox.com>
Date: Sun, 25 Nov 2007 11:35:19 +0530
To: silklist at lists.hserus.net
Subject: [silk] A trick of the light
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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))


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