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By Adrian Cho
ScienceNOW Daily News
29 February 2008
It sounds like a headline from the spoof newspaper The Onion, but for physicists, this is actually an achievement: Two teams have stored nothing in a puff of gas and then retrieved it a split second later. Storing a strange form of vacuum builds on previous efforts in which researchers stopped light in its tracks (ScienceNOW, 22 January 2001) and may mark a significant step toward new quantum information and telecommunication technologies.
To stop light, researchers first shine an intense and continuous beam of laser light into a gas of atoms. That "control beam" tickles the atoms to allow a pulse of laser light of another wavelength to enter the gas. To trap the pulse, researchers turn off the control beam, which causes the pulse to imprint itself on the atoms. To release it again, they turn on the control laser.
So storing a vacuum might sound ridiculously simple: Follow the same procedure but leave out the pulse, and you store nothing. However, Alexander Lvovsky of the University of Calgary in Canada and his colleagues and Mikio Kozuma of the Tokyo Institute of Technology in Japan and his group have stored a very peculiar type of nothingness called a "squeezed vacuum."
To see what this is, begin with a normal light wave. Classically, this is a smooth wave of electromagnetic fields with equally spaced peaks and dips. But throw in quantum mechanics and things get more complicated. The precise height of the wave becomes uncertain, so the wave gets fuzzy (see figure). Physicists have learned how to manipulate that inevitable uncertainty--for example, making it smaller at the peaks and larger in between. That makes "phase-squeezed light." Now imagine turning down the intensity of the phase-squeezed light to zero. The wave itself goes away, but the waxing and waning uncertainty remains, creating a squeezed vacuum.
vocabulary
1. retrieve 復得,收回,取回;恢復
2. spoof 愚弄;欺騙
3. puff of 陣風
4. split 撕開
5. track 軌跡
6. tickle 喚起,激起
7. pulse 脈衝
8. imprint 壓印
9. peculiar 奇特 獨特的
10. squeeze 壓縮
11. precise 精確的
12. fuzzy 模糊不清的
13. manipulate 熟練操作
14. inevitable 不可避免的
15. wax 增大
16. wane 缺蝕
trap 捕捉
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