Re: "Atomic Laser" Gavin Wheeler (wheeler@lpbc.jussieu.fr)
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13 Feb 1997 16:31:19 -0500

In article <5dosrt$mb6@foglet.rutgers.edu>, mreinbol@falcon.lhup.edu (Morgan D. Reinbold) wrote:

> Just a few bits and pieces I overheard on CNN... Evidently, scientists
> at MIT have developed a huge mass of machinery which is able to move
> atoms in a controlled, predictable, wave-like pattern, as opposed to
> chaotically bouncing through space.

Not quite - it's a magnetic trap containing super-cold Sodium atoms. Get them cold enough and you obtain a Bose-Einstein condensate (remember your old statistical thermodynamics courses?)

This B-E condensate trap acts somewhat like the resonant cavity of a laser: all the atoms are in the same state (that's the B-E condensate bit) and apparently their wavefunctions are also coherent - although I don't recall enough quantum thermo to be able to say if that is necessarily the case for a bose einstein condensate.

The funky bit comes when they let a burst of atoms out of the trap with a radio frequency pulse disruping the magnetic trap. This produces a clump of atoms buzzing along like any other- BUT if you cut this clump in half with a laser (actually I think it was the trap itself that was divided in two, producing two clump at the start) then when these clumps overlap as they diffuse, instead of getting a superposition of intensities you get interference fringes, just like in Young's slit experiment with light.

Anyway, go see the pictures (and even movies) on http://bink.mit.edu/dallin/news.html
or http://www.aip.org/physnews/special.htm and you'll understand more than my poor explanation can make clear. On the first site there are a few links to discussions of nanotech applications, but I seem to recall that they mostly apply to micromachining rather than MNT.

-- 
Gavin Wheeler    wheeler@lpbc.jussieu.fr