Atomic Optics Uses Light To Focus Atom Beams

dcshoes writes: "Nonlinear Atom Optics uses laser light to cool atoms to one millionth a degree Kalvin. At this low temperature, atom wavelengths are elongated, making the wave nature of atoms more easy to observe, and enable scientists to focus, reflect, defract, etc, atom beams. Atom lasers could lead to advances in, among other things, Nanolithography and Holography. Cool. Literally."

Comments

Crib Mountable?

[sharkey]

Does anyone make one of these to fit on a crib? The $CHILD_PROCESS is 6 months old now, and nothing pisses her off like going to bed. We need something to quiet her down. A quantum state of relaxation on her part would enable a good nights sleep for me and the SO.

--

The Doctor

[TechLawyer]

So the Doctor on Star Trek: Voyager might actually be possible, but he'd be really, really cold.

Laser Cooling

[Muerte23]

Laser cooling is an application of using the Doppler shift to selectively absorb photons propagating counter to the direction of the atom's movement. The laser is slighty red-detuned from some spectral line of the atom, so when the atom moves towards the laser, it absorbs a now correctly blue-shifted photon and gets a kick of momentum to slow it down. Since the atom emits the photon again in a random direction, then net result after millions of collisions is to slow its net velocity to zero.

Since the atom is also emitting photons in random directions, it settles down to a minimum kinetic energy / temperature of about 240 microKelvin (for Sodium, for example). To cool atoms furter, you have to add in magnetic traps, then selectively "heat" the hottest atoms with RF energy to "boil" off the highest part of the temperature distribution to result in a lower average temperature of the condensate.

Check the MIT Center for UltraCold Atoms for more details.

Muerte

Re:1 uK isn't that low.

[mindstrm]

Can you explain what a 'negative' temperature would be, given that 0k is the absence of all temperature? I assume this is some kind of quantum theory thing...

can you elaborate a bit? I've never heard of 'negative heat' before.

cooling with a laser?

[Sebastopol]

Can someone explain how you cool something with a laser? That seems a bit counter-intuitive.


---

Re:cooling with a laser?

[Wind_Walker]

Basically, this is how you cool with lasers: Imagine you have six lasers, all pointed at the same place, and all in perpendicular directions (imagine a cube with a laser pointing directly at the center of each face, but the cube is actually transparent, the laser beams oriented towards each other)

Now we put some amount of mass right at the point where the 6 laser beams cross. The mass at the center will be hit by some photons from one of the lasers (for argument's sake). This will cause the mass to absorb the momentum of the photon, as well as excite the particle. The excited particle will then emit another photon in a random direction. However, there will be some recoil from this photon being ejected. Instead of being pushed away by this ejection, the particle is "persuaded" by the other lasers to stick around, so to speak. The process then repeats, but it takes about 10 minutes. Since the particle has lost momentum (to the ejected photon) it has less energy (in the Physics department here, we call it "tired").

Eventually, the mass at the center gets so "tired" that it falls into a quantum state of relaxation, as described by Schroedinger's equation and its wavefunction. Interesting things happen when it gets incredibly cold, and that's what the article is talking about. This was a very simplistic explanation, so if you want something more, just head over to Google and search for "laser cooling".

------
That's just the way it is

Bill Nye dead in bicarb explosion...

[Midnight Ryder]

Damn... I can't help it. Seeing Bill Nye the Science Guy mentioned on here means I have to post this:

Bill Nye killed in Experement!

Yes - it's a joke (it's at The Onion, of course it's a joke!)

Other ultracold atom links

[selectspec]

Ultracold plazma and good old Fermi degeneracy. Both from scientific american.

Re:Clarification

[sien]

No, no ! This is the Kalvin scheme. 200 Kalvin is one Hobbes. Hey, it makes as much sense as Fahrenhiet ;-)

Clarification

[Kozz]

The temperature scale is "Kelvin", not "Kalvin". And the measurements are known as "Kelvins", not "degrees Kelvin" (any physics student knows this). The proper phrase would be "to one millionth of one Kelvin".

Thank you.


Quidquid latine dictum sit, altum viditur.

NIST

[resonance]

They use the same technology in the latest atomic clocks at NIST. Pretty cool stuff, they have a video there to check out that shows how the lasers make a ball of supercooled cesium and fling it up in the air to make a clock. Check it out.

Re:1 uK isn't that low.

[fatphil]

I always direct people to the Usenet Physics FAQ:

http://math.ucr.edu/home/baez/physics/neg_temper at ure.html

They say it better than I could, and what's more they understand it, I just parrot it.

FatPhil
-- Real Men Don't Use Porn. -- Morality In Media Billboards

Intel to Buy rights

[tonywestonuk]

Latest News: Intel to buy rights to laser - Technology required to keep next future Pentium V processor from overheating...... :-)

Why is it so damn cold?

[popular]

When will scientists figure out how to do cool stuff like this at room temperature? Bill Nye amd Beakman and Jax can perform all kinds of science wizardry with an empty bottle of Coke and a tablespoon of baking soda!

--

Re:Both Memepool and Slashdot?

[gfxnrrd]

Well, considering that it was posted to memepool YESTERDAY and the "poster" on Slashot even ripped off the final pun of that article, I'd say the odds had nothing to do with it. I notice a lot of memepool articles are reposted here, often verbatim. The Slashdot editors should be more careful about reviwing submissions to make sure they aren't just ripping off content from other websites. It just makes Slashdot look bad.

Cooling atoms using laser light is not "new"

[Big Nothing]

This is exactly what Steven Chu, Claude Cohen-Tannoudji and William D. Phillips got their Nobel Price in Physics for back in 1997. They've been working with this kind of stuff since approx. 1985. Cool stuff, though (no pun intended).

Sorry if this info has been posted earlier on the list, I didn't have time to read through it, just wanted to inform you geeks (and geekettes).

1 uK isn't that low.

[fatphil]

Helsinki University have acheived macroscopic temperatures measured in pK (pico-Kelvin). I believe that the most recent record was circa 18 months ago.

I feel obliged to plug this result as I had dinner with the daughter of one of the professors only 2 weeks ago.

There are pathological non-macroscopic situations where lower _even negative_ "temperatures" are involved. However, there require setting up bizarrely improbable situations with only small numbers of atoms (hence this is not a macroscopic situation). The laws relatiing entropy to temperature prove that in order to be that improbable, the temperature must be negative!
(Method - line up polar atoms in a strong field, reverse the field as quickly as you can - voila you now have almost every atom pointing in the wrong direction - now _that_'s improbable.)

Phil
-- Real Men Don't Use Porn. -- Morality In Media Billboards