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Researchers Chill Mirror to Near Absolute Zero

Posted by samzenpus on from the barely-moving dept.

An anonymous reader writes "Physicists have managed to cool a dime-sized mirror to within one degree of absolute zero. This is the lowest laser-induced freeze yet achieved with a visible object. Laser cooling involves firing pulses of light at a specific frequency that exactly matches an atom's motions."

16 of 202 comments (clear)

  1. Re:This is cool stuff and all... by sholden · · Score: 3, Informative

    You could try reading the first sentence of the article.

  2. I imagine that by pavon · · Score: 5, Informative

    the surface has to be highly reflective for this to work. If it absorbed the photons, then it's temperature would increase, and if it was transparent the photons wouldn't interact with the material very much, and thus would not be able to cool it.

  3. Confirms quantum theory by quokkapox · · Score: 4, Informative

    It confirms our understanding of light and matter and how they interact. You would think that shining light (energy) on something would warm it up. If it cools it down, something strange is going on.

    In a broader sense, it means that we can manipulate matter and energy in ways nobody imagined 100 years ago (well, except for Einstein).

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    1. Re:Confirms quantum theory by NightHwk1 · · Score: 4, Informative

      It seems like it's the same effect as noise cancellation... firing pulses at the exact opposite frequency of the atom.

      And about the mirror versus using an actual dime or something else--a perfectly smooth, very thin object probably makes atomic-level laser targeting much easier than a relatively rough object such as a coin.

    2. Re:Confirms quantum theory by tomatensaft · · Score: 4, Informative

      There is no such thing as opposite frequency. There is a thing like counterphase, though. So, noise cancellation works by emitting noise of the same frequency, but in a counterphase.

    3. Re:Confirms quantum theory by growse · · Score: 3, Informative

      You are correct, and I believe GP is wrong to assume that matter at absolute zero has no energy. It actually has whatever the zero-point energy is (for it's particles), which all quantum physics and wikipedia-browsers will know is the expectation value of the Hamiltonian :)

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    4. Re:Confirms quantum theory by Hektor_Troy · · Score: 2, Informative

      Nah, you can cool it to absolute zero, you'd just never be able to find it ;)

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    5. Re:Confirms quantum theory by aeonturnip · · Score: 2, Informative

      I've had optical damping explained to me in a classical sense - rather than wave interactions causing maximum destruction, think of an excited atom being like a child on a swing, and rather than pushing them every time they start to move away from your to get their swing higher and higher, to push them every time they approach you to get them to swing lower and lower.

      As you say, though, whichever analogy you use, it's not possible to remove all the energy in the system due to Heisenbergs Uncertainty principle and the effect of zero-point energy: absolute zero is a theoretical minimum temperature, not one that can be practically achieved for any length of time or for any object with mass.

  4. I thought this was a breakthrough by Barkmullz · · Score: 5, Informative

    IANAP, so I figured this was some sort of breakthrough. As it turns out:

    1. Others have gotten much, much closer to 0 K using atoms and laser cooling.
    2. Others have gotten much, much closer to 0 K using solid objects and different cooling methods.
    3. Their method has the potential of getting closer to 0 K.

    So, even if it is not a breakthrough it is still impressive.

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    1. Re:I thought this was a breakthrough by btgreat · · Score: 4, Informative

      Actually, this really is a breakthrough. According to the article, laser supercooling has been used in the past by researchers, but never on anything more than a few atoms. These researchers successfully lasercooled a mirror the size of a dime (which would probably be about .01 to .1 moles, on the order of 10^21 or 10^22 atoms, more than just "a few" (probably meaning on the order of 10^6 or so, but IANAP, so don't quote me there)).

    2. Re:I thought this was a breakthrough by imsabbel · · Score: 2, Informative

      What _you_ seem to know as laser cooling is esentially using a modified penning trap with 6 circular polarized lasers. There is no way to use such an assembly on any _visible object_ (thats why that sentence was used in the blurb). It needs the volume of entrapment to be translucent.

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  5. Re:This is cool stuff and all... by norton_I · · Score: 1, Informative

    Thermal motion of mirrors are a limiting factor in high precision experiments. This allows those fluctuations to be reduced, allowing cool physics.

  6. Re:So.... by zazelite · · Score: 2, Informative

    Well, it does say in the article that a major goal is the detection of so-called gravity waves. As far as I know, there's no irrefutable evidence that gravity doesn't propagate faster than lightspeed - that, in fact, it's speed might very well be unbounded. I can bet you that once we have a gravity wave emitter that the next step will be a coherent gravity wave emitter i.e. a gravitational laser.

  7. Website on laser cooling and trapping by XchristX · · Score: 2, Informative

    The JILA group at UC Boulder does lots of work on laser cooling and trapping (the Weimann/Ketterle/Cornell group got the 2001 Nobel Prize for generating BEC by laser cooling). They have a neat java applet demonstrating the effect

    http://www.colorado.edu/physics/2000/bec/lascool1. html

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  8. Laser Cooling by FreemanPatrickHenry · · Score: 2, Informative

    "Laser cooling involves firing pulses of light at a specific frequency that exactly matches an atom's motions."

    I may be wrong on this, as I'm just an undergrad physics major, but in my experience laser cooling involves detuning a laser slightly below some atomic transition frequency, and counterpropagating the same beam back. What happens is as a laser moves quickly in the direction of the beam, it observes the laser's frequency to be higher due to the Doppler shift, and suddenly this laser that was not resonating with the atoms comes into resonance, and the atom starts absorbing photons, which have momentum. This knocks the atom back such that it can't move quickly in the direction of the laser. Often this is done with six beams along three orthogonal axes so that you cool the atoms in all directions.

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  9. Re:Obligatory Star Trek Refference by Mifflesticks · · Score: 3, Informative

    You realize that star trek reference (the star trek enterprise episode title) is itself a reference to Corinthians in the new testament, right? And that it's not the only time star trek has referenced it... another translation comes out not as "in a mirror darkly" but "through a glass, darkly", for the same passage, which Picard says in Star Trek Nemesis.

    Plus many books have used the same reference too.... but now I'm rambling.