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Stopping Light

Posted by Hemos on from the but-isn't-it-just-night? dept.

Jon Abbott writes "NASA is reporting that physicists at Harvard University have managed to stop light altogether. The implications of this discovery are rather staggering -- quantum encryption and quantum computers might be just around the corner! " Well, I don't think this will mean any immediate changes - but it is a significant step.

6 of 243 comments (clear)

  1. slow glass... by cowtamer · · Score: 2, Interesting

    There was an old sci-fi story about "slow glass" where people would let these light-storing windows in interesting places and then sell them.

    This really sounds like a cool way of storing holographic data (which means storing a LOT of information in a small space)

  2. p=mv by loydcc · · Score: 3, Interesting
    If the momentum of the particle nature of light is true then it's mass must be infinate if velocity is zero. But that doesn't say anything about it's wave nature. Since the light is stopped we know it's momentum. So we can't know it's position. Since the light is contained in an area we know it's approximate position but not it's certain position. Therefore the light is not actually stopped as position has some wiggle room. Which ipmlies a change in position over time.

    I just don't believe they stopped the light.

  3. It's not a throwaway line. by jcsehak · · Score: 3, Interesting


    He means that it won't mean any significant changes in how we build computers--that is, quantum comptuers are still a ways away. But it is a VERY significant step. If you read the article, they explain how they stopped a laser beam and turned it into information, stored in the up-and-down patterns of the vapor's atom's spin axes.

    I mean, you don't have to be a scientist to imagine the possibilities of a vaporous hard drive, with a huge capacity, that gets written to by a laser that changes the state of the atoms within. Drool...

    And the best part is no more annoying spinning noise!

    --

    c-hack.com |
  4. Re:Stopping light altogether? by Dances+with+Sheep · · Score: 3, Interesting

    My read is that it's just the information about the light that's stopping: wave amplitude and frequency. This information is imprinted on a non-moving medium (spin states of the atoms) and then released later when the atoms are excited: a wave released with the same properties of the incoming wave that was absorbed.

    I can't see what the technical reason is for saying dramatically that this information is "stored" and not "absorbed" - looks like it's just arguing about the spin [ :) ] of the story. I'm not a physics guy either and sometimes I think they try too hard to mystify and dramatize the terminology when it's moved from math to English (especially on "Isn't it a wonderful time to be alive"-NASA press releases).

  5. Re:They did NOT stop light! by MonkeyBot · · Score: 2, Interesting

    They stored the information AND the energy associated with light, didn't they? The medium absorbed the energy and the information associated with the photons in one side of the medium, then re-emited it out of the other side (albeit with stimulation), so how is that not stopping it?
    Either the photons stopped, or they are floating around in the imaginary universe you live in (just kidding).
    Just because you are storing it in a different form doesn't mean you aren't stopping it. Yeah, they may not be the exact same photons, but since photons are massless particles anyways, it's hard to define the Newtonian definition of "stopping" and "going."

  6. Light wasn't stopped. Misleading headline. by Anonymous Coward · · Score: 2, Interesting

    Slashdot and articles in general on the net are so misleading when it comes to anything related to physics. Where do you people come from? Leave the physics to physicist. Anyway, they didn't "stop" light. This is nothing more than a simple setup (in theory) that's based on what any grad physics student must do (time dependant pertubation theory). The light perturbs the spin 1/2 states of the Rb with off diagonal matrix elements that mix states. The polarization of the light with respect to the Rb is also very important. The physics going on here is what you could call Rabi flops. It's a simple time dependant pertubation theory problem that is exactly solvable and can be reduced to two by two subspaces. As far as the physics goes, they've done nothing all that new or exciting. The only advances they've made are perhaps technical advances in setting things up.