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'Laser Tweezers' Used to Sort Atoms

Posted by ryuzaki0 on from the like-plucking-nosehairs-only-less-painful dept.

luckyguesser writes to tell us that Physicists at the University of Bonn are claiming to have knocked down one more quantum computing hurdle. Utilizing what they term "laser tweezers" they were able to sort and align seven atoms while capturing it on film. The plan is to construct a quantum gate using atoms imprinted with data.

5 of 92 comments (clear)

  1. quantum fuzzy logic by Quadraginta · · Score: 1, Interesting

    I'm damned if I can see how this is jumping an "important" hurdle along the way to a quantum computer. I don't think anyone is going to build a quantum computer with moving parts, i.e. with laser "conveyor belts" and "tweezers" that are constantly shuffling atoms around (and at a mere 0.5 sort operations per second at that).

    I'm guessing the hurdle jumped here has something to do with construction techniques. But...there are already many ways to get atoms perfectly lined up with each other. Using a crystal, or part of one, would be one rather obvious idea. Indeed, the impression that the article gives that it's somehow a triumph to get atoms "perfectly" lined up with each other is silly: atoms naturally line up "perfectly" with each other, especially metal atoms like the caesium in the article. It's quite hard to get metal atoms not to "perfectly" line up together, i.e. to make amorphous (glassy) metallic materials.

    Anyway, it's a nice little bit of single-atom manipulation, yes. One more trick you can do with laser cooling and tweezers, which may be interesting from the research perspective. But I don't see how it has anything very directly to do with quantum computing.

    1. Re:quantum fuzzy logic by The+Philosophers+Cat · · Score: 3, Interesting

      I think you might be getting a little confused. For Quantum Computing you need the atoms/qbits to be entangled with each other and then seperated and for them to remain that way. You can't achieve this in a crystal (well you might achieve entanglement, but it'll be hard to remove the entangled atom and make it interact with a completely different atom without destroying the existing entanglement).

      Its not about getting them "aligned perfectly", rather its about controlling the atoms without introducing noise to the system. This is why the laser approach has a significant advantage. Although I agree that a clock speed of 0.5Hz isn't particularly impressive! but they do say its not about clock speed but number of operations per second (do I hear someone from AMD shouting "hell yeah!"). And with QC's the number of equivalent FLOPS you can do for something like quick searching rises exponentially with the number of atoms you have!

    2. Re:quantum fuzzy logic by Quadraginta · · Score: 1, Interesting

      Nonsense. The obvious way to create, alter or remove entanglement would be altering the many-body wavefunction through some kind of interaction with photons. You can do that as fast as you can switch the field -- gigahertz at least. Moving the atoms is about as clumsy and screwball a method for changing a wavefunction as I can imagine. You might as well turn your car around by stopping it by the side of the road, dismantling it piece by piece, and rebuilding it facing the other direction. Pfui.

  2. How many of these to make a computer? by jmcwork · · Score: 2, Interesting

    I thought I remembered reading that these quantum level gates would need to be redundant to get stable state information - something on the order of 1k quantum gates per transister based gate. If this is true, how long would it take to produce a computer? Years? Not a knock against the results - just a question.

  3. Re:University of Chicago has been doing this... by Anonymous Coward · · Score: 1, Interesting

    What chicago is doing, is again not very different from what Hannover has been doing
    for 5 years with micro lens array. The point is that both these experiments have little
    to do with the Bonn experiment. What the Bonn guys do, is actualy sort the atoms out, so
    that the have exactly one atom in every well of the standing light wave they use as a
    conveyer belt. Chicago and Hannover have only limited control of how many atoms are in
    each micro trap. Furthermore, the whole conveyor belt is just the start. Now, the conveyor
    belt will be used to pull the atoms through a high finesse optical cavity to have entanglement
    of the atoms in different sites, through interaction with the light field in the optical cavity.