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Double-Slit Experiment in Time, Not Space

Posted by timothy on from the that-young-guy-did-a-bunch-of-stuff dept.

TheMatt writes "Thomas Young's double-slit experiment is a classic experiment that helped establish the wave-like nature of light. Since then, it has been done with atoms, buckyballs, and biomolecules. It has even been seen in a single molecule, and the single electron version was voted the most beautiful experiment by Physics World readers (covered previously on Slashdot). Now, PhysicsWeb is reporting that Gerhard Paulus and coworkers have conducted the double-slit experiment using a double-slit in time, not space. The "slit" was a crafted femtosecond pulse consisting of one-and-a-half cycles--say, two maxima and one minima--passed through an argon gas. Each maxima has a probability of ionizing an argon atom and producing an electron. The electrons were accelerated to a detector which observed an interference pattern since the detector had no idea which maximum produced the electron."

6 of 535 comments (clear)

  1. Hrm by TupperTrenine · · Score: 3, Interesting

    I know I'm probably going to be rated down for not being all-knowing, but could someone try to explain this in a bit more simplific terms? I know what the dual-slit experiment was, but I don't understand the purpose of this particular one.

  2. Speaking of time... by serutan · · Score: 3, Interesting

    Relativistic time dilation has been demonstrated by synchronizing atomic clocks and sending one of them into space for a while at high speed. The one sent into space slows down a tiny bit. As I interpret this, one of the clocks is slightly in the past relative to the other one.

    Suppose you did the same thing with two entangled particles. The particle sent into orbit be slightly in the past relative to the other one. So would they then be entangled across the dimension of time? Seems like this has big implications, though what they are is beyond me.

    1. Re:Speaking of time... by Quantum+Fizz · · Score: 3, Interesting
      The particle sent into orbit be slightly in the past relative to the other one. So would they then be entangled across the dimension of time?

      Firstly, you're not sending one particle in the past, it's that time just moves slower for that particle. You'd still have no way of sending information back in time to that person, everything would still be causal.

      Regarding the entangled particles, they would remain entangled, but now you have to resolve the problem of simultaneity. Ie, simultaneous events for me will be non-simultaneous for him, etc.

      Quantum Field Theory has merged Quantum Mechanics with Special Relativity for over 50 years now, so there might be some interesting differences that happen as opposed to the non-relativistic quantum mechanics. But there still shouldn't be any way to send information through time or faster than light, etc.

    2. Re:Speaking of time... by nurbman · · Score: 3, Interesting

      Too lazy to look it up but I seem to remember a thought experiment that someone cooked up where a photon is passed throug a gravitational lens a billion light years in the past. The problem was what if you were able to do a measurement now to collapse the wave? I seem to recall that someone prooved that this is the case: where the photon then appears to go back in time a billion years and choose which side of the lens to traverse. Anyone read about this?

  3. Interesting by Husgaard · · Score: 4, Interesting
    I am not a physicist, but a bit interested in stuff like this.

    Looks to be that they have redone the classic double-slit experiment in a new variation.

    Instead of having the two slits existing at the same time but in different 3d space, they made the slits in different time, but in same 3d space.

    Probably we have the same quantum effect as in the traditional double-slit experiment: When trying to determine which slit the particle passes through the interference pattern goes away, as the waves change change to particles.

    It doesn't look to me like they have seen that experimentally yet. Their setup that did not produce the interference pattern looks more like a single-slit to me.

    But I think that an attempt to find out at which of the two maxima are ionizing an argon atom should make the interference pattern go away.

  4. pi in the sky by Doc+Ruby · · Score: 3, Interesting

    I'd love to see a geometric illustration of how this demonstration is identical to Young's, rotated in spacetime.

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    make install -not war