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posted by martyb on Wednesday August 02 2017, @04:52AM   Printer-friendly
from the beating-Heisenberg dept.

Quantum mechanics comes with something called the uncertainty principle. This states that there are pairs of properties that cannot be simultaneously known to arbitrary precision. This is not due to the way a measurement changes the properties of what it measures. Instead, it is due to how quantum mechanics forces us to make measurements.

The uncertainty principle was once something that was discussed as, well, something that would only cause problems in principle. But since the 1980s, physicists have been making measurements that bump up against the uncertainty principle. These were once time-consuming and difficult measurements that only a few labs could do. Two decades later, and we are contemplating mass production of sensors that are going to be limited by the uncertainty principle.

Avoiding the uncertainty principle is now a cottage industry in physics. The way to go about it is to more carefully examine the sort of measurement you want to make. For instance, the position and momentum of an oscillator are bound by the uncertainty principle. But the relative position and momentum of two oscillators is not. By ensuring that your measurement device depends on that relative measurement, you can gain a substantial advantage, according to a group of international researchers who recently published in Nature.

Source: https://arstechnica.com/science/2017/08/negative-mass-swing-beats-the-uncertainty-principle/

Journal Reference: Christoffer B. Møller, et. al., Quantum back-action-evading measurement of motion in a negative mass reference frame, Nature 547, 191–195 (13 July 2017) doi:10.1038/nature22980


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  • (Score: 0) by Anonymous Coward on Wednesday August 02 2017, @05:06AM

    by Anonymous Coward on Wednesday August 02 2017, @05:06AM (#547850)

    Trek my Stars!

  • (Score: 2) by Grishnakh on Wednesday August 02 2017, @05:08AM (4 children)

    by Grishnakh (2831) on Wednesday August 02 2017, @05:08AM (#547851)

    Working around the Heisenberg Uncertainty Principle isn't that hard. All you need is a Heisenberg compensator [wikia.com].

    • (Score: 0) by Anonymous Coward on Wednesday August 02 2017, @06:00AM (3 children)

      by Anonymous Coward on Wednesday August 02 2017, @06:00AM (#547857)

      But it requires lots of cats as fuel.

      • (Score: 0) by Anonymous Coward on Wednesday August 02 2017, @06:06AM (2 children)

        by Anonymous Coward on Wednesday August 02 2017, @06:06AM (#547858)

        And the intermix ratio of live cats to dead cats needs to be calibrated precisely.

        • (Score: 2) by Grishnakh on Wednesday August 02 2017, @02:52PM (1 child)

          by Grishnakh (2831) on Wednesday August 02 2017, @02:52PM (#547942)

          This is a really dumb post. You don't use dead cats in a Heisenberg compensator, you use live cats and butter.

          • (Score: 0) by Anonymous Coward on Wednesday August 02 2017, @04:25PM

            by Anonymous Coward on Wednesday August 02 2017, @04:25PM (#547982)

            Pffft, look at this amateur. You totally forgot the toast, and I bet you would probably forget to secure it to the topside of the cat anyway. Don't fly on whatever ship this guy is engineer of!

  • (Score: 0) by Anonymous Coward on Wednesday August 02 2017, @09:24AM (6 children)

    by Anonymous Coward on Wednesday August 02 2017, @09:24AM (#547886)

    Mainstream coverage of physics gives an impression these people are claiming more and more nonsensical things. Using "relative position" rather than "absolute position" will improve you sensors, really? I am sure they did something that actually makes sense but either the researchers themselves described it in some hyped up way or the PR office/journalist just made things up. You are not helping science with this, please stop.

    • (Score: 0) by Anonymous Coward on Wednesday August 02 2017, @01:02PM (1 child)

      by Anonymous Coward on Wednesday August 02 2017, @01:02PM (#547924)

      God, I hate "Internet experts."

      • (Score: 0) by Anonymous Coward on Wednesday August 02 2017, @04:27PM

        by Anonymous Coward on Wednesday August 02 2017, @04:27PM (#547984)

        Heh I was about to hop in with something similar.

        Relative position to each other, not relative in some more abstract way. Internet experts often make simple errors in reading comprehension.

    • (Score: 2) by Grishnakh on Wednesday August 02 2017, @02:53PM

      by Grishnakh (2831) on Wednesday August 02 2017, @02:53PM (#547943)

      There should be a law that journalists or other non-scientists are not allowed to write articles about science without getting a panel of actual experts in the field to review and approve the article.

    • (Score: 0) by Anonymous Coward on Wednesday August 02 2017, @03:25PM

      by Anonymous Coward on Wednesday August 02 2017, @03:25PM (#547954)

      Read the abstract. They don't talk about subverting Heisenberg, but the "quantum limit" (which Uncertainty plays a role in—this is what Ars took as license to start making shit up.) See: https://en.wikipedia.org/wiki/Quantum_limit [wikipedia.org]

      For bonus points, the abstract explicitly mentions subverting difficulty involved in measurements causing changes in the system which really fucks up the Ars narrative.

      Seriously folks this is Ars, they're not a good source on anything.

    • (Score: 0) by Anonymous Coward on Wednesday August 02 2017, @04:32PM (1 child)

      by Anonymous Coward on Wednesday August 02 2017, @04:32PM (#547987)

      I would think you'd take more of an issue with "negative mass". But ok, you tell those PhDs how a software engineer really handles things!

      • (Score: 0) by Anonymous Coward on Wednesday August 02 2017, @06:49PM

        by Anonymous Coward on Wednesday August 02 2017, @06:49PM (#548050)

        There's nothing wrong with negative mass.

  • (Score: 2, Interesting) by infodragon on Wednesday August 02 2017, @12:00PM (4 children)

    by infodragon (3509) on Wednesday August 02 2017, @12:00PM (#547900)

    Back before GPS was "unlocked" it was incredibly inaccurate for civilian use. I was involved in a project that used 2 GPS systems, one was fixed at a very well-known location, and the other was on a model helicopter. Using high accuracy clocks and the well known position of the fixed GPS receiver we used the difference of the two GPS positions to calculate the position of the helicopter to accuracy better than GPS is now.

    I would assume* the principle is the same.

    *You know what they say about assume... It makes ass-u-me!

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    • (Score: 0) by Anonymous Coward on Wednesday August 02 2017, @12:07PM (3 children)

      by Anonymous Coward on Wednesday August 02 2017, @12:07PM (#547902)

      What was the error on the locked gps like? Would it just give back random numbers within a certain range (gaussian, uniformm, etc)?

      • (Score: 1) by infodragon on Wednesday August 02 2017, @12:31PM (2 children)

        by infodragon (3509) on Wednesday August 02 2017, @12:31PM (#547907)

        The error was very deterministic across all receivers but non-repeating so impossible to predict. We were able to get resolution to 1-2 cm with the system we were using...

        Read more...

        https://en.wikipedia.org/wiki/Differential_GPS [wikipedia.org]

        --
        Don't settle for shampoo, demand real poo!
        • (Score: 0) by Anonymous Coward on Wednesday August 02 2017, @12:38PM (1 child)

          by Anonymous Coward on Wednesday August 02 2017, @12:38PM (#547913)

          Thanks, I think this explains it well:

          Since the SA signal was changed slowly, the effect of its offset on positioning was relatively fixed – that is, if the offset was "100 meters to the east", that offset would be true over a relatively wide area. This suggested that broadcasting this offset to local GPS receivers could eliminate the effects of SA, resulting in measurements closer to GPS's theoretical performance, around 15 meters. Additionally, another major source of errors in a GPS fix is due to transmission delays in the ionosphere, which could also be measured and corrected for in the broadcast. This offered an improvement to about 5 meters accuracy, more than enough for most civilian needs.

          I'm not sure how much that type of error would track to the uncertainty principle, but suspect not much.

          • (Score: 1) by infodragon on Wednesday August 02 2017, @02:06PM

            by infodragon (3509) on Wednesday August 02 2017, @02:06PM (#547933)

            The analogy is using a separate measurement and measuring the differential gave us a very precise signal, enough to map a simulated toxic waste field identifying barrels with extreme precision.

            Having a reference signal/point/measurement in quantum mechanics may be able to give a differential that reduces or eliminates the uncertainty.

            --
            Don't settle for shampoo, demand real poo!
  • (Score: 0) by Anonymous Coward on Wednesday August 02 2017, @04:08PM (1 child)

    by Anonymous Coward on Wednesday August 02 2017, @04:08PM (#547973)

    Quantum back-action-evading measurement of motion in a negative mass reference frame,

    Can someone explain the title please?

    • (Score: 0) by Anonymous Coward on Wednesday August 02 2017, @04:43PM

      by Anonymous Coward on Wednesday August 02 2017, @04:43PM (#547992)

      Ah, the journal title is what you are referring to. Ok:

      Back action is the energy change that happens when we measure something on the quantum level. The energy involved in the measurement physically alters the system being measured. Using a negative mass reference frame with two detectors allows them to cancel out the back action measurement, kind of like astro photography where you take a picture of an empty section of sky so you can subtract out the camera's internal noise from your actual picture.

  • (Score: 2) by aristarchus on Wednesday August 02 2017, @06:24PM

    by aristarchus (2645) on Wednesday August 02 2017, @06:24PM (#548036) Journal

    This is not due to the way a measurement changes the properties of what it measures. Instead, it is due to how quantum mechanics forces us to make measurements.

    In other words, there is no uncertainty principle, based on the theoretical presuppositions of the phenomenal paradigm we are unconsciously employing, it is instead just the way (quantum) reality is! I just love the smell of scientific realists in the morning! it smells like, I don't know, marzipan?

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