• hamsamrich@lemmy.world
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    6 hours ago

    “Quantum sensors can sense the tiniest of changes in the gravity or magnetic field and use a previously prepared map of these properties to determine their location. Since a quantum sensor does not need to receive or send a signal to an external device, it cannot be hacked or be spoofed by a fake incoming signal either. “ Very cool!

  • Zedstrian@sopuli.xyz
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    7 hours ago

    The team achieved 10 times better performance than GNSS systems, with a one nautical mile of positioning accuracy.

    Variation up to a full nautical mile doesn’t seem very accurate?

    • Hasnep@lemmy.ml
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      3 hours ago

      If I were in the middle of the ocean I couldn’t find my location within 100 nautical miles without GPS so I’m pretty impressed

    • Gsus4@mander.xyzOP
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      7 hours ago

      this article is better written:

      https://science.report/discover/quantum-gravimeter-demonstrates-gps-free-navigation-in-coral-sea-trial-86654/

      it maintained bounded position accuracy within 1 nautical mile over an 83-kilometer trajectory. This performance, achieved without access to satellite navigation, represents a more than tenfold improvement over standard navigation-grade inertial backup systems under similar conditions.

      • stylusmobilus@aussie.zone
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        30 minutes ago

        That’s better, thank you

        As a holder of a spatial degree I found it difficult to directly compare it favourably to GNSS. Even a simple binary code calculating a position with GNSS gives sub 10-20 metre accuracy, generally closer to 2 or 3.

      • SatanClaws@lemmy.world
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        3 hours ago

        Inertial navigation (INSS) and GNSS (Sat nav)is two completely different concepts. Too bad the article misses this. Perhaps AI hallucinations?

    • cmnybo@discuss.tchncs.de
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      6 hours ago

      That’s comparable to what a skilled navigator can do with a sextant and chronometer. That’s more than enough accuracy to cross the ocean and get close enough to the port that you can see it.

    • Deebster@infosec.pub
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      7 hours ago

      The only thing I can think is that they’re comparing with a single system (e.g. GPS or BeiDou), even though GNSS receivers will combine all four systems to get very high accuracy (a few metres).

      • Dimand@aussie.zone
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        3 hours ago

        They are comparing purely inertial navigation (I assume using the advanced nav boreas D90) and inertial nav combined with gravity map matching.

        It is more of a demonstration than a comparison. Pure inertial nav has no way to re zero from an external reference so the error only grows.

        Both of these systems are worse than any form of sat nav. But both of them keep working if the sat nav is jammed.

        https://doi.org/10.48550/arXiv.2608.25563

        • zqps@sh.itjust.works
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          5 hours ago

          GPS is actually far more accurate than that. There is deterministic jitter introduced to make civilian use cases precise to only a few meters, but military equipment has the algorithm to subtract that jitter and achieve precision measured in centimeters.

          Anyway, that statement is highly misleading. They were comparing to previous inertial navigation systems, not GPS navigation.

        • Deebster@infosec.pub
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          6 hours ago

          Is that true globally? I seem to remember that some ocean areas wouldn’t have as many satellites visible as e.g. polar orbits don’t visit all of the globe.

    • Gsus4@mander.xyzOP
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      7 hours ago

      Yeah, I agree that I didnt understand that bit. I also didn’t understand why you need a quantum sensor to follow a map of gravitational and magnetic anomalies for orientation.

      • Dimand@aussie.zone
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        3 hours ago

        You don’t. Any appropriately sensitive/accurate accelerometer or magnetometer is sufficient to do this.

        The quantum part is 90% hype used to and attract funding. There are some advantages to the cold atom based sensors Q-CTRL makes, along with issues that need to be worked on, but they are other sensing technologies that could beat it in the long run.

        • SmoothOperator@lemmy.world
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          1 hour ago

          You don’t. Any appropriately sensitive/accurate accelerometer or magnetometer is sufficient to do this.

          There are limits to sensitivity and accuracy that can only be overcome by quantum sensing though. So yes, you’re right, but that’s actually the point of the quantum part.

          • Dimand@aussie.zone
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            50 minutes ago

            This is a rather common misconception about sensitivity, it is only true under the constraint where you are unable to increase the amplitude of your measurement.

            You are always limited by shot noise (counting noise, quantisation noise, Poisson noise, whatever name you give it). And people love to say that you can only beat it by squeezing (increase noise in one quadrature to reduce it in another). But another option is to just increase N, turn up the laser power to have more photons or atoms in your sensor and watch your noise floor drop way faster than you will ever get using squeezing.

            Now the cold atom sensors are an interesting case. No one has managed to laser cool atoms faster than an overall rate of around 10^9 atoms per second. And we have been stuck there since the mid 2000s. As a result, the fundamental noise limit from shot noise hampers these cold atom accelerometers significantly in short term sensitivity, as they just don’t have enough N of atoms in free fall. In this case, you might look to squeeze to get a better signal, but that’s a lot of complexity for not much gain.

            There are only 2 examples I know of where squeezing has made a difference to a real world measurement. LIGO, can’t increase photons without thermally heating the mirrors too much, and confocal microscopes looking at biological samples, cant turn up the laser power without burning the tissue. In 99% of cases, just increase N to make a better sensor.

    • MalReynolds@slrpnk.net
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      4 hours ago

      Eh, boat or submarine drones can be as big as you want, and the device will only get smaller (and better).