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London Underground Hosts Tests For 'Quantum Compass' That Could Replace GPS (theguardian.com) 65

Posted by BeauHD from the out-with-the-old-in-with-the-new dept.
An anonymous reader quotes a report from The Guardian: Dr Joseph Cotter takes some unusual pieces of luggage on his trips on the London underground. They include a stainless steel vacuum chamber, a few billion atoms of rubidium and an array of lasers that are used to cool his equipment to a temperature just above absolute zero. While not the average kit you would expect to find being dragged into carriages on the District Line, this is the gear that Cotter -- who works at Imperial College London's Centre for Cold Matter -- uses on his underground travels. Though the baggage may be bizarre, it has an ambitious purpose. It is being used to develop a quantum compass -- an instrument that will exploit the behavior of subatomic matter in order to develop devices that can accurately pinpoint their locations no matter where they are placed, paving the way for the creation of a new generation of underground and underwater sensors. The ideal place to test it is the London underground, Cotter and his team have discovered. "We are developing very precise new sensors using quantum mechanics, and these are showing great promise in the laboratory," he told the Observer last week. "However, they are less accurate in real-life settings. That is why we are taking our equipment to the London underground. It's the perfect place for smoothing out the rough edges and getting our equipment to work in real life." [...]

At the heart of the quantum compass -- which could be ready for widespread use in a few years -- is a device known as an accelerometer that can measure how an object's velocity changes over time. This information, combined with the starting point of that object, allows its future positions to be calculated. Mobile phones and laptops possess accelerometers but these versions cannot maintain their accuracy over lengthy periods. However, quantum mechanics offers scientists a way to provide new precision and accuracy by measuring properties of supercool atoms. At extremely low temperatures, atoms behave in a "quantum" way. They act like matter and like waves. "When atoms are ultra-cold, we can use quantum mechanics to describe how they move, and this allows us to make accurate measurements that tell us how our device is changing its position," said Cotter. In the devices -- which have been carried on board London underground track-testing trains and not on commuter services -- rubidium is inserted into the vacuum chamber that lies at the machine's heart. Powerful lasers are then used to cool these atoms to a fraction of a degree above absolute zero (-273.15C). In these conditions, the wave properties of the rubidium atoms are affected by the acceleration of the vehicle that is carrying the equipment, and these minute changes can be measured accurately. The system has been found to work well in a stable laboratory but needs to be tested in more extreme conditions if it is to be turned into a transportable, standalone device that can be used in remote or complex locations, added Cotter.
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London Underground Hosts Tests For 'Quantum Compass' That Could Replace GPS More

London Underground Hosts Tests For 'Quantum Compass' That Could Replace GPS

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  • Pushing the bounds of impracticality, scientists create a super expensive version of fiber optic gyroscope. These small, light-weight gyroscopes have been in use for over 20 years.

    • They're working on nano-scale FOGs now; apparently some boffins have overcome the noise issue.

    • Re: (Score:2)

      by ceoyoyo ( 59147 )

      This is an accelerometer, not a gyroscope.

      Laser gyroscopes were a super expensive version of the good old spinning metal gyroscope when first proposed. They have their uses though.

    • sounds like a much more expensive version of an inertial guidance system to me

    • Pushing the bounds of dark magic and devilry, so called scientists aka wizards create a very expensive version of a sunstone called a gyroscope. These sunstones have been in in use for over 2000 years.

    • In a supercooled handheld device, which eventually breaks and supercools somebody's pants.

  • He'd better be careful that he doesn't open the gates to the netherworld & call forth daemons. He should definitely have a priest with him at all times who is thoroughly versed & well-equipped in such matters & can act quickly in case it happens.

    The last time that happened, we had to deal with dragons terrorising the land & kidnapping damsels.
  • Inertial guidance, but with hookers and blackjack.

    • Re: (Score:2)

      by rahmrh ( 939610 )

      It is important when you are really designing a better common Inertial guidance to use the word "Quantum" to make what you are doing seem like some new breakthrough rather than an incremental improvement/size reduction in an already existent Inertial guidance system.

      • Sprinkle in a little bit of A.I. for the kids and a pinch of blockchain for the old folks and you got your first and second round of funding.

      • It is important when you are really designing a better common Inertial guidance to use the word "Quantum" to make what you are doing seem like some new breakthrough rather than an incremental improvement/size reduction in an already existent Inertial guidance system.

        Hmm... I've heard different advice: :-)

        Morty: What's wrong Rick? Is it the quantum carburetor or something?

        Rick: "Quantum carburetor?" Jesus Morty, you can't just add a sci-fi word to a car word and hope it means something. Huh, looks like something's wrong with the micro-verse battery.

  • Nethack (Score:3)

    by Errol backfiring ( 1280012 ) on Tuesday June 18, 2024 @09:21AM (#64557715) Journal
    Finally you can meet a real quantum mechanic!

  • The description of what it takes to make the tracking unit makes it impossible to slip one on some or even their car, if they can even manage to field them in the real world in semi controlled conditions.

    Another use might be to pre-place a unit in a target building's basement during peacetime. Can jam gps but not this.

    Or put them in planes. No more "where the fuck did our plane crash?" questions.

    • Or put them in planes. No more "where the fuck did our plane crash?" questions.

      This technology at best will tell the pilots where plane is. It does not tell everybody else outside the plane where the plane where it is. There is already a solution for that; satellite uplink. However not every country/airline/plane is required to have satellite connections. Newer planes sometimes have the equipment but the airline does not want to pay for satellite fees.

      • If this is a bonded pair then shouldn't the other side of the connection from the plane know where's partner on the plane is relative to it's own position?

        • If this is a bonded pair then shouldn't the other side of the connection from the plane know where's partner on the plane is relative to it's own position?

          What bonded pair? The technology being described in the summary and article is an accelerometer that means how far something has traveled from a previously known location. This is not quantum entanglement. The only "quantum" part relates to using quantum properties of atoms.

  • So it's a form of inertial navigation, and all you'll need to make it practical is a very small refrigeration mechanism that will "cool these atoms to a fraction of a degree above absolute zero" and keep them like that for the duration. No prob!

    • I mean we this is why we gave up the search for high temperature superconductors, right? It wasn't a problem to just keep them really cold all the time, even for portable applications. Heck to get magnets for the LHC, they just went to the local Swiss Radio shack and picked them off the shelf, because Radio shack also still exists and carries super conducting magnets on their shelves suitable for particle colliders as well as kits for making your own super conducting crystal radio.

  • When they were digging out the Channel Tunnel, the English and French diggers managed to meet in the middle with an accuracy of about 2cm. Obviously they weren't using GPS for that. How does this compare to what they used?

  • This apparently calculates future positions based on movement direction and velocity changes from a known position, a process known as dead reckoning (https://en.wikipedia.org/wiki/Dead_reckoning). I see two problems with this:
    - You first need to have it at a known position, and give it that position;
    - Its calculation of changes in position and velocity must be perfectly accurate.
    The second one is the main problem. Unless it's perfectly accurate (unlikely?), it'll need recalibration often/occasionally, and

    • The second is what they are working on. This has the potential to be a more stable and accurate sensor of velocity than accelerometers or gyroscopes. Just a few technical issues to address, like keeping your rubidium close to absolute zero for a long time.

    • The second one is the main problem. Unless it's perfectly accurate (unlikely?), it'll need recalibration often/occasionally, and how do you do that?

      Are you trying to hint that the system might require GPS as a prerequisite, rather than replacing it? But that would make this the first ever Slashdot title that wasn't completely accurate! /shocked face

    • You first need to have it at a known position, and give it that position

      You start where there is GPS. This is why they talk about underground or underwater. Start above ground/water and then move.

      Its calculation of changes in position and velocity must be perfectly accurate.

      \ That's the whole point of the super cool lasers. Dead reckoning has been around for a long time. They want to make it much more accurate using quantum properties.

    • The more expensive the accelerometer, the more accurate presumably it would be. It could be combined with other systems like radio beacons, optical flow / cameras. Compass (consumer at least) seems to be not accurate enough to be useful, as is consumer grade accelerometers (maybe there's been recent advancement?). There's some information here on how an open source drone project deals with the non gps location problem https://ardupilot.org/copter/d... [ardupilot.org]

    • So, the missile knows where it is because it knows where it isn't?

  • The only reason to pitch this as a GPS replacement, which it clearly is not is to obtain MoD/DoD funding -- orgs that are very concerned about the usefulness of GPS in a modern war.
  • So not that cool for most of us. Cooling requires a lot of space/weight
    • Well, if you took out the camera... Bear in mind that you only need a tiny amount of the gas. I don't know that much about the specifics of laser cooling, but I imagine that diode lasers would do the job. It seems as though the bulkiest thing would be the insulation.

      Of course, if you look at the picture in the article the prototype that they're using is about twice the size of a person. I don't think it would fit in your pocket.

  • On the Underground sure, but ... (Score:4, Funny)

    by fahrbot-bot ( 874524 ) on Tuesday June 18, 2024 @11:25AM (#64557989)

    Dr Joseph Cotter takes some unusual pieces of luggage on his trips on the London underground. They include a stainless steel vacuum chamber, a few billion atoms of rubidium and an array of lasers ...

    Better not try that at the airport. The limit is only 1 billion atoms of rubidium and they have to be kept in a plastic bottle, in a quart-size zip-lock bag. Not sure how many lasers are allowed, or if they have to be in a linked-list rather than an array, but they definitely can't be pointed at the pilots.

    • Re: (Score:2)

      by Megane ( 129182 )

      but they definitely can't be pointed at the pilots.

      That's because pointers are unsafe. You need to use Rust instead!

  • the fun stuff happens at 88 MPH!

  • ./ = idiocracy (Score:5, Insightful)

    by timeOday ( 582209 ) on Tuesday June 18, 2024 @12:40PM (#64558229)
    This story is exactly what /. should be about, and yet all the responses in here are garbage. Super-accurate accelerometers are a critical foundational technology, just like super-accurate clocks. This implementation actually does use quantum mechanics, so it's only correct to mention that, and no reason to whine about it. The difficult engineering considerations of making this work outside the lab do currently limit its practicality; that's why they're working on it.

    This is a very neat and useful piece of science + technology.

    • Great for developing theories and science basics, but not so much for real world use.

      The inherent problem is that any error is compounded as you go/move. Even if it is just one error at all it will be magnified the further you are from that point of error.

      Current GPS has redundancy referencing multiple fixed points, yes it can be disrupted or spoofed but errors can be corrected.

      • Re: (Score:2)

        by Plugh ( 27537 )
        Yes, the question is how accurate the thing is. If it is say 5 or 6 orders of magnitude more precise than a phone accelerometer (and has a decently high time resolution) then it may well be that the accumulating errors do not functionally matter for many real world usecases. Especially ones where your autonomous drone needs to keep track of where it is despite it being nighttime and GPS being jammed.

      • Re: (Score:2)

        by ceoyoyo ( 59147 )

        Accelerometers are used all the time in "real world use." There are three in your phone, quite possibly another three in your laptop; most drones have at least three, and quadcopters almost require them; most aircraft have a set; piles of industrial equipment have them for monitoring vibration, and we have many thousands of them spread around the world to detect earthquakes and explore for oil and gas.

        The MEMs ones in your phone are kind of crappy because they're really small. The ones in aircraft can provi

      • This tech is exactly what you need to get your drones and missiles where they need to go when GPS is jammed. If they make it small and cheap enough, then you could also go spelunking while guided by inertial GPS on your cellphone.

    • Re: (Score:2)

      by AmiMoJo ( 196126 )

      Sadly I expect the first major deployment will be military use, to counter the now routine jamming of GNSS.

  • Immediate use: submarines (it's in TFA) (Score:3)

    by fabioalcor ( 1663783 ) on Tuesday June 18, 2024 @05:45PM (#64559209)

    No one's mentioning the obvious use for this: submarine guidance.
    See, under the deep blue sea there are no GPS signals. Submarines often need to get to the possibly risky and hostile surface just to get some needed coordinates, sometimes just to find such signals jammed, and a too cloudy night for celestial navigation. Current dead reckoning technologies (i.e. accelerometers), as per TFA, are not sensible enough to keep precision for too long.
    So this technology will be very welcome in such scenarios. No need to be miniaturized to fit in a smartphone, it can be used basically as is, even in airplanes.

    • Re: (Score:2)

      by mjwx ( 966435 )

      No one's mentioning the obvious use for this: submarine guidance.
      See, under the deep blue sea there are no GPS signals. Submarines often need to get to the possibly risky and hostile surface just to get some needed coordinates, sometimes just to find such signals jammed, and a too cloudy night for celestial navigation. Current dead reckoning technologies (i.e. accelerometers), as per TFA, are not sensible enough to keep precision for too long.
      So this technology will be very welcome in such scenarios. No need to be miniaturized to fit in a smartphone, it can be used basically as is, even in airplanes.

      How did subs navigate before GPS? Position, speed and heading (OK, probably a bit more complex than that). Whilst I'm a fan of technologies like GPS, we really shouldn't become overly reliant on them.

  • Didn't our boys in The Black Hole already invent this? For the USAF, no less?

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