If this was developed in the US this would immediately be ITAR restricted
London Underground hosts tests for 'quantum compass' that could replace GPS
71–80 of 146 posts
Re: London Underground hosts tests for 'quantum compass' that could replace GPS
#72Earlier quoted context omitted.
>>> It will never replace GNSS. It will have to. That is the point. This isn't about better in-car navigation. The big money behind quantum gyroscopes is the potential to guide submarines/aircraft/missiles in times of war when the GNSS systems are down or otherwise unreliable, just like the best of traditional gyroscopes. Dead reckoning is a legitimate means of navigation, but there are also some aspects where actual…
That's an extremely niche application unlikely to be scaled down to anything smaller than a backpack like laser ring gyros. As such, this type of positioning gear isn't for consumer use and is targeted mostly for underground surveying. (I worked for Trimble.)
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Re: London Underground hosts tests for 'quantum compass' that could replace GPS
#73Journalists get it wrong, again. Sigh. It will never replace GNSS. It's quantum inertial navigation (QIN) that double-integrates acceleration like another method, requiring external position, heading, and velocity (re)calibration and drifts without them. It has absolutely no idea where it is from only itself.
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Re: London Underground hosts tests for 'quantum compass' that could replace GPS
#74I remember doing laser cooling of rubidium atoms in physics class. It's really cool how it works: * Rubidium will absorb photons of a certain wavelength and re-emit it in a random direction. Since photons have momentum, it will get some net momentum change from absorbing photons all coming from a particular direction, but the re-emissions are in random directions so they have net zero momentum. * Shine laser light at…
Maybe I'm missing something but hitting a gas just above absolute zero with lasers from every direction doesn't sound as something that could be miniaturised.
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Re: London Underground hosts tests for 'quantum compass' that could replace GPS
#75Earlier quoted context omitted.
Actually, in a train context, inertial is pretty damn high accuracy because you already have the world's best odometer showing (A) how many times your known size wheel has turned on your known track; and (B) you can test many axels simultaneously to ensure no slippage (I guess you wouldn't test the wheels as they move faster creating a higher frequency sampling requirement for ~no benefit whereas a dedicated axel fea…
Re odometer - don't the wheels of a train slide a little bit? I know the train is big pile of heavy iron, but still. My naive thinking is that when braking or during a rush start some extra distance can be covered. Don't know, just thinking out loud.
Not only do they slide, the "known size" changes not only due to wear but also due to variations in the gauge from metre to metre along the track.
Re: London Underground hosts tests for 'quantum compass' that could replace GPS
#76Earlier quoted context omitted.
Maybe I'm missing something but hitting a gas just above absolute zero with lasers from every direction doesn't sound as something that could be miniaturised.
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You don't need to copy/paste the exact same comment three times in one topic. We read it the first time.
Re: London Underground hosts tests for 'quantum compass' that could replace GPS
#77Re: London Underground hosts tests for 'quantum compass' that could replace GPS
#78It's a shame all the cool stuff is all hidden in a white box, but I suppose it does look a bit like a Hollywood depiction of a homemade nuclear bomb so the British Transport Police would be getting a few panicked calls if it were in a perspex box.
There's also no step-free access at South Kensington or Gloucester Road, so that must be a fun struggle for a grad student!
Re: London Underground hosts tests for 'quantum compass' that could replace GPS
#79Earlier quoted context omitted.
Not to mention wireless networks like the ones for the airtag or the wifi endpoints mapping google has could be adapted to share positions of "right here, right now" anonymously. Which means that if only one device knows where it is, you can calibrate, and if several know, you can even correct for mistakes. If the system is precise enough, you only need to calibrate once in a while. Being at home/office, on the local…
Yes, but these are approximate. I mean the exact position, down to a millimeter, when e.g. a photo sensor on a train passes past a LED mounted below the station platform. The LED's light is modulated so there can be no mistake, and its location is precisely known.
A meter precision is fine for what most people use GPS for. If the device is as precise as they say, you won't add much imprecision to the original calibration, so you will be in the right tunnel at the right time.
Re: London Underground hosts tests for 'quantum compass' that could replace GPS
#80Earlier quoted context omitted.
Maybe I'm missing something but hitting a gas just above absolute zero with lasers from every direction doesn't sound as something that could be miniaturised.
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The “nuke Moscow” case doesn’t require GPS. You’ll get plenty sufficient precision from inertial systems.