London Underground hosts tests for 'quantum compass' that could replace GPS

Post by soulofmischief » Mon, Jun 17, 2024, 6:59 PM UTC

lawlessone wrote: post #19

sandworm101 wrote: post #15

Earlier 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…

Fair point, this would fit quite snugly on a ship or a sub. the real ones will probably smaller. I wonder will having more than one improve accuracy.

Post by [deleted] » Mon, Jun 17, 2024, 7:14 PM UTC

ForHackernews wrote: post #17

hi-v-rocknroll wrote: post #14

Earlier quoted context omitted.

Because it can't. There are always cumulative errors in INS. There is no way around this without external references, but then it's no longer inertial navigation and it's inertial-assisted navigation. An underground navigation system based on triangulation of UWB cells would be a better solution than some nonstarter project the size of a refrigerator that requires liquid nitrogen.

> There are always cumulative errors in INS. Is that necessarily true of this quantum thing? I know nothing about it except this article, theoretically if it kept track of exact Plank lengths or something, then there would be no errors to accumulate, right? Lots of the things that seem intuitively true break down in weird ways when dealing with quantum effects.

Post by hi-v-rocknroll » Mon, Jun 17, 2024, 7:17 PM UTC

ForHackernews wrote: post #17

hi-v-rocknroll wrote: post #14

Earlier quoted context omitted.

Because it can't. There are always cumulative errors in INS. There is no way around this without external references, but then it's no longer inertial navigation and it's inertial-assisted navigation. An underground navigation system based on triangulation of UWB cells would be a better solution than some nonstarter project the size of a refrigerator that requires liquid nitrogen.

> There are always cumulative errors in INS. Is that necessarily true of this quantum thing? I know nothing about it except this article, theoretically if it kept track of exact Plank lengths or something, then there would be no errors to accumulate, right? Lots of the things that seem intuitively true break down in weird ways when dealing with quantum effects.

Post by aeyes » Mon, Jun 17, 2024, 7:19 PM UTC

surfingdino wrote: post #20

ben_w wrote: post #11

So far as I can tell, it's this accelerometer: https://www.imperial.ac.uk/news/188973/quantum-compass-could... (2018, I'm unclear what's changed since then?)

Russia launched a satellite capable of destroying GPS satellites and suddenly funding became available?

Post by tanseydavid » Mon, Jun 17, 2024, 7:30 PM UTC

porphyra wrote: post #9

I 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…