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Royal Navy says quantum navigation test a success

thequantuminsider.com

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Re: Royal Navy says quantum navigation test a success

#161

Post by fho »

hwillis wrote: post #149
fho wrote: post #143

Earlier quoted context omitted.

May I ask: how sensitive? Sensitive enough to, say, detect the movement of something moving at a known frequency on the other side of the planet? Are we on the edge of gravitation based communication channels?

Local surface gravity varies by up to a ten-thousandth, about .001 m/s: https://en.wikipedia.org/wiki/Gal_(unit) Sensitive detectors can measure differences in hundreds of millionths (10^-8 parts) or around .1 um/s^2. A 1 million tonne mass on the other side of the earth will create a TOTAL acceleration of 4*10^-16. Changes in that will not be detectable.

Ah yes ... That's some orders of magnitude too much :-)

Re: Royal Navy says quantum navigation test a success

#162

Post by [deleted] »

awesometech wrote: post #153
jchallis wrote: post #13

This is the most obvious practical application of my PhD topic. A Bose Einstein Condensate is an extremely sensitive detector of gravity- a nuclear submarine could use it to make an ultra-accurate map of the world based on variations in the gravitational constant g. This would remove one of the primary reasons subs need to surface , in order to GPS lock. It’s a naval chart that would not require surfacing. A French p…

Submarines do not have to surface to get a GPS lock. https://en.wikipedia.org/wiki/Submarine_navigation "On the surface or at periscope depth, submarines have used these methods to fix their position"...GPS being one of them. A submarine can also navigate by the stars without surfacing. https://www.usni.org/magazines/proceedings/2021/october/navi... "This is precisely the information required by the traditional metho…

[deleted]

Re: Royal Navy says quantum navigation test a success

#163

Post by fho »

white_dragon88 wrote: post #146
fho wrote: post #143

Earlier quoted context omitted.

May I ask: how sensitive? Sensitive enough to, say, detect the movement of something moving at a known frequency on the other side of the planet? Are we on the edge of gravitation based communication channels?

I would imagine that there is is an insane amount of gravitational noise from things like the planet’s asymmetry and events occurring all the way from the core to the crust, the ocean… to cut through that noise you need one big thumper.

Thing is, you don't have to cut through the noise these days. Low energy/low bandwidth radio communication routinely sends messages below the noise floor.

Depends on you application, but if you only send some bits of information ("stocks just crashed") having a big thumper with a very known impact profile is sufficient.

Re: Royal Navy says quantum navigation test a success

#164

Post by yodon »

wslh wrote: post #103

Hobby and business wise: is it difficult to build this thing? Someone could explain what a startup need to do something similar?

> Is it difficult to build this thing?

Yes.

> What would a startup need to make this work as a business?

Extensive contacts in the submarine navigation ecosystem and several decades of deep knowledge of highly complex, highly classified, related navigation systems that this product would need to interoperate with.

This tech is not a magic locator machine on its own, it's a component that improves one small but important part of a very large and complex locator system and locator ecosystem.

If the startup has that sort of contact list and experience, it's probably not a startup, it is most likely a division of one of a very small number of very large defense contractors.

(And for those who might argue it's not just for submarines, if the startup has the relevant contacts in the submarine navigation ecosystem, it probably also has the relevant contacts in the other equally classified navigation ecosystems like for cruise missiles and etc., and the technicals aspects of this particular part of the problem domain will probably be relevant across other platform types, even if the details of submarine vs cruise missile inertial navigation platforms are different.)

Re: Royal Navy says quantum navigation test a success

#165

Post by paulsutter »

jchallis wrote: post #13

This is the most obvious practical application of my PhD topic. A Bose Einstein Condensate is an extremely sensitive detector of gravity- a nuclear submarine could use it to make an ultra-accurate map of the world based on variations in the gravitational constant g. This would remove one of the primary reasons subs need to surface , in order to GPS lock. It’s a naval chart that would not require surfacing. A French p…

Does this detect gravity as distinct from acceleration?

Re: Royal Navy says quantum navigation test a success

#166

Post by digging »

paulsutter wrote: post #165
jchallis wrote: post #13

This is the most obvious practical application of my PhD topic. A Bose Einstein Condensate is an extremely sensitive detector of gravity- a nuclear submarine could use it to make an ultra-accurate map of the world based on variations in the gravitational constant g. This would remove one of the primary reasons subs need to surface , in order to GPS lock. It’s a naval chart that would not require surfacing. A French p…

Does this detect gravity as distinct from acceleration?

Gravity isn't distinct from acceleration though - how would it?

Re: Royal Navy says quantum navigation test a success

#167

Post by etrautmann »

tehlike wrote: post #49
etrautmann wrote: post #32

Earlier quoted context omitted.

With a highly detailed map, it becomes a statistical fitting problem, to locate yourself based on an estimate of position history using intertidal measurements and your time history of gravitational measurements, starting from an initial position estimate. I would imagine this could be quite accurate.

Pretty much a slam application.

exactly - presumably a subset of the full SLAM challenge if a detailed map already exists and you're just localizing within it

Re: Royal Navy says quantum navigation test a success

#168

Post by mertd »

aaron695 wrote: post #98
andromeduck wrote: post #31

Looks like what's happening is they've found a way to use BSEs [1] to measure small variations in the earth's gravity caused by undersea terrain, probably so that they can then use existing satelite measured data [2], to recover absolute position via Terrain Contour Matching [3] like a gulf war tomahawk missle. Edit: Seems like there's another company that's doing the same thing [4] with BSEs [5]. [1] https://physics…

> measure small variations in the earth's gravity This would be incorrect. It is just a very accurate, unproven in the field, accelerometer. https://www.youtube.com/watch?v=XwKKOPd-5cU - "Royal Navy's experimental ship carries out first trial of quantum navigation system" "The quantum accelerometer uses ultracold atoms to make highly accurate measurements. When cooled to extremely low temperatures the atoms start to…

Naive question: don't need a precise initial location to tell subsequent locations using an accelerometer? This doesn't fully obviate GPS then?

Re: Royal Navy says quantum navigation test a success

#169

Post by etrautmann »

etrautmann wrote: post #32
rogers18445 wrote: post #29

Earlier quoted context omitted.

What would you do with the g measurement to get your location? Can g deltas be matched to sea floor contour maps? Otherwise it seems like subs would have to be following g-mapped routes.

With a highly detailed map, it becomes a statistical fitting problem, to locate yourself based on an estimate of position history using intertidal measurements and your time history of gravitational measurements, starting from an initial position estimate. I would imagine this could be quite accurate.

Oops fat fingers - s/intertidal/inertial

Re: Royal Navy says quantum navigation test a success

#170

Post by failbuffer »

Rygian wrote: post #154
fho wrote: post #143

Earlier quoted context omitted.

May I ask: how sensitive? Sensitive enough to, say, detect the movement of something moving at a known frequency on the other side of the planet? Are we on the edge of gravitation based communication channels?

I would wonder how massive the thing on the other side of the planet has to be, in order to be detectable. The more mass necessary, the more energy you'll need to send messages. Unless the detection is extremely accurate, you would be better off spending that energy in electromagnetic radiation that bounces off the atmosphere.

For the most part yes, but for market arbitrage, the milliseconds saved by communicating thru the planet might be worth figuring out how to oscillate an extremely large weight very rapidly.
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