We’ve had other discussions of these sort of quantum compass ideas, see<p><a href="https://news.ycombinator.com/item?id=40692333">https://news.ycombinator.com/item?id=40692333</a><p>for example.<p>I can never quite wrap my head around it or figure out if they are all the same idea, or what, and what exactly the idea is.<p>In particular, the article soften describe something that “could replace GPS.” But then they start taking about compasses, and things that sound a lot like IMUs. Integrating accelerations is well known as a bad way of keeping track of position over longer timescales due to catastrophic cancellation. A more accurate IMU might let you do it for a little longer, but eventually you need an absolute reference point to correct your drift.<p>But then, sometimes there are references to making very careful measurements of the change in the gravitational field. So maybe those could act as landmarks or something?<p>I wish there was an article for people who, like, had <i>a</i> control theory or signal processing class, but it was too early in the morning and not very interesting.
I wonder if we are within a century of having pulsar detection on a chip.<p>Document enough millisecond pulsars and find your position anywhere in the galaxy.<p>When signal reception and computing power get powerful enough, put it on your wrist.
If Sandia is revealing this, they probably have a secret version that is already being loaded into cruise missiles and ICBMs. Seeing what’s happening over in Ukraine, it has to be clear to every military in the world that GPS is no longer of much practical use on its own.
So, remembering the exact location once, and then tracking all movement with almost absolute precision, thus calculating all future locations? Did I get it right?
The main application would obviously be missiles and autonomous military drones. If you can use GPS - you should. It's crazy cheap and it doesn't accumulate errors over time. But in a war GPS can be jammed. This can't.
Ships are big, if this were a real problem it would be easy to find space for a "lab sized" laser.<p>ICBM warheads are small. Space in drones and fighter jets is at a premium.<p>This is military.
An ultra sensitive motion sensor. Intriguing.<p>Could one derive the Earth's rotation? The motion of the solar system?<p>By watching vibrations could it be a microphone?
Another obvious idea: use mega-constellations.<p>GPS signals can't be signed because the signal bandwidth is limited, a digital signature is going to take hours to get transmitted.<p>But by using something like a Starlink satellite, it's possible to transmit digitally signed timing packets that can't be spoofed.