These quantum compasses are pretty cool, but they are not a GPS replacement. They are a more accurate version of an IMU to use for dead reckoning. They will still drift over time.
I'm guessing that once these are put in production, they will be about 1 order of magnitude better, which is still a significant improvement, but not a "quantum leap" so to speak.
Also, an electronic/physical device that "doesn't drift over time" is a device that hasn't been tested for long enough.
They say that the magnetic field detectors are intended to be used in conjunction with a detailed 3D map of Earth's magnetic field.
By identifying various kinks (anomalies) in the direction and magnitude of the magnetic field it is possible to identify exact points on the map.
Therefore there is no drift as long as you are not far away from the last identified point.
The only downside is that the magnetic maps need to be brought up-to-date from time to time, due to slow changes in Earth's magnetic field, and only few countries have the resources to keep such magnetic maps up-to-date.
Also .. the "coarse" map models (linked in comment) are good for five years, the enhanced models less so .. and there's those other factors.
It's also a wee bit trickier than you might think to (say) fly a route and identify your location only from DTM contour path directly under craft. (Subsitute mag vectors for DTM values)
It's more like old school missile plotting via DTM's where a preprogrammed "follow this" path is generated to facilitate optimal "when the value rises, turn here" instructions .. which are great "recipe navigation" commands .. until something goes wrong, it strays too far off course and has to recover.
Identifying any position via a "random" 50 line km slice is a much harder problem.
Is it a compass? It sounds to me like they are mapping these magnetic anomalies. If they have a map it should provide an absolute position, not a movement vector to integrate, so no accumulation of error. But they have to map the anomalies.
They are often called "quantum compasses" although they are complete inertial measurement units which have an accelerometer, magnetometer (a compass is a magnetometer), and a gyroscope.
The subtle parts of the magnetic field of the Earth shift a lot related to the movement of metal through the mantle. NOAA and the DoD periodically create new maps of the magnetic field, but they have a lot of error and noise.
From what I have read the magnetic mapping it not enough for a position. It needs additional information to limit the possible positions. So the technology could be fairly accurate on a train or car. On a ship or airplane with an imperfect current position and course assumption it may not be very accurate and even drift over time.
All magnetic compasses are magnetometers, but not all magnetometers are compasses. Some magnetometers output absolute magnetic field strength (scalar) while vector magnetometers output heading and strength of a field.
Order of magnitude is sufficient to remove reliance on GPS in a lot of military applications. The Russian aggression in Ukraine has shown that a lot of Western precision weapons were rendered ineffective due to GPS jamming.
no one seems to be claiming that it's a GPS replacement. the article specifically calls this out as a check on or a fallback for GPS and that getting accuracy to within 200m would be a huge success.
>They are a more accurate version of an IMU to use for dead reckoning. They will still drift over time.
A magnetometer is a completely different device than an IMU.
A sensitive enough magnetometer coupled with accurate magnetic maps can act as a GNSS alternative, albeit not as spatially accurate. There's a handful of companies currently working on quantum PNT and magnetic/gravity map matching solutions. I work for one of them.
Depending on how much more accurate they are than an IMU (mems or gyroscope based) - you might see them have a very real and significant effect in submarine navigation, especially for drones.
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I'm guessing that once these are put in production, they will be about 1 order of magnitude better, which is still a significant improvement, but not a "quantum leap" so to speak.
Also, an electronic/physical device that "doesn't drift over time" is a device that hasn't been tested for long enough.
By identifying various kinks (anomalies) in the direction and magnitude of the magnetic field it is possible to identify exact points on the map.
Therefore there is no drift as long as you are not far away from the last identified point.
The only downside is that the magnetic maps need to be brought up-to-date from time to time, due to slow changes in Earth's magnetic field, and only few countries have the resources to keep such magnetic maps up-to-date.
See https://news.ycombinator.com/item?id=41188347 and realise that the EMM "high res" map has a wavelength of 50+km .. compare that to, say, old school LORAN positioning accuracy.
Also .. the "coarse" map models (linked in comment) are good for five years, the enhanced models less so .. and there's those other factors.
It's also a wee bit trickier than you might think to (say) fly a route and identify your location only from DTM contour path directly under craft. (Subsitute mag vectors for DTM values)
It's more like old school missile plotting via DTM's where a preprogrammed "follow this" path is generated to facilitate optimal "when the value rises, turn here" instructions .. which are great "recipe navigation" commands .. until something goes wrong, it strays too far off course and has to recover.
Identifying any position via a "random" 50 line km slice is a much harder problem.
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The subtle parts of the magnetic field of the Earth shift a lot related to the movement of metal through the mantle. NOAA and the DoD periodically create new maps of the magnetic field, but they have a lot of error and noise.
I wonder how much those anomalies change over time and how updates would get rolled out without breaking that "unhackable" aspect of it
A magnetometer is a completely different device than an IMU.
A sensitive enough magnetometer coupled with accurate magnetic maps can act as a GNSS alternative, albeit not as spatially accurate. There's a handful of companies currently working on quantum PNT and magnetic/gravity map matching solutions. I work for one of them.
I just want to say that I love this phrase, it reflects my experience perfectly.
BTW couldn't they use Starlink and the few other LEO sat networks with thousands of nodes as some kind of augment to GPS (SBAS)
https://en.m.wikipedia.org/wiki/GNSS_augmentation