>Our result is enabled by improving the fractional frequency measurement uncertainty by more than a factor of 10, now reaching 7.6 × 10−21.

This is mindboggling. That timeframe is to one second roughly as a millisecond is to the estimated age of the universe.

Theoretically, could you use an 3D grid of these devices to continuously sample the gravitational potential they're experiencing, and build a dead-reckoning navigational system?

For measurements as accurate as this, if you sent out a fleet of these things to map the gravitational potential of the Earth by location, for example, you would find that the potential at a given location was changing all the time, so such a map wouldn't be useful for navigation.

It would also make stealth-proof gravitational radar equivalent. You would probably have to work on the acronym though.

> This is a preview of subscription content

Is there a readable version if this somewhere? Was it govt funded?

Thanks!