How to use an atomic clock...

I saw this TV program the other day about quantum mechanics. One segment talked about the atomic clock as an example of how quantum physics has changed the way we do things. I gather that all over the world, accurate time is set to the atomic clock in Boulder colorado.

Then the show went on to talk about a new version of the atomic clock that uses lasers and a different element, strontium 87, and is vastly more sensitive. "The new clock optimizes the previous techniques by using strontium 87 whose atoms tick at femtoseconds (1 million billion times per second)" (as put by https://www.worldatlas.com/articles/where-is-the-world-s-most-accurate-clock.html).

If you had two of these clocks at the same altitude, they would beat in sync. But if you raised one just the thickness of a human hair, thus distancing it that much from the core of the earth's gravity it will beat a little faster because the weaker the gravity, the faster time flows according to Einstein's theory of relativity. So this new clock is sensitive enough to measure that minute change.

I could imagine that in a decade or two air travel and submarines might use altimeters based on these clocks. My question then is what kinds of applications could be derived from such a sensitive device. Is there a host of applications already developed that would become more accurate? Can we imagine new applications?

I guess I'm just trolling for physicists you know, or any visionaries, or maybe even some carpenter's wives.