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].
"The quantum accelerometer uses ultracold atoms to make highly accurate measurements. When cooled to extremely low temperatures the atoms start to display their ‘quantum’ nature, resulting in wave-like properties. As the atoms move through the sensor, an ‘optical ruler’ is formed by using a series of laser pulses. This allows the acceleration of the atoms to be precisely measured."
Edit: Seems like there's another company that's doing the same thing [4] with BSEs [5].
[1] https://physics.stackexchange.com/questions/570707/why-is-ru...
[2] https://en.wikipedia.org/wiki/TERCOM
[3] https://earthobservatory.nasa.gov/images/87189/seafloor-feat...
[4] https://www.youtube.com/watch?v=9ZiUfw6ftq4
[5] https://www.youtube.com/watch?v=X7Y7MikUS4M